The current research examines the impact of Ca²⁺ substitution on the phase and electrical properties of (Ba_1−xCa_x)Ti₄O₉, (x = 0.0, 0.3, 0.6, and 0.9) sintered pellets synthesized by solid-state reaction method. The as-synthesized samples were analyzed using X-ray diffraction (XRD) and impedance spectroscopy. The emergence of orthorhombic phase fit into space group Pnmm was revealed by XRD, and the addition of Ca resulted in a considerable shift in grain size. Dielectric properties were determined using an impedance spectroscopy in a wide frequency range from 1MHz to 3 GHz. The dielectric properties i.e., dielectric constant (ε_r) and dielectric loss ($tan\sigma$), were measured at 3 GHz frequency. The frequency-dependent parameters such as conductivity, dielectric constant, and dielectric loss indicated that the relaxation process is a Maxwell–Wagner type of interfacial polarization. The improved dielectric properties and low energy loss have made (Ba_1−xCa_x)Ti₄O₉ a prominent energy storage material. This study provides the possibility to improve its dielectric properties and reduce energy loss, making it an excellent energy storage material.

The energy storage properties of [ ][ ][ ]TiO₃–[ ]BaTiO₃([ ]) (BNT–BT) ceramics obtained via sol–gel method are determined from the polarization versus electric field ([ ]–[ ]) loops at various temperatures. The energy storage densities are observed to increase with increase in temperature and this may be attributed to the presence of antiferroelectric (AFE) phase at higher temperature ([ ]C). Obvious changes are observed in the saturation polarization ([ ] and remnant polarization ([ ] with increasing temperature. The maximum energy storage density of 0.6[ ]J/cm³ is observed for [ ] in the AFE phase at 150^∘C for 90[ ]kV/cm of applied electric field. BNT–BT can be a promising candidate for energy storage devices to be used in above-room-temperature environment.

Flexible PVC/BT (Polyvinyl chloride/Barium Titanate) composite thick films with (0–30%) volume fractions of BaTiO₃ were fabricated via the solution casting method. The effects of BaTiO₃ filler on the phase, microstructure and dielectric properties of composite films were investigated. The XRD results revealed that BT particles are embedded in the PVC matrix with no chemical reaction taking place between the two phases. It was observed that the glass transition temperature of PVC had increased with the addition of BT. The frequency dispersion in the dielectric constant versus temperature curves indicated the relaxor nature of the composites. The dielectric constant (ε_r) measured at 40 °C, increased from 7.6 for pure PVC to 16.1 for 30% of BaTiO₃ content in PVC polymer matrix. It is suggested that BaTiO₃ ceramic powder enhanced the dielectric properties of PVC and may be used as a flexible dielectric material.

Solid solutions of Ba(Ti_1−xZr_x)₄O₉ (0 ≤ x ≤ 0.8) were fabricated via mixed oxides, solid state route. The phase, microstructural and dielectric properties of the fabricated samples were investigated. A structural phase transition was observed from orthorhombic (Amm2) to tetragonal (P4/mmm) with increasing Zr⁴⁺ contents (x ≥ 0.6). The dielectric constant (ϵ_r) increased with the substitution of Zr⁴⁺ contents which may be attributed to the larger ionic size and higher polarisability of Zr⁴⁺ relative to Ti⁴⁺. The maximum ϵ_r of 48.27 was observed for x = 0.2. The lowest dielectric loss (tan δ) of 5.5 × 10⁻⁴ and maximum quality factor (Q × f) of 5.6 × 10⁴ MHz were obtained (at 30 MHz) for Ba(Ti_0.8Zr_0.2)₄O₉ ceramics sintered at 1300°C for 2 h in air.

The single phase Ba_1−xSr_xTiO₃ (x = 0, 0.4, 0.8) ceramic compositions were fabricated through solid state (mixed oxides) method calcined at 850 °C and sintered at 1200 °C in air. The XRD patterns revealed the single phase BaTiO₃ composition with a space group of pm-3m. The shifting of the (1 0 0) XRD peak to higher 2θ values is accredited to the substitution of comparatively smaller ion of Sr²⁺ (1.4 Å) for larger Ba²⁺ (1.6 Å) ion following the Braggs diffraction law (2dsinθ = mλ). The phase transition or Curie point from polar ferroelectric phase to non-polar paraelectric phase of Ba_1−xSr_xTiO₃ was reported to decrease with increasing Sr²⁺ content in Ba_1−xSr_xTiO₃ compositions. The value of the dielectric constant decreased with increasing the content of Sr²⁺, which may be attributed to the substitution of comparatively smaller ion of Sr²⁺ for Ba²⁺ in the perovskite structured Ba_1−xSr_xTiO₃.