Name: Spark Plasma Sintering Apparatus Used for the Formation of Strontium Titanate Bicrystals (Video) | JoVE Journal
Uploaded: 2017-02-09T15:00:00.000+00:00
Duration: 11 min 17 s
Description: Learn to form strontium titanate bicrystals using Spark Plasma Sintering with controlled grain boundary misorientations. This method enables precise microstructure control for advanced ceramic materials research.

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5 minutes

LH gratefully acknowledges financial support by an US National Science Foundation Graduate Research Fellowship under Grant No. 1148897. Electron microscopy characterization and SPS processing at UC Davis was financially supported by a University of California Laboratory Fee award (#12-LR-238313). Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

1. Sample Preparation of Single Crystal Strontium Titanate
NOTE: Single crystal STO is supplied with a (100) surface polished to a mirror finish.
<ol>
	<li>Section STO into 5x5 mm2 pieces using diamond wire saw.</li>
	<li>Ultrasonically clean samples at 50-60 Hz consecutively in baths of acetone, isopropanol, and methanol for fifteen minutes each.</li>
	<li>Remove STO from methanol bath to immediately place on hot plate held at a temperature of 200 &#176;C. Heating the sample after cleaning prevents formation of evaporation spotting from the alcohol.</li>
	<li>Place samples for ten minutes in buffered hydrofluoric acid (pH=4), a 6:1 solution of ammonium fluoride and 49% hydrofluoric acid.22 This solution etches the STO, forming a predominantly (100) TiO2 terminated surface. If the optically flat side of the single crystal has a rainbow patina, the sample has been over-etched and should not be used.</li>
	<li>After ten minutes in the etchant solution, rinse samples in deionized (DI) water and then in isopropanol. Dry using clean house air.</li>
</ol>
2. Bicrystal Formation via Spark Plasma Sintering Apparatus
NOTE: For 5x5 mm2 crystal use a 30 mm diameter graphite die. If a die with a diameter smaller than 30 mm is used, the bicrystal catastrophically fractures during bonding. Optimal die size as well as pressure exerted by the SPS apparatus is highly dependent on the size of the crystals.
<ol>
	<li>Place a 30 mm circle of graphite paper on a graphite plunger with a 30 mm diameter. Graphite paper prevents STO from bonding to the graphite plunger during the experiment.</li>
	<li>Stack two 5x5 mm2 STO single crystals with their optically flat surfaces placed facing inward to form the bicrystal boundary. Center the stack on top of the graphite paper and plunger.</li>
	<li>Rotate the top single crystal around the &#60;100&#62; axis to a chosen misorientation angle. The &#60;100&#62; axis is perpendicular to the optically flat surface of crystal.</li>
	<li>Slide the graphite die over the plunger and crystals. Place a second 30 mm diameter circle of graphite paper and then 30 mm diameter plunger over the stacked STO crystals.</li>
	<li>Stack the combined plungers and die onto the graphite spacers in SPS apparatus (Figure 1).</li>
	<li>Apply a uniaxial force of 3 kN to minimize contact resistance using the z-axis control buttons. Throughout the experiment, the user must keep the force at 3 kN via the z-axis control buttons.</li>
	<li>Insert k-type thermocouple into graphite die at the small hole, shown in Figure 1. The thermocouple extends through the die to the sample.</li>
	<li>Set the chamber pressure of the SPS apparatus to ~10 Pa using the vacuum push buttons.</li>
	<li>Select bond temperature, time, and heating rates via program instrument control software (Table 1). For the bonding temperature and time, use a heating rate of 70-80 &#176;C/min and a cooling rate of 50 &#176;C/min.</li>
