Ln_2CuSnO_6(Ln=La, Pr, Nd, Sm)の高圧合成

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La2CuSnO6, even though it contains CuO2 layers, does not exhibit superconductivity. It might result from the in-plain Cu-O bond length being too long(about 2.0 Å, compared with 1.9 Å of La2CuO4). So, we replaced La with smaller atoms Pr, Nd, Sm, expecting that these might contract the CuO2 layers and lead to superconductivity. For synthesis we used high pressure(6Gpa for Pr, Nd and 8Gpa for Sm). The result Is that, contrary to our wish, the CuO2 layers buckled even more seriously and the Cu-O bond did not get shorter. In this paper, we focused on the magnetism of Ln2CuSnO6(Ln=La, Pr, Nd). In the temperature range of 150 to 350K, these compounds showed almost the same characteristics which have been explained assuming spin-canted weak ferromagnetism. However, Pr2CuSnO6and Nd2CuSnO6exhibited ferromagnetic behavior at lower temperature suggesting ordering of the Pr3+(Nd3+)moments. Antlferromagnetic coupling between the weak ferromagnetic CuO2 layers and the ferromagnetic LnO layers has also been suggested.
社団法人粉体粉末冶金協会の論文
1997-02-15