The Role of ZnO as a Dopant and an Intergranular Phase in the Electrical Properties of Ca0.6Sr0.4TiO3 Ceramics

ZnO was introduced into Ca0.6Sr0.4TiO3 ceramics as a dopant and an intergrangular phase in this research, followed by detailed structure characterization, energy storage performance analysis, and electrical behavior studies. The results revealed that the existence of ZnO as a dopant led to the decrease of conduction activation energy and the deterioration of energy storage behavior, while appropriate introduction of ZnO as an intergranular phase resulted in the increase of conduction activation energy and the optimization of energy storage performance. Additionally, the inverse relation between interfacial polarization and energy storage performance was observed in this study. Finally, an increased energy storage density of 1.16 J/cm3 was achieved in 1 mol% ZnO-added Ca0.6Sr0.4TiO3 ceramics.

Microstructures and Electrical Conduction Behaviors of Gd/Cr Codoped Bi3TiNbO9 Aurivillius Phase Ceramic

In this work, a kind of Gd/Cr codoped Bi3TiNbO9 Aurivillius phase ceramic with the formula of Bi2.8Gd0.2TiNbO9 + 0.2 wt% Cr2O3 (abbreviated as BGTN−0.2Cr) was prepared by a conventional solid-state reaction route. Microstructures and electrical conduction behaviors of the ceramic were investigated. XRD and SEM detection found that the BGTN−0.2Cr ceramic was crystallized in a pure Bi3TiNbO9 phase and composed of plate-like grains. A uniform element distribution involving Bi, Gd, Ti, Nb, Cr, and O was identified in the ceramic by EDS. Because of the frequency dependence of the conductivity between 300 and 650 °C, the electrical conduction mechanisms of the BGTN−0.2Cr ceramic were attributed to the jump of the charge carriers. Based on the correlated barrier hopping (CBH) model, the maximum barrier height WM, dc conduction activation energy Ec, and hopping conduction activation energy Ep were calculated with values of 0.63 eV, 1.09 eV, and 0.73 eV, respectively. Impedance spectrum analysis revealed that the contribution of grains to the conductance increased with rise in temperature; at high temperatures, the conductance behavior of grains deviated from the Debye relaxation model more than that of grain boundaries. Calculation of electrical modulus further suggested that the degree of interaction between charge carriers β tended to grow larger with rising temperature. In view of the approximate relaxation activation energy (~1 eV) calculated from Z’’ and M’’ peaks, the dielectric relaxation process of the BGTN−0.2Cr ceramic was suggested to be dominated by the thermally activated motion of oxygen vacancies as defect charge carriers. Finally, a high piezoelectricity of d33 = 18 pC/N as well as a high resistivity of ρdc = 1.52 × 105 Ω cm at 600 °C provided the BGTN−0.2Cr ceramic with promising applications in the piezoelectric sensors with operating temperature above 600 °C.

Synthesis and conductive performance about a kind of high-proton conductor, Dawson structure heteropoly acid H6P2W16Mo2O40 ⋅ 29H2O

A heteropoly acid (HPA) with Dawson structure, H6P2W[Formula: see text]Mo2O[Formula: see text]⋅29H2O, is synthesized with characterization and the investigation toward its proton conductive behavior. Actually, at 18[Formula: see text]C with 80% relative humidity (RH), H6P2W[Formula: see text]Mo2O[Formula: see text] ⋅ 29H2O displays the conductivity as 2.30 × 10[Formula: see text] S ⋅ cm[Formula: see text], indicating an excellent protonic conductor. The proton conduction activation energy is 32.19 kJ ⋅ mol[Formula: see text], implying proton migration following vehicle mechanism. During the measured range, higher temperature can boost the conductivity.

DC Conductivity of Illite with Fly-Ash between 20 – 1050 °C

The temperature dependence of the electrical DC conductivity of fly-ash and illite-based ceramics was measured in the temperature range of 20 – 1050 °C. The measurements were done for illite samples with no fly-ash and fired illite added and illite samples containing 10 wt. %, 20 wt. %, 30 wt. %, and 40 wt. % of fly-ash and 0 wt. %, 10 wt. %, 20 wt. %, and 30 wt. % of fired illite. Addition of fly-ash substantially influences temperature dependences of the DC conductivity and introduces a temperature region with a high conduction activation energy which precedes the dehydroxylation. At the lowest temperatures, the main charge carriers are H+ and OH− ions, while at higher temperatures K+ and Na+ ions also play a role. The phase transformation metaillite -> Al-Si spinel is characterized with a current peak at 940 °C.

Electrical and Optical Properties of Indium-Modified SeSbTe Thin Films for Low Power Memory Devices

The electrical and optical characteristics of indium doped Se2Sb2Te6phase-change alloy are studied. It is found that adding indium to Se2Sb2Te6 alloy (In0.3Se2Sb2Te6) increased the crystallization temperature and reduced the electrical conduction activation energy. The capacitance-temperature measurements showed a drastic change in the capacitance of the modified film when the temperature approaches the crystallization temperature, and eventually the capacitance becomes negative and nonlinear. The negativity and nonlinearity in the capacitancevoltage dependence can be attributed to the growth of conductive crystalline islands by increasing the temperature.

Physical origin of colossal dielectric constant in CaCu3Ti4O12 thin film by Pulsed Laser Deposition

ABSTRACTThe (001) preferentially oriented CCTO thin film was grown on Pt/Ti/TiO2/Si (100) substrate by pulsed laser. I-V and C-V relationships of the CCTO thin film showed characteristics typical of a tunnel metal-insulator-semiconductor (MIS) structure and its capacitance response is the origin of the high apparent dielectric constant observed in CCTO thin films. The very thin insulating layer on top of the film can be reduced in thickness by treatment in HCl acid, as shown by smaller threshold voltages in the I-V curves. The overall behavior is compatible with a conduction activation energy of ∼80 to 100 meV in the bulk of the film, and a diffusion potential at the interface of 500 to 800 meV. The acceptor concentration is of the order of 1019cm−3.