A giant electromechanical d33 coefficient 110pC∕N is obtained in ferroelectric V-doped ZnO films, which is nearly one order of magnitude higher than that of undoped samples. It is considered that the switchable spontaneous polarization induced by V dopants and the accompanying relatively high permittivity should be responsible for the enhancement of piezoelectric response. Moreover, from another point of view, an easier rotation of V–O bonds which are noncollinear with c axis under electric field might be the microscopic origin of this anomaly. The improved piezoelectric properties could make V-doped ZnO a promising candidate for piezoelectric devices.

An efficient heat activating mediator with an enhanced specific absorption rate (SAR) value is attained via control of the iron oxide (Fe3O4) nanoparticle size from 3 to 32 nm. Monodispersed Fe3O4 nanoparticles are synthesized via a seed-less thermolysis technique using oleylamine and oleic acid as the multifunctionalizing agents (surfactant, solvent and reducing agent). The inductive heating properties as a function of particle size reveal a strong increase in the SAR values with increasing particle size up to 28 nm. In particular, the SAR values of ferromagnetic nanoparticles (>16 nm) are strongly enhanced with the increase of ac magnetic field amplitude than that for the superparamagnetic (3-16 nm) nanoparticles. The enhanced SAR values in the ferromagnetic regime are attributed to the synergistic contribution from the hysteresis and susceptibility loss. Specifically, the 28 nm Fe3O4 nanoparticles exhibit an enhanced SAR value of 801 W g-1 which is nearly an order higher than that of the commercially available nanoparticles.

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Ag-doped ZnO films were prepared by direct current reactive magnetron sputtering using a zinc target with various Ag-chips attached. The influence of Ag doping on the microstructure, photoluminescence and Raman scattering of ZnO films were systematically investigated. The results indicate that ZnO films doped with Ag can still retain a wurtzite structure, although the c-axis as preferred orientation is decreased by Ag doping. The near band edge emission of ZnO film can be enhanced by Ag doping with a concentration of 1.6–2.8 at.% and quench with a further increase in the Ag concentration. A local vibrational mode at 411 cm−1 induced by Ag dopant can be observed in the Raman spectra of the Ag-doped ZnO films, which might be used as an indication of Ag incorporation into the ZnO lattice.

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ZnO film is promising for high frequency surface acoustic wave device application when coupled with diamond. In order to get good performance and reduce insertion loss of the device, which demand a piezoelectric material possessing high electrical resistivity and piezoelectric constant d33, Cu-doped ZnO films have been prepared by direct current reactive magnetron sputtering using a zinc target with various Cu-chips attached. The influences of a Cu-doping condition on the microstructure and properties of ZnO films are investigated by x-ray diffraction, x-ray photoelectron spectroscopy, a four-point probe resistivity test system and the periodic compressional force method. The experimental results indicate that high resistivity (9 × 108 Ω cm) and piezoelectric constant (d33 = 13.5 pC N−1) ZnO films with perfect c-axis orientation and fine grain polycrystalline can be achieved by 2.0 at% Cu-doping. The contribution of the Cu-doping to the electrical resistivity and piezoelectric constant d33 is discussed.

Large-scale single-crystalline In2O3 nanowires were successfully synthesized by a simple physical evaporation method at 950 °C. The as-synthesized products, characterized by XRD, SEM and TEM, are pure, structurally uniform and single crystalline with typical diameters of 10–100 nm and lengths of up to a few hundreds of micrometres. Two strong and wide violet emission bands centred at 388 and 401 nm are observed in the room-temperature photoluminescence measurements and their mechanism is discussed.

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