Synthesis and Thermal Properties of Nanoscale Skutterudite via Cross-Coprecipitation

2007 ◽  
Vol 336-338 ◽  
pp. 831-833
Author(s):  
Ying Chu ◽  
Xin Feng Tang ◽  
Ling Wan ◽  
Qing Jie Zhang
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Grain Size ◽  
Room Temperature ◽  
Single Phase ◽  
Antimony Oxide ◽  
Hydrogen Atmosphere ◽  
Plasma Sintering ◽  
Average Grain Size ◽  
Spark Plasma

CoSb3 with nanoscale was synthesized by Cross-coprecipitation. A precursor consisting of antimony oxide and cobalt hydrate was prepared by the reaction of CoCl2, SbCl3 and both precipitators at room temperature. The precursor was reduced in thermal treatment under hydrogen atmosphere whereby the CoSb3 was thus obtained. The parameters especially reducing temperature and atmosphere (content of H2) influence the constituent phases and particle size of product significantly. The single phase CoSb3 with the average grain size of 60~70 nm was obtained after reduced at 723 K for 2 h with pure H2. Nanoscale CoSb3 powder was used as starting materials, and bulk CoSb3 compound was prepared by spark plasma sintering (SPS). The effect of grains size on thermal conductivity was investigated.

Microstructure and Thermoelectric Properties of CoSb3 Synthesized by MA-SPS Method

2007 ◽  
Vol 336-338 ◽  
pp. 834-837 ◽  
Author(s):  
Wei Shu Liu ◽  
Bo Ping Zhang ◽  
Jing Feng Li ◽  
Heng Wang
Keyword(s):  
Grain Size ◽  
Thermoelectric Properties ◽  
Room Temperature ◽  
Single Phase ◽  
New Combination ◽  
Plasma Sintering ◽  
Average Grain Size ◽  
Spark Plasma ◽  
Xrd Patterns ◽  
Type Conduction

Single-phase polycrystalline CoSb3 skutterudite was prepared through a new combination of mechanical alloying (MA) and spark plasma sintering (SPS). In order to investigate the influence of MA conditions on the microstructure and thermoelectric properties, MA synthesis were carried out under various conditions with different milling times. The powder sample MAed for 6h still consisted of metal Sb, and then transformed to CoSb3 with a little amount of metal Sb and CoSb2 phases after MA for 15h. Further prolonging the MA time resulted in the decomposition of CoSb3 to CoSb2 phase. The average grain size of the SPSed samples decreased from 650nm to 250nm as MA-time was prolonged from 6 to 24h. Lattice parameters estimated form XRD patterns increase with the increasing MA time. All samples SPSed at 600°C for holding 5 min show an n-type conduction. The electrical resistivity was 1030, 895, 410, 260 μm for the samples from the MA-derived powders with MA-time of 6, 15, 24 and 33h at room temperature, respectively, then reduced to 60 μm at 400°C for all samples. An optimum MA time is 24 h in which the sample shows the highest power factor 612μW/m*K2 at 150°C.

Controlled Atmosphere Thermal Treatment for Pyrochlore Phase Elimination of PMN-PT/CFO Prepared by Spark Plasma Sintering

2014 ◽  
Vol 975 ◽  
pp. 274-279 ◽  
Author(s):  
Diego Seiti Fukano Viana ◽  
José Antônio Eiras ◽  
William Junior Nascimento ◽  
Fabio Luiz Zabotto ◽  
Ducinei Garcia
Keyword(s):  
Grain Size ◽  
Spark Plasma Sintering ◽  
Single Phase ◽  
Magnetoelectric Effect ◽  
Pyrochlore Phase ◽  
Practical Applications ◽  
Plasma Sintering ◽  
Average Grain Size ◽  
Spark Plasma ◽  
Phase Elimination

Multiferroics are interesting materials which present more than one ferroic property and have a great potential for practical applications [,,]. In addition, the coupling of magnetic and electric properties, the magnetoelectric effect (ME), offers news possibilities to applications [2,]. The magnetoelectric effect can be observed in single-phase materials like LuFe2O4, BiFeO3, etc. [1,] or in composites like PMN-PT/CFO, BaTiO3/CoFe2O4, etc. The ME composites have advantages over single-phase materials. They are easier to fabricate, less expensive, and have a wider range of working temperatures than single-phase materials []. However, some parameters that enhance the ME response need to be optimized. These parameters are the composition, the microstructure (grain size, grain orientation) and sintering parameters [6]. Thus, this work attempts to create a synthesis protocol to prepare the ME composite PMN-PT/CFO by Spark Plasma Sintering (SPS) keeping the average grain size as small as possible.

