Preparation and Thermoelectric Properties of LaCoO3 Ceramics

2010 ◽  
Vol 434-435 ◽  
pp. 404-408 ◽  
Author(s):  
Li Fu ◽  
Jing Feng Li
Keyword(s):  
Electrical Conductivity ◽  
Solid State ◽  
Thermoelectric Properties ◽  
Sintering Temperature ◽  
Conventional Solid State Reaction ◽  
Seebeck Coefficients ◽  
Different Temperatures ◽  
Higher Temperature ◽  
Increasing Temperature ◽  
Semiconducting Behavior

LaCoO3 ceramics were prepared by conventional solid state reaction and normal sintering at the temperatures ranging from 1373 to 1523 K. The sintered densities increased with increasing sintering temperature and exceeded 90 % of the theoretical values when sintered above 1473 K. The thermoelectric properties of the samples sintered at different temperatures were investigated from 323 to 673 K. The LaCoO3 samples showed a negative Seebeck coefficient, whose absolute values decreased dramatically with increasing temperature in the range of 323 to 460 K, then changed to a positive value and lightly decreased above 460 K. The electrical conductivity increased with increasing temperature, indicating a semiconducting behavior. The Seebeck coefficients showed little difference between the samples sintered at different temperatures, but the power factor of the sample sintered at a higher temperature was larger because of the higher electrical conductivity.

Thermoelectric Properties of Co1-xNbxSb3 Prepared by Induction Melting

2005 ◽  
Vol 486-487 ◽  
pp. 554-557
Author(s):  
J.B. Park ◽  
S.-W. You ◽  
K.W. Cho ◽  
J.I. Lee ◽  
Soon Chul Ur ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Thermoelectric Properties ◽  
Induction Melting ◽  
Thermoelectric Power Factor ◽  
Seebeck Coefficients ◽  
High Temperature Maximum ◽  
Higher Temperature ◽  
Nb Doping ◽  
Increasing Temperature ◽  
P Type

Induction melting was attempted to prepare the undoped and Nb-doped CoSb3 compounds, and their thermoelectric properties were investigated. Single phase d-CoSb3 was successfully obtained by induction melting and subsequent annealing at 400°C for 2 hours in vacuum. The positive signs of Seebeck coefficients for all the specimens revealed that Nb atoms acted as p-type dopants by substituting Co atoms. Electrical conductivity decreased and then increased with increasing temperature, indicating mixed behaviors of metallic and semiconducting conductions. Electrical conductivity increased by Nb doping, and it was saturated at high temperature. Maximum value of the thermoelectric power factor was shifted to higher temperature with the increasing amount of Nb doping, mainly originated from the Seebeck coefficient variation.

Thermoelectric Properties of Co1-xNbxSb3 Prepared by Induction Melting

2005 ◽  
Vol 486-487 ◽  
pp. 602-605 ◽  
Author(s):  
J.B. Park ◽  
S.-W. You ◽  
K.W. Cho ◽  
J.I. Lee ◽  
Soon Chul Ur ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Thermoelectric Properties ◽  
Induction Melting ◽  
Thermoelectric Power Factor ◽  
Seebeck Coefficients ◽  
Maximum Value ◽  
High Temperature Maximum ◽  
Higher Temperature ◽  
Nb Doping ◽  
P Type

Induction melting was attempted to prepare the undoped and Nb-doped CoSb3 compounds, and their thermoelectric properties were investigated. Single phase d-CoSb3 was successfully obtained by induction melting and subsequent annealing at 400°C for 2 hours in vacuum. The positive signs of Seebeck coefficients for all the specimens revealed that Nb atoms acted as p-type dopants by substituting Co atoms. Electrical conductivity decreased and then increased withincreasing temperature, indicating mixed behaviors of metallic and semiconducting conductions. Electrical conductivity increased by Nb doping, and it was saturated at high temperature. Maximum value of the thermoelectric power factor was shifted to higher temperature with the increasing amount of Nb doping, mainly originated from the Seebeck coefficient variation.

