The geometry,stability,binding energy and electronic properties of（SiO2）n and Ge（SiO2）n clusters（n = 7） have been investigated by Density functional theory（DFT）.The results show that the lowest energy structur...The geometry,stability,binding energy and electronic properties of（SiO2）n and Ge（SiO2）n clusters（n = 7） have been investigated by Density functional theory（DFT）.The results show that the lowest energy structures of Ge（SiO2）n are obtained by adding one Ge on the end site of the O atom or the Si near end site of the O atom in（SiO2）n.The chemical activation of Ge-（SiO2）n is improved compared with（SiO2）n.The calculated second-order difference of energies and fragmentation energies show that the Ge（SiO2）n clusters with n = 2 or 5 are stable.展开更多
We report the pressure dependence of Ge nanocrystals embedded in SiO2 film matrix on Si substrate using Raman scattering and finite element analysis. Delamination of SiO2 film from the Si substrate occurs at ～23 kbar...We report the pressure dependence of Ge nanocrystals embedded in SiO2 film matrix on Si substrate using Raman scattering and finite element analysis. Delamination of SiO2 film from the Si substrate occurs at ～23 kbar due to the large difference between the compressibility of the SiO2 matrix and Si substrate. The observed effect can be understood by the nonhomogeneous distribution of the elastic field in the Ge/SiO2/Si nanosystem. Previous high pressure PL results on the Si/SiO2/Si nanosystem can also be explained by the nonuniform distribution of the elastic field. Although our investigation focuses on the Ge/SiO2/Si nanosystem, our results could provide generally understanding on the elastic properties of different multi-component nanosystems.展开更多
SiO2 glassy materials with Ge crystals embedded were formed by heating GeO2/SiO2 glass at 700 in the presence of hydrogen. GeO2/SiO2 glass was prepared with the sol-gel technique. The Ge/SiO2 samples show a special ph...SiO2 glassy materials with Ge crystals embedded were formed by heating GeO2/SiO2 glass at 700 in the presence of hydrogen. GeO2/SiO2 glass was prepared with the sol-gel technique. The Ge/SiO2 samples show a special photoluminescence property and exhibit strong luminescence at 392 nm（3.12 eV）, secondary strong luminescence at 600 nm（2.05 eV） and weak luminescence at 770 nm（1.60 eV） when excited under 246 nm（5.01 eV） ultra-violet light at room temperature. The structure of this new luminescence material was studied with XRD, XPS, and TEM. The results show that the presence of nanometer sized（around 10 nm） Ge and GeO crystals in the SiO2 may cause the three-band photoluminescence. The GeO2/SiO2 glass without going through the reducing process only has GeO2 in the SiO2 glass, and does not show the photo-（luminescence）.展开更多
基金Project supported by the foundation start up for high level talents of Shihezi university (No. RCZX200747)
文摘The geometry,stability,binding energy and electronic properties of（SiO2）n and Ge（SiO2）n clusters（n = 7） have been investigated by Density functional theory（DFT）.The results show that the lowest energy structures of Ge（SiO2）n are obtained by adding one Ge on the end site of the O atom or the Si near end site of the O atom in（SiO2）n.The chemical activation of Ge-（SiO2）n is improved compared with（SiO2）n.The calculated second-order difference of energies and fragmentation energies show that the Ge（SiO2）n clusters with n = 2 or 5 are stable.
文摘We report the pressure dependence of Ge nanocrystals embedded in SiO2 film matrix on Si substrate using Raman scattering and finite element analysis. Delamination of SiO2 film from the Si substrate occurs at ～23 kbar due to the large difference between the compressibility of the SiO2 matrix and Si substrate. The observed effect can be understood by the nonhomogeneous distribution of the elastic field in the Ge/SiO2/Si nanosystem. Previous high pressure PL results on the Si/SiO2/Si nanosystem can also be explained by the nonuniform distribution of the elastic field. Although our investigation focuses on the Ge/SiO2/Si nanosystem, our results could provide generally understanding on the elastic properties of different multi-component nanosystems.
文摘SiO2 glassy materials with Ge crystals embedded were formed by heating GeO2/SiO2 glass at 700 in the presence of hydrogen. GeO2/SiO2 glass was prepared with the sol-gel technique. The Ge/SiO2 samples show a special photoluminescence property and exhibit strong luminescence at 392 nm（3.12 eV）, secondary strong luminescence at 600 nm（2.05 eV） and weak luminescence at 770 nm（1.60 eV） when excited under 246 nm（5.01 eV） ultra-violet light at room temperature. The structure of this new luminescence material was studied with XRD, XPS, and TEM. The results show that the presence of nanometer sized（around 10 nm） Ge and GeO crystals in the SiO2 may cause the three-band photoluminescence. The GeO2/SiO2 glass without going through the reducing process only has GeO2 in the SiO2 glass, and does not show the photo-（luminescence）.
