The authors wish to acknowledge the competitive faculty-initiated collaboration (FIC) grant from KAUST.

1. Preparation of Pr-doped SrTiO3 Powder
<ol>
	<li>In order to prepare 10 g of Sr0.95Pr0.05TiO3 powder, weigh the stoichiometric amounts of SrCO3 powder (7.53407 g), TiO2 nanopowder (4.28983 g), and Pr2O3 sintered lump (0.44299 g) following the reaction for x = 0.05:</li>
</ol>
<img alt="Equation 1" fo:content-width="5in" src="/files/ftp_upload/52869/52869eq1.JPG" width="550" />
<ol start="2">
	<li>Grind the weighed Pr2O3 sintered lumps to fine particles using an agate mortar and pestle.</li>
	<li>Add the weighed SrCO3 powder and TiO2 nanopowder to the Pr2O3 and continue grinding and mixing using an agate mortar and pestle until a visually homogenous powder is achieved.</li>
	<li>Load the ground powder into a glass jar and mix using a turbulator for 30 min to homogenize the mixture.</li>
	<li>Load the resulting mixed powder into a meticulously cleaned and polished stainless steel die (1 inch in diameter) and sandwich it between two stainless steel plungers.</li>
	<li>Cold press the powder using a press under an approximately 1 metric ton load.</li>
	<li>Eject the cold-pressed pellet by placing the die on a hollowed stainless steel cylinder and pushing the plungers and the pellet out from the top using a pushing rod. Upon ejection of the cold pressed pellet (green body) from the die, clean any contamination on the circumferential surface of the pellet by gently covering the pellet with a small piece of scotch-tape and removing a thin layer by ripping the tape.</li>
	<li>Place the pellet vertically in an alumina boat filled with commercially purchased SrTiO3 powder as the barrier between the alumina boat and the cold press pellet.</li>
	<li>Place the boat in a tube furnace, heat up to 1,300 &#176;C in 3 hr and keep it at this temperature for 15 hr. Allow the pellet to cool down to RT inside the furnace when the calcination is over. This step is referred to as the &#8220;calcination process&#8221; thereafter.</li>
	<li>Grind the pellet using the agate mortar and pestle and load the resulting powder into a glass jar for further mixing using the turbulator.</li>
	<li>Load the powder into the stainless steel die and cold pressed under an approximately 3 metric tons of load.</li>
	<li>Repeat the step 1.9 one more time at 1,400 &#176;C in 3 hr and keep it at this temperature for 20 hr.</li>
	<li>Grind the pellet using the agate mortar and pestle.</li>
	<li>Repeat steps 1.11, 1.12, and 1.13 one more time for the solid state reaction to reach completion.</li>
</ol>
2. Preparation of Bulk Polycrystalline Pr-doped SrTiO3 Ceramic
<ol>
	<li>Weigh 1.6 g of the as-prepared powder (for a disk 2 mm thick and 12.7 mm in diameter).</li>
	<li>Prepare circular graphoil pieces to cover the top and bottom interface of the sandwiched powder and graphite plungers in the graphite die. Also, prepare another rectangular graphoil piece to cover the inner wall of the graphite die.</li>
	<li>Load the as-prepared powder into a graphite die (12.7 mm in inner diameter) and sandwich the powder between two graphite plungers of the same size. Drill a 2-mm hole in the middle of the length of the graphite die and from the outer surface of the die to about 2 mm of the inner surface for temperature reading. 
	Note: Adjust the length of the graphite plungers remaining outside the die and position the center of the sandwiched powder cylinder where the hole is placed to get an accurate temperature reading. The faces of the graphite plungers need to be meticulously leveled during the machining of the pieces. Any misalignment can result in the cracking of the sintered pellet during spark plasma sintering.</li>
	<li>Cold-press the powder gently (load &#60; 200 kg) using a press prior to mounting on the spark plasma sintering plate inside the chamber. Use flat polished stainless steel support plates between the top and bottom plungers and the press stage to avoid damaging the graphite plungers.</li>
	<li>Wrap a piece of graphite felt around the die for insulation and secure it with graphite yarn. Devise a window on the graphite felt by cutting a rectangular piece of the felt where the temperature reading hole is placed on the die.</li>
	<li>Place the loaded graphite die and plungers in the spark plasma sintering chamber. Move the stage to the final position.</li>
	<li>Focus and align the Pyrometer target circle on the temperature reading hole of the die. Make sure the emissivity setting of the pyrometer is set for graphite.</li>
	<li>Close the chamber and put a 7.7 kN load (approximately 60 MPa) on the sample. Vacuum and purge the chamber with Ar three times and leave the chamber under dynamic vacuum of 6 Pa.</li>
	<li>Increase the temperature by increasing the current (manually or using a program). Use 250 A min-1 (corresponding to approximately 300-400 &#176;C min-1) for the optimized samples. This is the most important step of the spark plasma sintering process.</li>
	<li>Keep the temperature at 1,500 &#176;C for 5 min by manually adjusting the current or using the program. At the end of the 5 min holding period, shut the current off and quickly release the 7.7 kN load to avoid cracking the sample during the cooling down. Let the sample cool to RT inside the chamber.</li>
	<li>Release the bulk pellet from the graphite die gently using the cold press. This is done by placing the graphite die on a hollowed steel cylinder and ejecting the pellet and the graphite plungers using a steel pushing rod from the top.</li>
	<li>Remove the graphoil on top and bottom faces of the pellet as well as the circumferential surface using a sharp razor blade.</li>
