THERMAL-EXPANSION COEFFICIENTS OF ZIRCONOLITE (CAZRTI2O7) AND PEROVSKITE (CATIO3) FROM X-RAY-POWDER DIFFRACTION ANALYSIS

The thermal expansion coefficients of zirconolite, both ordered and disordered, and perovskite, were measured by X-ray powder diffraction analysis in the temperature range 25-1200-degrees-C. The principal results are: (1) The mean thermal expansion coefficients (K-1) of ordered zirconolite are: alpha(a) = (11.35 +/- 0.25) x 10(-6); alpha(b) = (8.72 +/- 0.22) x 10(-6) ; alpha(c) = (10.0 +/- 0.5) x 10(-6). (2) The mean thermal expansion coefficients (K-1) of disordered zirconolite are alpha(parallel-to) = (9.89 +/- 0.15) x 10(-6) in the (001) plane and alpha(perpendicular-to) = (9.37 +/- 0.14) x 10(-6) normal to (001). (3) The mean thermal expansion coefficients (K-1) of perovskite are: alpha(a) = (7.86 +/- 0.30) x 10(-6); alpha(b) = (13.46 +/- 0.17) x 10(-6); alpha(c) = (16.55 +/- 0.26) x 10(-6).