Abstract
We present detailed Raman studies of SrZrO3 (SZO) that show three anomalies in Raman modes: One has a small jump in frequency ω, one has its intensity vanish, and a third has a sharp change in temperature derivative dω(T)/dT from flat below T = 600 K to a Curie–Weiss dependence above 600 K with extrapolation to zero frequency at the known transition temperature T = 970 K, thereby proving the latter to be displacive. In addition, the P4mm ferroelectric phase predicted at high stresses has preliminary support from polarization-voltage experiments. The inference of a new transition in the temperature region 600–650 K is in disagreement with neutron studies. Comparisons are given for family member SrSnO3 and SrHfO3, and we discuss the different conclusions of Kennedy and Knight. We show that a known transition in SrHfO3 is also displacive with a well-behaved soft mode.
Highlights
Pervoskites such as SrZrO3 (SZO), SrSnO3, SrHfO3, and SrTiO3 are important high-k dielectrics that possess a highly tilted B-site octrahedron in this ABO3-crystal structure
We have reported polaron-assisted giant dielectric dispersion in SZO, which may suggests a strong tilt in ZrO6 octahedra in the intermediate temperature range.[20]
We found nearly complete merger of two Ag modes and one B1g (B3g) modes between 240–315 cm−1 below 800 K, above which a single temperature-independent 280 cm−1 Ag Raman mode persists until the higher structural phase transition temperature
Summary
Pervoskites such as SrZrO3 (SZO), SrSnO3, SrHfO3, and SrTiO3 are important high-k dielectrics that possess a highly tilted B-site octrahedron in this ABO3-crystal structure. Due to the tilting of BO6 octahedra, these systems follow a series of phase transitions from high-crystal to low-crystal symmetry with decrease in temperature.
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