High-pressure rare earth silicates: Lanthanum silicate with barium phosphate structure, holmium silicate apatite, and lutetium disilicate type X
作者:Michael E. Fleet、Xiaoyang Liu
DOI:10.1016/j.jssc.2005.08.007
日期:2005.11
3×b and 7×b superstructures identified. (2) Ho8.67(SiO4)6(OH)2: hexagonal, P63/m, Z=1, a=9.3221(4), c=6.7347(2) Å, R=0.026; silicate hydroxyapatite. (3) Lu2Si2O7: tetragonal, P41212, Z=4, a=6.5620(2), c=11.9535(4) Å, R=0.023; type X diorthosilicate structure, and the silicate analogue of tetragonal Er2Ge2O7.
使用活塞缸和多砧设备对高达10 GPa和1700°C的多种稀土二硅酸盐的相关系进行了研究。已获得以下高压相的单晶X射线结构:(1)La 2.67(SiO 4)2:单斜晶,空间群C 2 / m,Z = 2,a = 9.419(2),b= 5.445(1),c= 7.214(1),β= 115.71(3)°,R= 0.042。Ba 3(PO 4)2无序结构类型,具有3× b和7× b确定上层建筑。(2)何8.67(SIO 4)6(OH)2:六边形,P 6 3 /米,Ž = 1,一个= 9.3221(4),C ^ = 6.7347(2)埃,- [R = 0.026; 硅酸盐羟基磷灰石。(3)Lu 2 Si 2 O 7:四方的,P 4 1 2 1 2,Z= 4,a= 6.5620(2),c= 11.9535(4),R= 0.023。X型原硅酸盐结构和四方Er的硅酸盐类似物2 Ge 2 O 7。