The dielectric properties and phase transition behavior of the [001] and [111] oriented PMN-32%PT single crystal under the different dc bias (E) have been investigated as a function of temperatures. Under the applicat...The dielectric properties and phase transition behavior of the [001] and [111] oriented PMN-32%PT single crystal under the different dc bias (E) have been investigated as a function of temperatures. Under the application of dc bias ranging from 1.5 to 4.0 kV/cm, the dielectric spectrum of a [001] oriented single crystal showed an abnormal dielectric peak within the rhombic phase-stable temperature range. However, this peak disappeared at E>4.0 kV/cm and was not yet found in the [111] oriented single crystal. The abnormal dielectric peak was attributed to the filed-induced phase transition.展开更多
ZnSe nanocrystals were in-situ grown in silica gel-glasses by using sol-gel process and the reductive thermal treatment. The transparent, homogeneous ZnSe/SiO2 nano-composites with the yellow color were first obtained...ZnSe nanocrystals were in-situ grown in silica gel-glasses by using sol-gel process and the reductive thermal treatment. The transparent, homogeneous ZnSe/SiO2 nano-composites with the yellow color were first obtained. We used X-ray diffraction pattern (XRD), UV-VIS optical absorption and Raman scattering to characterize the spectrum proper-ties of ZnSe nanocrystals. The broadening of XRD peaks, the blueshift of interband optical absorption edge and the change of Raman spectrum were observed. From these experimental results, we theoretically calculated the size of ZnSe nanocrystals. The results of XRD, optical absorption and Raman spectra were approximately consistent, with the mean diameter of about 4.6 nm. The discrepancies from dif-ferent methods were discussed.展开更多
Semiconductor(Zn\-\%x\%Cd 1-x S) doped silica glasses were prepared by Sol_Gel process and \%in situ\% growth technique. The structure of the materials was characterized by X_ray diffraction technique, the particle si...Semiconductor(Zn\-\%x\%Cd 1-x S) doped silica glasses were prepared by Sol_Gel process and \%in situ\% growth technique. The structure of the materials was characterized by X_ray diffraction technique, the particle size of semiconductor crystallites from X_ray patterns was estimated less than 10 nm. From absorption spectra, it is obtained that the absorption edges shifted to short wavelength diraction when Zn contents increased, and the absorption edge can be adjusted from 2.46 eV to 2.96 eV by controlling Zn contents. The third_order nonlinear optical susceptibility was studied at 532 nm with 8 ns pulse laser by degenerate four wave mixing (DFWM) technique.展开更多
The multiple field-induced phase transition in 4 at.% La modified Pb(Zr,Sn,Ti)O 3 family with temperature from -40℃ to 45℃ in reported. Two electric field-induced transitions from a metastable antiferroelectric phas...The multiple field-induced phase transition in 4 at.% La modified Pb(Zr,Sn,Ti)O 3 family with temperature from -40℃ to 45℃ in reported. Two electric field-induced transitions from a metastable antiferroelectric phase to two ferroelectric phases are observed is polarization at the applied field of 4 MV/m. The critical field of phase transition between two ferroelectric phases is not larger than 2.5 MV/m, about ten to twenty percent of that ever found in PZT based ceramics. Lattice structure is shown to be orthorhombic by X-ray diffraction. Dielectric investigation reveals a relaxor-like ferroelectric behavior. Temperature-electric field phase diagram is also presented. An appreciate kind of materials is provided to investigate multiple field-induced phase transition with PZT-based ceramics.展开更多
基金This work was supprted by the University Key Studies Project of Shanghai.
文摘The dielectric properties and phase transition behavior of the [001] and [111] oriented PMN-32%PT single crystal under the different dc bias (E) have been investigated as a function of temperatures. Under the application of dc bias ranging from 1.5 to 4.0 kV/cm, the dielectric spectrum of a [001] oriented single crystal showed an abnormal dielectric peak within the rhombic phase-stable temperature range. However, this peak disappeared at E>4.0 kV/cm and was not yet found in the [111] oriented single crystal. The abnormal dielectric peak was attributed to the filed-induced phase transition.
文摘ZnSe nanocrystals were in-situ grown in silica gel-glasses by using sol-gel process and the reductive thermal treatment. The transparent, homogeneous ZnSe/SiO2 nano-composites with the yellow color were first obtained. We used X-ray diffraction pattern (XRD), UV-VIS optical absorption and Raman scattering to characterize the spectrum proper-ties of ZnSe nanocrystals. The broadening of XRD peaks, the blueshift of interband optical absorption edge and the change of Raman spectrum were observed. From these experimental results, we theoretically calculated the size of ZnSe nanocrystals. The results of XRD, optical absorption and Raman spectra were approximately consistent, with the mean diameter of about 4.6 nm. The discrepancies from dif-ferent methods were discussed.
文摘Semiconductor(Zn\-\%x\%Cd 1-x S) doped silica glasses were prepared by Sol_Gel process and \%in situ\% growth technique. The structure of the materials was characterized by X_ray diffraction technique, the particle size of semiconductor crystallites from X_ray patterns was estimated less than 10 nm. From absorption spectra, it is obtained that the absorption edges shifted to short wavelength diraction when Zn contents increased, and the absorption edge can be adjusted from 2.46 eV to 2.96 eV by controlling Zn contents. The third_order nonlinear optical susceptibility was studied at 532 nm with 8 ns pulse laser by degenerate four wave mixing (DFWM) technique.
文摘The multiple field-induced phase transition in 4 at.% La modified Pb(Zr,Sn,Ti)O 3 family with temperature from -40℃ to 45℃ in reported. Two electric field-induced transitions from a metastable antiferroelectric phase to two ferroelectric phases are observed is polarization at the applied field of 4 MV/m. The critical field of phase transition between two ferroelectric phases is not larger than 2.5 MV/m, about ten to twenty percent of that ever found in PZT based ceramics. Lattice structure is shown to be orthorhombic by X-ray diffraction. Dielectric investigation reveals a relaxor-like ferroelectric behavior. Temperature-electric field phase diagram is also presented. An appreciate kind of materials is provided to investigate multiple field-induced phase transition with PZT-based ceramics.
