Effect of different pH values adjusted by ammonia on the dielectric properties of CaCu3Ti4O12 ceramics prepared by a sol-gel method

Grain boundary engineering that induces ultrahigh permittivity and decreased dielectric loss in CdCu3Ti4O12 ceramics

“…Two responses can be observed in Z ′‐ f , which are denoted as the contributions from the grain boundaries at low frequencies and the grain/bulk at high frequencies. Only one response can be seen in Z ″‐ f , which is referred to as the grain boundary response due to the limits of the measurement processes . Impedance spectroscopy is a useful tool to analyze the resistivity and conductivity when long‐range conduction dominates because it provides information about the element with the elevated resistance.…”

“…Indeed, the radii of the semicircles decrease with increasing temperature, confirming that the resistivity of the grain boundaries is inversely proportional to temperature, which is a typical behavior of degenerate semiconductors. According to the temperature dependence of the resistivity, the activation energy E gb can be calculated by the Arrhenius law:where σ 0 is the pre‐exponential temperature‐dependent constant, k B is the Boltzmann constant, and T is the absolute temperature. A linear fitting of ln σ gb vs 1000/ T provides E gb , as displayed in the inset.…”

“…Only one response can be seen in Z″-f, which is referred to as the grain boundary response due to the limits of the measurement processes. [39][40][41][42] Impedance spectroscopy is a useful tool to analyze the resistivity and conductivity when long-range conduction dominates because it provides information about the element with the elevated resistance. Therefore, it is easy to conclude that the R gb of CdZn x Cu 3−x Ti 4 O 12 ceramics is enhanced by Zn doping, as shown in Figure 5D.…”

First observation of reversible mechanochromism and chromaticity study on calcium–copper–titanate

“…Since 2000, a large number of research articles discussing theoretical and experimental aspects of fascinating frequency and temperature independent dielectric properties, strong nonlinear I-V characteristics, spectroscopic investigations, intriguing magnetic properties, photocatalytic activity study of pure and substituted perovskite derivative calcium-copper-titanates (CaCu 3 Ti 4 O 12 ) in polycrystalline, nanocrystalline, nanocomposites, single crystalline, and thin film forms are available in the literature. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] A very little number of studies is found on electric (thermoelectric power, dc resistivity, etc), and elastic properties 27,28 of these materials suitable for potential applications such as supercapacitors, varistors, resistive switching memory cells, photoluminescence devices, and gas sensors. 18 Recently, we have carried out positron annihilation spectroscopic investigation of high-energy ball-milling engendered defects in CaCu 3 Ti 4 O 12 , 29 and external stimuli, microwaveassisted heating, rapid thermal cooling, and mechanical milling, induced magnetic ordering in polycrystalline CaCu 3 Ti 4 O 12 quadruple perovskite.…”

“…[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] A very little number of studies is found on electric (thermoelectric power, dc resistivity, etc), and elastic properties 27,28 of these materials suitable for potential applications such as supercapacitors, varistors, resistive switching memory cells, photoluminescence devices, and gas sensors. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] A very little number of studies is found on electric (thermoelectric power, dc resistivity, etc), and elastic properties 27,28 of these materials suitable for potential applications such as supercapacitors, varistors, resistive switching memory cells, photoluminescence devices, and gas sensors.…”