Characterization and dielectric properties of Ba5LnNiTa9O30 (Ln = La, Nd and Sm) ceramics

Abstract

Three novel Ba 5 LnNiTa 9 O 30 (Ln = La, Nd and Sm) ceramics were prepared and characterized in the BaO-Ln 2 O 3 -NiO-Ta 2 O 5 system. All three compounds adopted the filled tetragonal tungsten bronze (TB) structure at room temperature. The present ceramics exhibited relaxor behavior, and the Curie temperature (at 10kHz) were −130, -80 and -45 • C for Ba 5 LaNiTa 9 O 30 , Ba 5 NdNiTa 9 O 30 , and Ba 5 SmNiTa 9 O 30 respectively. At room temperature, Ba 5 LnNiTa 9 O 30 ceramics have a high dielectric constants in the range 102∼118, a low dielectric loss in range 0.0019∼0.0036, and the temperature coefficients of the dielectric constant (τ ε ) in the range -320∼−460 ppm • C −1 (at 1 MHz).

Towards novel multiferroic and magnetoelectric materials: dipole stability in tetragonal tungsten bronzes

“…A few general observations have been reported [21] as well as more quantitative predictive parameters, for example tolerance factor [22] (analogous to perovskites), but the latter includes an additional proviso regarding the electronegativity difference [23] between the cations and anions. While these provide a starting point, they do not seem to be universal for this structure and developing a more complete understanding of structure-property relationships is vital if novel multiferroic materials are to be designed with this structure type.…”

“…Although ferroelectric TTBs were widely studied in the 1960s and 1970s and are garnering renewed interest, our overall understanding of the general structure-property relationships in this class of materials is not as comprehensive as in perovskite and closely related materials. A few general observations have been reported [21] as well as more quantitative predictive parameters, for example tolerance factor [22] (analogous to perovskites), but the latter includes an additional proviso regarding the electronegativity difference [23] between the cations and anions. While these provide a starting point, they do not seem to be universal for this structure and developing a more complete understanding of structure-property relationships is vital if novel multiferroic materials are to be designed with this structure type.…”

High dielectric constant and low-loss dielectric ceramics of Sr5LnTi3Ta7O30 (Ln=La, Nd, Sm and Y)

“…Recently, Sebastian et al proposed some promising compounds with tungsten bronze (TB) structure and general formula Ba 3 (RE) 3 Ti 5 Nb 5 O 30 (RE=La, Y, Sm, Nd) to yield high dielectric constants of more than 130 [6,7] . Fang [8][9][10][11][12][13][14][15][16][17] .…”