Unusual thermal expansion behaviour of scandium vanadate at elevated temperatures

The thermal expansivity of zircon-type scandium vanadate (ScVO 4 ) was determined by the X-ray powder diffraction method in the temperature range 300-634 K. The thermal expansion is anisotropic at room temperature as it has a larger coefficient of expansion along the a direction than along the perpendicular direction ( alpha a > alpha c ). At about 400 K, alpha c becomes equal to alpha a and, above 400 K and up to 634 K, alpha c is greater than alpha a . The mean values of alpha a and alpha c , evaluated in the temperature range 300-634 K, are found to be 9.16*10 -6 K -1 and 11.27*10 -6 K -1 , respectively.