Negative thermal expansion in Sc2(WO4)3

被引:370
作者
Evans, JSO
Mary, TA
Sleight, AW
机构
[1] Oregon State Univ, Dept Chem, Corvallis, OR 97331 USA
[2] Oregon State Univ, Ctr Adv Mat Res, Corvallis, OR 97331 USA
基金
美国国家科学基金会;
关键词
D O I
10.1006/jssc.1998.7744
中图分类号
O61 [无机化学];
学科分类号
070301 ; 081704 ;
摘要
Sc-2(WO4)(3) has been found to show the highly unusual property of negative thermal expansion over a temperature range of 10 to 1073 K. Powder neutron diffraction data from 10 to 450 K shows an essentially linear decrease in cell volume as a function of temperature. The intrinsic linear coefficient of thermal expansion from this data is -2.2x10(-6)K(-1). The linear coefficient of thermal expansion measured on a ceramic bar of Sc-2(WO4)(3) can be as negative as -11x10(-6) K-1 due to microstructure changes as a function of temperature. Rietveld refinement as a function of temperature suggests that the intrinsic negative thermal expansion can be related to transverse vibrations of bridging oxygen atoms in the structure. The anharmonic nature of these vibrations leads to a coupled tilting of the quasi-rigid framework polyhedra. This tilting in turn causes the structure to become more dense with increasing temperature. (C) 1998 Academic Press.
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页码:148 / 160
页数:13
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