Thermal expansion of (Ca1-xPux)TiO3

The phase relationship between PuO2-x and CaTiO3 at room temperature was in vestigated by X-ray diffraction. It was found that Pu was soluble to at lea st 20 mol% in CaTiO3 in Ar-8% H-2. Solubility of Pu in CaTiO3 was extremely limited (below 5 mol%) under oxidizing condition. The thermal expansion of (Ca1-xPux)TiO3 (x = 0-0.15) was investigated in the temperature range from room temperature to 1273 K by high-temperature X-ray diffraction. The linea r thermal expansion coefficients showed considerable anisotropy for the ort horhombic Pbnm structure and decreased with increasing Pu content. The stru ctural phase-transition temperatures were estimated from the lattice consta nts and were relatively insensitive to the content of Pu dopant. The estima ted melting point increased with increasing Pu content, indicating that the thermodynamic stability of CaTiO3 increased with the addition of Pu. (C) 2 001 Elsevier Science B.V. All rights reserved.