Different bilayer structures of HfO_(x)/Ti(TiO_(x)) are designed for hafnium-based memory to investigate the switching characteristics. The chemical states in the films and near the interface are characterized by x-ra...Different bilayer structures of HfO_(x)/Ti(TiO_(x)) are designed for hafnium-based memory to investigate the switching characteristics. The chemical states in the films and near the interface are characterized by x-ray photoelectron spectroscopy,and the oxygen vacancies are analyzed. Highly improved on/off ratio(~104) and much uniform switching parameters are observed for bilayer structures compared to single layer HfO_(x) sample, which can be attributed to the modulation of oxygen vacancies at the interface and better control of the growth of filaments. Furthermore, the reliability of the prepared samples is investigated. The carrier conduction behaviors of HfO_(x)-based samples can be attributed to the trapping and de-trapping process of oxygen vacancies and a filamentary model is proposed. In addition, the rupture of filaments during the reset process for the bilayer structures occur at the weak points near the interface by the recovery of oxygen vacancies accompanied by the variation of barrier height. The re-formation of fixed filaments due to the residual filaments as lightning rods results in the better switching performance of the bilayer structure.展开更多
We report the detailed crystal structures and physical properties of Ru_(1-x)Mo_(x)alloys in the solid solution range of x=0.1-0.9.Structure characterizations indicate that the crystal structure changes from the hcp-M...We report the detailed crystal structures and physical properties of Ru_(1-x)Mo_(x)alloys in the solid solution range of x=0.1-0.9.Structure characterizations indicate that the crystal structure changes from the hcp-Mg-type,toβ-CrFe-type,and then bcc-W-type.The measurements of physical properties show that the Ru_(1-x)Mo_(x)samples with x≥0.2are superconductors and the superconducting transition temperature T_c as a function of Mo content exhibits a dome-like behavior.展开更多
In this work,we reported a high-performance-based ultraviolet-visible(UV-VIS)photodetector based on a TiO_(2)@GaO_(x)N_(y)-Ag heterostructure.Ag particles were introduced into TiO_(2)@GaO_(x)N_(y)to enhance the visibl...In this work,we reported a high-performance-based ultraviolet-visible(UV-VIS)photodetector based on a TiO_(2)@GaO_(x)N_(y)-Ag heterostructure.Ag particles were introduced into TiO_(2)@GaO_(x)N_(y)to enhance the visible light detection perfor-mance of the heterojunction device.At 380 nm,the responsivity and detectivity of TiO_(2)@GaO_(x)N_(y)-Ag were 0.94 A/W and 4.79×109 Jones,respectively,and they increased to 2.86 A/W and 7.96×1010 Jones at 580 nm.The rise and fall times of the response were 0.19/0.23 and 0.50/0.57 s,respectively.Uniquely,at 580 nm,the responsivity of fabricated devices is one to four orders of magnitude higher than that of the photodetectors based on TiO_(2),Ga_(2)O_(3),and other heterojunctions.The excellent optoelectronic characteristics of the TiO_(2)@GaO_(x)N_(y)-Ag heterojunction device could be mainly attributed to the synergistic effect of the type-Ⅱband structure of the metal-semiconductor-metal heterojunction and the plasmon resonance effect of Ag,which not only effectively promotes the separation of photogenerated carriers but also reduces the recombination rate.It is fur-ther illuminated by finite difference time domain method(FDTD)simulation and photoelectric measurements.The TiO_(2)@GaO_(x)N_(y)-Ag arrays with high-efficiency detection are suitable candidates for applications in energy-saving communica-tion,imaging,and sensing networks.展开更多
为了利用X射线吸收精细结构(X-ray absorption fine structure,XAFS)谱学技术开展热化学反应动力学研究,在上海光源X射线吸收精细结构谱学线站(BL14W1)开展了时间分辨热化学原位XAFS方法的研究。采用自主研制的数据采集设备解决了时间分...为了利用X射线吸收精细结构(X-ray absorption fine structure,XAFS)谱学技术开展热化学反应动力学研究,在上海光源X射线吸收精细结构谱学线站(BL14W1)开展了时间分辨热化学原位XAFS方法的研究。采用自主研制的数据采集设备解决了时间分辨XAFS技术中不同类型信号同步触发和同步采集的问题,实现了数据间的精准匹配。在单色器转速为720"/s、数据采集设备采样率为2MS/s、数据长度为1200eV的条件下,获得了一个9.6s的Cu标样的数据谱,通过与常规XAFS数据和标准XAFS数据进行对比,结果表明本文得到的时间分辨XAFS实验系统具有良好的准确性、分辨率和信噪比。在此基础上,进一步结合线站自主研制的原位装置开展了时间分辨热化学原位XAFS方法,并利用高温常压原位装置开展了CuO还原为金属Cu的验证性实验。在230℃恒温氢气气氛下30min内观测到Cu吸收边能量逐渐向低能量处偏移,同时它位于8998eV的主峰强度逐渐减弱并且劈裂为双峰结构,出现明显的金属Cu的特征。实验结果表明此方法达到了捕获物质动态演化过程的预期目的,在拓展XAFS谱学实验平台的同时,为热化学反应的动力学过程研究提供了一种强大的实验手段。展开更多
