Spark Plasma Sintering of PbTe Thermoelectric Bulk Materials With Small Grains

2008 ◽  
Author(s):  
Chia-Hung Kuo ◽  
Chii-Shyang Hwang ◽  
Jie-Ren Ku ◽  
Ming-Shan Jeng ◽  
Fang-Hei Tsau
Keyword(s):  
Electron Microscopy ◽  
Spark Plasma Sintering ◽  
X Ray Diffraction ◽  
Bulk Materials ◽  
Combination Process ◽  
Plasma Sintering ◽  
Transmission Electron ◽  
Spark Plasma ◽  
Diffraction Patterns ◽  
Microscopy Images

PbTe is a conventional thermoelectric material for thermoelectric generator at intermediate temperature. Small grain size effect has been reported to improve PbTe ZT values (figure of merit). We report a combination process of attrition milling and spark plasma sintering (SPS) for preparing PbTe bulk materials with small grain sizes. The PbTe powders were milled by attrition under 600 rpm for 6–96 h and followed by SPS process under the sintering temperature of 573–773 K, the heating rate of 100 K/min, and the sintering pressure of 50 MPa. The powders and bulk materials as-prepared were then studied by X-ray diffraction patterns, scanning electron microscopy images, and transmission electron microscopy images. Transport properties of polycrystalline PbTe bulks were evaluated through temperature dependent thermal conductivity measurements.

scholarly journals Microstructure and properties of nano-laminated Y3Si2C2 ceramics fabricated via in situ reaction by spark plasma sintering

2021 ◽  
Vol 10 (3) ◽  
pp. 578-586
Author(s):  
Lin-Kun Shi ◽  
Xiaobing Zhou ◽  
Jian-Qing Dai ◽  
Ke Chen ◽  
Zhengren Huang ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Atomic Scale ◽  
Max Phase ◽  
X Ray Diffraction ◽  
Selected Area Electron Diffraction ◽  
Plasma Sintering ◽  
Transmission Electron ◽  
Spark Plasma ◽  
Diffraction Patterns

AbstractA nano-laminated Y3Si2C2 ceramic material was successfully synthesized via an in situ reaction between YH2 and SiC using spark plasma sintering technology. A MAX phase-like ternary layered structure of Y3Si2C2 was observed at the atomic-scale by high resolution transmission electron microscopy. The lattice parameters calculated from both X-ray diffraction and selected area electron diffraction patterns are in good agreement with the reported theoretical results. The nano-laminated fracture of kink boundaries, delamination, and slipping were observed at the tip of the Vickers indents. The elastic modulus and Vickers hardness of Y3Si2C2 ceramics (with 5.5 wt% Y2O3) sintered at 1500 °C were 156 and 6.4 GPa, respectively. The corresponding values of thermal and electrical conductivity were 13.7 W·m-1·K-1 and 6.3×105 S·m-1, respectively.

scholarly journals Microstructure and properties of nano-laminated Y3Si2C2 ceramics fabricated via in situ reaction by spark plasma sintering

2020 ◽  
Author(s):  
Lin-Kun Shi ◽  
Xiaobing Zhou ◽  
Jian-Qing Dai ◽  
Ke Chen ◽  
Zhengren Huang ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Atomic Scale ◽  
Max Phase ◽  
X Ray Diffraction ◽  
Selected Area Electron Diffraction ◽  
Plasma Sintering ◽  
Transmission Electron ◽  
Spark Plasma ◽  
Diffraction Patterns

Abstract A new nano-laminated Y3Si2C2 ceramic material, for the first time, was successfully synthesized via in situ reaction between YH2 and SiC by spark plasma sintering. A MAX phase-like ternary layered structure of Y3Si2C2 was observed at the atomic-scale by high resolution transmission electron microscopy. The lattice parameters calculated from both X-ray diffraction and selected area electron diffraction patterns are in good agreement with the reported theoretical results. The nano-laminated fracture of kink boundaries, delamination, and slipping was observed at the tip of the Vickers indent. The values of elastic modulus and Vickers hardness of the Y3Si2C2 ceramics sintered at 1500 °C were 156 and 6.4 GPa, respectively. The corresponding values of thermal and electrical conductivity were 13.7 W m-1 k-1 and 6.3 × 105 S m-1, respectively.

scholarly journals Synthesis of Novel YbxSb2 − xTe3Hexagonal Nanoplates: Investigation of Their Physical, Structural, and Photocatalytic Properties

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Younes Hanifehpour ◽  
Sang Woo Joo
Keyword(s):  
Electron Microscopy ◽  
Emission Spectra ◽  
Hydrothermal Condition ◽  
X Ray Diffraction ◽  
Dopant Content ◽  
Transmission Electron ◽  
Intensity Changes ◽  
Diffraction Patterns ◽  
Green Solution ◽  
Microscopy Images

