Giant dielectric response in microwave processed CaCu3Ti4O12 ceramics: A correlation among microstructure, dielectric and impedance properties

The effect of sintering temperature on the phase evolution, microstructures, dielectric properties and energy-storage properties of lead lanthanum zirconate titanate antiferroelectric ceramics has been investigated. Scanning electron microscopy images showed that a gradual increase in grain size with increasing sintering temperature. The dielectric measurements revealed that the variation of sintering temperature did not lead to a systematic trend. A correlation between the dielectric properties and microstructures was established. The room temperature dielectric properties demonstrated that both the dielectric constant and saturation polarization increased with increasing sintering temperature up to 1180 °C and then slightly decreased. Furthermore, as for the sintering temperature dependence of energy storage properties, it has shown that with the increase of sintering temperature, both the charged density and discharged density first increased and then decreased. There is an intermediate optimum sintering temperature range (1180 ∼ 1200 °C) in which the samples have better energy storage performance. The dependence of released energy and power densities on the sintering temperature was also investigated. These charge-discharge measurement results were consistent with the calculated values obtained from polarization-electric field hysteresis loops.

Microwave sintering of dielectric CaCu3Ti4O12: An interfacial conductance and dipole relaxation effect

Tuning dielectric properties in ceramics with anisotropic grain structure: The effect of sintering temperature on BaLa4Ti4O15

Frequency dependence studies of dielectric, impedance and permeability properties of Y3+ substituted Li0.5Zn0.1Ti0.1Fe2.3O4 ferrites

Influence of sintering temperature on dielectric properties and crystal structure of corundum-structured Mg4Ta2O9 ceramics at microwave frequencies

Effect of sintering temperature on electromagnetic properties of NiCuZn ferrite

In order to obtain dense PbNb2O6‐based piezoelectric ceramics with a single orthorhombic ferroelectric phase, Ba, and excess Ti were doped into PbNb2O6 ceramics with the composition of Pb0.92Ba0.08Nb2O6–0.25 wt% TiO2 via a conventional solid‐state reaction method. The ceramics were sintered at 1210°–1300°C. The effects of sintering temperature on the crystallite structure, microstructure, and dielectric and piezoelectric properties were studied in detail. All ceramics had shown a high relative density (>94%) and a single orthorhombic phase. The lattice parameters, grain size, and shape varied with changing sintering temperature. All ceramics exhibited a typical characteristic in ferroelectrics with normal paraelectric–ferroelectric phase transition at the Curie temperature. With increasing sintering temperature from 1210° to 1300°C, the Curie temperature decreased from 554° to 523°C, while the maximum dielectric constant increased. The change in dielectric properties with changing sintering temperature is associated with a competing effect among internal stress, porosity, and grain size. The ceramic sintered at 1260°C possesses an excellent piezoelectric constant (d33=82 pC/N), low mechanical quality factor (Qm=20.52), low dielectric loss (tan δ=0.0062), and high Curie temperature (Tc=535°C), presenting a high potential to be used in high‐temperature applications as piezoelectric transducers.

In this study, the physical properties, dielectric properties, and micro-hardness of (Ba0.90Ca0.10)0.90(Na0.50Bi0.50)0.10TiO3 or BCT-NBT ceramics prepared by molten salt method with various sintering temperatures were investigated. The powders were calcined at 500-1100°C for 4 h with heating rate of 5°C/min. It was found that the optimum calcination condition was 1000°C for 4 h. These powders were pressed and sintered at 1200-1400°C for 3 h with a heating rate of 5°C/min. The microstructure was examined by scanning electron microscope (SEM). The density of the sintered samples was measured by Archimedes method with distilled water as the fluid medium. Dielectric properties were examined by LCR meter. The micro-hardness of the BCT-NBT ceramics was determined using the Vickers and Knoop indentation techniques. The results showed that the average grain sizes increased with increasing sintering temperatures. At sintering temperatures higher than 1200°C, the fracture mode changed from partial intra-granular to mainly intra-granular. The sintering temperature at which the density, dielectric and hardness properties were maximal was 1350°C. The highest density was about 5.4 g/cm3, and the Vickers and Knoop micro-hardnesses were 6.6 and 6.4 GPa, respectively. The dielectric constant at the Curie temperature was 3682 and the dielectric loss was 0.01 at 1 kHz frequency.

Dielectric and impedance properties’ studies of the of lead doped (PbO)-Co 2Y type hexaferrite (Ba 2Co 2Fe 12O 22 (Co 2Y))

Lead-free 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 composites have been synthesized via sol-gel chemical route. We have systematically investigated the influence of sintering temperature on the structural and electrical properties of the BZT-BCT composites. The 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 composites were prepared by combining Ba(Zr0.2Ti0.8)O3 (BZT) and (Ba0.7Ca0.3)TiO3 (BCT) powders and sintered at different temperatures 900-14000C. The electrical properties of BZT-BCT composites improve with increasing sintering temperature. The composites sintered at 1300 and 14000C exhibit enhanced ferroelectric properties with spontaneous polarization Ps ~ 11.2 μC/cm2 and 8.66 μC/cm2 respectively. The dielectric and piezoelectric properties of BZT-BCT composites also improve with increasing sintering temperature. The dielectric constant value εʹ ~ 2938, tan δ ~ 0.016 and piezoelectric co-efficient d33 ~ 278 pC/N were measured for BZT-BCT composite sintered at 14000C while observing a considerably high transition temperature of Tc ~ 1200C. The observed results are discussed in terms of structural and microstructural analysis as a function of sintering temperature.

Dramatic impact of raw chemicals on the electrical properties of SrTiO3 ceramics

In this study, structural, dielectric, impedance and humidity properties of Cr3+-doped Mg–Zn ferrite, produced by co-precipitation method, have been investigated. Structural, morphological and compositional analyses were studied by XRD, SEM and EDX, respectively. The X-ray diffraction result shows that Mg0.75Zn0.25Cr0.2Fe1.8O4 crystallizes in the cubic spinel structure with the space group of Fd3m. The lattice constant and crystal size of the sample were calculated as 8.4046 A and 11.29 nm. The dielectric and impedance properties were investigated in the frequency range between 20 and 10 MHz and in the temperature range from 290 to 710 K. The dielectric results are supported by Maxwell–Wagner polarization principles. Relaxation mechanism of the sample is explained by Nyquist graph. According to the impedance results, relaxation process is compatible with Cole–Cole model. The conductivity mechanism of the sample is explained by the mechanism of correlated barrier hopping (CBH) model. Finally, the humidity sensing properties of sample were investigated by impedance measurements in the range of 25–90 RH % at room temperature.

The correlation between the sintering temperature and ferroelectric properties of relaxor ceramics in the 0.625Pb(1-3X/2)Lax(Mg1/3Ta2/3)O3- 0.325PbTiO3-0.05PbZrO3 solid solution series have been investigated. The stability of the perovskite phase was studied as a function of sintering temperature. The dielectric constant at T c increases with additions of La2O3 up to 1 mole% and then decreases with further additions of La2O3. Small additions of La2O3 produced uniform grain structure which gave superior properties for pyroelectric detectors. The effect of La-doping on dielectric properties was to shift the T c downward about 8 °C/mole%. The dielectric and pyroelectric properties of this system were improved by adding a small amount of La2O3.

Enhanced dielectric and piezoelectric properties in Li/Sb-modified (Na, K)NbO3 ceramics by optimizing sintering temperature

Effects of sintering temperature on microstructure and dielectric properties of Sr0.985Ce0.01TiO3 ceramics