Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR, United Kingdom.
J Am Chem Soc. 2011 Nov 16;133(45):18397-405. doi: 10.1021/ja207616c. Epub 2011 Oct 25.
Reduction of La(1-x)Ca(x)MnO(3) (0.6 ≤ x ≤ 1) perovskite phases with sodium hydride yields materials of composition La(1-x)Ca(x)MnO(2+δ). The calcium-rich phases (x = 0.9, 1) adopt (La(0.9)Ca(0.1))(0.5)Mn(0.5)O disordered rocksalt structures. However local structure analysis using reverse Monte Carlo refinement of models against pair distribution functions obtained from neutron total scattering data reveals lanthanum-rich La(1-x)Ca(x)MnO(2+δ) (x = 0.6, 0.67, 0.7) phases adopt disordered structures consisting of an intergrowth of sheets of MnO(6) octahedra and sheets of MnO(4) tetrahedra. X-ray absorption data confirm the presence of Mn(I) centers in La(1-x)Ca(x)MnO(2+δ) phases with x < 1. Low-temperature neutron diffraction data reveal La(1-x)Ca(x)MnO(2+δ) (x = 0.6, 0.67, 0.7) phases become antiferromagnetically ordered at low temperature.
氢化钠还原 La(1-x)Ca(x)MnO(3) (0.6 ≤ x ≤ 1)钙钛矿相得到组成式为 La(1-x)Ca(x)MnO(2+δ)的材料。富钙相（x = 0.9, 1）采用 (La(0.9)Ca(0.1))(0.5)Mn(0.5)O 无序岩盐结构。然而，利用中子总散射数据得到的配分函数对模型进行反向蒙特卡罗精修的局部结构分析表明，富镧 La(1-x)Ca(x)MnO(2+δ)（x = 0.6, 0.67, 0.7）相采用由 MnO(6)八面体片和 MnO(4)四面体片相互交织而成的无序结构。X 射线吸收数据证实，x < 1 的 La(1-x)Ca(x)MnO(2+δ)相中存在 Mn(I)中心。低温中子衍射数据表明，La(1-x)Ca(x)MnO(2+δ)（x = 0.6, 0.67, 0.7）相在低温下呈反铁磁有序。
