CAJ | 학술논문

采用第一性原理方法研究了β-La_2Mo_2O_9结构性质.研究发现结构中Mo和周围的O形成MoO_4或MoO_5两种形式的多面体,La则形成LaO_8和LaO_7多面体.O(1)、O(2)、O(3)三种氧位置的占有率分别为100%、91.7%和25%,与实验相符.对Mo-O(1)键长分析表明,在MoO_4和MoO_5两种多面体中Mo-O(1)键长劈裂成两种键长形式.所有结构组态可通过P2_13空间群的相应操作而互相转换,显示结构具有P2_13空间群的对称性.模拟结果可能是β-La_2Mo_2O_9结构在空间的局域或者本征极小结构.
채용제일성원리방법연구료β-La_2Mo_2O_9결구성질.연구발현결구중Mo화주위적O형성MoO_4혹MoO_5량충형식적다면체,La칙형성LaO_8화LaO_7다면체.O(1)、O(2)、O(3)삼충양위치적점유솔분별위100%、91.7%화25%,여실험상부.대Mo-O(1)건장분석표명,재MoO_4화MoO_5량충다면체중Mo-O(1)건장벽렬성량충건장형식.소유결구조태가통과P2_13공간군적상응조작이호상전환,현시결구구유P2_13공간군적대칭성.모의결과가능시β-La_2Mo_2O_9결구재공간적국역혹자본정겁소결구.
. The structure of β-La_2Mo_2O_9 was studied by using two methods based on first-principles theory. Each Mo cation is surrounded by four or five O-ions, forming MoO_4 tetrahedra or MoO_5 hexahedra,La has LaO_8 and LaO_7 polyhedra. It is found that the occupancies of three crystallographic distinct O sites O(1), O(2) and O(3) are 100%, 91.7% and 25%, respectively, consistent with experiments. The analysis of Mo-O(1) bond length demonstrates the split of O(1) sites into two groups. All configurations are related to each other by one of 12 symmetry operations of P2_1 3 space group, suggesting that the structure observed experimentally may be interpreted as a time and spatial average of these local or inherent structures.