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化学学报
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化学学报 ›› 1995, Vol. 53 ›› Issue (11): 1065-1070. 上一篇    下一篇

研究论文

Ln～nMCo～nO～3n+1(Ln=Sm, GD; M=Sr, Ba; n=1,2)的合成、结构、电和磁性质研究

李思温;任玉芳   

  1. 中国科学院长春应用化学研究所;中国科学院稀土化学与物理开放实验室
  • 发布日期:1995-11-15

Studies on the synthetic, structural, electrical and magnetic properties of Ln～nMCo～nO～3n+1(Ln=Sm, GD; M=Sr, Ba; n=1,2)

LI SIWEN;REN YUFANG   

  • Published:1995-11-15

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用固相反应法合成了三个新的交生相氧化物: S2SC2O7,G2SC2O7和Sm2BaCo2O7。它们均具有Sr3Ti2O7型的结构, 其中Sm2BaCo2O7属于正交晶系, 其他属于四方晶系。与LnSrCoO4相比, Ln2SrCo2O7(Ln=Sm, Gd)中CoO2平面上的Co-O键缩短, 电子离域化趋势增强, 导电能力提高。在300-1100K之间, 电阻率与温度关系表明, 五个氧化物均表现弱定域系统的特性。300-1100K之间的磁化率与温度关系表明, 在较低温度下, GdSrCoO4和Gd2SrCo2O7符合Curie-Weiss定律, 但前者的CoO2平面上的磁交换作用是反铁磁性的, 而后者是铁磁性的; 含Sm^3^+的三个氧化物表现出较为复杂的磁性质, 这可能与Sm^3^+离子磁性的复杂性有关。

关键词: 氧化钴, 氧化钡, 氧化锶, 氧化镉, 相结构, 磁化强度, 氧化钐, 电磁性质

Three new oxides Sm2SrCo2O7, Sm2BaCo2O7 and Gd2SrCo2O7 have been synthesized successfully by solid state reaction mathod. The X-Ray diffraction spectra show that they are all isostructural with Sr3Ti2O7, and Ln2SrCo2O7 (Ln=Sm, Gd) crystallized in tetragonal system, Sm2BaCo2O7 in orthrhombic system. The Co-O bonds in CoO2 planes of Ln2SrCo2O7 are shorter than those of LnSrCoO4 (Ln=Sm, Gd), and so their delectrons are more delocalized and their electrical resistivities are smaller. The electrical resistivities versus temperature in the range300-1100K showed that the five oxides show the characters of weakly localized systems. In the lower temperature range, the magnetic behaviors of Gd2SrCo2O7 and GdSrCoO4 fit Curie-Weiss law well, and the magnetic exchange reaction in CoO2 sublattices of Gd2SrCo2O7 is ferromagnetic, but that of GdSrCoO4 is antiferromagnetic. The other three oxides with Sm^3^+ showed complex magnetic behaviors which is perhaps related with the complexity of Sm^3^+.

Key words: COBALT OXIDE, BARIUM OXIDE, STRONTIUM OXIDE, CADMIUM OXIDE, PHASE STRUCTURE, MAGNETIZATION, SAMARIUM OXIDE, ELECTROMAGNETIC PROPERTIES

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