Relaxor behavior of (Ba,Bi)(Ti,Al)O3 ferroelectric ceramic

Abstract

Perovskite type ͑Ba 0.9 Bi 0.1 ͒͑Ti 0.9 Al 0.1 ͒O 3 ͑BBTA͒ ceramics have been prepared through solid state reaction route. The room temperature x-ray diffraction study suggests that BBTA ceramics have single phase tetragonal symmetry with space group P4mm. In contrast to the sharp dielectric transition of pure BaTiO 3 , a broad dielectric anomaly coupled with the shift in dielectric maxima toward a higher temperature with increasing frequency has been observed in BBTA. The quantitative characterization based on empirical parameters ͑⌬T m , ␥, ⌬T relax , and ⌬T diffuse͑1 kHz͒ ͒ confirms its relaxor nature. The dielectric relaxation which follows the Vogel-Fulcher relationship with E ␣ = 0.011 eV, T f = 356 K, and f 0 = 1.38ϫ 10 10 Hz, further supports spin-glass-like characteristics. In this system, the relaxor behavior can be attributed to the dynamic response of the polar clusters induced by the combined substitutions of Bi 3+ and Al 3+ on the Ba 2+ and Ti 4+ site. Moreover, the curie temperature of BBTA shows the decreasing trend compared to that of pure BaTiO 3 , which doesn't follow the normal Vegard's law, confirming that no BiAlO 3 sublattice formed in BBTA. All these features indicate that BBTA is a promising candidate for lead-free relaxors.

Dielectric anomaly and magnetic properties of multiferroic GaFe0.75Mn0.25O3

“…4a and b shows the temperature dependence of ' and tan d at different frequencies for GaFe 0.75 Mn 0.25 O 3 . The sample has a dielectric anomaly at $ 255 K; as frequency is increased, the dielectric constant is observed to decrease, since there is no remarkable shift of peaks being observed over the investigated frequency range, which is usually observed in BaTiO 3 ferroelectric [15]. The dielectric constant at 255 K and 10 kHz are 19 and 57 for GaFeO 3 [13] and GaFe 0.75 Mn 0.25 O 3 , respectively.…”

Oxidation-induced strain relaxation and related dielectric-temperature behavior in core/shell grained BaTiO3

“…The formation of ferroelectric domains in the shell alleviates the residual strain in core/shell grains, resulting in the degradation of the temperature stability. The residual strain effect can be explained by the formation of polar nano regions (PNRs) in the shell region, which leads to stable dielectric-temperature behavior [24,44,45]. …”

The Phase Transition Behavior of (1−x)Pb(Sc0.5Ta0.5)O3-(x)PbHfO3 Ceramics

“…As a result, broad dielectric peaks and diffuse phase transition are observed. The degree of diffuseness in this system can be determined using the broadening of the peaks from the following relation, 13,14 Where ɛ r is dielectric constant, ɛ rm is the maximum dielectric constant, T is temperature, T m is the peak temperature, γ is the diffusivity parameter, and C is a constant. The plot of log(1/ɛ r −1/ɛ rm ) vs log( T − T m ) at 1000 Hz under different dc bias fields are drawn, and the linear fit of the curve provides the value of γ, which are shown in Fig.…”

“…In addition, the parameter of Δ T is introduced to investigate the frequency dispersion of PSTH( x ) ceramics. The specific symbol of the degree is defined as, 14,15 …”