	<li>Set 12 s on, 2 s off DC pulse using the instrument sintering button. A pulsed bias of ~ 4 V and direct current of ~550 A are applied incrementally to the sample once the program is set to run.</li>
	<li>Press the start button on the machine.</li>
	<li>Remove the sample when the program ends. After bicrystal formation, the sample will appear grey-black due to the reducing environment of the SPS apparatus.</li>
	<li>Use a high temperature furnace at a temperature of 1,200 &#176;C for 140 h, apply no pressure during this procedure, to anneal and re-oxidize the sample in air. Annealing parameters were selected according to previous work done by Hutt et al. in which bicrystals formed in high vacuum13. After annealing, the sample reveals an off-white color and is oxidized.</li>
</ol>
3. Sample Preparation of Bicrystal for Electron Beam Imaging
<ol>
	<li>Cross-section bicrystal with diamond wire saw into 5x1 mm2 sections.</li>
	<li>Polish cross-section samples with diamond lapping film. The grit size on the diamond lapping film is gradually decreased from 9 &#181;m to 0.1 &#181;m. Change to smaller grit size once scratches are uniform across the surface. Use a counter clockwise platen motion for 9 &#181;m to 6 &#181;m lapping film. Use a counter clockwise platen motion with an oscillating sample head for 6 &#181;m to 0.1 &#181;m lapping film.</li>
	<li>Polish cross-section samples with colloidal silica for two minutes using a mat cloth. Continuously pour colloidal silica onto the mat with counter clockwise platen motion and oscillating sample head.</li>
	<li>Fifteen seconds before removing the sample, stop pouring colloidal silica and pour DI water onto platen. Pour DI water for fifteen seconds, remove sample, and immediately rinse sample in DI water for 1 min. If this procedure is not followed, the colloidal silica will bond the sample&#39;s surface and obscure the grain boundary during scanning electron microscopy (SEM).</li>
	<li>Once the sample is polished to an optically smooth surface, ultrasonically clean samples consecutively in baths of acetone, isopropanol, and methanol for fifteen minutes each.</li>
	<li>Remove STO from methanol bath to immediately place on hot plate held at a temperature of 200 &#176;C. Heating the sample after cleaning prevents formation of evaporation spotting from the alcohol.</li>
	<li>Mount sample polished surface up onto a sample stub using colloidal graphite.</li>
	<li>Sputter coat sample surface with 2-3 nm of carbon. Use the following parameters for the carbon coater: a pulse resolution of 0.2 nm/pulse, current step rate of 0.2 A/pulse, pulse current of 40 A, pulse length of 2 s, and maximum pulses of 50.</li>
</ol>
4. Cleaning the FIB Copper Grid
NOTE: Improper cleaning of the FIB grid can lead to carbon contamination of the lamella in the TEM.
<ol>
	<li>Place copper FIB grid in an acetone and then isopropanol bath for 1 h each.</li>
	<li>Plasma clean copper FIB grid for 10 min.</li>
</ol>
5. Preparation of Transmission Electron Microscopy (TEM) Lamella via Focused Ion Beam (FIB) Apparatus
NOTE: All parameters used in FIB preparation are typed or selected from a drop down menu in the FIB apparatus software.
<ol>
	<li>Place STO sample and copper FIB grid in FIB apparatus. The stage is at 7 mm.</li>
	<li>Find a region of interest along the interface between the two single crystals, i.e., the grain boundary.</li>
	<li>Select Patterning dialogue box. In Patterning Control, select the Rectangle Patterning Tool with application property C-e-dep surface. Insert C-dep for gas injection. Deposit a 15&#215;2&#215;2 &#181;m3 protective layer of carbon using the electron beam at a voltage of 5.0 kV, a current of 13.0 nA, and a tilt angle of 0&#176;. Retract C-dep.</li>
