THE ELECTRICAL PROPERTIES OF LANTHANUM AND CERIUM SESQUISULFIDES (in Russian)
Samples of La/sub 2/S/sub 3/ and Ce/sub 2/S/sub 3/ with a residual porosity of 13 to 18% were prepared by sintering in a H/sub 2/S atmosphere. The electrical resistance and thermal emf were measured from 100 to 1000 deg C. Both sulfides are p-type, impurity semiconductors. The transition temperature for a particular type of conductivity is 600 to 700 deg C for La/sub 2/S/sub 3/ and 670 plus or minus 50 deg C for Ce/sub 2/S/sub 3/. The impurity activation energy DELTA E/sub im p/ is 0.32 ev for La/sub 2/S/sub 3/ and 0.25 ev for Ce/sub 2/S/sub 3/. The width of the forbidden zone DELTA E0 is 1.32 ev for La/sub 2/S/sub 3/, and 1.12 ev for Ce/sub 2/S/sub 3/. The positive thermal emf is given by the formula alpha /sub t/ = +861( DELTA E/sub imp//2kT) --1.98! for La/sub 2/S/sub 3/ , and by the f ormula alpha /sub t/ = DELTA E/sub imp//2kT mu V/deg for Ce/sub 2/S/sub 3/. The negative ther mal emf is directly proportional to the temperature, and is given by the following empirical formulas: alpha /sub t/ = -- STA250 + 3(t -- 800)! mu V/deg for La/sub 2/8/sub 3/, and alpha /ub t/ = --4(t - - 800) mu V/ deg for Ce/sub 2/S/sub 3/. The thermoelectric factor of merit for the lanthandum and cerium sesquisulfides is approximately equal to Z/sub 1200 deg / = 10/sup -3/ deg/sup -1/. (TTT)
- Research Organization:
- Inst. of Cermets and Special Alloys, Academy of Sciences, Ukrainian SSR
- NSA Number:
- NSA-18-003735
- OSTI ID:
- 4133791
- Journal Information:
- Doklady Akademii Nauk SSSR (U.S.S.R.) English translation currently published in a number of subject-oriented journals, Journal Name: Doklady Akademii Nauk SSSR (U.S.S.R.) English translation currently published in a number of subject-oriented journals Vol. Vol: 152; ISSN DANKA
- Country of Publication:
- Country unknown/Code not available
- Language:
- Russian
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THERMOEMISSION PROPERTIES OF LANTHANUM AND CERIUM SULFIDES