Electrical property and defect structure of lanthanum-doped polycrystalline barium titanate

Electrical conductivity of two types of lanthanum-doped barium titanote ceramics with different dopant levels was measured at temperatures between 900 and 1250° C andP _{O 2}from 10^–5 to 1 atm. The activation energies of the conduction for the two are interpreted in terms of the formation energy of ionized oxygen vacancies even in such a highP _{O 2}region. This fact is in contrast with a well -known controlled -valency model proposed for rare- earth -doped semi-conducting perovskites. In a lightly lanthanum-doped specimen, semiconduction achieved at elevated temperatures is retained on cooling the specimen to room temperature, whereas in a heavily doped specimen, the resultant high-temperature semiconduction changed to insulation on cooling. The former behaviour on cooling is successfully explained by a metastabilization of oxygen vacancies accompanied by electrons formed at elevated temperatures.     

Acceleration of the redox kinetics of VO2+/VO2 + and V3+/V2+ couples on carbon paper

The redox kinetics of VO²⁺/VO₂ ⁺ and V³⁺/V²⁺ couples on a carbon paper (CP, HCP030 N, Shanghai Hesen, Ltd., China) electrode were investigated in terms of their standard rate constant (k ₀) and reaction mechanism. The values determined for k ₀ for VO²⁺ ?? VO₂ ⁺ and V³⁺ ?? V²⁺ using the CP electrode are 1.0 × 10^?3 and 1.1 × 10^?3 cm s^?1, respectively. The value of k ₀ increases by one or two order(s) of magnitude compared with values obtained using electrodes composed of pyrolytic graphite and glassy carbon. The acceleration of the redox kinetics of vanadium ions is a result of the large surface area of the CP electrode. An inner-sphere mechanism for the reaction on the surface of the electrode is proposed. The kinetic features of vanadium redox reactions on the CP electrode reveal that CP is suitable for use as the electrodes in vanadium redox-flow batteries.     

Effect of Excess PbO on the Densification of PLZT Ceramics

The densification behavior and electrical properties of PLZT ceramics as a function of excess PbO in the starting powder have been investigated. The hot-pressed PLZT ceramics, prepared from powders containing 0% to 4% excess PbO, were transparent, and their electrical properties were similar in general. PLZT with PbO deficiency up to 1.4 mol% from stoichiometry can be regarded as a single phase-PLZT.     

Quantum Oscillations of Thermoelectric Effects in a Pseudo-one-dimensional Electron Gas With a Spin–Orbit Interaction

We consider thermoelectric effects in a pseudo-one-dimensional electron gas (P1DEG) with a spin–orbit interaction (SOI). The SOI splits the dispersion relation of the P1DEG into subbands with an energy gap. We find quantum oscillations in transport coefficients, which coincide with the locations of the subband edges, as a function of the electrochemical potential.     

The volume and pH of gastric fluid in elective surgical patients after preoperative oral fluid intake

The effect of preoperative oral fluid intake on the volume and pH of gastric fluid was examined in 45 elective surgical patients ranged in ages from 18 to 70 years. Two hours preoperatively they all received oral roxatidine 75 mg with 10 ml water, immediately followed by 150 ml oral water or 150 ml refreshing drink or no fluid as control. Just after the induction of anesthesia, a Salem-sump tube was put down to the stomach to collect gastric fluid in each patient. The volume and pH of gastric fluid taken were 10.9 +/- 7.9 ml, 16.3 +/- 2.3 in control group, 8.0 +/- 6.0 ml, 6.2 +/- 2.4 in the water group and 6.3 +/- 6.0 ml, 7.1 +/- 1.7 in the refreshing drink group. As there were no significant differences in gastric pH values in the three groups, the highest value was found in the refreshing drink group. No significant difference in VAS of hungry and thirsty feeling was found among the three groups. We conclude that preoperative oral water or refreshing drink with roxatidine 75 mg 2 hours before the start of anesthesia may not increase the risk of aspiration during the induction of anesthesia.     

Preparation of Pb(Zr,Ti)03 Through the Use of Cupferron

An organic chelation reagent, cupferron, was used to coprecipitate Ti⁴⁺ andZr⁴⁺. After the materials were fired, they were mixed with PbO powder and fired again at high temperatures to obtain Pb(Zr,Ti)0₃ (PZT). It was confirmed that this method is useful for the preparation of homogeneous PZT having no compositional fluctuations. No coexistence range of the tetragonal and rhombohedral phases was observed in the PZT compositions near the morphotropic phase boundary.     

Underwater optical connector for remotely operated submersibles

A low-loss small-sized underwater optical connector with six optical contacts is presented. An oil-filled optical fibre cord is adopted to simplify the structure. The body of the adaptor is made of synthetic resin which is practically free from erosion. The distribution of stress is calculated by using the finite-element method to evaluate the mechanical strength of the adaptor.