Abstract
Orthorhombic In0.5Sc1.5(MoO4)3 ceramics with 3 wt% MgO as sintering aid were synthesized via solid state method at various temperatures. The effects of sintering temperature and 3 wt% MgO additive on the microstructure, density and negative thermal expansion property of the In0.5Sc1.5(MoO4)3 ceramics were examined using XRD, SEM and TMA. The results indicate that the increase of twice-sintering temperature promotes densification, and the grain size grows from 1 μm to 7 μm. When the twice-sintering temperature is further raised to 1200 °C, impurity Sc2O3 is detected due to the decomposition of In0.5Sc1.5(MoO4)3. The introduction of MgO as a sintering aid strongly affects the densification and negative thermal expansion stability of the In0.5Sc1.5(MoO4)3 ceramics owing to the formation of the liquid phase MgMoO4. The In0.5Sc1.5(MoO4)3 ceramics with 3 wt% MgO show more stable negative thermal expansion, and their average linear coefficients of thermal expansion (CTEs) are all tested to be between 4 × 10 −6 °C−1 and 5 × 10 −6 °C−1 at 30–700 °C. The variable temperature XRD results reveal In0.5Sc1.5(MoO4)3 shows anisotropic negative thermal expansion. The average CTEs of In0.5Sc1.5(MoO4)3 along a, b and c-axis are calculated to be −4.86 × 10 −6 °C−1, 4.25 × 10 −6 °C−1 and -3.25 × 10 −6 °C−1, respectively, and the volumetric CTE is calculated to be −3.83 × 10 −6 °C−1 at 25–700 °C.
Published Version
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