	<li>Polish the sample using a rough sand paper (400 grid) down for 0.3-0.5 mm from each side to assure the complete removal of the graphoil. Clean the sample with acetone.</li>
</ol>
3. Characterization of Electronic and Thermal Transport Properties of Bulk Ceramics
<ol>
	<li>Determine the density of the ceramic disk, &#961;, using the Archimedes method.</li>
	<li>Measure the weight of the sample, Wdry, and then the weight of the sample submerged in water, Wwet, on a stabilized density measurement system and calculate the Archimedes density from</li>
</ol>
<img alt="Equation 2" fo:content-width="2.1in" src="/files/ftp_upload/52869/52869eq2.JPG" width="260" />
where &#961;water is the density of the water at the measurement temperature (e.g., equals 1 g cm-3 at 300 K).14
<ol start="2">
	<li>Measure the thermal diffusivity of the sample, d, using the transient laser-flash technique under a 75 ml min-1 flow of Ar. Measure the thickness of the sample, L, accurately first using a digital micrometer. 
	Note: Parallel-faced samples with different sizes and shapes (e.g., round discs 12.7 mm in diameter or square 10 x 10 mm2 disks) and thicknesses between 0.5 and 5 mm can be easily measured.
	<ol>
		<li>In the laser-flash thermal diffusivity technique, irradiate one face of the sample by a short (~1 msec) laser pulse and record the temperature rise on the opposite face by an infra-red detector. Then calculate thermal diffusivity by the laser-flash interface software from the thickness of the sample and the temperature rise-time profile using the Parker equation15</li>
	</ol>
	</li>
</ol>
<img alt="Equation 3" fo:content-width="1.9in" src="/files/ftp_upload/52869/52869eq3.JPG" width="220" />
where L is the thickness of the disk and t1/2 is the half-time of the maximum temperature rise of the other side of the sample.
Note: The Parker model15 assumes ideal conditions of adiabatic sample and instantaneous pulse heating, other models have been proposed over the years, which account for various losses in the measurement such as heat losses, finite pulse duration, non-uniform pulse heating and nonhomogeneous structures. We have used the Cowan model16 with pulse correction which is one of the most advanced methods. It should be noted that in order to maximize the amount of thermal energy transmitted from the front surface and to maximize the signal observed by the IR detector, the sample surfaces must be highly emissive. Usually this requires the application of a thin coating of graphite to the sample surfaces. An uncertainty of 2%-5% in the measurement of thermal diffusivity exists, arising from the determination of dimension.17
<ol start="3">
	<li>Cut the disk pellet using a diamond saw into rectangular bars, 2 x 2 x 10 mm3, electrical conductivity and Seebeck coefficient measurements as well as a square disk, 4 x 4 x 1.5 mm3 for high-temperature specific heat and a thin rectangular piece, 8 x 5 x 1 mm3 for Hall measurements.</li>
	<li>Measure the specific heat, Cp, of the sample on the flat and mirror-polished square piece (4 x 4 x 1.5 mm3) using a differential scanning calorimetry (DSC) under argon flow.18
	<ol>
		<li>Use a heating rate of 5 K min-1 up to 40 &#176;C for an isothermal hold for 10 min to allow the sample to reach thermal equilibrium followed by 20 K min-1 heating rate up to 500 &#176;C, with an exact cooling rate which followed. Perform the measurement under the flow of argon (50 ml min-1 is suggested).</li>
	</ol>
	</li>
</ol>
Note: Due to the sensitivity of the method used for analysis, conduct three measurements to determine the heat capacity including (1) a baseline measurement to subtract the background, (2) measurement of the specific heat of a standard material (such as sapphire) with a known CP, and (3) measurement of the specific heat of the sample. Ensure that samples are flat and mirror-polished in order to make an ideal contact with the bottom of the measurement crucible (Pt/Rh pans with Al2O3 crucibles used in this work). More details on the exact structure of the DSC stage, a comparison of the DSC techniques to others, and exact instructions for measuring a sample can be found in various sources.19
<ol start="5">
	<li>Calculate the high-temperature thermal conductivity, &#954;, of the sample from the measured values of thermal diffusivity, d, the specific heat, CP, and the density, &#961; using20</li>
</ol>
<img alt="Equation 4" fo:content-width="1.4in" src="/files/ftp_upload/52869/52869eq4.JPG" width="200" />
<ol start="6">
	<li>Gold plate the probes contact points (4 contacts) on the 2 x 2 x 10 mm3 piece cut from the sample to alleviate the contact resistance issues.
	<ol>
		<li>In order to sputter gold only on the desired contact areas, wrap a scotch-tape around the 2 x 2 x 10 mm3 sample to use as a stencil. Leave the 2 x 2 mm2 faces un-covered. Using a razor blade, cut out 2 very small holes (approximately 1 mm in diameter) in the middle of the 2 x 10 mm2 face along a line separated by the probes distance.</li>
		<li>Sputter a ~ 200 nm-thick gold film using a bench-top gold sputtering unit.21</li>
	</ol>
	</li>
	<li>Measure the electrical transport properties, namely the electrical conductivity and Seebeck coefficient) of the sample as a function of temperature22,23.
	<ol>
		<li>Measure electrical conductivity using the four-terminal method. Measure the Seebeck coefficient on the same setup using the measurements of temperature and voltage via the two middle thermocouple &#8220;probes&#8221;. Measure the distance between these two probes using a digital microscope. More details on the electrical transport measurements can be found elsewhere.22,23</li>
	</ol>
	</li>
	<li>Measure the Hall carrier concentration as a function of temperature on the 8 x 5 x 1 mm3 sample using a Physical Properties Measurement System.24</li>
</ol>