Yb-doped Sb2Te3nanomaterials were synthesized by a coreduction method in hydrothermal condition. Powder X-ray diffraction patterns indicate that theYbxSb2−xTe3crystals (x=0.00–0.05) are isostructural with Sb2Te3. The cell parameteradecreases forYbxSb2−xTe3compounds upon increasing the dopant content (x), whilecincreases. Scanning electron microscopy and transmission electron microscopy images show that doping of Yb3+ions in the lattice of Sb2Te3produces different morphology. The electrical conductivity of Yb-doped Sb2Te3is higher than the pure Sb2Te3and increases with temperature. By increasing concentration of the Yb3+ions, the absorption spectrum of Sb2Te3shows red shifts and some intensity changes. In addition to the characteristic red emission peaks of Sb2Te3, emission spectra of doped materials show other emission bands originating fromf-ftransitions of the Yb3+ions. The photocatalytic performance of as-synthesized nanoparticles was investigated towards the decolorization of Malachite Green solution under visible light irradiation.

Microstructural properties and formation mechanisms of GaN nanorods grown on Al2O3 (0001) substrates

2009 ◽  
Vol 24 (8) ◽  
pp. 2476-2482
Author(s):  
Kyu H. Lee ◽  
Jeong Y. Lee ◽  
Y.H. Kwon ◽  
Tae W. Kang ◽  
Dong H. Kim ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Hydride Vapor Phase Epitaxy ◽  
Formation Mechanisms ◽  
Gas Mixing ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Increasing Temperature ◽  
Microscopy Images

X-ray diffraction patterns, scanning electron microscopy images, and transmission electron microscopy images showed that one-dimensional GaN nanorods with [0001]-oriented single-crystalline wurtzite structures were grown on Al2O3 (0001) substrates by hydride vapor-phase epitaxy without a catalyst. The tip morphology of the GaN nanorods became flat with increasing temperature difference between the gas mixing and the substrate zones. The gas mixing temperature significantly affected the formation of the nanorods, and the substrate temperature influenced the morphology and the strain of the GaN nanorods near the GaN/Al2O3 heterointerface. The strain and the stress existing in the GaN layer near the heterointerface were decreased with increasing growth rate. The formation mechanisms of the GaN nanorods grown on the Al2O3 (0001) substrates are described on the basis of the experimental results.

Effect of the Dwell Temperature on Spark Plasma Sintered CaCu3Ti4O12

2012 ◽  
Vol 727-728 ◽  
pp. 982-987
Author(s):  
E. de Carvalho ◽  
Marcelo Bertolete ◽  
Izabel Fernanda Machado ◽  
E.N.S. Muccillo
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Lattice Parameter ◽  
Solid State Reactions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Diffraction Patterns ◽  
Scanning Electron

Polycrystalline CaCu3Ti4O12 ceramics were prepared by solid state reactions by spark plasma sintering (SPS) technique. In this study, the effects of the dwell temperature on structural, microstructural and dielectric properties of CaCu3Ti4O12 ceramics have been investigated. Powder mixtures were calcined at 900°C for 18 h before SPS consolidation. The dwell temperatures were 850, 900, 915 and 930°C. Sintered pellets were characterized by X-ray diffraction, scanning electron microscopy and impedance spectroscopy. X-ray diffraction patterns show evidences of a single-phase perovskite-type structure. The calculated lattice parameter is 7.40 Å. The hydrostatic density increases slightly with increasing dwell temperature. Scanning electron microscopy observations revealed a heterogeneous microstructure for all samples. The dielectric loss remains constant over a wide temperature range. The obtained permittivity is approximately 103 at 1 kHz. The increase of the dwell temperature is found to produce a brittle ceramic.

THE GROWTH OF MnSi1.73 PREPARED BY SPARK PLASMA SINTERING

2004 ◽  
Vol 18 (01) ◽  
pp. 87-93 ◽  
Author(s):  
ZHIMIN WANG ◽  
YIDONG WU ◽  
YUANJIN HE
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Spark Plasma Sintering ◽  
X Ray Diffraction ◽  
Mechanical Pressure ◽  
Growth Processes ◽  
X Ray ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Scanning Electron

Crystals of MnSi 1.73 were prepared by Spark Plasma Sintering (SPS) technique, analyzed by X-ray diffraction (XRD), and invested by metalogragh and scanning electron microscopy (SEM). The growth processes of the samples were studied. It was found that the Mn–Si powders partly formed MnSi 1.73 crystals at 912–937 K under the mechanical pressure of 20 MPa in low vacuum (about 5.0 Pa), and fully formed MnSi 1.73 crystals after sintered at 1173 K for 15 minutes under 40 MPa.

