High-pressure and high-temperature electrical resistivity studies on Nd-123

2005 ◽  
Vol 59 (14-15) ◽  
pp. 1764-1766 ◽  
Author(s):  
R. Selva Vennila ◽  
N. Victor Jaya ◽  
S. Natarajan
2019 ◽  
Vol 34 (01) ◽  
pp. 2050006
Author(s):  
Lisha Xue ◽  
Chao Fang ◽  
Weixia Shen ◽  
Manjie Shen ◽  
Wenting Ji ◽  
...  

High-pressure technique is an effective route to synthesize thermoelectric materials and tune transport properties simultaneously. In this work, S-doped copper–selenium compounds [Formula: see text], [Formula: see text] were successfully synthesized by high-pressure and high-temperature (HPHT) technology in just 30 min. [Formula: see text] samples show layered morphology composed of abundant pores and lattice defects. The appropriate S introduction ([Formula: see text] and 0.03) can effectively enhance Seebeck coefficient and reduce the thermal conductivity of [Formula: see text]. Compared with the pure [Formula: see text] sample, [Formula: see text] exhibits a 30% lower thermal conductivity, but the decline of power factor by the distinctly increased electrical resistivity at high temperature results in a smaller zT at temperature [Formula: see text] K. The variations of thermoelectric properties are resulted from the competitive effects between S-doping and actual composition change (Cu:S). It indicates that S-doping is not so effective in improving the zT value of [Formula: see text] materials by high-pressure synthesis.


Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1212 ◽  
Author(s):  
Changchun Wang ◽  
Lele Song ◽  
Yupeng Xie

Single-phase tungsten diboride (WB2) was synthesized at high pressure and high temperature. The different grain sizes ranging from 300 nm to 3 µm were successfully obtained in WB2 by controlling the experimental conditions. The effects of grain size on hardness and resistivity properties were investigated. The Vickers hardness of WB2 was modulated with grain size. The maximum asymptotic Vickers hardness is 25.5 GPa for WB2 with a grain size of 300 nm which is a 10% increase compared to WB2 with a grain size of 3 µm. The optimal electrical resistivity of WB2 was 10−7 Ωm with the biggest grain size of 3 µm, which is ascribed to low grain boundary density. The superior properties of hardness and electrical resistivity demonstrate that WB2 should be a new functional hard material replacing WC which is widely used in industrial production.


Pramana ◽  
1985 ◽  
Vol 24 (6) ◽  
pp. 825-835 ◽  
Author(s):  
Mohammad Yousuf ◽  
P Ch Sahu ◽  
K Govinda Rajan

2017 ◽  
Vol 31 (28) ◽  
pp. 1750261 ◽  
Author(s):  
Yiping Jiang ◽  
Xiaopeng Jia ◽  
Hongan Ma

The skutterudite CoSb[Formula: see text]Te[Formula: see text]Sn[Formula: see text] compound was synthesized successfully by high pressure and high temperature (HPHT) method using Co, Sb, Te and Sn powder as raw materials. The effects of pressure on its structure and the thermoelectric properties are investigated systematically from 300 K to 800 K. The electrical resistivity and the absolute value of the Seebeck coefficient for the sample increases with rising synthetic pressure. The thermal conductivity of the sample decreases with synthetic pressure and temperature rising in the range of 300–800 K. In this study, the maximum dimensionless figure of merit (ZT) value of 1.17 has been achieved at 793 K, 3 GPa for this thermoelectric material.


2006 ◽  
Vol 20 (29) ◽  
pp. 4885-4890
Author(s):  
R. SELVA VENNILA ◽  
S. REZA GHORBANI ◽  
N. VICTOR JAYA

High pressure-high temperature electrical resistivity study on composition-controlled Nd 0.9 Ca 0.1 Ba 2 Cu 3 O 7-δ high T c superconductor (HTSC) is carried out by a four-probe technique using Bridgman anvils. A simple heating coil arrangement is used for heating the samples. Electrical resistivity behavior under pressure (up to a maximum of 8 GPa) at various temperatures (up to a maximum of 523 K) were studied and reported in this paper. Simulation of energy dispersive X-ray diffraction confirms substitution of calcium at the Nd site of Nd -123. Variation of the electrical resistivity under pressure is compared with that of the structural changes and the bulk modulus was determined.


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