Indium oxide(In_(2)O_(3)),as a promising candidate for CO_(2)hydrogenation to C_(1) products,often suffers from sintering and activity decline,closely related to the undesirable structural evolution under reaction con...Indium oxide(In_(2)O_(3)),as a promising candidate for CO_(2)hydrogenation to C_(1) products,often suffers from sintering and activity decline,closely related to the undesirable structural evolution under reaction conditions.Based on the comprehension of the dynamic evolution,this study presents an efficient strategy to alleviate the agglomeration of In_(2)O_(3)nanoparticles by the surface decoration with highly dispersed silica species(SiO_(x)).Various structural characterizations combined with density functional theory calculations demonstrated that the sintering resulted from the over-reduction,while the enhanced stability originated from the anchoring effect of highly stable In-OSi bonds,which hinders the substantial formation of metallic In(In^(0))and the subsequent agglomeration.0.6Si/In_(2)O_(3)exhibited CO_(2)conversion rate of10.0 mmol g^(-1)h^(-1)at steady state vs.3.5 mmol g^(-1)h^(-1)on In_(2)O_(3)in CO_(2)hydrogenation.Enhanced steady-state activity was also achieved on Pd-modified catalysts.Compared to the traditional Pd/In_(2)O_(3)catalyst,the methanol production rate of Pd catalyst supported on 0.6Si/In_(2)O_(3)was enhanced by 23%,showing the potential of In_(2)O_(3)modified by SiO_(x)in serving as a platform material.This work provides a promising method to design new In_(2)O_(3)-based catalysts with improved activity and stability in CO_(2)hydrogenation.展开更多
基金financially supported by the National Natural Science Foundation of China (Grant No.51802025)the Natural Science Basic Research Plan in Shaanxi Province of China (Grant No.2020JQ-384)。
文摘Different bilayer structures of HfO_(x)/Ti(TiO_(x)) are designed for hafnium-based memory to investigate the switching characteristics. The chemical states in the films and near the interface are characterized by x-ray photoelectron spectroscopy,and the oxygen vacancies are analyzed. Highly improved on/off ratio(~104) and much uniform switching parameters are observed for bilayer structures compared to single layer HfO_(x) sample, which can be attributed to the modulation of oxygen vacancies at the interface and better control of the growth of filaments. Furthermore, the reliability of the prepared samples is investigated. The carrier conduction behaviors of HfO_(x)-based samples can be attributed to the trapping and de-trapping process of oxygen vacancies and a filamentary model is proposed. In addition, the rupture of filaments during the reset process for the bilayer structures occur at the weak points near the interface by the recovery of oxygen vacancies accompanied by the variation of barrier height. The re-formation of fixed filaments due to the residual filaments as lightning rods results in the better switching performance of the bilayer structure.
基金Project supported by Beijing Natural Science Foundation (Grant No.Z200005)the National Key R&D Program of China (Grant Nos.2018YFE0202600 and 2022YFA1403800)+1 种基金the National Natural Science Foundation of China (Grant No.12274459)Beijing National Laboratory for Condensed Matter Physics,and Collaborative Research Project of Laboratory for Materials and Structures,Institute of Innovative Research,Tokyo Institute of Technology。
文摘We report the detailed crystal structures and physical properties of Ru_(1-x)Mo_(x)alloys in the solid solution range of x=0.1-0.9.Structure characterizations indicate that the crystal structure changes from the hcp-Mg-type,toβ-CrFe-type,and then bcc-W-type.The measurements of physical properties show that the Ru_(1-x)Mo_(x)samples with x≥0.2are superconductors and the superconducting transition temperature T_c as a function of Mo content exhibits a dome-like behavior.
基金supported by National Natural Science Foundation of China(Nos.62027818,61874034,and 51861135105)Natural Science Foundation of Shanghai(No.18ZR1405000)Shanghai Science and Technology Innovation Program(No.19520711500).