	<li>Select Patterning dialogue box. In Patterning Control, select the Rectangle Patterning Tool with application property W-dep. Insert W-dep for gas injection. Deposit 15&#215;2&#215;2 &#181;m3 protective layer of tungsten using the ion beam at a voltage of 30.0 kV, a current of 0.3 nA, and a tilt angle of 52&#176;. Retract W-dep.</li>
	<li>Select Patterning dialogue box. In Patterning Control, select the Regular Cross Section Patterning Tool with application property Si. Use 22&#215;25&#215;15 &#181;m3 for the bottom pattern and of 22&#215;27&#215;15 &#181;m3 for the top pattern at a voltage of 30.0 kV, a current of 30.0 nA, and a tilt angle of 52&#176; via the ion beam. The pattern will create a trench mill on both sides of the protective layer.</li>
	<li>Select Patterning dialogue box. In Patterning Control, select the Clean Cross Section Patterning Tool with application property Si. Use 22&#215;3&#215;60 &#181;m3 for the top and bottom pattern at a voltage of 30.0 kV and a current of 1.0 nA via the ion beam. The tilt angle is 53.5&#176; for the bottom pattern and 50.5&#176; for the top pattern. The pattern cleans the surface of the trenched lamella from the curtaining pattern that results from the regular cross section patterning.</li>
	<li>Cut a J-pattern into the sample using the Rectangle Patterning tool with application property Si. Use 2 &#181;m for the width at a voltage of 30.0 kV and a current of 1.0 nA via the ion beam.</li>
	<li>Select Easy Lift dialogue box. Insert the micromanipulator to the park position. Lower the micromanipulator and attach the sample to the copper FIB grid via a tungsten weld using the process detailed in 5.4.</li>
	<li>Using the steps detailed in 5.7, &#181;cut a U-pattern, continuing from the original J-pattern, in the sample using the ion beam at a voltage of 30.0 kV and a current of 1.0 nA.</li>
	<li>Lift the lamella via the micromanipulator above the bulk sample.</li>
	<li>Rotate the micromanipulator 180&#176;, so the grain boundary is no longer parallel to ion beam, but perpendicular to the ion beam.</li>
	<li>Tungsten weld the lamella to a copper FIB grid using the steps detailed in 5.4 with the ion beam at a voltage of 30.0 kV and a current of 0.3 nA.</li>
	<li>Cut the micromanipulator from the lamella using the steps detailed in 5.7 with the ion beam at a voltage of 30.0 kV and a current of 1.0 nA.</li>
	<li>Repeat the steps detailed in 5.3. Deposit a 15&#215;2&#215;4 &#181;m3 protective layer of carbon using an electron beam at a voltage of 5.0 kV, a current of 13.0 nA, and a tilt angle of 0&#176;.</li>
	<li>Repeat the steps detailed in 5.4. Deposit 15&#215;2&#215;8 &#181;m3 protective layer of tungsten using an ion beam at a voltage of 30.0 kV, a current of 0.3 nA, and a tilt angle of 52&#176;.</li>
	<li>With the ion beam, thin the sample to approximately 200 nm using a voltage of 30.0 kV and a systematically decreasing current of 0.5 nA, 0.3 nA, and 0.1 nA. At this stage, a cleaning cross section pattern is used and the sample is tilted to an angle of 52 &#177;&#177; 1.5&#176;.</li>
	<li>With the ion beam, thin the sample to electron transparency using a voltage of 5.0 kV and a current of 77.0 pA. At this stage, a rectangle pattern is used with a tilt angle of 52 &#177; 3&#176;.</li>
	<li>Remove amorphous damage incurred from the FIB by cleaning the sample at a voltage of 500 eV and a current of 150 &#181;A.</li>
	<li>Place TEM sample in TEM holder and insert holder in scanning transmission electron microscope (STEM). Select &#39;Capture&#39;, image sample grain boundary.</li>
</ol>