Thermoelectric properties of bulk MoSi2 synthesized by solid state microwave heating

2016 ◽  
Vol 30 (19) ◽  
pp. 1650234 ◽  
Author(s):  
Yu Lan ◽  
Mianyu Xie ◽  
Ting Ouyang ◽  
Song Yue
Keyword(s):  
Solid State ◽  
Microwave Heating ◽  
Single Phase ◽  
Sintering Temperature ◽  
Seebeck Coefficients ◽  
Long Duration ◽  
Powder Factor ◽  
High Efficient ◽  
Different Temperatures ◽  
Precursor Powders

In this research, single phase [Formula: see text]-MoSi2 was prepared by solid state hybrid microwave heating within 90 min at relatively low temperature 1273 K. Such precursor powders were then ball milled and sintered by microwave heating at different temperatures. The thermoelectric (TE) properties of MoSi2 bulks were investigated in the temperature range of 300–673 K. When the sintering temperature increases from 973 K to 1273 K, the electrical resistivity decreases significantly and the Seebeck coefficients increase obviously, leading to the maximum TE powder factor of [Formula: see text] at 673 K. These results demonstrate the feasibility of high efficient and economical synthesis of MoSi2 by microwave heating technique, with the final products having comparable TE performance in comparison to those from typical methods with long duration and energy-extensive consumption.

Effect of Sintering Temperature on Properties of Multiferroic BaFe12O19/MgFe2O4/BaTiO3 Composites

2016 ◽  
Vol 846 ◽  
pp. 410-415
Author(s):  
M.F.A. Zolkepli ◽  
Rozidawati Awang ◽  
Zalita Zainuddin
Keyword(s):  
Grain Size ◽  
Solid State ◽  
Electrical Properties ◽  
Sintering Temperature ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Solid State Reaction Technique ◽  
Conventional Solid State Reaction ◽  
Different Temperatures ◽  
Tetragonal Batio

In this paper, the structural, magnetic and electrical properties of multiferroic BaFe12O19/MgFe2O4/BaTiO3 composites have been studied. BaFe12O19/MgFe2O4/BaTiO3 composites were synthesized by using the conventional solid state reaction technique and sintered at different temperatures. XRD analysis confirmed the existence of hexagonal BaFe12O19, cubic spinel MgFe2O4 and tetragonal BaTiO3 for ferrites and ferroelectric phases, respectively. The suitable sintering temperature for preparing BaFe12O19/MgFe2O4/BaTiO3 composites is between 1000 °C and 1050 °C. SEM analysis showed that as a whole the grain size increases and the pores is reduced with sintering temperature; thus the sample became denser. The coercive field and saturation magnetization decreases when sintering temperature is increased. Resistance of the samples decrease from 103 kW to 19 kW while the capacitance increases from 0.8 nF to 4.0 nF with sintering temperature.

Thermoelectric Properties of Cu-Substituted Bi2Ca2Co2Oy Misfit Oxides

2011 ◽  
Vol 284-286 ◽  
pp. 2263-2267 ◽  
Author(s):  
Hao Shan Hao ◽  
Qing Lin He ◽  
Li Min Zhao
Keyword(s):  
Electrical Conductivity ◽  
Grain Size ◽  
High Temperature ◽  
Solid State ◽  
Thermoelectric Properties ◽  
Solid State Reaction Method ◽  
Reaction Method ◽  
Seebeck Coefficients ◽  
Cu Substitution ◽  
Performance System

Co2-xCuxOy (x=0.0, 0.2, 0.4) Samples were prepared by solid-state reaction method and the effect of Cu substitution on the thermoelectric properties was investigated. The presence of Cu element improved the grain size and electrical conductivity, but Seebeck coefficients were reduced by Cu substitution. It was found Cu substitution is an effective way to improve the thermoelectric performance system at high temperature.