文摘In this work,we reported a high-performance-based ultraviolet-visible(UV-VIS)photodetector based on a TiO_(2)@GaO_(x)N_(y)-Ag heterostructure.Ag particles were introduced into TiO_(2)@GaO_(x)N_(y)to enhance the visible light detection perfor-mance of the heterojunction device.At 380 nm,the responsivity and detectivity of TiO_(2)@GaO_(x)N_(y)-Ag were 0.94 A/W and 4.79×109 Jones,respectively,and they increased to 2.86 A/W and 7.96×1010 Jones at 580 nm.The rise and fall times of the response were 0.19/0.23 and 0.50/0.57 s,respectively.Uniquely,at 580 nm,the responsivity of fabricated devices is one to four orders of magnitude higher than that of the photodetectors based on TiO_(2),Ga_(2)O_(3),and other heterojunctions.The excellent optoelectronic characteristics of the TiO_(2)@GaO_(x)N_(y)-Ag heterojunction device could be mainly attributed to the synergistic effect of the type-Ⅱband structure of the metal-semiconductor-metal heterojunction and the plasmon resonance effect of Ag,which not only effectively promotes the separation of photogenerated carriers but also reduces the recombination rate.It is fur-ther illuminated by finite difference time domain method(FDTD)simulation and photoelectric measurements.The TiO_(2)@GaO_(x)N_(y)-Ag arrays with high-efficiency detection are suitable candidates for applications in energy-saving communica-tion,imaging,and sensing networks.
文摘为了利用X射线吸收精细结构(X-ray absorption fine structure,XAFS)谱学技术开展热化学反应动力学研究,在上海光源X射线吸收精细结构谱学线站(BL14W1)开展了时间分辨热化学原位XAFS方法的研究。采用自主研制的数据采集设备解决了时间分辨XAFS技术中不同类型信号同步触发和同步采集的问题,实现了数据间的精准匹配。在单色器转速为720"/s、数据采集设备采样率为2MS/s、数据长度为1200eV的条件下,获得了一个9.6s的Cu标样的数据谱,通过与常规XAFS数据和标准XAFS数据进行对比,结果表明本文得到的时间分辨XAFS实验系统具有良好的准确性、分辨率和信噪比。在此基础上,进一步结合线站自主研制的原位装置开展了时间分辨热化学原位XAFS方法,并利用高温常压原位装置开展了CuO还原为金属Cu的验证性实验。在230℃恒温氢气气氛下30min内观测到Cu吸收边能量逐渐向低能量处偏移,同时它位于8998eV的主峰强度逐渐减弱并且劈裂为双峰结构,出现明显的金属Cu的特征。实验结果表明此方法达到了捕获物质动态演化过程的预期目的,在拓展XAFS谱学实验平台的同时,为热化学反应的动力学过程研究提供了一种强大的实验手段。
基金financially supported by the National Natural Science Foundation of China(22172013)the Special Project for Key Research and Development Program of Xinjiang Autonomous Region(2022B01033-3)+3 种基金the Liaoning Revitalization Talent Program(XLYC2008032 and XLYC2203126)the Fundamental Research Funds for the Central Universities(DUT22LK24,DUT22QN207 and DUT22LAB602)the CUHK Research Startup Fund(No.#4930981)financial support from Catalyst:Seeding funding(CSG-VUW2201)provided by the New Zealand Ministry of Business,Innovation and Employment and administered by the Royal Society Aparangi。
文摘Indium oxide(In_(2)O_(3)),as a promising candidate for CO_(2)hydrogenation to C_(1) products,often suffers from sintering and activity decline,closely related to the undesirable structural evolution under reaction conditions.Based on the comprehension of the dynamic evolution,this study presents an efficient strategy to alleviate the agglomeration of In_(2)O_(3)nanoparticles by the surface decoration with highly dispersed silica species(SiO_(x)).Various structural characterizations combined with density functional theory calculations demonstrated that the sintering resulted from the over-reduction,while the enhanced stability originated from the anchoring effect of highly stable In-OSi bonds,which hinders the substantial formation of metallic In(In^(0))and the subsequent agglomeration.0.6Si/In_(2)O_(3)exhibited CO_(2)conversion rate of10.0 mmol g^(-1)h^(-1)at steady state vs.3.5 mmol g^(-1)h^(-1)on In_(2)O_(3)in CO_(2)hydrogenation.Enhanced steady-state activity was also achieved on Pd-modified catalysts.Compared to the traditional Pd/In_(2)O_(3)catalyst,the methanol production rate of Pd catalyst supported on 0.6Si/In_(2)O_(3)was enhanced by 23%,showing the potential of In_(2)O_(3)modified by SiO_(x)in serving as a platform material.This work provides a promising method to design new In_(2)O_(3)-based catalysts with improved activity and stability in CO_(2)hydrogenation.
