三次元ヘテロ金属集合体,{Ln[Cr(ox)_3]・10H_2O}_x(Ln=La,Pr or Nd),を出発原料とするペロブスカイト型酸化物の調製とその性質

概要

論文の詳細を見る
Three kinds of heterometal assemblies, {Ln[Cr(ox)_3]・10H_2O}_x (Ln=La, Pr or Nd), were prepared by the reaction of K_3[Cr(ox)_3]・3H_2O with Ln(NO_3)_3・6H_2O in water. These compounds were regarded to have the oxalato-bridged three-dimensional lattice. The thermal decomposition behavior of these assemblies was investigated in an air stream. The behavior was similar to each other. The mixed oxides, LnCrO_4, and the perovskite-type oxides, LnCrO_3, were found to form in the temperature range of 823 to 973 K and above 1023 K, respectively. Specific surface areas of LaCrO_3, PrCrO_3, and NdCrO_3 obtained by calcining the corresponding complex assemblies at 1073 K were 1.82, 1.85, and 1.91 m^2・g^<-1>, respectively. The effective magnetic moment per LaCr unit of LaCrO_3 increased from 1.98 μ_B at 296 K to 2.79 μ_B at 285 K, and then the moment decreased below 285 K because of the phase transition. PrCrO_3 and NdCrO_3 showed ferrimagnetic behavior. That is, the magnetic moments per LnCr units of PrCrO_3 and NdCrO_3 increased drastically below 240 and 225 K, respectively, also due to the phase transition. The moments of PrCrO_3 and NdCrO_3 were 9.79 μ_B at 219 K and 18.98 μ_B at 223 K, respectively, which were much larger than those expected from the respective total spin states, S_T=5/2 for PrCrO_3 and S_T=3 for NdCrO_3.
社団法人日本セラミックス協会の論文
1992-10-01