The origin of weak coupling between polar clusters in Ta2O5-doped 0.94Bi0.5Na0.5TiO3-0.06BaTiO3

Ta2O5-doped 0.94Bi0.5Na0.5 TiO3-0.06BaTiO3 [( )(0.94BNT-0.06BT)-xTa ( )] ceramics were prepared by a solid-state reaction technique. The single perovskite structure with space group R3c of the ceramics was identified by X-ray diffraction (XRD). Raman spectroscopy revealed the evolution of the local...

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Published inEurophysics letters Vol. 129; no. 3; pp. 37004 - 37009
Main Authors He, Xiafeng, Zhou, Shuo, Yuan, Zhi, Li, Yunhua, Lan, Zhencheng, Chen, Kaiyuan, Han, Feifei, Lei, Xiuyun, Liu, Laijun
Format Journal Article
LanguageEnglish
Published Les Ulis EDP Sciences, IOP Publishing and Società Italiana di Fisica 01.02.2020
IOP Publishing
Subjects
Activation energy
Anomalies
Ceramics
Clusters
Coupling
Dielectric relaxation
Dielectric strength
Distribution functions
High temperature
Low temperature
Normal distribution
Perovskite structure
Perovskites
Phase transitions
Raman spectroscopy
Relaxors
Tantalum
Tantalum oxides
Temperature dependence
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Summary:Ta2O5-doped 0.94Bi0.5Na0.5 TiO3-0.06BaTiO3 [( )(0.94BNT-0.06BT)-xTa ( )] ceramics were prepared by a solid-state reaction technique. The single perovskite structure with space group R3c of the ceramics was identified by X-ray diffraction (XRD). Raman spectroscopy revealed the evolution of the local structure with Ta2O5 concentration. The temperature dependence of dielectric permittivity of the ceramics were deconvoluted by three Gaussian distribution functions which suggests that three dielectric anomalies exist in this system. The low-temperature dielectric anomaly exhibits a typical relaxor behavior with strong frequency dispersion (reentrant relaxor behavior). The activation energy derived from the V-F law is 0.298 eV, 0.338 eV, 0.412 eV and 0.449 eV, for , 0.005, 0.01 and 0.02, respectively. The mid-temperature and high-temperature anomalies are attributed to two structure phase transitions. The increase of the activation energies suggests that the coupling between polar clusters or polar nanoregions (PNRs) becomes weaker. The origin of the interaction between PNRs and phase transition behavior has been proposed according to the average structure, local structure and defect compensation mechanism of the system.
ISSN:0295-5075
1286-4854
DOI:10.1209/0295-5075/129/37004