Abstract
Temperature-dependent structural phase transitions and dielectric properties for a series of (NBT-BT) samples where ranges from 0.05 to 0.30 have been investigated. Non-ambient x-ray diffraction together with dielectric data as a function of temperature have demonstrated an enhancement in the ferroelectric to paraelectric phase transition temperature with the increase in NBT content, including inhibition of two well-known low-temperature polymorphic phase transitions of . Anomalous dielectric response has been observed for samples with suggesting a crossover from a first-order to a second-order phase transition. The critical point lies between and . Deviation from the classical Curie-Weiss law has been seen for samples having . A modified Curie-Weiss law was employed to model the dielectric response in the paraelectric phase and the maximum value of the critical exponent was found to be 1.45 for . It is suggested that the dielectric properties are heavily influenced by the induced strain upon doping rather than chemical inhomogeneities and structural disorder, which are common occurrences in doped ferroelectrics.
- Received 28 June 2010
DOI:https://doi.org/10.1103/PhysRevB.82.224105
©2010 American Physical Society