A novel lead-free relaxor ferroelectric ceramic of (0.67 -x)BiFeO 3 -0.33BaTiO 3 -xBa(Mg 1/3 Nb 2/3 )O 3 [(0.67 -x)BF-0.33BT-xBMN, x = 0-0.1] was prepared by a solid-state reaction method. A relatively high maximum polarization P max of 38 lC/cm 2 and a low remanent polarization P r of 5.7 lC/cm 2 were attained under 12.5 kV/mm in the x = 0.06 sample, leading to an excellent energy-storage density of W~1.56 J/cm 3 and a moderate energy-storage efficiency of g~75%. Moreover, a good temperature stability of the energy storage was obtained in the x = 0.06 sample from 25°C to 190°C. The achievement of these characteristics was basically attributed to an electric field induced reversible ergodic to ferroelectric phase transition owing to similar free energies near a critical freezing temperature. The results indicate that the (0.67 -x)BF-0.33BT-xBMN lead-free realxor ferroelectric ceramic could be a promising dielectric material for energy-storage capacitors.

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 Based on Z-scan technique, the nonlinear absorption characteristics and nonlinear refraction characteristics of ZnO crystal, ZnS crystal and ZnSe crystal were studied under the picosecond (ps) laser pulses and the femtosecond (fs) laser pulses respectively. The experimental results show that the nonlinear absorption characteristics of the three kinds of crystals are reverse saturable absorption mainly due to two-photon absorption under the ps laser pulses. The nonlinear refraction characteristics are self-defocusing and the nonlinear refractive indexes are positive because of free carrier. The nonlinear absorption characteristics of the ZnO crystal and ZnS crystal are reverse saturable absorption mainly due to three-photon absorption under the fs laser pulses, and the ZnSe crystal is two-photon absorption. The nonlinear refraction characteristics of the three kinds of crystals are self-focusing because of bound electron. The experimental results show that zinc semiconductor crystals materials and laser pulse width can influence the optical nonlinear characteristics of materials.