The influence of the preparation methods on the properties of SnO_2 and ZrO_2 powders,especially the specific surface area and the stability upon calcination was investigated.SnO_2 and ZrO_2 prepared by chemical preci...The influence of the preparation methods on the properties of SnO_2 and ZrO_2 powders,especially the specific surface area and the stability upon calcination was investigated.SnO_2 and ZrO_2 prepared by chemical precipitation using reflux-digestion process with NaOH possess high surface area at the calcination temperature of 500℃～1000℃.A novel solvothermal process in the presence of urea was used to synthesize nanocrystalline SnO_2 powders excluding the adulteration of Si.As increasing the concentration of urea,the grain size of the as-prepared powders reduced and the surface area increased. SnO_2 nanocrystals with a grain size of ca.1 nm and a high surface area of 331 m^2g^(-1) were obtained by this method.These high-surface-area powders are favorable for gas-sensing and catalysis applications,and the development of an advanced material for structural engineering ceramics.展开更多
High-surface-area ZnO nanosheets are prepared using a template-assisted hydrothermal method.A saturation moment as high as 0.02 emu/g is obtained for the ZnO nanosheets.Both photoluminescence spectroscopy and x-ray ph...High-surface-area ZnO nanosheets are prepared using a template-assisted hydrothermal method.A saturation moment as high as 0.02 emu/g is obtained for the ZnO nanosheets.Both photoluminescence spectroscopy and x-ray photoelectron spectroscopy demonstrate the existence of abundant oxygen vacancies on the surfaces of the nanosheets.In addition,the oxygen vacancy concentration increases with an increasing nanosheet surface area.The results show that the origin of the room-temperature ferromagnetism is closely related with a large surface area and oxygen vacancies of the nanosheets.This finding suggests that the high-surface-area ZnO nanosheets are promising to be applied to spintronic devices.展开更多
文摘The influence of the preparation methods on the properties of SnO_2 and ZrO_2 powders,especially the specific surface area and the stability upon calcination was investigated.SnO_2 and ZrO_2 prepared by chemical precipitation using reflux-digestion process with NaOH possess high surface area at the calcination temperature of 500℃～1000℃.A novel solvothermal process in the presence of urea was used to synthesize nanocrystalline SnO_2 powders excluding the adulteration of Si.As increasing the concentration of urea,the grain size of the as-prepared powders reduced and the surface area increased. SnO_2 nanocrystals with a grain size of ca.1 nm and a high surface area of 331 m^2g^(-1) were obtained by this method.These high-surface-area powders are favorable for gas-sensing and catalysis applications,and the development of an advanced material for structural engineering ceramics.
基金Supported by the National Key Research and Development Program of China under Grant No 2016YFA0201001the National Natural Science Foundation of China under Grant No 11574071+1 种基金the Natural Science Foundation for Outstanding Young Researcher in Hebei Province under Grant No E2016210093the Natural Science Foundation of Hebei Province under Grant No A2018210123
文摘High-surface-area ZnO nanosheets are prepared using a template-assisted hydrothermal method.A saturation moment as high as 0.02 emu/g is obtained for the ZnO nanosheets.Both photoluminescence spectroscopy and x-ray photoelectron spectroscopy demonstrate the existence of abundant oxygen vacancies on the surfaces of the nanosheets.In addition,the oxygen vacancy concentration increases with an increasing nanosheet surface area.The results show that the origin of the room-temperature ferromagnetism is closely related with a large surface area and oxygen vacancies of the nanosheets.This finding suggests that the high-surface-area ZnO nanosheets are promising to be applied to spintronic devices.