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We have nothing to disclose.

The bonding temperature of 1,200 &#176;C was chosen to maximize diffusion as small changes in temperature can greatly impact the kinetics of all diffusion bonding mechanisms. A temperature of 1,200 &#176;C is outside the brittle-ductile transition temperature range of STO. However, the sample underwent brittle fracture at this temperature. The catastrophic failure of the STO bicrystal was not unexpected as STO has ~ 0.5% ductility at 1,200 &#176;C. Also, the sample was held at a pressure of 140 MPa throughout the heating...

Spark plasma sintering (SPS) is a technique in which application of high uniaxial pressure and pulsed direct current leads to the rapid densification of powder compacts1. This technique also leads to the successful formation of composite structures from various materials, including silicon nitride/silicon carbide, zirconium boride/silicon carbide, or silicon carbide, with no additional sintering aids required2,3,4,5. The synthesis of these composite structures by conventional hot-pressing had been challenging in the past. While application of a high uniaxial pressure and fast heating rate via the SPS technique enhances consolidation of powders and composites, the phenomenon causing this enhanced densification debated in the literature2,3,6,7. There also exists only limited information regarding the influence of electric fields on grain boundary formation and the resulting atomic structures of grain boundary cores8,9. These core structures determine the functional properties of SPS sintered materials, including electric breakdown of high voltage capacitors and the mechanical strength and toughness of ceramic oxides10. Therefore, understanding the fundamental grain boundary structure as a function of SPS processing parameters, such as applied current, is necessary for the manipulation of a material&#39;s overall physical properties. One method to systematically elucidate the fundamental physical mechanisms underpinning SPS is the formation of specific grain boundary structures, i.e., bicrystals. A bicrystal is created by manipulation of two single crystals, which are then diffusion bonded with specific misorientation angles11. This method provides a controlled way to investigate the fundamental grain boundary core structures as a function of processing parameters, dopant concentration, and impurity segregation12,13,14.
Diffusion bonding is dependent on four parameters: temperature, time, pressure, and bonding atmosphere15. Conventional diffusion bonding of strontium titanate (SrTiO3, STO) bicrystals typically occurs at a pressure below 1 MPa, within a temperature range of 1,400-1,500 &#176;C, and time scales ranging from 3 to 20 hours13,14,16,17. In this study, bonding in a SPS apparatus is achieved at significantly lower temperature and time scales in comparison to conventional methods. For polycrystalline materials, reduced temperature and time scales via SPS significantly limits grain growth, thereby providing advantageous control of a material&#39;s properties through manipulation of its microstructure.
The SPS apparatus, for a 5&#215;5 mm2 sample, exerts a minimum pressure of 140 MPa. Within the conventional diffusion bonding temperature range, Hutt et al. report instantaneous fracture of STO when the bonding pressure exceeds 10 MPa18. However, STO exhibits temperature dependent plasticity behavior, indicating bonding pressure can exceed 10 MPa at specific temperatures. Above 1,200 &#176;C and below 700 &#176;C, STO exhibits some ductility, at which stresses greater than 120 MPa can be applied without instantaneous fracture of the sample. Within the intermediate temperature range of 700-1,200 &#176;C, STO is brittle and experiences instantaneous fracture at stresses greater than 10 MPa. At 800 &#176;C, STO has minor deformability prior to fracture at stresses less than 200 MPa19,20,21. Hence, bonding temperatures for STO bicrystal formation via SPS apparatus must be selected according to the plasticity behavior of the material.

<table><tbody><tr><td>Strontium titanate single crystal (100)</td><td>MTI Corporation</td><td>STOa101005S1-JP</td><td></td></tr><tr><td>Buffered oxide etch, hyrofluoric acid 6:1</td><td>JT Baker</td><td>&amp;nbsp;MBI 1178-03</td><td></td></tr><tr><td>Scanning electron microscope (SEM)</td><td>FEI</td><td>Model: 430 NanoSEM</td><td></td></tr><tr><td>SPS apparatus&amp;nbsp;</td><td>Sumitomo Coal Mining Co</td><td>Model: Dr. Sinter 5000 SPS Apparatus</td><td></td></tr><tr><td>High Temperature Furnace</td><td>Thermolyne</td><td>Model: 41600</td><td></td></tr><tr><td>Ultrasonic Cleaner</td><td>Bransonic</td><td>Model: 221</td><td></td></tr><tr><td>Mechanical polisher</td><td>Allied High Tech Products</td><td>15-2100-TEM</td><td></td></tr><tr><td>Diamond lapping film</td><td>3M</td><td>660XV</td><td>1 &amp;#956;m to 9 &amp;#956;m Grit Size</td></tr><tr><td>Diamond lapping film</td><td>3M</td><td>661X</td><td>0.5 &amp;#956;m to 0.1 &amp;#956;m Grit Size</td></tr><tr><td>Colloidal silica</td><td>Allied High Tech Products</td><td>180-20000</td><td>0.05 &amp;#956;m Grit Size</td></tr><tr><td>Sputter coater</td><td>QuorumTech</td><td>Model: Q150RES</td><td></td></tr><tr><td>Focused ion beam (FIB) instrument&amp;nbsp;</td><td>FEI</td><td>Model: Scios dual-beamed focused ion beam (FIB) instrument&amp;nbsp;</td><td></td></tr><tr><td>Nanomill TEM specimen preparation system</td><td>Fischione Instruments</td><td>Model: 1040</td><td></td></tr><tr><td>Transmission electron microscope (TEM)&amp;nbsp;</td><td>JEOL</td><td>Model: JEM2500 SE&amp;nbsp;</td><td></td></tr><tr><td>Scanning transmission electron microscope (STEM)</td><td>FEI</td><td>Model: TEAM 0.5&amp;nbsp;</td><td></td></tr></tbody></table>