<ol>
	<li>Ohta, S., Nomura, T., Ohta, H., Koumoto, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-temperature+Carrier+Transport+and+Thermoelectric+Properties+of+Heavily+La-or+Nb-doped+SrTiO3+Single+Crystals.">High-temperature Carrier Transport and Thermoelectric Properties of Heavily La-or Nb-doped SrTiO3 Single Crystals.</a> J. Appl. Phys. 97, (2005).</li><li>Wang, H. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhancement+of+Thermoelectric+Figure+of+Merit+by+Doping+Dy+in+La0.1Sr0.9TiO3+Ceramic.">Enhancement of Thermoelectric Figure of Merit by Doping Dy in La0.1Sr0.9TiO3 Ceramic.</a> Mater. Res. Bull. 45, 809-812 (2010).</li><li>Bhattacharya, S., Mehdizadeh Dehkordi, A., Alshareef, H. N., Tritt, T. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis&#8211;Property+Relationship+in+Thermoelectric+Sr1&#8722;xYbxTiO3&#8722;&#948;+Ceramics.">Synthesis&#8211;Property Relationship in Thermoelectric Sr1&#8722;xYbxTiO3&#8722;&#948; Ceramics.</a> J. Phys. D: Appl. Phys. 47, 385302 (2014).</li><li>Wang, Y., Lee, K. H., Ohta, H., Koumoto, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermoelectric+Properties+of+Electron+Doped+SrO(SrTiO3)n+(n=1,2)+Ceramics.">Thermoelectric Properties of Electron Doped SrO(SrTiO3)n (n=1,2) Ceramics.</a> J. Appl. Phys. 105, 1037011-1037016 (2009).</li><li>Wang, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+YSZ+Additions+on+Thermoelectric+Properties+of+Nb-Doped+Strontium+Titanate.">Effects of YSZ Additions on Thermoelectric Properties of Nb-Doped Strontium Titanate.</a> J. Electron. Mater. 39, 1777-1781 (2010).</li><li>Muta, H., Kurosaki, K., Yamanaka, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermoelectric+Properties+of+Rare+Earth+Doped+SrTiO3.">Thermoelectric Properties of Rare Earth Doped SrTiO3.</a> J. Alloys Compd. 350, 292-295 (2003).</li><li>Shang, P. -. P., Zhang, B. -. P., Li, J. -. F., Ma, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+Sintering+Temperature+on+Thermoelectric+Properties+of+La-doped+SrTiO3+Ceramics+Prepared+by+Sol-gel+Process+and+Spark+Plasma+Sintering.">Effect of Sintering Temperature on Thermoelectric Properties of La-doped SrTiO3 Ceramics Prepared by Sol-gel Process and Spark Plasma Sintering.</a> Solid State Sciences. 12, 1341-1346 (2010).</li><li>Wang, Y., Fan, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sr1-xLaxTiO3+Nanoparticles:+Synthesis,+Characterization+and+Enhanced+Thermoelectric+Response.">Sr1-xLaxTiO3 Nanoparticles: Synthesis, Characterization and Enhanced Thermoelectric Response.</a> Scripta Materialia. 65, 190-193 (2011).</li><li>Kikuchi, A., Okinakab, N., Akiyama, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Large+Thermoelectric+Figure+of+Merit+of+La-doped+SrTiO3+Prepared+by+Combustion+Synthesis+with+Post-Spark+Plasma+Sintering.">A Large Thermoelectric Figure of Merit of La-doped SrTiO3 Prepared by Combustion Synthesis with Post-Spark Plasma Sintering.</a> Scripta Materialia. 63, 407-410 (2010).</li><li>Obara, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermoelectric+Properties+of+Y-Doped+Polycrystalline+SrTiO3.Jpn.">Thermoelectric Properties of Y-Doped Polycrystalline SrTiO3.Jpn.</a> J. Appl. Phys. 43, L540-L542 (2004).</li><li>Koumoto, K., Wang, Y., Zhang, R., Kosuga, A., Funahashi, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxide+Thermoelectric+Materials:+A+Nanostructuring+Approach.">Oxide Thermoelectric Materials: A Nanostructuring Approach.</a> Annu. Rev. Mater. Res. 40, 363-394 (2010).</li><li>Mehdizadeh Dehkordi, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large+Thermoelectric+Power+Factor+in+Pr-Doped+SrTiO3&#8722;&#948;+Ceramics+via+Grain-Boundary-Induced+Mobility+Enhancement.">Large Thermoelectric Power Factor in Pr-Doped SrTiO3&#8722;&#948; Ceramics via Grain-Boundary-Induced Mobility Enhancement.</a> Chem. Mater. 26, 2478-2485 (2014).</li><li>Mehdizadeh Dehkordi, A., Bhattacharya, S., He, J., Alshareef, H. N., Tritt, T. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Significant+Enhancement+in+Thermoelectric+Properties+of+Polycrystalline+Pr-doped+SrTiO3+Ceramics+Originating+from+Nonuniform+distribution+of+Pr+dopants.">Significant Enhancement in Thermoelectric Properties of Polycrystalline Pr-doped SrTiO3 Ceramics Originating from Nonuniform distribution of Pr dopants.</a> Appl. Phys. Lett. 104, 1939021-1939024 (2014).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Standard Test Methods for Density of Compacted or Sintered Powder Metallurgy (PM) Products Using Archimedes&#8217; Principle. , (2015).</li><li>Parker, W. J., Jenkins, R. J., Butler, C. P., Abbott, G. