Ba0.6Sr0.4TiO3 (BST) thin films were fabricated on Pt coated Si (100) substrates by sol-gel techniques with molar ratio of (Ba+Sr) to Ti changing from 0.76 to 1.33. The effect of (Ba+Sr)/Ti ratio deviating from the st...Ba0.6Sr0.4TiO3 (BST) thin films were fabricated on Pt coated Si (100) substrates by sol-gel techniques with molar ratio of (Ba+Sr) to Ti changing from 0.76 to 1.33. The effect of (Ba+Sr)/Ti ratio deviating from the stoichiometry on microstructure, grain growth, dielectric and tunable properties of BST thin films were investigated. TiO2 and (Ba,Sr)2TiO4 were found as a second phase at the ratios of 0.76 and 1.33, respectively. The variation of the ratio reveals more significant effect on the grain size in B-site rich samples than that in A-site rich samples. The dissipation factor decreases rapidly from 0.1 to 0.01 at 1 MHz with decreasing (Ba+Sr)/Ti ratio. The tunability increases with decreasing ratio from 1.33 to 1.05, and then decreases with decreasing ratio from 1.05 to 0.76. The film with (Ba+Sr)/Ti ratio of 1.05 has a maximum tunability of 32% and a dissipation factor of 0.03 at 1 MHz.展开更多
采用分步沉积法制备不同Sr/Ti摩尔比例的Sr/Ti O2催化剂,以X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、傅里叶变换红外(FT-IR)光谱、紫外-可见漫反射光谱(UV-Vis RDS)等手段对样品进行了表征,以可见光催化降解亚甲基蓝为模型反应...采用分步沉积法制备不同Sr/Ti摩尔比例的Sr/Ti O2催化剂,以X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、傅里叶变换红外(FT-IR)光谱、紫外-可见漫反射光谱(UV-Vis RDS)等手段对样品进行了表征,以可见光催化降解亚甲基蓝为模型反应考察样品光催化活性.结果表明,催化剂的活性和结构随Sr/Ti摩尔比(n(Sr)/n(Ti))的变化而变化,当n(Sr)/n(Ti)≤3/2时,催化剂呈由Ti O2和Sr Ti O3组成的球状结构;而当n(Sr)/n(Ti)在3/2与4/1之间时,催化剂呈片状结构,且随着n(Sr)/n(Ti)增大,催化剂组成由Sr Ti O3和Sr2Ti O4变为Sr2Ti O4和Sr(OH)2H2O;当n(Sr)/n(Ti)=9/1时,催化剂呈以Sr(OH)2H2O为主的针状结构.其中,n(Sr)/n(Ti)=4/1的样品表现出最高的光催化活性,一级反应速率为Sr Ti O3钙钛矿催化剂的5.0倍,商用P25的86.7倍.展开更多
The Nd-doped BaTiO3 nanocrystalline powders and ceramics with different Ti/Ba ratios were prepared by sol-gel method. Phases and microstructures of the Nd-doped BaTiO3based powders and ceramics were characterized by X...The Nd-doped BaTiO3 nanocrystalline powders and ceramics with different Ti/Ba ratios were prepared by sol-gel method. Phases and microstructures of the Nd-doped BaTiO3based powders and ceramics were characterized by XRD, SEM and TEM methods. The results revealed that the powders synthesized by sol-gel method were nanometer scale (30-60 nm)and were mainly composed of cubic BaTiO3 with a small amount of BaCO3. After sintering at high temperature, both cubic BaTiO3 and BaCO3 were transformed into tetrahedron BaTiO3 phase.The dielectric properties of the ceramics were also determined and the influence of Ti/Ba ratio on the dielectric properties was discussed. The Tc did not change with the variation of Ti/Ba ratio,while the εmax increased firstly and then decreased. The excess TiO2 is benefit for the modification of ceramics' microstructure and dielectric properties.展开更多
基金Project (50332030) supported by the National Natural Science Foundation of China
文摘Ba0.6Sr0.4TiO3 (BST) thin films were fabricated on Pt coated Si (100) substrates by sol-gel techniques with molar ratio of (Ba+Sr) to Ti changing from 0.76 to 1.33. The effect of (Ba+Sr)/Ti ratio deviating from the stoichiometry on microstructure, grain growth, dielectric and tunable properties of BST thin films were investigated. TiO2 and (Ba,Sr)2TiO4 were found as a second phase at the ratios of 0.76 and 1.33, respectively. The variation of the ratio reveals more significant effect on the grain size in B-site rich samples than that in A-site rich samples. The dissipation factor decreases rapidly from 0.1 to 0.01 at 1 MHz with decreasing (Ba+Sr)/Ti ratio. The tunability increases with decreasing ratio from 1.33 to 1.05, and then decreases with decreasing ratio from 1.05 to 0.76. The film with (Ba+Sr)/Ti ratio of 1.05 has a maximum tunability of 32% and a dissipation factor of 0.03 at 1 MHz.
文摘采用分步沉积法制备不同Sr/Ti摩尔比例的Sr/Ti O2催化剂,以X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、傅里叶变换红外(FT-IR)光谱、紫外-可见漫反射光谱(UV-Vis RDS)等手段对样品进行了表征,以可见光催化降解亚甲基蓝为模型反应考察样品光催化活性.结果表明,催化剂的活性和结构随Sr/Ti摩尔比(n(Sr)/n(Ti))的变化而变化,当n(Sr)/n(Ti)≤3/2时,催化剂呈由Ti O2和Sr Ti O3组成的球状结构;而当n(Sr)/n(Ti)在3/2与4/1之间时,催化剂呈片状结构,且随着n(Sr)/n(Ti)增大,催化剂组成由Sr Ti O3和Sr2Ti O4变为Sr2Ti O4和Sr(OH)2H2O;当n(Sr)/n(Ti)=9/1时,催化剂呈以Sr(OH)2H2O为主的针状结构.其中,n(Sr)/n(Ti)=4/1的样品表现出最高的光催化活性,一级反应速率为Sr Ti O3钙钛矿催化剂的5.0倍,商用P25的86.7倍.
文摘The Nd-doped BaTiO3 nanocrystalline powders and ceramics with different Ti/Ba ratios were prepared by sol-gel method. Phases and microstructures of the Nd-doped BaTiO3based powders and ceramics were characterized by XRD, SEM and TEM methods. The results revealed that the powders synthesized by sol-gel method were nanometer scale (30-60 nm)and were mainly composed of cubic BaTiO3 with a small amount of BaCO3. After sintering at high temperature, both cubic BaTiO3 and BaCO3 were transformed into tetrahedron BaTiO3 phase.The dielectric properties of the ceramics were also determined and the influence of Ti/Ba ratio on the dielectric properties was discussed. The Tc did not change with the variation of Ti/Ba ratio,while the εmax increased firstly and then decreased. The excess TiO2 is benefit for the modification of ceramics' microstructure and dielectric properties.
