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

Cr 2 Mo 3 O 12 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 Zr 4+ /V 5+ for Cr 3+ /Mo 6+ due to limited possible substitution ratios. Considering these results, Cr 1.5 Zr 0.5 Mo 2.5 V 0.5 O 12 is chosen as a basis material and further substitution of Sc 3+ for Cr 3+ is performed. Experimental results indicate that the phase transition temperature decreases with the increase of Sc 3+ content. Sc x Cr 1.5-x Zr 0.5 Mo 2.5 V 0.5 O 12 (x ≥ 0.5) adopt orthorhombic structure at room temperature. Near-zero thermal expansion property in a wide temperature range for Cr 0.8 Sc 0.7 Zr 0.5 Mo 2.5 V 0.5 O 12 , Cr 0.5 ScZr 0.5 Mo 2.5 V 0.5 O 12 and Sc 1.5 Zr 0.5 Mo 2.5 V 0.5 O 12 is realized. Particularly, the intrinsic CTE value for Sc 1.5 Zr 0.5 Mo 2.5 V 0.5 O 12 is slightly negative in 81 ∼ 573 K. [ABSTRACT FROM AUTHOR]