Magnetic Properties and High Thermal Conductivity of Al2O3 Ceramics Prepared by Spark Plasma Sintering

2013 ◽  
Vol 750-752 ◽  
pp. 512-516 ◽  
Author(s):  
Zhen Hua Jia ◽  
Xin Gui Tang ◽  
Donge Chen ◽  
Jun Bo Wu ◽  
Qiu Xiang Liu
Keyword(s):  
Thermal Conductivity ◽  
Magnetic Properties ◽  
Spark Plasma Sintering ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
High Thermal Conductivity ◽  
X Ray ◽  
Plasma Sintering ◽  
Average Grain Size ◽  
Spark Plasma

The Al2O3 ceramics with high thermal conductivity prepared the spark plasma sintering (SPS) technology. The structure, image and magnetic properties of the SPS Al2O3 ceramics was characterized by X-ray, field emission scanning electron microscope (FE-SEM) and the vibrating sample magnetometer (VSM) at room temperature. The results shown that the average grain size of the Al2O3 ceramics is about 5~15μm, the thermal conductivity of Al2O3 ceramics up to 24.928 W/(m·K), and the remanent magnetization as higher as 0.00546emu/g and the saturation magnetization as higher as 0.0321 emu/g, respectively. The room-temperature ferromagnetism, which is different from the traditional, possibly originates from the oxygen vacancies.

scholarly journals Thermoelectric properties of Cu3SbSe3 with intrinsically ultralow lattice thermal conductivity

2014 ◽  
Vol 2 (38) ◽  
pp. 15829-15835 ◽  
Author(s):  
Kriti Tyagi ◽  
Bhasker Gahtori ◽  
Sivaiah Bathula ◽  
A. K. Srivastava ◽  
A. K. Shukla ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Solid State ◽  
Spark Plasma Sintering ◽  
Thermoelectric Properties ◽  
Solid State Reaction ◽  
Electrical Transport ◽  
Single Phase ◽  
Lattice Thermal Conductivity ◽  
Plasma Sintering ◽  
Spark Plasma

Intrinsically ultra-low thermal conductivity and electrical transport in single-phase Cu2SbSe3 synthesized employing a solid state reaction and spark plasma sintering.

Preparation of Nanocrystalline Fe2O3 Powder by Cryomilling with Liquid Nitrogen and its Magnetic Property

2020 ◽  
Vol 993 ◽  
pp. 806-810
Author(s):  
Zhi Wei Zhang ◽  
Bing Wei Luo ◽  
Hai Tao Zhou ◽  
Fen Wang
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Magnetic Property ◽  
Liquid Nitrogen ◽  
Room Temperature ◽  
Single Phase ◽  
Rapid Preparation ◽  
Mean Particle Size ◽  
Milling Temperature ◽  
The Mean

Rapid preparation of nanocrystalline γ-Fe2O3 powder with superparamagnetism was realized by cryomilling commercial Fe2O3 powder using liquid nitrogen. The effects of milling temperature and duration on the grain size, phase and microstructure of the nanocrystalline Fe2O3 powder were analyzed. Magnetic property of the nanocrystalline γ-Fe2O3 powder was also tested by magnetometer at room temperature. The results demonstrate that nanocrystalline γ-Fe2O3 powder with single phase can be prepared rapidly by cryomilling with liquid nitrogen. The mean particle size of γ-Fe2O3 powder can be reduced from 300 nm to 13 nm by cryomilling at −130 °C within 3 hours. The nanocrystalline γ-Fe2O3 powder shows superparamagnetism at room temperature.

Enhanced Thermoelectric Properties of Mg2Si0.3Sn0.7 Compounds by Bi Doping

2014 ◽  
Vol 616 ◽  
pp. 174-177
Author(s):  
Mei Jun Yang ◽  
Qiang Shen ◽  
Lian Meng Zhang
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Doping Concentration ◽  
Single Phase ◽  
Doping Content ◽  
Maximum Value ◽  
Plasma Sintering ◽  
Bi Doping ◽  
Spark Plasma

The single phase of Bi-doped Mg2Si0.3Sn0.7compounds have been successfully fabricated by solid state reaction and spark plasma sintering (SPS). The effect of Bi doping concentration on the thermoelectric properties of Mg2Si0.3Sn0.7is investigated. The doping of Bi atom results in the increase of carrier concentrations and ensures the increase of electrical conductivity. Although the thermal conductivity and Seebeck coefficient shows a slight increase, the figure of merit of Mg2Si0.3Sn0.7compounds still increases with the increasing contents of Bi-doping. When Bi-doping content is 1.5at%, the Mg2Si0.3Sn0.7compound obtained the maximum value,ZT, is 1.03 at 640 K.

Preparation of Fine-grained BaTiO3 Ceramics by Spark Plasma Sintering

2002 ◽  
Vol 17 (3) ◽  
pp. 575-581 ◽  
Author(s):  
Tomonari Takeuchi ◽  
Claudio Capiglia ◽  
Nalini Balakrishnan ◽  
Yasuo Takeda ◽  
Hiroyuki Kageyama
Keyword(s):  
Grain Size ◽  
Spark Plasma Sintering ◽  
Fine Powder ◽  
Fine Grained ◽  
Plasma Sintering ◽  
Average Grain Size ◽  
Ferroelectric Domains ◽  
Spark Plasma ◽  
Ray Density ◽  
Permittivity Measurements

Dense BaTiO3 ceramics consisting of fine grains were prepared using fine powder (average grain size of 0.06 μm; BT006) as a starting material and the spark plasma sintering (SPS) method. The powder was densified to >95% of theoretical x-ray density by the SPS process, and the average grain size of the resulting ceramics was <0.5 μm; the particle size of the initial powder significantly affects the grain size of the resulting SPS pellets. Fixed-frequency (100 kHz), room-temperature permittivity measurements of the BT006-SPS ceramics showed relatively low values (3000–3500) compared with those (typically 5000) for SPS ceramics consisting of larger grains (approximately 1 μm). Lower permittivity was attributed to poor development of ferroelectric domains in the ceramics, which originated from incomplete development of the tetragonal structure as well as the presence of a local orthorhombic structure.

