Semiconducting properties of (LnI,LnII)CuO4 and of (Ln,A)2CuO4 (Ln=rare earth, A=alkaline earth).
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概要
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The ternary oxides, (La,Pr)<SUB>2</SUB>CuO<SUB>4</SUB>, (Gd,Tb)<SUB>2</SUB>CuO<SUB>4</SUB>, (La,Tb)<SUB>2</SUB>CuO<SUB>4</SUB>, (La,Ca)<SUB>2</SUB>CuO<SUB>4</SUB> and (La,Ba)<SUB>2</SUB>CuO<SUB>4</SUB>, were prepared and their semiconducting properties were investigated. When the mean ionic radius of Ln<SUP>3+</SUP> (\bar<I>r</I>) is increased, the (La,Pr)<SUB>2</SUB>CuO<SUB>4</SUB> compounds transform from semiconductors to metals at a critical \bar<I>r</I> value of 1.05 Å. The metal-semiconductor transition which accompanies the shrinkage of the a axis, is explained as being due to the π-bond formation of the Cu–O bond. Compounds in the composition range from La<SUB>1.3</SUB>Tb<SUB>0.7</SUB>. CuO<SUB>4</SUB> to La<SUB>1.4</SUB>Tb<SUB>0.64</SUB>CuO<SUB>4</SUB> are peculiar to the (La,Tb)<SUB>2</SUB>CuO<SUB>4</SUB> compounds. The crystal structure is the same as that of Ln<SUB>2</SUB>CuO<SUB>4</SUB>, but it is different from Ln<SUB>2</SUB>CuO<SUB>4</SUB> as regards the <I>c/a</I> ratio and resistivity. The doping of 20 mol% CaO or 10 mol% BaO into La<SUB>2</SUB>CuO<SUB>4</SUB> lowers the resistivity to tenth of that of La<SUB>2</SUB>CuO<SUB>4</SUB>.
- 公益社団法人 日本化学会の論文
著者
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YAJIMA Seishi
Oarai Branch, Research Institute for Iron, Steel and Other Metals, Tohoku University
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Kenjo Tadao
Oarai Branch, Research Institute for Iron, Steel and Other Metals, Tohoku University
関連論文
- Semiconducting properties of (LnI,LnII)CuO4 and of (Ln,A)2CuO4 (Ln=rare earth, A=alkaline earth).
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