High-Temperature Thermoelectric Properties of Silicon Boride Ceramics as a Smart Material

1999 ◽  
Vol 604 ◽  
Author(s):  
Noriyuki Takashima ◽  
Yasuo Azuma ◽  
Jun-Ichi Matsushita
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
High Temperature ◽  
Seebeck Coefficient ◽  
Relative Density ◽  
Thermoelectric Properties ◽  
Room Temperature ◽  
Sintering Temperature ◽  
Smart Material ◽  
Increasing Temperature

AbstractSeveral silicon boride phases such as SiB4, SiB6, SiB6-x, SiB6+x, and Si11B31, were previously reported. Among them, SiB6has proved to be a potentially useful material because of its excellent electrical conductivity, high degree of hardness, moderate melting point, and low specific gravity. The sintering conditions and thermoelectric properties of silicon boride (SiB6) ceramics produced by hot pressing were investigated in order to determine the suitability of this material for high-temperature thermoelectric applications as a smart material. The relative density increased with increasing sintering temperature. With a sintering temperature of 1923 K, a sintered body having a relative density of more than 99% was obtained. X-ray diffraction analysis showed no crystalline phase other than SiB6 in the sintered body. The specimens were prepared for measurement of the electrical conductivity and Seebeck coefficient by the D.C. four-terminal method. The thermal conductivity of SiB6 was obtained by calculation from the thermal diffusivity and specific heat capacity of the specimen. The electrical conductivity of SiB6 increased with increasing temperature. The electrical conductivity of the polycrystalline SiB6 (99% dense) was 0.5 to 1.1 × 103 S/m at 298 to 1273 K. The thermal conductivity decreased with increasing temperature in the range of room temperature to 1273 K. The thermal conductivity was 9.1 to 2.5 W/mK in the range of room temperature to 1273 K. The Seebeck coefficient of SiB6 increased with increasing temperature. The Seebeck coefficient of SiB6 was 140 × 10−6 V/K at 1273 K. The figure of merit Z of SiB6 increased with increasing temperature. The Z of SiB6 reached 8.1 × 10−6/K at 1273 K. The ZT value is useful to evaluate the ability of thermoelectric materials. The ZT value reached 0.01 at 1273 K. Based on the results, SiB6 showed very good thermoelectric material characteristics at high temperature.

EFFECT OF SINTERING TEMPERATURE ON THE MICROSTRUCTURE AND THERMOELECTRIC PROPERTIES OF Ca2.7Bi0.3Co4O9

2009 ◽  
Vol 23 (18) ◽  
pp. 3777-3787 ◽  
Author(s):  
HAOSHAN HAO ◽  
SHAOFENG LI ◽  
LIMIN ZHAO ◽  
XING HU
Keyword(s):  
Solid State ◽  
Transport Properties ◽  
Thermoelectric Properties ◽  
Solid State Reaction ◽  
Sintering Temperature ◽  
Solid State Reaction Method ◽  
Conventional Solid State Reaction ◽  
Reaction Method ◽  
Cooling Stage ◽  
Oriented Structure

Ca 2.7 Bi 0.3 Co 4 O 9 samples have been sintered in temperature range of 1183–1243 K by conventional solid-state reaction method. XRD and SEM investigations show that c-axis-oriented structure could be formed in these samples and Lotgering factors increase with the increase of sintering temperature when it is below 1223 K, from 52% for the sample sintered at 1183 K to 86% for the sample sintered at 1223 K. Due to decomposition of Ca 2.7 Bi 0.3 Co 4 O 9, however, the c-axis-oriented structure was destroyed in the sample sintered at 1243 K although Ca 2.7 Bi 0.3 Co 4 O 9 phase could be recovered at the cooling stage. The size of grains in all samples increases with the increase of sintering temperature, but the relative densities are almost kept unchanged for the samples sintered at the temperature higher than 1183 K. Due to the highly textured structure, the transport properties of the sample sintered at 1223 K are anisotropic and its ZT values in the ab plane are obviously larger than those along the c-axis.

scholarly journals Preparation, Sinterability, Electrical Transport and Thermal Expansion of Perovskite-Type La0.8Ca0.2CrO3 Composites