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flash+Method+of+Determining+Thermal+Diffusivity,+Heat+Capacity+and+Thermal+Conductivity.">Flash Method of Determining Thermal Diffusivity, Heat Capacity and Thermal Conductivity.</a> J. Appl. Phys. 32, 1679-1684 (1961).</li><li>Cowan, R. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pulse+Method+of+Measuring+Thermal+Diffusivity+at+High+Temperatures.">Pulse Method of Measuring Thermal Diffusivity at High Temperatures.</a> J. Appl. Phys. 34, 926-927 (1963).</li><li>Mehdizadeh-Dehkordi, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> An Experimental Investigation Towards Improvement of Thermoelectric Properties of Strontium Titanate Ceramics. , (2014).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> DSC Pegasus 404C Operating Manual. , (1999).</li><li>Daw, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+Specific+Heat+Capacity+Using+Differential+Scanning+Calorimeter.">Measurement of Specific Heat Capacity Using Differential Scanning Calorimeter.</a> Report of US Department of Energy. , (2008).</li><li>Tritt, T. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Thermal Conductivity: Theory, Properties and Applications. , (2004).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> SC7610 Sputter Coater Operating Manual. , (2002).</li><li>Tritt, T. M., Rowe, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrical+and+Thermal+Transport+Measurement+Techniques+for+Evaluation+of+the+figure-of-Merit+of+Bulk+Thermoelectric+Materials.">Electrical and Thermal Transport Measurement Techniques for Evaluation of the figure-of-Merit of Bulk Thermoelectric Materials.</a> Thermoelectrics Handbook: Macro to Nano. , 23-1-23-17 (2006).</li><li>Burkov, A. T., Rowe, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurements+of+Resistivity+and+Thermopower:+Principles+and+Practical+Realization.">Measurements of Resistivity and Thermopower: Principles and Practical Realization.</a> Thermoelectrics Handbook: Macro to Nano. , 22-1 (2006).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Physical Property Measurement System: AC Transport Option User&#8217;s Manual. , (2003).</li><li>Ohta, S., Ohta, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Grain+Size+Dependence+of+Thermoelectric+Performance+of+Nb-doped+SrTiO3.">Grain Size Dependence of Thermoelectric Performance of Nb-doped SrTiO3.</a> Polycrystals. J. Ceram. Soc. Jpn. 114, 102 (2006).</li><li>Wang, N., He, H., Ba, Y., Wan, C., Koumoto, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermoelectric+Properties+of+Nb-doped+SrTiO3+Ceramics+Enhanced+by+Potassium+Titanate+Nanowires+Addition.">Thermoelectric Properties of Nb-doped SrTiO3 Ceramics Enhanced by Potassium Titanate Nanowires Addition.</a> J. Ceram. Soc. Jpn. 118, 1098 (2010).</li><li>Ohta, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large+Thermoelectric+Performance+of+Heavily+Nb-doped+SrTiO3+Epitaxial+Film+at+High+Temperature.">Large Thermoelectric Performance of Heavily Nb-doped SrTiO3 Epitaxial Film at High Temperature.</a> Appl. Phys. Lett. 87, 092108 (2005).</li><li>Kovalevsky, A., Yaremchenko, A., Populoh, S., Weidenkaff, A., Frade, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhancement+of+Thermoelectric+Performance+in+Strontium+Titanate+by+Praseodymium+Substitution.">Enhancement of Thermoelectric Performance in Strontium Titanate by Praseodymium Substitution.</a> J. Appl. Phys. 113, 053704 (2013).</li><li>Kovalevsky, A. V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+a+High+Thermoelectric+Performance+in+Rare-Earth+Substituted+SrTiO3:+Effects+Provided+by+Strongly-Reducing+Sintering+Conditions.">Towards a High Thermoelectric Performance in Rare-Earth Substituted SrTiO3: Effects Provided by Strongly-Reducing Sintering Conditions.</a> Phys. Chem. 16, 26946 (2014).</li><li>Dawson, J. A., Tanaka, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Local+Structure+and+Energetics+of+Pr-+and+La-Doped+SrTiO3+Grain+Boundaries+and+the+Influence+on+Core–Shell+Structure+Formation.">Local Structure and Energetics of Pr- and La-Doped SrTiO3 Grain Boundaries and the Influence on Core–Shell Structure Formation.</a> J. Phys. Chem. C. 118, 25765-25778 (2014).</li><li>Mehdizadeh Dehkordi, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+Insights+on+the+Synthesis+and+Electronic+Transport+in+Bulk+Polycrystalline+Pr-doped+SrTiO3&#8722;&#948;.">New Insights on the Synthesis and Electronic Transport in Bulk Polycrystalline Pr-doped SrTiO3&#8722;&#948;.</a> Appl. Phys. Lett. 117, 055102 (2015).</li></ol>