Fullerene-Metal Composites: Phase Transformations During Milling and Sintering

2011 ◽  
Vol 172-174 ◽  
pp. 727-732 ◽  
Author(s):  
Ileana Irais Santana ◽  
Francisco Carlos Robles Hernandez ◽  
Vicente Garibay-Febles ◽  
Hector A. Calderon
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Phase Transformations ◽  
Mechanical Milling ◽  
X Ray Diffraction ◽  
Metal Composites ◽  
X Ray ◽  
Plasma Sintering ◽  
Transmission Electron ◽  
Spark Plasma

Composites of Fe-C60and Al C60produced by mechanical milling and sinterized by Spark Plasma Sintering are investigated with special attention to the mechanical properties of the products. The processing involves phase transformations of the fullerenes that are interesting to follow and characterize. This involves formation of tetragonal/rhombohedral diamond and carbides during sintering and milling. Transmission Electron Microscopy (TEM) and Raman Spectroscopy techniques are also used to confirm preliminary results of X Ray Diffraction (XRD) related to the formation of nanostructures i.e., grain size of the crystals during mechanical milling and after sintering, spatial distribution of phases and the different phases that are developed during processing.

Synthesis of Physically Functionalized Carbon Nanotube Reinforced Al-Si Nanocomposite by Spark Plasma Sintering

2014 ◽  
Vol 783-786 ◽  
pp. 1542-1547
Author(s):  
Anway Maiti ◽  
Ram S. Maurya ◽  
Tapas Laha
Keyword(s):  
Carbon Nanotube ◽  
Spark Plasma Sintering ◽  
High Energy ◽  
X Ray Diffraction ◽  
Multiwalled Carbon ◽  
Tem Analysis ◽  
Activity Effect ◽  
Plasma Sintering ◽  
Transmission Electron ◽  
Spark Plasma

Multiwalled carbon nanotube (MWCNT) reinforced Al-Si (11 wt%) alloy based nanocomposites were synthesized by spark plasma sintering using high energy ball milled nanocrystalline Al-Si powders mixed with physically functionalized MWCNTs. Improvement in MWCNT dispersion and associated improvement in densification of the nanocomposites were confirmed. The microhardness and elastic modulus of the nanocomposites measured by nanoindentation exhibited appreciable improvement. Grain size measurement by X ray diffraction and transmission electron microscopy confirmed achievement of nanocrystalline grains in Al-Si powder after ball milling, as well as in the consolidated nanocomposites. TEM analysis was performed to reveal the dislocation activity, effect of presence of primary Si and distribution of MWCNTs in the nanocomposites.

Microstructural Characterization of In Situ TiB Whiskers in Ti MMCs Fabricated by SPS

2007 ◽  
Vol 336-338 ◽  
pp. 1310-1312
Author(s):  
Hai Bo Feng ◽  
De Chang Jia ◽  
Yu Zhou ◽  
Qing Chang Meng
Keyword(s):  
Electron Microscopy ◽  
Spark Plasma Sintering ◽  
Sintering Temperature ◽  
Microstructural Characterization ◽  
Average Diameter ◽  
Matrix Composites ◽  
Plasma Sintering ◽  
Transmission Electron ◽  
Spark Plasma

The in situ TiB whisker reinforced titanium matrix composites were prepared by mechanical alloying followed by spark plasma sintering. X-ray diffraction, scanning electron microscopy and transmission electron microscopy were used to characterize the microstructure of the TiB whiskers. The effect of sintering temperature on morphologies of in situ TiB whiskers was evaluated. With the increase of spark plasma sintering temperature, the average diameter of in situ TiB whiskers increased. The in situ TiB whiskers exhibited a hexagonal shape with (100), (101) and (10 1 ) planes at the transverse section and a growth orientation of [010]TiB direction.

scholarly journals Bioglass-fibre reinforced hydroxyapatite composites synthesized using spark plasma sintering for bone tissue engineering

2021 ◽  
Vol 15 (3) ◽  
pp. 270-278
Author(s):  
Muhammad Rizwan ◽  
Ali Chandio ◽  
Muhammad Sohail ◽  
Nasir Bashir ◽  
Sumra Yousuf ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Bone Scaffold ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Microscopy Images ◽  
Selection Of

Hydroxyapatite (HA) exhibits several desirable characteristics, but it still lacks osteoinduction, which is a necessary requirement for a bone scaffold. HA-based composites with different amounts of Bioglass? (BG) were prepared using spark plasma sintering (SPS). Careful selection of the SPS parameters avoided undesirable reactions between the calcium phosphate (CaP) and bioglass (BG present in the form of powder and fibres), as confirmed through X-ray diffraction analysis. Scanning electron microscopy images of the composite scaffolds revealed a fibre like appearance of the glassy region. The in vitro bioactivity and biodegradation analyses were performed by immersing the composites in simulated body fluid (SBF) and tris(hydroxymethyl)aminomethane (Tris), respectively. The ability to obtain only the CaP phase and glassy phase with desirable bioactive and biodegradation behaviour, indicated that these SPS scaffolds can be employed as bone scaffolds for clinical trials, after further in vivo analyses.

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