ZnO-SnO2 hollow spheres were successfully synthesized through a hydrothermal method-combined carbon sphere template. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR). The average diameter of hollow spheres is about 150 nm. The photocatalytic activity of the as-prepared samples was investigated by photodegrading Rhodamine B. The results indicated that the photocatalytic activities of ZnO-SnO2 hollow spheres are higher than ZnO hollow spheres. The degradation efficiency of the hollow spheres could reach 99.85% within 40 min, while the ZnO hollow spheres need 50 min.

Solid solutions of (1-x)BiFeO₃-xBaTiO₃ (BF-BT, 0.05 ≤ x ≤ 0.98) were prepared and characterized. It was found that the dielectric constant ε_m, remnant polarization P_r and piezoelectric coefficient d₃₃ reach their maximum values near the rhombohedral–pseudocubic phase boundary. In particular, the 0.7BF-0.3BT composition shows large polarization (P_r > 20 μC/cm²) and a temperature-stable piezoelectric property (d₃₃ > 100 pC/N when the annealing temperature is lower than ~400 °C). Near the tetragonal–pseudocubic phase boundary, ε_m and P_r decrease, and the piezoelectric property vanishes when the BF content reaches 4 mol %.