Investigating phase transitions in ABO₃perovskites using perturbed angular correlation spectroscopy

Temperature dependence of the nuclear quadrupole interaction at Zr-Ti sites in in the Zr-rich rhombohedral and cubic phases

“…In figure 2 we show the variations of the lattice parameters as functions of titanium concentration. We determined that the compounds with x = 0.9 and 0.8 had the space groups R3c, that with x = 0.6 had the space group R3m and those with x = 0.4, 0.2, 0.1 and 0 had the space group P 4mm, in good agreement with previous reports [4][5][6]9]. For the rhombohedral phase, the value of the c-axis lattice parameter is referred to as the hexagonal double-unit-cell parameter [7].…”

“…For the cubic phase of pure ABO 3 compounds it has been observed by PAC spectroscopy that probes are perturbed by a dynamic EFG, while samples with the formula AB x B (1−x) O 3 show a static EFG. For example, BaTiO 3 [9] and BaHfO 3 [21] each show a hyperfine relaxation process in their respective cubic phases. The same result has been obtained for PbZrO 3 by us and for PbTiO 3 [16].…”

“…With the knowledge of atomic positions and phase characterizations, many models have been applied to these and other perovskite-type compounds, in efforts to understand the origin of the ferroelectricity and the nature of the phase transitions. Although the perovskite-type compounds are simple in their atomic structure, it is still not clear whether the phase transitions have displacive or dynamic character [8,9]. In this work we present for the first time a hyperfine analysis of PZT using perturbed angular correlation (PAC) spectroscopy.…”