The order-disorder phase transitions in fcc thin films are investigated by using the mean field method. The result shows that there is a significant difference in the phase transitions and surface segregation between ...The order-disorder phase transitions in fcc thin films are investigated by using the mean field method. The result shows that there is a significant difference in the phase transitions and surface segregation between the films of even-number and odd-number layers. There are various types of phase transitions involving several ordered phases with spatial variation for the film of even-number layers, while there is only one phase transition for the film of odd-number layers.展开更多
Electronic properties are investigated for three alumina polymorphs(corundum,Rb_(2)O_(3)(Ⅱ)and Pbnm perovskite),which are predicted as the stable structures under different pressure range,by means of the first-princi...Electronic properties are investigated for three alumina polymorphs(corundum,Rb_(2)O_(3)(Ⅱ)and Pbnm perovskite),which are predicted as the stable structures under different pressure range,by means of the first-principles molecular dynamics method within local density functional framework.The similarity in electronic properties of the polymorphs of alumina is observed.The effect of possible phase transitions on ruby(Cr^(+3)-doped Al_(2)O_(3))fluorescences is discussed.展开更多
The static nonlinear magnetic response of randomly pinned flux-line lattice in a type-Ⅱ super-conductor has been investigated using variational replica-symmetry-broken method.A peak in the curve of susceptibility as ...The static nonlinear magnetic response of randomly pinned flux-line lattice in a type-Ⅱ super-conductor has been investigated using variational replica-symmetry-broken method.A peak in the curve of susceptibility as a function of external magnetic field is found.When the magnetic field is low,there is a softening in the susceptibility as an effect of pinning potential with nonzero correlation length.At some critical magnetic field,the softening changes into hardening.After reaching the maximum in hardening,the susceptibility decreases to its value of piire states with the increase of magnetic field.展开更多
The 1/2{111}-type ordered structure observed in lanthanum-modified lead zirconate titanate has been proved to be stable in the next-nearest-neighbor approximation by the eightpoint cluster variation method.The order p...The 1/2{111}-type ordered structure observed in lanthanum-modified lead zirconate titanate has been proved to be stable in the next-nearest-neighbor approximation by the eightpoint cluster variation method.The order parameter as a function of the composition of La3+and lead vacancies and the order-disorder phase diagram have been obtained.展开更多
The dependence of optical interface phonon on structure was demonstrated for thin layer inserted GaAlAs quantum well structures. It was found that the dispersion is sensitive to the Al-content of the inserted layer bu...The dependence of optical interface phonon on structure was demonstrated for thin layer inserted GaAlAs quantum well structures. It was found that the dispersion is sensitive to the Al-content of the inserted layer but almost independent of the position of the layer. The results showed that phonon modes can be modulated by adjusting the well parameters, which is useful for some device applications.展开更多
Hydrogenated nanocrystalline silicon nitrogen(nc-SiN_(x):H)films were prepared by rf glow discharge of gas mixture of silane(SiH_(4))and nitrogen(N_(2))diluted heavily by hydrogen(H_(2)).The effect of the gas volume r...Hydrogenated nanocrystalline silicon nitrogen(nc-SiN_(x):H)films were prepared by rf glow discharge of gas mixture of silane(SiH_(4))and nitrogen(N_(2))diluted heavily by hydrogen(H_(2)).The effect of the gas volume ratios X_(g) of(SiU_(4)+N_(2))/H_(2) and X_(N)of N_(2)/SiH_(4) on the crystallization and composition of films is described.The growth process and crystallization mechanism of nc-SiN_(x):H films are discussed in detail.展开更多
基金Supported by the National Key Programme of Basic Research Development of China under Grant No.G2000067107the National Natural Science Foundation of China under Grant No.19804007。
文摘The order-disorder phase transitions in fcc thin films are investigated by using the mean field method. The result shows that there is a significant difference in the phase transitions and surface segregation between the films of even-number and odd-number layers. There are various types of phase transitions involving several ordered phases with spatial variation for the film of even-number layers, while there is only one phase transition for the film of odd-number layers.
文摘Electronic properties are investigated for three alumina polymorphs(corundum,Rb_(2)O_(3)(Ⅱ)and Pbnm perovskite),which are predicted as the stable structures under different pressure range,by means of the first-principles molecular dynamics method within local density functional framework.The similarity in electronic properties of the polymorphs of alumina is observed.The effect of possible phase transitions on ruby(Cr^(+3)-doped Al_(2)O_(3))fluorescences is discussed.
文摘The static nonlinear magnetic response of randomly pinned flux-line lattice in a type-Ⅱ super-conductor has been investigated using variational replica-symmetry-broken method.A peak in the curve of susceptibility as a function of external magnetic field is found.When the magnetic field is low,there is a softening in the susceptibility as an effect of pinning potential with nonzero correlation length.At some critical magnetic field,the softening changes into hardening.After reaching the maximum in hardening,the susceptibility decreases to its value of piire states with the increase of magnetic field.
基金Supported by the National Natural Science Foundation of China under Grant No.59572036。
文摘The 1/2{111}-type ordered structure observed in lanthanum-modified lead zirconate titanate has been proved to be stable in the next-nearest-neighbor approximation by the eightpoint cluster variation method.The order parameter as a function of the composition of La3+and lead vacancies and the order-disorder phase diagram have been obtained.
文摘The dependence of optical interface phonon on structure was demonstrated for thin layer inserted GaAlAs quantum well structures. It was found that the dispersion is sensitive to the Al-content of the inserted layer but almost independent of the position of the layer. The results showed that phonon modes can be modulated by adjusting the well parameters, which is useful for some device applications.
基金Supported in part by the National Postdoctoral Foundation of China.
文摘Hydrogenated nanocrystalline silicon nitrogen(nc-SiN_(x):H)films were prepared by rf glow discharge of gas mixture of silane(SiH_(4))and nitrogen(N_(2))diluted heavily by hydrogen(H_(2)).The effect of the gas volume ratios X_(g) of(SiU_(4)+N_(2))/H_(2) and X_(N)of N_(2)/SiH_(4) on the crystallization and composition of films is described.The growth process and crystallization mechanism of nc-SiN_(x):H films are discussed in detail.
