Static and dynamic strain relaxation associated with the paraelectric-antiferroelectric phase transition in PbZrO3
Static and dynamic strain relaxation associated with the paraelectric-antiferroelectric phase transition in PbZrO3
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DOI：
10.1016/j.jallcom.2021.162804
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发表时间：
2021-11
影响因子：
6.2
通讯作者：
M. A. Carpenter;E. Salje;M. B. Costa;A. Majchrowski;K. Roleder
中科院分区：
文献类型：
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作者：
M. A. Carpenter;E. Salje;M. B. Costa;A. Majchrowski;K. Roleder
从应变和弹性的角度分析了PbZrO 3在~ 510 K的一级反常铁弹（Pm 3-Pbam）相变的序参量耦合.从文献中的晶格参数数据的自发应变的正式治疗揭示了典型的耦合与八面体倾斜，QR，和更强的耦合与反铁电位移，Q的序参数。这表明两个阶参数之间通过共同应变的耦合不仅是双二次的λ Q2 RQ 2，而且可能有高阶项λ Q2 RQ 4的贡献。通过共振超声光谱（罗斯）在1 MHz附近的频率下获得的弹性和滞弹性性质的变化显示软化的过渡点接近从上面，不连续的硬化在过渡点和图案的进一步硬化的正交结构的稳定领域。在转变点以下，硬化模式类似于Q 2 R和Q 2 R的演化，这是典型的由λe 2 Q 2项主导的耦合，其中e是自发剪切应变。由于λeQ 2形式的项导致的软化的缺失意味着响应于诱导剪切应变的序参数变化的弛豫时间慢于~ 10-6 s。此外，在较低的频率从文献中的测量相比，没有证据的铁弹畴壁的流动性观察到在罗斯频率。在过渡点和前体软化的立方相的稳定性领域中观察到的声损失的峰值是一致的本地动态极性集群的证据。除了在弛豫时间上的一些差异，PbZrO 3中的反铁电转变似乎并不明显不同于BaTiO 3中发生的铁电转变。
Order parameter coupling associated with the first order, improper ferroelastic (Pm 3 ̅ m-Pbam) transition at~ 510 K in PbZrO 3 has been analysed from the perspective of strain and elasticity. Formal treatment of spontaneous strains using lattice parameter data from the literature reveals typical coupling with the order parameter for octahedral tilting, Q R, and stronger coupling with the order parameter for antiferroelectric displacements, Q Σ. These indicate that coupling between the two order parameters via common strains is not only biquadratic, λQ 2 R Q 2 Σ, but may also have contributions from a higher order term, λQ 2 R Q 4 Σ. Variations of elastic and anelastic properties obtained by resonant ultrasound spectroscopy (RUS) at frequencies in the vicinity of 1 MHz show softening as the transition point is approached from above, discontinuous stiffening at the transition point and a pattern of further stiffening in the stability field of the orthorhombic structure. Below the transition point, the pattern of stiffening resembles the evolution of Q 2 R and Q 2 Σ, as is typical of coupling dominated by terms with the form λe 2 Q 2, where e is a spontaneous shear strain. The absence of softening due to terms of the form λeQ 2 implies that the relaxation time for changes in the order parameters in response to an induced shear strain is slower than~ 10-6 s. Also in contrast with measurements from the literature made at lower frequencies, no evidence for mobility of ferroelastic domain walls was observed at RUS frequencies. A peak in acoustic loss observed at the transition point and precursor softening in the stability field of the cubic phase are consistent with evidence for local dynamical polar clusters. Apart from some differences in relaxation times, the antiferroelectric transition in PbZrO 3 does not appear to be overtly different from ferroelectric transitions such as occur in BaTiO 3.