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High temperature lead-free piezoelectric ceramics 0.67BiFeO3–0.33BaTiO3 doped with 0.35 mol% MnO2 and xBiScO3 (x = 0, 0.005, 0.01, 0.015, 0.02) were prepared by conventional solid-state sintering method. The effects of BiScO3 doping on the crystal structure, piezoelectric, ferroelectric and dielectric properties of BiFeO3-BaTiO3 piezoelectric ceramics were investigated. The results show that the BiScO3 doping can not change the crystal structure of the ceramics and the grain size of ceramics increases first and then decreases with the BiScO3 doping content increasing. The optimum piezoelectric properties d33 = 165 pC/N, kp = 0.349 and Qm = 52.132 were obtained when x = 0.01, with the highest remanent polarization Pr = 37.1 μC/cm2. The ceramics become normal ferroelectrics determined by temperature spectrum with the increase of x, and the Curie temperature and depolarization temperature of 425 and 408 °C are respectively obtained when x = 0.01. In particular, a small amount of BiScO3 doping is beneficial to the improvement of the temperature stability. Moreover, a perovskite solid solution forms between the BiScO3 and BiFeO3-BaTiO3 ceramics, which can improve the electrical properties of BF-BT ceramic system.

Anodization is a widely used method to obtain multicoloured oxidized titanium sheets. However, most researchers paid great attention to the colour-related properties instead of photoelectrical properties of titanium oxide film obtained by anodization. In this work, to study their photoelectrical properties, a series of multicoloured oxidized titanium sheets were prepared by anodization method, and UV–vis absorption and photocurrents were tested. The relationship between anodization voltages/anodization durations and photocurrents of titanium sheets was studied. Results show that titanium sheets have excellent photoelectrical performance. With the increase of anodization voltage, the number of UV–vis absorption peaks increased under visible light which means increasing absorption. When anodization duration increased, absorption band edge also increased in the visible light region, which means the band gap needed to produce charge transfer transition decreased. Under simulated sunlight and applied voltage of +0.4 V, photocurrent increased with the increase of either anodization voltage or anodization duration, and can be expressed by linear equations. In addition, anodization currents were recorded during anodization. Morphology, crystal structure and photoelectrical properties of anodized titanium sheets were characterized. The anodized titanium sheets can not only be used as decorative material in jewellery and architecture fields etc. but also are supposed to be used as photoelectrical catalyst in further work.

CTE mismatch between direct bonding copper (DBC) layers results in excessive thermal stress, causing the fatigue cracks and delamination after long time run, which deteriorate the reliability of DBC and the power module in the end. A method of designing mesh patterns on DBC is proposed in this paper to release the thermal stress. At the same time, the comprehensive analysis of the relationship between the mesh patterns and the DBC reliability is made. The finite element method is used to simulate the distributions and variations of thermal stress on DBC with different mesh patterns. Both the theoretical and experimental results prove the function of the thermal stress release for the mesh on DBC. Furthermore, the meshes on the edge or corner, and with smaller size are most effective. In experiment, compared with the DBC without mesh, the thermal cycling lifetime for the DBC with the optimized mesh pattern could be improved by 15 times.