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Sr(Fe(1-x)Nb_x)O_(3-δ)陶瓷系统中非化学计量比参量δ的实验测定
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作者 刘东航 吴小清 姚熹 《硅酸盐学报》 EI CAS CSCD 北大核心 1991年第5期464-468,共5页
本文描述了利用失重测量和EDTA滴定方法对Sr(Fe_(1-x)Nb_x)O_(3-δ)陶瓷系统当X取不同值时,非化学计量比参量δ的数值进行实验测定的过程和方法。
关键词 氧化物陶瓷 非化学计量化 EDTA滴定
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非化学计量比铌酸锌微波介电陶瓷的低温烧结行为 被引量:3
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作者 张云 丁士华 +2 位作者 宋天秀 张晓云 黄龙 《硅酸盐学报》 EI CAS CSCD 北大核心 2019年第9期1268-1275,共8页
采用固相烧结工艺制备低损耗、非化学计量比Zn1.01Nb2O6微波介电陶瓷。研究了添加不同量的Li2CO3–B2O3–V2O5(LBV)对Zn1.01Nb2O6陶瓷烧结温度、表面形貌以及微波介电性能的影响。结果表明:LBV作为助烧剂,在陶瓷烧结过程中产生了液相,... 采用固相烧结工艺制备低损耗、非化学计量比Zn1.01Nb2O6微波介电陶瓷。研究了添加不同量的Li2CO3–B2O3–V2O5(LBV)对Zn1.01Nb2O6陶瓷烧结温度、表面形貌以及微波介电性能的影响。结果表明:LBV作为助烧剂,在陶瓷烧结过程中产生了液相,当添加剂含量大于1.5%(质量分数)时,LBV与基体陶瓷发生了化学反应。液相的产生、副相LiZnNbO4的形成以及V5+的扩散共同改善了陶瓷的烧结行为,使烧结温度由1 175℃低至950℃。LBV加入到基体陶瓷后对微波介电性能影响较小。当LBV添加量为1.0%,并在950℃保温4 h后,Zn1.01Nb2O6陶瓷微波介电性能最优:εr=20.6,Q×f=90 472 GHz,τf=–85.9×10–6℃–1。 展开更多
关键词 微波介电陶瓷 低温烧结 铌酸锌陶瓷 非化学计量化
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Sequential Observation of Alkali-halide Gas Phase Clusters in High Resolution TOF-MS and Prediction of Their Structures 被引量:1
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作者 Hui Wen Yi-rong Liu +4 位作者 Kang-ming Xu Teng Huang Chang-jin Hu Wei-jun Zhang Wei Huang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2013年第6期729-738,I0004,共11页
Alkali halide clusters are interesting model systems that can provide information about how crystal properties evolve. To study these properties, a high-resolution atmospheric pressure inlet time-of-flight mass spectr... Alkali halide clusters are interesting model systems that can provide information about how crystal properties evolve. To study these properties, a high-resolution atmospheric pressure inlet time-of-flight mass spectrometry (APi-TOF-MS) study of the sequential sodium halides series, C1-(NaC1)n and Br-(NaBr)m, has been reported, and the viability of the APi-TOF- MS equipped with an electrospray ionization source in determining cluster compositions has been demonstrated. The isotopic patterns were well resolved, as n=4 and 7 were determined to be the magic numbers for C1-(NaC1)n clusters, which were particularly abundant in the mass spectra. A global minimum search based on density functional theory enabled basin hopping yield the most stable structures for the mentioned series. The structures exhibit several distinct motifs which can be roughly categorized as linear chain, rock salt, and hexag- onal ring. This work provides an effective way to discover and elucidate the nonstoichiometry sodium halide clusters. These clusters possess very high vertical detachment energies and are generally called as superhalogens, which play important roles in chemistry because they are widely used in the synthesis of new classes of charge-transfer salts. 展开更多
关键词 Atmospheric pressure interface time-of-flight mass spectrometry Density functional theory Sodium halide cluster
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High-entropy perovskite oxides: A versatile class of materials for nitrogen reduction reactions
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作者 Kaibin Chu Jingjing Qin +9 位作者 Haiyan Zhu Michiel De Ras Chuang Wang Lei Xiong Longsheng Zhang Nan Zhang Johan A.Martens Johan Hofkens Feili Lai Tianxi Liu 《Science China Materials》 SCIE EI CAS CSCD 2022年第10期2711-2720,共10页
