CARBONATE PRECURSOR ROUTE FOR PREPARATION OF CaCu3Ti4O12

A simple CaCu3Ti4O12 synthesis method by carbonate precipitation has been developed, which is not inferior to the known methods of precipitation from solutions. The optimum temperatures for the synthesis of powder (850 оС) and sintering of ceramics (1080 оС) have been found. The CCTO ceramic prepared has stable and fine electrical properties. In the frequency range of 1 kHz to 1 MHz, the ε’ value always is higher 104 with the dielectric losses, tan δ ~ 0.05–0.08. Such CCTO ceramic prepared by the сarbonate co-precipitation method with good electric properties should find applications in electric devices.

Investigation of micro- and nanoscale barrier layer capacitance mechanisms of conductivity in CaCu3Ti4O12via scanning probe microscopy technique

In this work we disclose micro- and nanoscale origins of the unusually high dielectric constant characteristic of CaCu3Ti4O12 (CCTO) ceramic by using the Scanning Probe Microscopy (SPM) technique.

Microwave assisted sol-gel synthesis of high dielectric constant CCTO and BFN ceramics for MLC applications

Ba(Fe1/2Nb1/2)O3 (BFN) and CaCu3Ti4O12 (CCTO) ceramic powders were synthesized by microwave assisted sol-gel synthesis technique and sintered at 1100?C and 1000?C, respectively. Calcination and sintering processes were carried out in a microwave furnace. Dielectric constant (?r)~2450 and dielectric loss (tan ?)~0.5 at frequency of 1 kHz and 20?C were observed for the BFN ceramic samples. Higher value of ?r ~ 3600 and lower value of tan ? ~ 0.07 at frequency of 1 kHz and in 20-60?C temperature range for the CCTO ceramic samples suggested its utility for MLC applications. Sharp decrease of ?r and sharp increase of tan ? at higher frequencies of BFN ceramic samples indicated the presence of Debye like relaxation.

Influence of interface point defect on the dielectric properties of Y doped CaCu3Ti4O12 ceramics

CaCu3Ti[Formula: see text]YxO[Formula: see text] (0[Formula: see text]0.12) ceramics were fabricated with conventional solid-state reaction method. Phase structure and microstructure of prepared ceramics were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The impedance and modulus tests both suggested the existence of two different relaxation behavior, which were attributed to bulk and grain boundary response. In addition, the conductivity and dielectric permittivity showed a step-like behavior under 405[Formula: see text]K. Meanwhile, frequency independence of dc conduction became dominant when above 405[Formula: see text]K. In CCTO ceramic, rare earth element Y[Formula: see text] ions as an acceptor were used to substitute Ti sites, decreasing the concentration of oxygen vacancy around grain-electrode and grain boundary. The reason to the reduction of dielectric behavior in low frequencies range was associated with the Y doping in CCTO ceramic.