The authors have nothing to disclose.

In this protocol, we have presented the steps of the synthesis strategy in order to successfully prepare bulk polycrystalline Pr-doped SrTiO3 ceramics exhibiting improved electronic and thermoelectric properties. The main steps of the protocol include (i) the solid-state synthesis of the doped SrTiO3 powder in air under atmospheric pressure and (ii) taking advantage of the capabilities of spark plasma sintering technique to densify the as-prepared powder into high-density bulk ceramics and at the sa...

Oxide thermoelectrics were shown to be promising candidates for high-temperature thermoelectric applications, from stability and cost perspectives to electronic transport properties. Among the n-type oxide thermoelectrics, highly doped strontium titanate (STO) has attracted much attention due to its intriguing electronic properties. However, a large total thermal conductivity (&#954; ~ 12 W m-1 K-1 at 300 K for single crystals)1 and a low carrier mobility (&#181; ~ 6 cm2 V-1 sec-1 at 300 K for single crystals)1 detrimentally affect the thermoelectric performance which is evaluated by a dimensionless figure of merit, ZT = &#945;2&#963;T/&#954;, where &#945; is the Seebeck coefficient, &#963; the electrical conductivity, T the absolute temperature in Kelvin, and &#954; the total thermal conductivity. We herein define the numerator as the power factor, PF = &#945;2&#963;T. In order for this oxide thermoelectric material to compete with other high-temperature thermoelectrics (such as SiGe alloys), a more pronounced increase in the power factor and/or decrease in lattice thermal conductivity are required.
The majority of the experimental studies in order to improve the thermoelectric properties of STO have mainly focused on the reduction of thermal conductivity through strain-field and mass fluctuation scattering of phonons. These attempts include: (i) Single- or double-doping of the Sr2+ and/or Ti4+ sites, as the main efforts with respect to this direction,2,3 (ii) Synthesis of natural superlattice Ruddlesden&#8211;Popper structures in order to further reduce the thermal conductivity through insulating SrO layers,4 and (iii) Composite engineering by addition of a nanosized second phase.5 However, up until recently, no enhancement strategy has been reported to substantially increase the thermoelectric power factor in these oxides. The reported maximum power factor (PF) values in bulk single- and poly-crystalline STO have been confined to an upper limit of PF &#60; 1.0 W m-1 K-1.
A variety of synthesis approaches and processing techniques have been employed to implement the ideas attempted above. The powder synthesis routes include conventional solid-state reaction,6 sol-gel,7 hydrothermal,8 and combustion synthesis,9 whereas conventional sintering,6 hot pressing10 and recently spark plasma sintering12 are among the common techniques used to densify the powders into bulk ceramics. However, for a similar dopant (e.g., La) and doping concentration, the resulting bulk ceramics exhibit a range of electronic and thermal transport properties. This is in large due to the strongly process-dependent defect chemistry of SrTiO3 which results in synthesis-dependent properties. There is only a handful of reports optimizing the synthesis and processing parameters to benefit thermoelectric transport. It is worth mentioning that due to the very small phonon mean free path in SrTiO3 (lph~2 nm at 300 K),11 nanostructuring is not a viable option for the improvement of the TE performance of bulk STO ceramics primarily through the reduction of the lattice thermal conductivity.
Recently, we reported more than 30% improvement in the thermoelectric figure of merit in non-uniformly Pr-doped SrTiO3 ceramics originating from a simultaneously enhanced thermoelectric power factor and reduced thermal conductivity.12,13 In this detailed video protocol, we present and discuss the steps of our synthesis strategy for the preparation of these Pr-doped STO ceramics exhibiting improved electronic and thermoelectric properties.

<table><tbody><tr><td>SrCO&lt;sub&gt;3&lt;/sub&gt; Powder, 99.9%</td><td>Sigma Aldrich</td><td>472018</td><td></td></tr><tr><td>TiO&lt;sub&gt;2&lt;/sub&gt; Nanopowder, 99.5%</td><td>Sigma Aldrich</td><td>718467</td><td></td></tr><tr><td>Pr&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Sintered Lumps, 99.9%</td><td>Alfa Aesar</td><td>35663&amp;nbsp;</td><td></td></tr><tr><td>Spark Plasma Sintering&amp;nbsp;</td><td>Dr. Sinter Lab</td><td>SPS-515S</td><td></td></tr><tr><td>Resistivity/Seebeck Coefficient Measurement System</td><td>Ulvac-Riko</td><td>ZEM-2</td><td></td></tr><tr><td>Laser Flash Thermal Diffusivity Measurement System</td><td>Netzsch</td><td>LFA-457 Microflash</td><td></td></tr><tr><td>Differential Scanning Calorimetry (DSC) System</td><td>Netzsch</td><td>404C Pegasus</td><td></td></tr><tr><td>Physical Property Measurement system (PPMS)</td><td>Quantum Design</td><td></td><td></td></tr><tr><td>Field Emission Scanning Electron Microscope (FE-SEM)</td><td>Hitachi</td><td>SU-6600</td><td></td></tr><tr><td>Energyy-dispersive X-ray Spectroscopy (EDS)</td><td>Oxford Instruments</td><td></td><td></td></tr><tr><td>X-ray Diffractometer</td><td>Rigaku</td><td>Ultima IV</td><td></td></tr><tr><td>Bench-top Sputter Coater</td><td>Denton Vacuum</td><td>Desk II</td><td></td></tr><tr><td>Diamond&amp;nbsp; Wheel Saw</td><td>South Bay Technology</td><td></td><td></td></tr></tbody></table>

synthesis of non-uniformly pr-doped srtio3 ceramics and their thermoelectric properties

We demonstrate a novel synthesis strategy for the preparation of Pr-doped SrTiO3 ceramics via a combination of solid state reaction and spark plasma sintering techniques. Polycrystalline ceramics possessing a unique morphology can be achieved by optimizing the process parameters, particularly spark plasma sintering heating rate. The phase and morphology of the synthesized ceramics were investigated in detail using X-ray diffraction, scanning electron microcopy and energy-dispersive X-ray spectroscopy. It was observed that the grains of these bulk Pr-doped SrTiO3 ceramics were enhanced with Pr-rich grain boundaries. Electronic and thermal transport properties were also investigated as a function of temperature and doping concentration. Such a microstructure was found to give rise to improved thermoelectric properties. Specifically, it resulted in a significant improvement in carrier mobility and the thermoelectric power factor. Simultaneously, it also led to a marked reduction in the thermal conductivity. As a result, a significant improvement (> 30%) in the thermoelectric figure of merit was achieved for the whole temperature range over all previously reported maximum values for SrTiO3-based ceramics. This synthesis demonstrates the steps for the preparation of bulk polycrystalline ceramics of non-uniformly Pr-doped SrTiO3.

