| Abstract Scope |
Characterization of the thermal expansion in the rare earth di-titanates is important for their use in high-temperature piezoelectric and dielectric applications. The thermal expansions of most rare-earth di-titanates, R2O3•2TiO2 (R = La, Pr, Nd, Sm, Gd, Dy, Er, Yb, Y), in both the monoclinic and cubic room temperature phases, were measured from room temperature to 1600℃. La2O3•2TiO2 undergoes a monoclinic to orthorhombic displacive transition on heating. The crystallographic orientation relation between these structures were studied. Crystalline powder samples were synthesized by the solution-based steric entrapment method. High temperature characterization was achieved with a quadrupole lamp furnace and 3-D thermal expansion coefficients leading to transformation mechanisms were obtained from in-situ synchrotron (APS-33BM-C) and neutron (SNS-BL11A) diffraction. Accurate temperature was determined using Pt as an internal temperature standard. Upon determination of the lattice parameters, the thermal expansion tensor was calculated and visualized using the program CTEAS. |