Compressibility, phase transitions, and oxygen migration in zirconium tungstate, ZrW2O8
Compressibility, phase transitions, and oxygen migration in zirconium tungstate, ZrW2O8
复制标题
DOI：
10.1126/science.275.5296.61
复制
发表时间：
1997-01-03
期刊：
影响因子：
56.9
通讯作者：
Sleight, AW
中科院分区：
文献类型：
--
作者：
Evans, JSO;Hu, Z;Sleight, AW
原位中子衍射实验表明，在2千巴以上的压力下，立方钨酸锆(ZrW2O8)经历了一个可淬火的相变，由粉末衍射数据确定了其结构。这种相变可以通过在393开尔文和1大气压下加热来逆转，并且涉及晶格中氧原子的迁移。高压相在20-300开尔文范围内表现为负热膨胀。立方体和正交体的相对热膨胀和压缩系数可以用相变引起的多面体之间的“交叉支撑”来解释。
In situ neutron diffraction experiments show that at pressures above 2 kilobars, cubic zirconium tungstate (ZrW2O8) undergoes a quenchable phase transition to an orthorhombic phase, the structure of which has been solved from powder diffraction data. This phase transition can be reversed by heating at 393 kelvin and 1 atmosphere and involves the migration of oxygen atoms in the lattice. The high-pressure phase shows negative thermal expansion from 20 to 300 kelvin. The relative thermal expansion and compressibilities of the cubic and orthorhombic forms can be explained in terms of the ''cross-bracing'' between polyhedra that occurs as a result of the phase transition.