Temperature‐stable unfilled tungsten bronze dielectric ceramics: Ba_3.5Sm_1.5Fe_0.75Nb_9.25O₃₀

Abstract

Unfilled tungsten bronze ceramic Ba3.5Sm1.5Fe0.75Nb9.25O30 was prepared by a conventional solid‐state reaction method. Its structure, microstructure, and dielectric properties were investigated. Dielectric behaviors indicate that the ceramics are ferroelectric at room temperature with a remnant polarization ~1.61 μC/cm2 and a coercive field ~13.91 kV/cm. Ba3.5Sm1.5Fe0.75Nb9.25O30 ceramics have temperature stability with a high dielectric constant (εr) varying from 172 to 202 at the temperature range −55 to 200°C (at 1 MHz). Capacitance change rate of the sample is less than 15%. These results indicate that Ba3.5Sm1.5Fe0.75Nb9.25O30 ceramics might be promising in temperature‐stable multi‐layer ceramic capacitors.

Tribocatalytic degradation of dyes by tungsten bronze ferroelectric Ba2.5Sr2.5Nb8Ta2O30submicron particles

“…16 The ions in the center of the oxygen octahedron and the ions in the gap position (mainly the A site) are displaced along the c-axis direction, forming a non-central symmetric structure with an electric dipole moment along the c-axis, which is also a tungsten bronze crystal ferroelectric source. [17][18][19][20] In recent years, due to the excellent ferroelectric, piezoelectric, pyroelectric, and nonlinear optical properties of tungsten bronze materials, 21,22 they have gradually attracted widespread attention. In addition, the ferroelectric polarization of the tungsten bronze compound helps guide the migration of carriers, oen playing an important role in the catalytic process.…”

“…Taking into account the high photocatalytic activity of tantalum-based photocatalysis, which is mainly due to their high conduction bands formed by Ta 5d orbitals. 27 We choose another unlled tungsten bronze structure, Ba 2.5 Sr 2.5 Nb 8 Ta 2 O 30 (BSNT) usually has a large number of oxygen vacancies and a larger movable charge density (holes), 18,19 which results in relatively better electrical conductivity (compared to Ba 0.75 -Sr 0.25 TiO 3 perovskites). In such a ferroelectric material with a large amount of internal movable charges, the shielding of the depolarization eld should come from its own internal charges (and not the adsorbed space charged particles, such as LiNbO 3 ).…”