spark plasma sintering apparatus used for the formation of strontium titanate bicrystals

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.

Bonding temperature, time, and misorientation angle were all altered to determine optimum parameters needed for the maximum possible bonded interface fraction of the STO bicrystal (Table 1). The interface was considered 'bonded' when the grain boundary was not visible during SEM imaging (Figure 2a). A 'non-bonded' interface was exhibited when a dark image contrast or voids were present at the boundary location (Figure 2b). Dark image cont...

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 ...

The goal of this procedure is to form strontium titanate bicrystals using a Spark Plasma Sintering apparatus in order to create grain boundary structures with well defined misorientations as a function of processing parameters, such as high pressure and heating rate. We need to understand whether grain boundaries generated during SPS are different from those produced during more traditional ceramic processing techniques. This will then help us generate new ceramic materials with unprecedented properties.The main advantage of this technique is to form specific grain boundaries with well defined misorientations for the systematic understanding of microstructure formation during spark plasma sintering. To begin sample preparation, use a diamond wire saw to cut five millimeter by five millimeter pieces of a strontium titanate single crystal with a 1-0-0 plane surface polished to a mirror finish. Clean the samples with an ultrasonic cleaner in baths of acetone, isopropanol, and methanol for 15 minutes each at 50 to 60 Hertz.Heat a hot plate to 200 degrees Celsius during the cleaning. Upon completing the ultrasonic cleaning in methanol, immediately place the samples on the hot plate to dry. Etch the samples in a six to one solution of ammonium fluoride and 49%hydrofluoric acid for 10 minutes.Rinse the etched samples in deionized water and isopropanol in sequence. Dry the samples with filtered dry air. Discard any samples that developed a rainbow patina on the optically flat side.First, place a 30 millimeter circle of graphite paper on a 30 millimeter diameter graphite plunger. Then, stack two STO single crystal samples with their optically flat sides facing each other on the center of the paper covered plunger. Rotate the top single crystal around the 1-0-0 axis to the desired misorientation angle.Carefully slide a 30 millimeter diameter graphite die over the crystals and plunger. Insert another 30 millimeter circle of graphite paper and plunger into the die on top of the crystal stack. Place the assembly on the lower graphite spacer of the SPS apparatus.And then place the other graphite spacer on top of the assembly. Use the z-axis control buttons to bring the upper punch down to apply a three kilonewton uniaxial force to the assembly. Insert a K type thermocouple into the side of the graphite die to reach the sample.Set the chamber pressure to approximately 10 Pascal. Then on the instrument program control, set the bond temperature, time, and heating rates for the experiment. Select sinter conditions of a DC pulse of 12 seconds on, two seconds off, and then start the sintering program.Once the program ends, allow the sample to cool to 150 degrees Celsius. Transfer the gray black reduced sample to a high temperature furnace. Anneal the sample at 1200 degrees Celsius for 140 hours in air at ambient pressure to obtain the off-white oxidized bicrystal.Use a diamond wire saw to slice the bicrystal into five millimeter by one millimeter pieces. Polish the cross-sections with decreasing grit sizes of diamond lapping film until the scratches are uniform at the smallest grit size. Then start a two minute polish of the cross-sections with continuously poured colloidal silica and a matte cloth.15 seconds before polishing ends, switch from pouring colloidal silica to pouring DI water onto the platen. Immediately rinse the polish sample in DI water for one minute. Clean the polished sample in consecutive ultrasonic cleaning baths of acetone, isopropanol, and methanol for 15 minutes each.Immediately after cleaning, dry the sample on a hot plate at 200 degrees Celsius. Melt the clean sample polished side up on a sample stub coated with colloidal graphite. Sputter coat the sample surface with two to three nanometers of carbon.First, place the focused ion beam copper grid in consecutive ultrasonic cleaner baths of acetone and isopropanol for one hour. Then, plasma clean the copper grid for 10 minutes. Place the STO bicrystal sample and the