Near-Zero Thermal Expansion in In(HfMg)(0.5)Mo3O12

作者：Miller Kimberly J; Romao Carl P; Bieringer Mario; Marinkovic Bojan A; Prisco Luciana; White Mary Anne^*

来源：Journal of the American Ceramic Society, 2013, 96(2): 561-566.

DOI：10.1111/jace.12085

In(HfMg)0.5Mo3O12, which can be considered as a 1:1 mole ratio solid solution of the low-positive thermal expansion material HfMgMo3O12 and the low-negative thermal expansion (NTE) material In2Mo3O12 was prepared. From DSC and XRPD results, we show that In(HfMg)0.5Mo3O12 exists in a monoclinic (P21/a) structure at low temperature and undergoes a phase transition at similar to 425K to an orthorhombic phase (Pnma), with an associated enthalpy change of 0.89kJmol1. Thermal expansion is large and positive in the low-temperature monoclinic phase (average =16x106K1 and 20x106K1, from dilatometry and XRPD, respectively). Remarkably, this material has a near-zero thermal expansion (ZTE) coefficient over the temperature range similar to 500 to similar to 900K in the high-temperature orthorhombic phase, both intrinsically and for the bulk sample. The average linear intrinsic (XRPD) value is =0.4x106K1, and the average bulk (dilatometric) value is =0.4x106K1 with an uncertainty of +/- 0.2x106K1. The slight difference between intrinsic and bulk thermal expansion is attributed to microstructural effects. XRPD results show that the thermal expansion is more isotropic than for the parent compounds HfMgMo3O12 and In2Mo3O12.

• 出版日期2013-2