Phase transition and thermal expansion in W-substituted In2Mo3O12 ceramics

Abstract

In2Mo3O12 is considered to be a positive thermal expansion (PTE) material at room temperature since its negative thermal expansion (NTE) response temperature range is above 343 °C. With the expectation of tuning the NTE performance of In2Mo3O12, a series of In2Mo3-xWxO12 solid solutions was synthesized via B-site replacement by W6+. The effects of W6+ substitution on the phase composition, morphology, phase transition temperature (Tpt) and thermal expansion behavior of In2Mo3-xWxO12 were systematically investigated. Results indicate that the replacement of Mo6+ by W6+ does not induce a change in the crystal structure of parent phase In2Mo3O12 and can form continuous solid solutions of In2Mo3-xWxO12. With increasing composition parameter x, the Tpt of In2Mo3-xWxO12 decreases, the corresponding NTE response temperature range is widened and NTE performance is improved. The coefficient of thermal expansion (CTE) of In2Mo3-xWxO12 becomes more negative. As expected, the Tpt of In2Mo3-xWxO12 is tunable by adjusting the composition parameter x, and the tuning mechanism of NTE performance is discussed from the prospect of crystal structure.