Effect of Oxygen Content on Thermoelectric Properties of Sintered Bi-Te Based Compounds

2004 ◽  
Vol 449-452 ◽  
pp. 905-908 ◽  
Author(s):  
Dong Choul Cho ◽  
Cheol Ho Lim ◽  
D.M. Lee ◽  
Seung Y. Shin ◽  
Chung Hyo Lee
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Oxygen Content ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Air Atmosphere ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Effect Of Oxygen

The n-type thermoelectric materials of Bi2Te2.7Se0.3 doped with SbI3 were prepared by spark plasma sintering technique. The powders were ball-milled in an argon and air atmosphere. Then, powders were reduced in H2 atmosphere. Effects of oxygen content on the thermoelectric properties of Bi2Te2.7Se0.3 compounds have been investigated. Seebeck coefficient, electrical resistivity and thermal conductivity of the sintered compound were measured at room temperature. It was found that the effect of atmosphere during the powder production was remarkable and thermoelectric properties of sintered compound were remarkably improved by H2 reduction of starting powder. The obtained maximum figure of merit was 2.4 x 10-3/K.

scholarly journals Synthesis and Property Characterization of Ternary Laminar Zr2SB Ceramic

2021 ◽  
Author(s):  
Qiqiang Zhang ◽  
Shuai Fu ◽  
Detian Wan ◽  
Yiwang Bao ◽  
Qingguo Feng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Physical Properties ◽  
Room Temperature ◽  
Thermal Capacity ◽  
Boron Powder ◽  
Plasma Sintering ◽  
Average Grain Size ◽  
Spark Plasma ◽  
Property Characterization

Abstract In this paper, Zr2SB ceramics with high relative density (99.03%) and high purity of 82.95 wt% (containing 8.96 wt% ZrB2 and 8.09 wt% zirconium) were successfully synthesized from ZrH2, sublimated sulfur and boron powder by spark plasma sintering at 1300 ℃. The reaction mechanism, microstructures, physical properties and mechanical properties of Zr2SB ceramic were systematically studied. The results show that Zr2SB was obtained by the reaction of zirconium sulfide, zirconium and boron, and ZrB2 coexisted in the sample as a symbiotic impurity phase. The average grain size of Zr2SB was 12.46 μm in length and 5.12 μm in width, and the mean grain sizes of ZrB2 and zirconium impurities were about 300 nm. In terms of physical properties, the measured thermal expansion coefficient was 7.64 × 10-6 K-1 from room temperature to 1200 ℃, and the thermal capacity and thermal conductivity at room temperature were 0.39 J·g−1·K−1 and 12.01 W∙m−1∙K−1, respectively. The room temperature electrical conductivity of Zr2SB ceramic was measured to be 1.74 × 106 Ω−1∙m−1. In terms of mechanical properties, Vickers hardness was 9.86 ± 0.63 GPa under 200 N load, and the measured flexural strength, fracture toughness and compressive strength were 269 ± 12.7 MPa, 3.94 ± 0.63 MPa·m1/2, and 2166.74 ± 291.34 MPa, respectively.

Fabrication of Mg2Si Thermoelectric Materials by Mechanical Alloying and Spark-Plasma Sintering Process

2006 ◽  
Vol 6 (11) ◽  
pp. 3429-3432
Author(s):  
Chung-Hyo Lee ◽  
Seong-Hee Lee ◽  
Sung-Yong Chun ◽  
Sang-Jin Lee
Keyword(s):  
Grain Size ◽  
Mechanical Alloying ◽  
Spark Plasma Sintering ◽  
Room Temperature ◽  
Atomic Ratio ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plasma Sintering ◽  
Spark Plasma

A mixture of pure Mg and Si powders with an atomic ratio 2:1 has been subjected to mechanical alloying (MA) at room temperature to prepare the Mg2Si thermoelectric material. Mg2Si intermetallic compound with a grain size of 50 nm can be obtained by MA of Mg66.7Si33.3 powders for 60 hours and subsequently annealed at 620 °C. Consolidation of the MA powders was performed in a spark plasma sintering (SPS) machine using graphite dies up to 800–900 °C under 50 MPa. The shrinkage of consolidated samples during SPS was significant at about 250 °C and 620 °C. X-ray diffraction data shows that the SPS compact from 60 h MA powders consolidated up to 800 °C consists of only nanocrystalline Mg2Si compound with a grain size of 100 nm.

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