Hydrothermal(HT)ZnO substrates were usually used as seeds for the vapor growth of ZnO crystals.In this work,ZnO bulk crystals were grown using the relatively low-cost GaN/AlOsubstrates as seeds by chemical vapor trans...Hydrothermal(HT)ZnO substrates were usually used as seeds for the vapor growth of ZnO crystals.In this work,ZnO bulk crystals were grown using the relatively low-cost GaN/AlOsubstrates as seeds by chemical vapor transport(CVT).With the increase of growth time,the dislocation densities in the crystal decreased from about 1×10^(6) to 6×10^(3) cm^(-2).The carrier concentration decreased from 1.24×10^(19) to 1.57×10^(17)cm^(-3),while the carrier mobility increased from 63.8 to 179 cm^(2)/(V·s).The optical transmittance in the VIS-NIR wavelength increased significantly in combination with the decreasing dislocation densities and impurity concentrations.The dislocation lines and related fast diffusion paths gradually decreased and disappeared in the late growth stage,and the crystal qualities were consequently improved.The experimental results show that the properties of as-grown ZnO crystals are comparable with bulk ZnO grown on the HT substrates to some extent.The GaN/Al_(2)O_(3) seeds may have a potential application value in the industrial production of ZnO single crystals.展开更多
AgNO3 is often used in the preparation of Au nanostructures since Ag-based substances （AgBS） can selectively be adsorbed on Au（100） and significantly modulate the growth of Au nanocrystals. High-index-faceted Au n...AgNO3 is often used in the preparation of Au nanostructures since Ag-based substances （AgBS） can selectively be adsorbed on Au（100） and significantly modulate the growth of Au nanocrystals. High-index-faceted Au nanostructures have demonstrated excellent performance in catalysis and surface enhanced Raman scattering （SERS）, thus attracting the interest of many researchers in the past several decades. Herein, high-index-faceted Pd@Au concave nanocubes （CNCs） were prepared using AgBS as growth-directing agents in the heterogeneous growth of Au on Pd nanocubes （NCs）. During the growth of Pd@Au CNCs, Au atoms are initially deposited on the Pd{100} facets leading to the formation of thin Au shells, and then AgBS are quickly adsorbed on the formed Au（100）, favoring the growth along 〈111〉 and the formation of Pd@Au CNCs. Transmission electron microscopy （TEM）, high resolution transmission electron microscopy （HRTEM）, energy dispersive spectroscopy （EDS）, high angle annular dark field （HAADF）, and scanning transmission electron microscopy EDS （STEM- EDS） were used to systematically investigate the growth of Pd@Au CNCs. We also demonstrated that the high-index-faceted Pd@Au CNCs exhibited excellent SERS performances.展开更多
基金Funded by the National Natural Science Foundation of China(Nos.11905199,11904299,and U1930124)。
文摘Hydrothermal(HT)ZnO substrates were usually used as seeds for the vapor growth of ZnO crystals.In this work,ZnO bulk crystals were grown using the relatively low-cost GaN/AlOsubstrates as seeds by chemical vapor transport(CVT).With the increase of growth time,the dislocation densities in the crystal decreased from about 1×10^(6) to 6×10^(3) cm^(-2).The carrier concentration decreased from 1.24×10^(19) to 1.57×10^(17)cm^(-3),while the carrier mobility increased from 63.8 to 179 cm^(2)/(V·s).The optical transmittance in the VIS-NIR wavelength increased significantly in combination with the decreasing dislocation densities and impurity concentrations.The dislocation lines and related fast diffusion paths gradually decreased and disappeared in the late growth stage,and the crystal qualities were consequently improved.The experimental results show that the properties of as-grown ZnO crystals are comparable with bulk ZnO grown on the HT substrates to some extent.The GaN/Al_(2)O_(3) seeds may have a potential application value in the industrial production of ZnO single crystals.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China （Nos. 21471117, 21173159, 21563009, and 51420105002）.
文摘AgNO3 is often used in the preparation of Au nanostructures since Ag-based substances （AgBS） can selectively be adsorbed on Au（100） and significantly modulate the growth of Au nanocrystals. High-index-faceted Au nanostructures have demonstrated excellent performance in catalysis and surface enhanced Raman scattering （SERS）, thus attracting the interest of many researchers in the past several decades. Herein, high-index-faceted Pd@Au concave nanocubes （CNCs） were prepared using AgBS as growth-directing agents in the heterogeneous growth of Au on Pd nanocubes （NCs）. During the growth of Pd@Au CNCs, Au atoms are initially deposited on the Pd{100} facets leading to the formation of thin Au shells, and then AgBS are quickly adsorbed on the formed Au（100）, favoring the growth along 〈111〉 and the formation of Pd@Au CNCs. Transmission electron microscopy （TEM）, high resolution transmission electron microscopy （HRTEM）, energy dispersive spectroscopy （EDS）, high angle annular dark field （HAADF）, and scanning transmission electron microscopy EDS （STEM- EDS） were used to systematically investigate the growth of Pd@Au CNCs. We also demonstrated that the high-index-faceted Pd@Au CNCs exhibited excellent SERS performances.