X-ray diffractions patterns were collected for the as-prepared powders and the corresponding bulk ceramics as a function of Pr-content (Figure 1) in order to study the effect of Pr-doping on the SrTiO3 lattice, solubility of Pr in SrTiO3 and the formation of secondary phase(s). The patterns confirm the formation of SrTiO3 phase in all the as-prepared powders where the reflections can be indexed to a cubic lattice with space group (Figure 1A). The monotoni...

Watch this Scientific Journal Video about Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties at JoVE.com

Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties

A protocol for the synthesis and processing of polycrystalline SrTiO3 ceramics doped non-uniformly with Pr is presented along with the investigation of their thermoelectric properties.

Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties

We demonstrate a novel synthesis strategy for the preparation of Pr-doped SrTiO3 ceramics via a combination of solid state reaction and spark plasma ...

synthesis-non-uniformly-pr-doped-srtio3-ceramics-their-thermoelectric

Research

JoVE Journal

Chemistry

9.8K Views.  Clemson University. A protocol for the synthesis and processing of polycrystalline SrTiO3 ceramics doped non-uniformly with Pr is presented along with the investigation of their thermoelectric properties.

Video: Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties

Fabrication of Spatially Confined Complex Oxides

Complex materials such as high Tc superconductors, multiferroics, and colossal magnetoresistors have electronic and magnetic properties that arise from the inherent strong electron correlations that reside within them. These materials can also possess electronic phase separation in which regions of vastly different resistive and magnetic behavior can coexist within a single crystal alloy material. By reducing the scale of these materials to length scales at and below the inherent size of the electronic domains, novel behaviors can be exposed. Because of this and the fact that spin-charge-lattice-orbital order parameters each involve correlation lengths, spatially reducing these materials for transport measurements is a critical step in understanding the fundamental physics that drives complex behaviors. These materials also offer great potential to become the next generation of electronic devices 1-3. Thus, the fabrication of low dimensional nano- or micro-structures is extremely important to achieve new functionality. This involves multiple controllable processes from high quality thin film growth to accurate electronic property characterization. Here, we present fabrication protocols of high quality microstructures for complex oxide manganite devices. Detailed descriptions and required equipment of thin film growth, photo-lithography, and wire-bonding are presented.

We describe the use of pulsed laser deposition (PLD), photolithography and wire-bonding techniques to create micrometer scale complex oxides devices. The PLD is utilized to grow epitaxial thin films. Photolithography and wire-bonding techniques are introduced to create practical devices for measurement purposes.

Complex materials such as high Tc superconductors, multiferroics, and colossal magnetoresistors have electronic and magnetic properties that arise from ...

Engineering

Atomically Defined Templates for Epitaxial Growth of Complex Oxide Thin Films

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain such surfaces are described. The first approach is the preparation of single terminated perovskite SrTiO3 (001) and DyScO3 (110) substrates. Wet etching was used to selectively remove one of the two possible surface terminations, while an annealing step was used to increase the smoothness of the surface. The resulting single terminated surfaces allow for the heteroepitaxial growth of perovskite oxide thin films with high crystalline quality and well-defined interfaces between substrate and film. In the second approach, seed layers for epitaxial film growth on arbitrary substrates were created by Langmuir-Blodgett (LB) deposition of nanosheets. As model system Ca2Nb3O10- nanosheets were used, prepared by delamination of their layered parent compound HCa2Nb3O10. A key advantage of creating seed layers with nanosheets is that relatively expensive and size-limited single crystalline substrates can be replaced by virtually any substrate material.

Various procedures are outlined to prepare atomically defined templates for epitaxial growth of complex oxide thin films. Chemical treatments of single crystalline SrTiO3 (001) and DyScO3 (110) substrates were performed to obtain atomically smooth, single terminated surfaces. Ca2 Nb3 O10- nanosheets were used to create atomically defined templates on arbitrary substrates.

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain ...

Synthesis and Reaction Chemistry of Nanosize Monosodium Titanate

This paper describes the synthesis and peroxide-modification of nanosize monosodium titanate (nMST), along with an ion-exchange reaction to load the material with Au(III) ions. The synthesis method was derived from a sol-gel process used to produce micron-sized monosodium titanate (MST), with several key modifications, including altering reagent concentrations, omitting a particle seed step, and introducing a non-ionic surfactant to facilitate control of particle formation and growth. The resultant nMST material exhibits spherical-shaped particle morphology with a monodisperse distribution of particle diameters in the range from 100 to 150&#160;nm. The nMST material was found to have a Brunauer-Emmett-Teller (BET) surface area of 285 m2g-1, which is more than an order of magnitude higher than the micron-sized MST. The isoelectric point of the nMST measured 3.34 pH units, which is a pH unit lower than that measured for the micron-size MST. The nMST material was found to serve as an effective ion exchanger under weakly acidic conditions for the preparation of an Au(III)-exchange nanotitanate. In addition, the formation of the corresponding peroxotitanate was demonstrated by reaction of the nMST with hydrogen peroxide.

The surfactant mediated sol-gel synthesis of nanosized monosodium titanate is described, along with preparation of the corresponding peroxide modified material. An ion-exchange reaction with Au(III) is also presented.

This paper describes the synthesis and peroxide-modification of nanosize monosodium titanate (nMST), along with an ion-exchange reaction to load the ...