Despite the intense research efforts directed to electrocatalytic nitrogen reduction reaction(eNRR),the NH_(3) yield and selectivity are still not up to the standard of practical application.Here,high-entropy perovski... Despite the intense research efforts directed to electrocatalytic nitrogen reduction reaction(eNRR),the NH_(3) yield and selectivity are still not up to the standard of practical application.Here,high-entropy perovskite oxides with composition Bax(FeCoNiZrY)_(0.2)O_(3−δ)(Bx(FCNZY)_(0.2)(x=0.9,1)are reported as eNRR catalysts.The eNRR activity of high-entropy perovskite oxide is enhanced by changing the nonstoichiometric metal elements at the A-site,thus generating additional oxygen vacancies.The NH_(3) yield and Faraday efficiency for B_(0.9)(FCNZY)_(0.2) are 1.51 and 1.95 times higher than those for B(FCNZY)_(0.2),respectively.The d-band center theory is used to theoretically predict the catalytically active center at the B-site,and as a result,nickel was identified as the catalytic site.The free energy values of the intermediate states in the optimal distal pathway show that the third protonation step(*NNH_(2)→*NNH_(3))is the rate-determining step and that the increase in oxygen vacancies in the high-entropy perovskite contributes to nitrogen adsorption and reduction.This work provides a framework for applying high-entropy structures with active site diversity for electrocatalytic nitrogen fixation. 展开更多
关键词 high entropy PEROVSKITE nitrogen reduction reaction catalytic activity center
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Amorphous nonstoichiometric oxides with tunable room-temperature ferromagnetism and electrical transport
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作者 Qinghao Li Ruimin Qiao +12 位作者 Apurva Mehta Weiming Lü Tie Zhou Elke Arenholz Cheng Wang Yanxue Chen Li Li Yufeng Tian Lihui Bai Zahid Hussain Rongkun Zheng Wanli Yang Shishen Yan 《Science Bulletin》 SCIE EI CAS CSCD 2020年第20期1718-1725,M0003,共9页
Material functionalities strongly depend on the stoichiometry,crystal structure,and homogeneity.Here we demonstrate an approach of amorphous nonstoichiometric inhomogeneous oxides to realize tunable ferromagnetism and... Material functionalities strongly depend on the stoichiometry,crystal structure,and homogeneity.Here we demonstrate an approach of amorphous nonstoichiometric inhomogeneous oxides to realize tunable ferromagnetism and electrical transport at room temperature.In order to verify the origin of the ferromagnetism,we employed a series of structural,chemical,and electronic state characterizations.Combined with electron microscopy and transport measurements,synchrotron-based grazing incident wide angle X-ray scattering,soft X-ray absorption and circular dichroism clearly reveal that the roomtemperature ferromagnetism originates from the In0.23Co0.77O1-v,amorphous phase with a large tunable range of oxygen vacancies.The room-temperature ferromagnetism is tunable from a high saturation magnetization of 500 emu cm-3 to below 25 emu cm-3,with the evolving electrical resistivity from5×103μΩ cm to above 2.5×105 μΩ cm.Inhomogeneous nano-crystallization emerges with decreasing oxygen vacancies,driving the system towards non-ferromagnetism and insulating regime.Our work unfolds the novel functionalities of amorphous nonstoichiometric inhomogeneous oxides,which opens up new opportunities for developing spintronic materials with superior magnetic and transport properties. 展开更多
关键词 Amorphous oxide Room-temperature ferromagnetism Grazing incident wide angle X-ray SCATTERING Soft X-ray spectroscopy
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