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Spin State Control of the Perovskite Rh/Co Oxides
Department of Applied Physics, Waseda University, Tokyo 169-8555, Japan
Waseda Institute for Advanced Study, Waseda University, Tokyo 169-8050, Japan
* Author to whom correspondence should be addressed.
Received: 30 December 2009; in revised form: 23 January 2010 / Accepted: 26 January 2010 / Published: 27 January 2010
Abstract: We show why and how the spin state of transition-metal ions affects the thermoelectric properties of transition-metal oxides by investigating two perovskite-related oxides. In the A-site ordered cobalt oxide Sr3YCo4O10.5, partial substitution of Ca for Sr acts as chemical pressure, which compresses the unit cell volume to drive the spin state crossover, and concomitantly changes the magnetization and thermopower. In the perovskite rhodium oxide LaRhO3, partial substitution of Sr for La acts as hole-doping, and the resistivity and thermopower decrease systematically with the Sr concentration. The thermopower remains large values at high temperatures (>150 μV/K at 800 K), which makes a remarkable contrast to La1-xSrxCoO3. We associate this with the stability of the low spin state of the Rh3+ ions.
Keywords: thermopower; spin state; oxide thermoelectrics; Heikes formula
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Terasaki, I.; Shibasaki, S.; Yoshida, S.; Kobayashi, W. Spin State Control of the Perovskite Rh/Co Oxides. Materials 2010, 3, 786-799.
Terasaki I, Shibasaki S, Yoshida S, Kobayashi W. Spin State Control of the Perovskite Rh/Co Oxides. Materials. 2010; 3(2):786-799.
Terasaki, Ichiro; Shibasaki, Soichiro; Yoshida, Shin; Kobayashi, Wataru. 2010. "Spin State Control of the Perovskite Rh/Co Oxides." Materials 3, no. 2: 786-799.