EFFECT OF LONG-TERM HEAT-TREATMENT ON THE ELECTRICAL-PROPERTIES OF RSE1.47 (R=LA AND ND) AND LASE1.48

Citation
J. Michiels et Ka. Gschneidner, EFFECT OF LONG-TERM HEAT-TREATMENT ON THE ELECTRICAL-PROPERTIES OF RSE1.47 (R=LA AND ND) AND LASE1.48, Journal of applied physics, 82(10), 1997, pp. 4952-4956
Citations number
13
Categorie Soggetti
Physics, Applied
Journal title
ISSN journal
00218979
Volume
82
Issue
10
Year of publication
1997
Pages
4952 - 4956
Database
ISI
SICI code
0021-8979(1997)82:10<4952:EOLHOT>2.0.ZU;2-A
Abstract
The phase stability of the gamma-cubic LaSe1.47, LaSe1.48 and NdSe1.47 compounds with the Th3P4 type structure, along with their electrical resistivity, Seebeck coefficient, and Hall effect were measured period ically as the materials were annealed at 800 degrees C or 1000 degrees C to determine their potential as thermoelectric materials for long t erm applications at high temperatures. The LaSex samples showed the pr esence of the ternary oxide La10Se14O (beta-phase), The content of thi s phase; increased with increasing anneal time, whereas the NdSe1.47 s amples showed no sign of a ternary oxide second phase. The room temper ature electrical resistivity and Seebeck coefficient of LaSe, increase d with increased annealing time, while those of NdSe1.47 decreased, Th e power factors remained relatively stable with annealing time. The hi gh temperature electrical resistivity of LaSe1.47 and NdSe1.47 increas ed with increasing temperature up to 1000 degrees C, while the Seebeck coefficient became more negative. The power factor, however, peaks at 800 degrees C for LaSe1.47 and at 500 degrees C for NdSe1.47. Based a n this study we find that LaSex is not a promising high temperature th ermoelectric material due to the formation of the beta-phase, whereas the NdSe1.47 which does not form the P-phase oxide is a potential cand idate material. (C) 1997 American Institute of Physics.