Nb‐Modified 0.9BaTiO₃–0.1(Bi_0.5Na_0.5)TiO₃ Ceramics for X9R High‐Temperature Dielectrics Application Prepared by Coating Method

Abstract

0.9BaTiO3–0.1Bi0.5Na0.5TiO3‐based (0.9BT–0.1BNT) ceramics with Tc = 180°C were prepared using a novel chemical coating method. The relationships among compositions, microstructures, and properties were investigated. TEM morphologies displayed the Nb‐coated powders, which were confirmed by energy dispersive spectroscopy (EDS). Temperature‐dependence of permittivity for Nb‐modified 0.9BT–0.1BNT ceramics measured at different frequencies showed no relaxor characteristic at high temperature, but frequency dispersion at low temperature. The microstructures were characterized by two types of grains: Nb‐rich grains and Nb‐free grains, which were responsible for temperature‐stable dielectric properties. The sample with 5 mol% Nb addition satisfied the X9R specification. The permittivity was 1934 and the dissipation factor was 1.53% at room temperature.

The effect of glass addition on the ultra-broad temperature stability of BaTiO3–Na0.5Bi0.5TiO3–Nb2O5-based ceramics

“…BaTiO 3 -Na 0.5 Bi 0.5 TiO 3 -Nb 2 O 5 (BNN) solid solution exhibits excellent dielectric properties, this system has been used prevalently in synthesizing X9R materials [4]. In our previous reports, the influence of rare earth and MgO on BNN-based system has been investigated [5][6][7].…”

“…The common method of researching X9R materials is to raise the Curie temperature by doping [4]. However, this method is inapplicable to develop ultra-broad temperature (À 55 to 300 1C) materials with high dielectric constant, since doping could significantly reduce the dielectric constant.…”

Structure, dielectric and impedance properties of BaTiO3–Bi(Y0.5Yb0.5)O3 lead-free ceramics

“…The dielectric material with the ''core-shell'' microstructure composed of chemically inhomogeneous grain is considered as a key factor to satisfy XR characteristics [2,3]. BaTiO 3 based ceramics are modified by the doping species such as BaNb 2 O 6 [4], CaZrO 3 [5], and oxides [6][7][8] to obtain a core-shell structure, which can satisfy the requirements of X8R characteristics (4C/ C 25°C = ±15 % or less, -55 to 150°C). But there are few report that systems without ''core-shell'' structure or two dielectric peaks can satisfy the requirement of the XR temperature range [9].…”

Effects of Nb2O5 addition on the microstructure and dielectric properties of BaTiO3–Bi0.5Na0.5TiO3 ceramics

“…BaTiO 3 does not meet the thermal stability requirement (TCC = ±15 %) because the dielectric constant decreases dramatically when the Curie temperature is exceeded at 130°C. BaTiO 3 -Bi 0.5 Na 0.5 TiO 3 [7,8] systems modified by Nb 2 O 5 [8] (or MgO [9], Pr 6 O 11 [10]) have been investigated for preparation of X9R MLCCs with Pd or Pd/ Ag as inner electrodes. Jing Wang et al [11] used a two-step soft chemical method to synthesize Ba 0.985 Bi 0.01 TiO3-BaTi 0.98 Sn 0.02 O 3 .…”