Epitaxial Growth of Perovskite Strontium Titanate on Germanium via Atomic Layer Deposition

Atomic layer deposition (ALD) is a commercially utilized deposition method for electronic materials. ALD growth of thin films offers thickness control and conformality by taking advantage of self-limiting reactions between vapor-phase precursors and the growing film. Perovskite oxides present potential for next-generation electronic materials, but to-date have mostly been deposited by physical methods. This work outlines a method for depositing SrTiO3 (STO) on germanium using ALD. Germanium has higher carrier mobilities than silicon and therefore offers an alternative semiconductor material with faster device operation. This method takes advantage of the instability of germanium's native oxide by using thermal deoxidation to clean and reconstruct the Ge (001) surface to the 2&#215;1 structure. 2-nm thick, amorphous STO is then deposited by ALD. The STO film is annealed under ultra-high vacuum and crystallizes on the reconstructed Ge surface. Reflection high-energy electron diffraction (RHEED) is used during this annealing step to monitor the STO crystallization. The thin, crystalline layer of STO acts as a template for subsequent growth of STO that is crystalline as-grown, as confirmed by RHEED. In situ X-ray photoelectron spectroscopy is used to verify film stoichiometry before and after the annealing step, as well as after subsequent STO growth. This procedure provides framework for additional perovskite oxides to be deposited on semiconductors via chemical methods in addition to the integration of more sophisticated heterostructures already achievable by physical methods.

This work details the procedures for the growth and characterization of crystalline SrTiO3 directly on germanium substrates by atomic layer deposition. The procedure illustrates the ability of an all-chemical growth method to integrate oxides monolithically onto semiconductors for metal-oxide semiconductor devices.

Atomic layer deposition (ALD) is a commercially utilized deposition method for electronic materials. ALD growth of thin films offers thickness control and ...

Spark Plasma Sintering Apparatus Used for the Formation of Strontium Titanate Bicrystals

A spark plasma sintering apparatus was used as a novel method for diffusion bonding of two single crystals of strontium titanate to form bicrystals with one twist grain boundary. This apparatus utilizes high uniaxial pressure and a pulsed direct current for rapid consolidation of material. Diffusion bonding of strontium titanate bicrystals without fracture, in a spark plasma sintering apparatus, is possible at high pressures due to the unusual temperature dependent plasticity behavior of strontium titanate. We demonstrate a method for the successful formation of bicrystals at accelerated time scales and lower temperatures in a spark plasma sintering apparatus compared to bicrystals formed by conventional diffusion bonding parameters. Bond quality was verified by scanning electron microscopy. A clean and atomically abrupt interface containing no secondary phases was observed using transmission electron microscopy techniques. Local changes in bonding across the boundary was characterized by simultaneous scanning transmission electron microscopy and spatially resolved electron energy-loss spectroscopy.

A viable technique for the formation of strontium titanate bicrystals at high pressure and fast heating rate via the spark plasma sintering apparatus is developed.

A spark plasma sintering apparatus was used as a novel method for diffusion bonding of two single crystals of strontium titanate to form bicrystals with ...

Growth and Electrostatic/chemical Properties of Metal/LaAlO3/SrTiO3 Heterostructures

The quasi 2D electron system (q2DES) that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) has attracted much attention from the oxide electronics community. One of its hallmark features is the existence of a critical LAO thickness of 4 unit-cells (uc) for interfacial conductivity to emerge. Although electrostatic mechanisms have been proposed in the past to describe the existence of this critical thickness, the importance of chemical defects has been recently accentuated. Here, we describe the growth of metal/LAO/STO heterostructures in an ultra-high vacuum (UHV) cluster system combining pulsed laser deposition (to grow the LAO), magnetron sputtering (to grow the metal) and X-ray photoelectron spectroscopy (XPS). We study step by step the formation and evolution of the q2DES and the chemical interactions that occur between the metal and the LAO/STO. Additionally, magnetotransport experiments elucidate on the transport and electronic properties of the q2DES. This systematic work not only demonstrates a way to study the electrostatic and chemical interplay between the q2DES and its environment, but also unlocks the possibility to couple multifunctional capping layers with the rich physics observed in two-dimensional electron systems, allowing the fabrication of new types of devices.

Growth and Electrostatic/chemical Properties of Metal/LaAlO3/SrTiO3 Heterostructures

We fabricate metal/LaAlO3/SrTiO3 heterostructures using a combination of pulsed laser deposition and in situ magnetron sputtering. Through magnetotransport and in situ X-ray photoelectron spectroscopy experiments, we investigate the interplay between electrostatic and chemical phenomena of the quasi two-dimensional electron gas formed in this system.

The quasi 2D electron system (q2DES) that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) has attracted much attention from the oxide ...

Chemical Synthesis of Porous Barium Titanate Thin Film and Thermal Stabilization of Ferroelectric Phase by Porosity-Induced Strain

Barium titanate (BaTiO3, hereafter BT) is an established ferroelectric material first discovered in the 1940s and still widely used because of its well-balanced ferroelectricity, piezoelectricity, and dielectric constant. In addition, BT does not contain any toxic elements. Therefore, it is considered to be an eco-friendly material, which has attracted considerable interest as a replacement for lead zirconate titanate (PZT). However, bulk BT loses its ferroelectricity at approximately 130 &#176;C, thus, it cannot be used at high temperatures. Because of the growing demand for high-temperature ferroelectric materials, it is important to enhance the thermal stability of ferroelectricity in BT. In previous studies, strain originating from the lattice mismatch at hetero-interfaces has been used. However, the sample preparation in this approach requires complicated and expensive physical processes, which are undesirable for practical applications.
In this study, we propose a chemical synthesis of a porous material as an alternative means of introducing strain. We synthesized a porous BT thin film using a surfactant-assisted sol-gel method, in which self-assembled amphipathic surfactant micelles were used as an organic template. Through a series of studies, we clarified that the introduction of pores had a similar effect on distorting the BT crystal lattice, to that of a hetero-interface, leading to the enhancement and stabilization of ferroelectricity. Owing to its simplicity and cost effectiveness, this fabrication process has considerable advantages over conventional methods.