2020 ◽  
Vol 10 (13) ◽  
pp. 4634
Author(s):  
Linlin Liu ◽  
Mingmei Jiang ◽  
Juanjuan Yin ◽  
Wenfeng Guo ◽  
Tifeng Jiao
Keyword(s):  
Electrical Conductivity ◽  
Thermal Expansion ◽  
Solid State ◽  
Electrical Transport ◽  
Sintering Temperature ◽  
Electronic Conductivity ◽  
Combustion Method ◽  
Synthesis Methods ◽  
Conventional Solid State Reaction ◽  
Perovskite Type

Perovskite-type was synthesized by two methods, the combustion method and conventional solid state reaction (SSR) method. The effect of synthesis methods on sinterability and physical properties of the ceramic were investigated. The results show that there are advantages of the combustion method in producing doped lanthanum chromites. Compared with the SSR method, the combustion method reduces the sintering temperature of La0.8Ca0.2CrO3, elevates the electronic conductivity and thermal expansion coefficient (TEC) of the ceramic, due to optimizing the microstructure. At the same densities level (–93%), the specimen synthesized by the combustion method reaches a superior electrical conductivity of 31.6 S·cm-1 and a compatible TEC of 10.7 × 10−6 K−1 at 800 °C.

scholarly journals Synthesis and Na+ Ion Conductivity of Stoichiometric Na3Zr2Si2PO12 by Liquid-Phase Sintering with NaPO3 Glass

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3790
Author(s):  
Yongzheng Ji ◽  
Tsuyoshi Honma ◽  
Takayuki Komatsu
Keyword(s):  
Solid State ◽  
Liquid Phase ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
Ion Conductivity ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Sintering Time ◽  
Lower Activation

Sodium super ionic conductor (NASICON)-type Na3Zr2Si2PO12 (NZSP) with the advantages of the high ionic conductivity, stability and safety is one of the most famous solid-state electrolytes. NZSP, however, requires the high sintering temperature about 1200 °C and long sintering time in the conventional solid-state reaction (SSR) method. In this study, the liquid-phase sintering (LPS) method was applied to synthesize NZSP with the use of NaPO3 glass with a low glass transition temperature of 292 °C. The formation of NZSP was confirmed by X-ray diffraction analyses in the samples obtained by the LPS method for the mixture of Na2ZrSi2O7, ZrO2, and NaPO3 glass. The sample sintered at 1000 °C for 10 h exhibited a higher Na+ ion conductivity of 1.81 mS/cm at 100 °C and a lower activation energy of 0.18 eV compared with the samples prepared by the SSR method. It is proposed that a new LPE method is effective for the synthesis of NZSP and the NaPO3 glass has a great contribution to the Na+ diffusion at the grain boundaries.

Electrical Properties of Fresnoite Ba2TiSi2O8 Using Impedance Spectroscopy

2013 ◽  
Vol 795 ◽  
pp. 640-643 ◽  
Author(s):  
Rozana A.M. Osman ◽  
Mohd Sobri Idris
Keyword(s):  
Activation Energy ◽  
Solid State ◽  
Sintering Temperature ◽  
Second Harmonic ◽  
Conventional Solid State Reaction ◽  
Reaction Phase ◽  
Tetragonal Unit Cell ◽  
Phase Pure ◽  
Very High ◽  
Centrosymmetric Structure

Fresnoite with composition Ba2TiSi2O8 (B2TS2) was first found in 1965, adopting a non-centrosymmetric structure. It also reported to crystallize in a tetragonal unit cell with a=8.52Å and c=5.210Å leading to some possible application as hydrophone, transducer and second harmonic generation and low temperature co-fired ceramics (LTCC). B2TS2 were synthesized by conventional solid state reaction. Phase pure B2TS2 was obtained after heating the pellets at a final sintering temperature of 1230 °C in air at 92 h. Study found that Fresnoite B2TS2 is a type of materials which are not ferroelectric and instead show perfect dielectric insulator behaviour with resistance >106Ωcm at temperatures below 750°C and also shows nonideal debye respone. The activation energy for conduction of B2TS2 samples is very high, indicating that these materials are highly insulating.

Sign in / Sign up

Export Citation Format

Share Document