Ferroelectric Relaxor Behavior and Spectroscopic Properties of Ba<SUP>2+</SUP> and Zr<SUP>4+</SUP> Modified Sodium Bismuth Titanate

Abstract

Polycrystalline ceramics (Na 0.5 Bi 0.5 ) 1-x Ba x Zr y Ti 1-y O 3, (BNBZT) (for x=0.10, 0.12; y=0.04), has been synthesized by conventional solid-state sintering. X-ray diffraction analysis indicates the formation of a single phase with tetragonal symmetry with pure perovskite structure. Scanning electron micrograph of the studied materials shows a distribution of grains. A broad dielectric peak with maximum permittivity has been observed near 1200 (for x=0.10, y=0.04) and 1600 (for x=0.12, y=0.04) respectively in the temperature range, RT-600℃. This result indicates that these materials may have great potential for a variety of high temperature applications. These ceramics show diffuse phase transition and the transition temperature shifting toward higher temperature with increasing frequency, which represents the relaxor behvaiour. The relaxor materials obey modified Curie-Weiss law and Vogel-Fulcher relationship. The values of the diffuseness parameter γ=2 for x = 0.10 and 1.67 for x = 0.12, obtained from the fit of a modified Curie-Weiss law established the relaxor type nature. For a more detailed interpretation of the ac data, the complex impedance (Z*) and electric modulus (M*) as a function of frequency f (i.e., 45 Hz-5 MHz) has been simultaneously analysed. Impedance study reveals that there exists a temperature dependent electrical relaxation phenomenon in the materials. Modulus represents hopping of ions and localized motion in studied compositions. Conductivity obey's Jonscher law

Structure, dielectric and electrical properties of relaxor lead-free double perovskite: Nd2NiMnO6

“…The rate of the diffuseness of the phase transformation can be determined by exponent γ. We obtained the value of γ to be 2.03 and 2.04 at 50 kHz and 100 kHz, respectively, which is very close to 2 (as per reference [26]). This result suggests that Nd 2 NiMnO 6 is a relaxor ferroelectric and its diffuseness increases with increment of frequency.…”

“…where all the symbols have their usual meaning, γ is known as the diffusion coefficient and it lies between 1 (a normal ferroelectric) and 2 (an ideal relaxor ferroelectric) [25,26]. To observe the effect of the diffuse phase transition nature, the graph of ln(1/ε − 1/ε m ) vs. ln(T −T m ) for 50 kHz and 300 kHz are shown in Fig.…”

Zr and Sn substituted (Na0.5Bi0.5)TiO3–based solid solutions

“…The increase of the content of zirconium which substitutes the titanium in the crystal lattice leads to a stabilization of the nonpiezoelectric antiferroelectric phase [3,4]. There are very few publications (see [5][6][7][8], for example) containing results on substitution of zirconium for titanium in the NBT-based solid solutions. However, it has been expected that the substitution of zirconium would also lead to the stabilization of the antiferroelectric state in these compounds.…”

B-site substituted solid solutions on the base of sodium-bismuth titanate

“…11,12 There are very few reports on the NBT-based solid solutions with the substitution of zirconium for titanium, in the literature (see, for example, Refs. [13][14][15][16][17]. Nonetheless, it has been expected that in this case, zirconium substitutions will also stabilize the AFE state.…”