Here, we present a protocol for the synthesis of porous barium titanate (BaTiO3) thin film by a surfactant-assisted sol-gel method, in which self-assembled amphipathic surfactant micelles are used as an organic template.

Barium titanate (BaTiO3, hereafter BT) is an established ferroelectric material first discovered in the 1940s and still widely used because of its ...

Bulk and Thin Film Synthesis of Compositionally Variant Entropy-stabilized Oxides

Here, we present a procedure for the synthesis of bulk and thin film multicomponent (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (Co variant) and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O (Cu variant) entropy-stabilized oxides. Phase pure and chemically homogeneous (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (x = 0.20, 0.27, 0.33) and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O (x = 0.11, 0.27) ceramic pellets are synthesized and used in the deposition of ultra-high quality, phase pure, single crystalline thin films of the target stoichiometry. A detailed methodology for the deposition of smooth, chemically homogeneous, entropy-stabilized oxide thin films by pulsed laser deposition on (001)-oriented MgO substrates is described. The phase and crystallinity of bulk and thin film materials are confirmed using X-ray diffraction. Composition and chemical homogeneity are confirmed by X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The surface topography of thin films is measured with scanning probe microscopy. The synthesis of high quality, single crystalline, entropy-stabilized oxide thin films enables the study of interface, size, strain, and disorder effects on the properties in this new class of highly disordered oxide materials.

The synthesis of high quality bulk and thin film (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O entropy-stabilized oxides is presented.

Here, we present a procedure for the synthesis of bulk and thin film multicomponent (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (Co variant) and ...

Tuning Oxide Properties by Oxygen Vacancy Control During Growth and Annealing

Electrical, optical, and magnetic properties of oxide materials can often be controlled by varying the oxygen content. Here we outline two approaches for varying the oxygen content and provide concrete examples for tuning the electrical properties of SrTiO3-based heterostructures. In the first approach, the oxygen content is controlled by varying the deposition parameters during a pulsed laser deposition. In the second approach, the oxygen content is tuned by subjecting the samples to annealing in oxygen at elevated temperatures after the film growth. The approaches can be used for a wide range of oxides and nonoxide materials where the properties are sensitive to a change in the oxidation state.
The approaches differ significantly from electrostatic gating, which is often used to change the electronic properties of confined electronic systems such as those observed in SrTiO3-based heterostructures. By controlling the oxygen vacancy concentration, we are able to control the carrier density over many orders of magnitude, even in nonconfined electronic systems. Moreover, properties can be controlled, which are not sensitive to the density of itinerant electrons.

Oxide materials show many exotic properties that can be controlled by tuning the oxygen content. Here, we demonstrate the tuning of oxygen content in oxides by varying the pulsed laser deposition parameters and by performing postannealing. As an example, electronic properties of SrTiO3-based heterostructures are tuned by growth modifications and annealing.

Electrical, optical, and magnetic properties of oxide materials can often be controlled by varying the oxygen content. Here we outline two approaches for ...

Deposition of Bi2Te3 and Sb2Te3 Thin Films on Glass Substrates via RF Sputtering

Fabrication of Bi2Te3 and Sb2Te3 Thermoelectric Thin Films using Radio Frequency Magnetron Sputtering Technique

Through various studies on thermoelectric (TE) materials, thin film configuration gives superior advantages over conventional bulk TEs, including adaptability to curved and flexible substrates. Several different thin film deposition methods have been explored, yet magnetron sputtering is still favorable due to its high deposition efficiency and scalability. Therefore, this study aims to fabricate a bismuth telluride (Bi2Te3) and antimony telluride (Sb2Te3) thin film via the radio frequency (RF) magnetron sputtering method. The thin films were deposited on soda lime glass substrates at ambient temperature. The substrates were first washed using water and soap, ultrasonically cleaned with methanol, acetone, ethanol, and deionized water for 10 min, dried with nitrogen gas and hot plate, and finally treated under UV ozone for 10 min to remove residues before the coating process. A sputter target of Bi2Te3 and Sb2Te3 with Argon gas was used, and pre-sputtering was done to clean the target&#39;s surface. Then, a few clean substrates were loaded into the sputtering chamber, and the chamber was vacuumed until the pressure reached 2 x 10-5 Torr. The thin films were deposited for 60 min with Argon flow of 4 sccm and RF power at 75 W and 30 W for Bi2Te3 and Sb2Te3, respectively. This method resulted in highly uniform n-type Bi2Te3 and p-type Sb2Te3 thin films.

Author Spotlight: Advancements in High-Performance Thermoelectric Thin Films Through Radio Frequency Magnetron Sputtering

The manuscript describes a protocol for radio frequency magnetron sputtering of Bi2Te3 and Sb2Te3 thermoelectric thin films on glass substrates, which represents a reliable deposition method that provides a wide range of applications with the potential for further development.

Synthesis of Non-uniformly Pr-doped SrTiO₃ Ceramics and Their Thermoelectric Properties

Summary

Explore More Videos

Chapters in this video