The main phase ZrV2O7 material, doped with zirconia and vanadium (V) oxide, was synthesized by solid state reaction and sol-gel methods. X-ray power diffraction patterns show that it is cubic structure. Thermal mechanic analysis measurements present a zero-thermal expansion of this material above 150℃. As well the heat capacity dependent on temperature, determined by differential scanning calorimetry, keeps in constant almost in the same temperature range. The relation between unusual thermal expansion and abnormal heat capacity is discussed with quantum mechanics.

Lattice parameters of lead titanate were precisely re-determined in the temperature range of −150-950℃ by high precision XRPD measurements. It was clarified that there was no any evidence for a new phase transition at low temperatures. Tetragonal distortion strain decreases with temperature increasing. A novel thermal expansion was observed, positive thermal expansion from −150℃ to room temperature (RT) and above 490℃, and the negative thermal expansion in the temperature range of RT-490℃. A big jump of thermal expansion coefficient is attributed to the tetragonal-cubic phase transition. A rationalization for the negative thermal expansion of PbTiO3 is due to the decrease of anion-anion repulsion as polyhedra become more regular at heating. The mechanisms of positive and negative thermal expansions were elucidated as the same nature in the homogenous tetragonal phase at present case.

The solid solution limit of Pb1-xSrxTiO3 was determined in the composition range of 0≤x≤1.0 at room temperature (RT). The phases 12x x 3 were isolated and indexed in a tetragonal system with x<0.5 and in a cubic one with x≥0.5. The cell parameters of Pb1-xSrxTiO3 continuously, but nonlinearly, change with solubility x. The intrinsic thermal expansions of the solid solution compounds Pb1-xSrxTiO3 (x=0, 0.15, 0.20, 0.50, 0.90, 1.0) were obtained in the temperature range from RT to 1173K with high-temperature X-ray powder diffraction. Negative thermal expansion coefficients of Pb Sr TiO (x=0, 0.15, 0.20) were found below the Curie points. The thermal expansions of these titanate ceramics were highly correlated with the solubility in the solid solution Pb1-xSrxTiO3.