Phase transition and thermal expansion properties of Cr1.5-xScxZr0.5Mo2.5V0.5O12

Cr2Mo3O12 exhibits negative thermal expansion after monoclinic to orthorhombic phase transition (above 658 K). It is shown that its phase transition temperature could be reduced considerably but could not be lowered to room temperature by substitution of Zr4+/V5+ for Cr3+/Mo6+ due to limited possible substitution ratios. Considering these results, Cr1.5Zr0.5Mo2.5V0.5O12 is chosen as a basis material and further substitution of Sc3+ for Cr3+ is performed. Experimental results indicate that the phase transition temperature decreases with the increase of Sc3+ content. ScxCr1.5-x Zr0.5Mo2.5V0.5O12 (x ≥ 0.5) adopt orthorhombic structure at room temperature. Near-zero thermal expansion property in a wide temperature range for Cr0.8Sc0.7Zr0.5Mo2.5V0.5O12, Cr0.5ScZr0.5Mo2.5V0.5O12 and Sc1.5Zr0.5Mo2.5V0.5O12 is realized. Particularly, the intrinsic CTE value for Sc1.5Zr0.5Mo2.5V0.5O12 is slightly negative in 81 ∼ 573 K.