Tetragonal to Cubic Phase Transition in Sr 0.75 Ba 0.25 HfO 3

Autor: A. López-García, D. G. Lamas, R. E. Alonso, Alberto Caneiro, C. M. Horowitz
Rok vydání: 2002
Předmět:
Zdroj: Ferroelectrics. 269:117-122
ISSN: 1563-5112
0015-0193
DOI: 10.1080/00150190211128
Popis: Using powder X-Ray Diffraction and Perturbed-Angular-Correlation spectroscopy, the crystal structure and the hyperfine interaction at 181 Ta probe in Sr 0.75 Ba 0.25 HfO 3 have been studied. A tetragonal (I4/mcm) to cubic (Pm &3macr;m) phase transition was observed. A two-phase field region, where the tetragonal and cubic phases coexist, was found between 673 and 923 K. The spin precession curves were measured from room temperature up to 1373 K. A static, asymmetric and disordered electric field gradient model was used to fit these time spectra. The hyperfine parameters corresponding to the tetragonal structure changed as the temperature increases: y T Q diminishes, m T is almost constant and i T diminishes. This interaction was observed to be unique up to 673 K. Above this temperature, a second interaction appeared and these two phases coexist up to 923K. Above this temperature, the hyperfine parameters corresponding to the cubic structure was only observed. The tetragonal to cubic transformation is char...
Databáze: OpenAIRE