Relaxor nature in Ba₅RZr₃Nb₇O₃₀ (R = La, Nd, Sm) tetragonal tungsten bronze new system

Abstract

Ba 5 RZr 3 Nb 7 O 30 (R = La, Nd, Sm) lead-free relaxor ferroelectrics were prepared by a standard solid-state reaction process, and the influence of A and B site ion occupation on the dielectric characteristics especially the relaxor nature were investigated systematically. Tetragonal tungsten bronze structure with space group P4/mbm was determined for all compositions, ion cross distribution by Ba 2+ and R 3+ in A1 site was observed, while A2 site was only occupied by Ba 2+ . Selected area electron diffraction patterns confirmed the existence of incommensurate superlattice modulation. Furthermore, temperature and frequency dependences of the dielectric properties showed a broad permittivity peak with strong frequency dispersion, following well the Vogel-Fulcher relationship. The maximum dielectric constant temperature increased gradually with decreasing A1 site ion size. Slim P-E hysteresis loops were obtained at room temperature for all compositions. Meanwhile, micro ferroelectric domains were observed in Ba 5 SmZr 3 Nb 7 O 30 . For Ba 4 R 2 Zr 4 Nb 6 O 30 and Ba 5 RZr 3 Nb 7 O 30 (R = Nd, Sm), the transition from normal ferroelectric to relaxor behavior originates from the increased t A1 , which is a result of cross distribution at A1 site. Compared with Ba 5 RTi 3 Nb 7 O 30 , Zr substitution at B site enhances the relaxor nature. K E Y W O R D S dielectric materials/properties, disorder, ferroelectricity/ferroelectric materials, relaxors

Dielectric relaxation and local domain structures of ferroelectric PIMNT and PMNT single crystals

“…The value of δ A is 30 K for PIMNT27, which is higher than the 24 K for PMNT27. In addition, the degree of dielectric relaxation could be quantified by the Δ T m defined as Δ T m = T m (100 kHz)‐ T m (100 Hz), the bigger is Δ T m , the stronger is the relaxation behavior . From Figure , we can get the parameter Δ T m of PIMNT27 as 8 K, which is larger than the value 5 K for PMNT27.…”

“…In addition, the degree of dielectric relaxation could be quantified by the ΔT m defined as ΔT m = T m (100 kHz)-T m (100 Hz), the bigger is ΔT m , the stronger is the relaxation behavior. [30][31][32] From Figure 2, we can get the parameter ΔT m of PIMNT27 as 8 K, which is larger than the value 5 K for PMNT27. Both parameters δ A and ΔT m indicate that the ternary PIMNT27 single crystal has 75 305 432 30 446 40 PMNT27 5.1 122 387 24 392 stronger relaxation behavior than that of the binary PMNT27 single crystal.…”

Preparation and dielectric properties of co-contained unfilled tungsten bronze ceramics Ba4RCo0.5Nb9.5O30

“…In order to make the abnormal dielectric peak more significant, we focus on the dielectric constant of the BRCN ceramics measured at the test frequency of 1 MHz and the temperature range of 101-523 K, also using used the Curie-Weiss law (Eq. ( 1)) [21] to fit in Fig. 5:…”

Room-Temperature Ferroelectric LiNb6Ba5Ti4O30 Spinel Phase in a Nanocomposite Thin Film Form for Nonlinear Photonics

“…Some of the reported TTB materials include Ba 5 La x Sm 1– x Ti 3 Nb 7 O 30 , Ba 4 Sm 2 Fe 2 Nb 8 O 30 , and so forth. However, most of the synthesized TTB materials are in bulk form; − limited efforts have been devoted to the growth of TTB thin films, especially epitaxial thin films. − Up to date, there are very limited or no prior reports on the atomic scale microstructure of the TTB thin film materials.…”