High-temperature stable dielectrics in Mn-modified (1-x) Bi0.5Na0.5TiO3-xCaTiO3 ceramics

Abstract

In the current work, the bulk (1-x) Bi 0.5 Na 0.5 TiO 3 -xCaTiO 3 [BNCT100x] system was synthesized via solidstate route. CaTiO 3 in solid solution with Bi 0.5 Na 0.5 TiO 3 was observed to decrease the dielectric constant at higher temperature and raise the dielectric constant at lower temperature. Polarization hysteresis measurements indicated that the ferroelectricity of Bi 0.5 Na 0.5 TiO 3 was weakened with an increase of CaTiO 3 , resulted in the shift of the depolarization temperature (T d ) toward lower temperatures. X-ray diffraction analysis revealed that TiO 2 was produced as a secondary phase due to the losses of Bi and Na during milling and sintering processes. Moreover, the addition of Ca promoted the segregation of Ti out of BNT grains. Dielectric properties of BNCT12 ceramics with different dopant levels of Mn were characterized as a function of temperature for potential use of high-temperature capacitors. Modification of BNCT12 materials with Mn improved the temperature characteristic of capacitance (−55°C to 250°C, △C/C 25°C ≤ ±15%). Finally, by doping 1.5 wt% Mn, the dielectric constant at room temperature could reach over 900, with a low dielectric loss below 1% and a high insulation resistivity about 10 12 Ω•cm. Furthermore, a small amount of Mn influenced the microstructure in the way to inhibit the long grains and grain growth of BNCT solution ceramics. However, excess Mn caused abnormal grain growth, and therefore, rectangle grains appeared again.

Effects of Ca and Mn Additions on the Microstructure and Dielectric Properties of (Bi0.5Na0.5)TiO3 Ceramics

“…The diffuse phase transition over a wide temperature range for the BNT-CT (BNCT) solid solution has already been established. 18 On the other hand, many researchers have reported their work on Mn-doped BNT-related materials. Nagata et al 13 investigated the effects of Mn addition on the dielectric, ferroelectric, and piezoelectric properties of BNT ceramics.…”

A new method for achieving enhanced dielectric response over a wide temperature range

“…The dielectric response of the core-shell structure has been modeled using semi empirical logarithmic mixing law4. Despite these prior efforts, achieving high dielectric constant with enhanced temperature stability still remains challenging6789101112. Here, we demonstrate high temperature stability of dielectric response in multilayer composite architecture that consists of several different compositions with varying Curie temperatures and a suitable electrical boundary condition.…”

Enhanced energy storage properties of Bi0.5Li0.5TiO3 modified Sr0.1Bi0.45Na0.45TiO3 based ceramics

“…Recently, binary and ternary system relaxor ceramics have been investigated for their high energy storage application, e.g., BNT-BaTiO 3 [3], BNT-BaTiO 3 -K 0.5 Na 0.5 NbO 3 [4][5][6], BNT-BaTiO 3 -NaNO 3 [7], BNTCaTiO 3 [8], BNT-SrTiO 3 -BaTiO 3 [9], BNT-K 0.5 Bi 0.5 TiO 3 -BaTiO 3 [10], etc. The decreased remnant polarization (P r ) value, which is favored to receive larger recoverable energy density compared with pure BNT, is found in these systems.…”