Combining effects of TiO6 octahedron rotations and random electric fields on structural and properties in Na0.5Bi0.5TiO3. Issue 5 (12th January 2020)

• Record Type: Journal Article
• Authors: Hao, Kaijun; Ge, Wenwei; Ren, Zhenan; Liu, Xiaojuan; Luo, Laihui; Li, Xiaobing; Luo, Haosu; Viehland, Dwight
• Is Part Of: Journal of the American Ceramic Society. Volume 103:Issue 5(2020)
• Page Start: 3349
• Page End: 3360
• Publication Date: 2020-01-12
• Subjects: dielectric relaxation -- ferroelectricity/ferroelectric materials -- lead‐free ceramics -- piezoelectric materials/properties; Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.16986
• Languages: English
• ISSNs: 0002-7820

Abstract

Abstract: The structural and dielectric properties of Na0.5 Bi0.5 TiO3 (NBT) ceramics and crystals have been investigated and are compared to that of Pb(Zr0.55 Ti0.45 )O3 (PZT55/45) and Pb(Mg1/3 Nb2/3 )0.72 Ti0.28 O3 (PMNT 72/28) ceramics. X‐ray diffraction (XRD) profiles for (100), (110), (111), (200), (220), and (222) (referred to cubic structure) reveal that the monoclinic structure with C c space group exists both in the NBT single crystal and ceramics. The diffraction profile obtained with high resolution laboratory XRD for the NBT single crystal can be well described, using C c model instead of R 3c model. The dielectric constant of NBT below T hump shows some similarity to that of PZT45/55 ceramics below 50°C in which oxygen octahedron rotations cause the frequency dispersion of the dielectric constant. The temperature‐dependent dielectric constant for NBT can be deconvolved into two independent processes. The lower temperature process shows a typical relaxor characteristic and follows the Vogel‐Fulcher relationship. The other process at higher temperature shows less frequency‐dependent behavior. Comparing the dielectric constant of NBT with that of PZT55/45 and PMNT72/28 reveals that both oxygen octahedral rotations and random electric fields play an important role in the frequency dispersion of the dielectric constant for NBT relaxor feroelectric.