clean copper grid in the FIB apparatus with the sample stage set at seven millimeters.In the FIB instrument software, identify a region of interest along the grain boundary. Navigate to patterning control and select the rectangle patterning tool with the CE depth surface application for electron beam deposition of carbon. Insert the carbon gas injection needle and deposit a 15 by two by two micrometers cubed protective layer of carbon over the region of interest.Then, retract the injection needle. Return to patterning control and choose the rectangle patterning tool with a W dep application for ion beam deposition of tungsten. Insert the tungsten gas injection needle and deposit a protective layer of tungsten of the same dimensions over the region of interest.Retract the injection needle. In patterning control, select the regular cross section patterning tool with the silicon application property. Mill a 22 by 27 by 15 micrometer cubed trench above the protected ROI and a 22 by 25 by 15 micrometer cubed trench below the ROI.Then, in patterning control, use the silicon clean cross section patterning tool to clean the trenched lamella surface. Next, use the silicon rectangle patterning tool to cut a two micrometer wide J pattern with two micrometer wide rectangles into the sample. Switch to the easy lift dialog box and set the micromanipulator to the park position.Lower the micromanipulator and weld the sample to the tip of the micromanipulator by tungsten deposition. Then, extend the J patten into a U pattern. Lift the lamella from the bulk sample and rotate the micromanipulator 180 degrees to set the grain boundary perpendicular to the ion beam.Tungsten welds with a lamella to the copper grid. Then, cut the micromanipulator free from the lamella using the rectangle patterning tool. Deposit a 15 by two by four micrometer cubed layer of carbon and a 15 by two by eight micrometer cubed layer of tungsten over the area of interest.Then, with the ion beam, thin the sample first to approximately 200 nanometers with a cleaning cross section pattern. And then, with a rectangle pattern, thin the sample to electron transparency. Remove the copper FIB grid from the FIB apparatus and place the grid onto a NanoMil sample holder.Then place the sample holder into the NanoMil apparatus. Using the NanoMil apparatus software, mil the sample at 500 electron volts for 10 minutes to remove amorphous damage caused by the FIB. Place the cleaned TEM sample in a sample holder and insert the sample and holder into the STEM.In the STEM software, use the capture tool to obtain an image of the sample grain boundary. Strontium titanate bicrystals were formed from single crystal pairs at various misorientation angles using a Spark Plasma Sintering apparatus. The interface was considered to be bonded wherever the grain boundary was not observable in SEM imaging.Areas of dark contrast in the images are either attributed to voids or colloidal graphite diffusion between the single crystals. The maximum bonded interface fraction was achieved with zero degrees of misorientation, a bonding temperature of 600 or 700 degrees Celsius, a bonding duration of 90 minutes, and an annealing time of 100 hours. Increasing the angle of misorientation to approximately 45 degrees necessitated a higher bonding temperature and a longer annealing time to achieve a 45%bonded interface.High resolution TEM and high angle annular dark field STEM show an atomically abrupt grain boundary with no observed second phases or intergranular film. Electron energy loss spectroscopy at the interface showed decreased crystal field splitting of the titanium L2 and L3 edges and decreased intensity in the oxygen K edge compared to the bulk crystal, suggesting a greater concentration of oxygen vacancies at the interface. Following the same procedure, we can also form doped grain boundaries using the SPS.This will help us to address whether the electric field will change grain boundary segregation. After watching this video, you should have a good understanding of how to form bicrystals with atomically abrupt interface structures using SPS. Don't forget that hydrofluoric acid can be extremely hazardous and precautions, such as personal protective wear, should be taken.

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Learn to form strontium titanate bicrystals using Spark Plasma Sintering with controlled grain boundary misorientations. This method enables precise microstructure control for advanced ceramic materials research.

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

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