The solid-state reaction of SrNb2O6, BaNb2O6, and CeO2 to form Sr0.5Ba0.5CexNb2O6+δ at different temperatures and heating rates was investigated. A nonisothermal kinetic empirical model was used to evaluate the activation energy and rate constant of Sr0.5Ba0.5CexNb2O6+δ. The values of the activation energy evaluated from the slopes are 762, 800, and 844 kJ/mol, respectively, for S50, 1CeS50, and 2CeS50, which increase with the increase in Ce doping. The order of reaction was found to decrease with the increase of the Ce doping. A kinetic equation was developed based on the parameters evaluated from the nonisothermal reaction model, which was successfully used to predict the isothermal reaction of Ce-doped strontium barium niobate.

Powdered samples of oxygen-deficient YBa2Cu3Oy were annealed in various atmospheres at 880 and 300 °C to study the relations of structural anomaly, phase transition, and oxygen content. It was found that the structural anomaly in the c axis is reversible during oxygenation and deoxygenation. The change of the c axis arose from the electrical repulsion among Ba and Cu cations as oxygen was removed or refilled. The anomaly in the c axis occurred when the oxygen was further removed or refilled to a critical value, at which structural relaxation and electrical repulsion changed greatly. The phase transition is attributed to the anomalous change in the c axis, and the mechanism is proposed and discussed in this paper.

Several experiments have been conducted to assess the possible mechanisms for the inhibition of reduction of Ca2+-doped barium titanate in a reducing atmosphere. Three methods, i.e., conventional, semiwet, and citrate processes, have been used to prepare the powders. It was found that the formation mechanism would influence the occupation of Ca2+ in the B site. Moreover, it was concluded that Ca2+ occupation of the B site is the major cause for the inhibition of reduction of Ca2+-doped barium titanate. Ti deficiency would be the driving force for Ca2+ to occupy the B site.

The effects of milling and Ag addition on the decomposition of single-phase LaBa2Cu3Oy have been evaluated. It was found that the decomposition of milled single-phase LaBa2Cu3Oy powders when sintered in pure N2 is attributed to the introduction of strain in the lattice which causes the instability of the structure. The possible reasons why single-phase LaBa2Cu3Oy could be synthesized by sintering in pure N2 at high temperatures and its transition width is always broadened are proposed. The decomposition of compacts of unmilled powders of single-phase LaBa2Cu3Oy when sintered in pure N2 for a long time is due to the fact that oxygen diffuses along the grain boundaries and evolves through the surface of the specimens. Silver might segregate to the grain boundaries and prevent decomposition. It is suggested that to obtain a high-quality LaBa2Cu3Oy, sintering in the reduced atmosphere to achieve a proper oxygen content is required. Reduced atmosphere and Ag addition could enhance the densification rate. For Ag-doped specimens, Tc is highest for x = 0.0001, but decreases for x > 0.0001.