Research Center for Functional Materials , National Institute for Materials Science (NIMS) , Namiki 1-1 , Tsukuba , Ibaraki 305-0044 , Japan.
Graduate School of Chemical Sciences and Engineering , Hokkaido University , North 10 West 8, Kita-ku , Sapporo , Hokkaido 060-0810 , Japan.
Inorg Chem. 2019 Mar 4;58(5):3492-3501. doi: 10.1021/acs.inorgchem.9b00049. Epub 2019 Feb 15.
SmMnMn(MnTi )O with 1 ≤ x ≤ 3 were prepared by a high-pressure, high-temperature method at 6 GPa and about 1570-1670 K. They belong to a family of A-site columnar-ordered quadruple perovskites AA'A″BO, where A' is a site with a square-planar coordination and A″ is a site with a tetrahedral coordination. Their crystal structures were investigated using synchrotron X-ray and neutron powder diffraction. They crystallize in space group P4/ nmc (No. 137) with a = 7.41172 Å and c = 7.97131 Å for x = 1, a = 7.54945 Å and c = 7.76756 Å for x = 2, and a = 7.63949 Å and c = 7.70339 Å for x = 3 at 295 K. The determined charge and cation distributions are [SmMn][Mn][MnSm][MnTi]O for x = 1, [SmMn][Mn][MnSm][MnTi]O for x = 2, and [SmMn][MnSm][Mn][MnTi]O for x = 3. Mn and Ti are distributed randomly in one B site in all compounds with the average oxidation state changing from +3.25 to +3.5 per one B atom, and such flexibility is realized because Mn at the A' site can change its oxidation state between +2 and +3. Sm and Mn are slightly disordered between the A and A″ sites for x = 1 and 2, and between the A and A' sites for x = 3. The x = 1 sample shows spin-canted antiferromagnetic properties with T = 27 K, and the x = 2 sample, with T = 62 K. On the other hand, the x = 3 sample is a ferrimagnet, confirmed by neutron diffraction, with T = 40 K. The x = 3 sample shows relaxor-like dielectric properties below 220 K.
SmMnMn(MnTi)O（1≤x≤3）采用高压高温法在 6 GPa 和 1570-1670 K 下制备。它们属于 A 位柱状有序四重钙钛矿 AA'A″BO 家族，其中 A'位为平面正方形配位，A″位为四面体配位。它们的晶体结构通过同步加速器 X 射线和中子粉末衍射进行了研究。它们在空间群 P4/ nmc（No.137）中结晶，a = 7.41172 Å，c = 7.97131 Å（x = 1），a = 7.54945 Å，c = 7.76756 Å（x = 2），a = 7.63949 Å，c = 7.70339 Å（x = 3）在 295 K 下。确定的电荷和阳离子分布为 x = 1 时为[SmMn][Mn][MnSm][MnTi]O，x = 2 时为[SmMn][Mn][MnSm][MnTi]O，x = 3 时为[SmMn][MnSm][Mn][MnTi]O。在所有化合物中，Mn 和 Ti 随机分布在一个 B 位，每个 B 原子的平均氧化态从+3.25 变为+3.5。这种灵活性是由于 A'位的 Mn 可以在+2 和+3 之间改变其氧化态。对于 x = 1 和 2，Sm 和 Mn 在 A 和 A″位之间略有无序，对于 x = 3，Sm 和 Mn 在 A 和 A'位之间略有无序。x = 1 样品显示出 T = 27 K 的自旋倾斜反铁磁性质，x = 2 样品显示出 T = 62 K 的自旋倾斜反铁磁性质。另一方面，x = 3 样品是铁磁体，通过中子衍射证实，T = 40 K。x = 3 样品在低于 220 K 时表现出类弛豫介电性质。
