Tuning the phase transition temperature of Cr2(MoO4)3 by A-site substitution of scandium

Abstract A series of Cr 2-x Sc x (MoO 4 ) 3 solid solutions with tunable monoclinic-to-orthorhombic phase transition temperature have been synthesized via solid-state reaction. X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) results show that all synthesized Cr 2-x Sc x (MoO 4 ) 3 (0  3+ has been substituted by Sc 3+ in Cr 2 (MoO 4 ) 3 . Monoclinic to orthorhombic phase transition temperature of Cr 2-x Sc x (MoO 4 ) 3 can be effectively tuned from 372 °C to room temperature as the substituted Sc 3+ -content (x) varies from 0 to 1.4. The synthesized Cr 0.6 Sc 1.4 (MoO 4 ) 3 crystalizes in an orthorhombic structure at room temperature, exhibiting anisotropic negative thermal expansion throughout the testing temperature range. The coefficient of thermal expansion measured by thermal mechanical analyzer (TMA) for Cr 0.6 Sc 1.4 (MoO 4 ) 3 is −11.17 × 10 −6 °C −1 in the testing temperature range of 30–600 °C. Moreover, the crystallization, micromorphology, density and coefficient of thermal expansion of Cr 0.6 Sc 1.4 (MoO 4 ) 3 are obviously sensitive to the twice sintering temperature, whereas none of such sensitivity is found for the phase transition temperature.