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Temperature-dependent Raman spectroscopic study of bismuth borate Bi_2ZnOB_2O_6
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作者 张季 张德明 +1 位作者 张庆礼 殷绍唐 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第1期503-506,共4页
A temperature-dependent Raman spectroscopic study on Bi2 Zn OB2O6crystal was carried out to investigate the structure change of the crystal with the increase of temperature. Raman spectra of crystal Bi2 Zn OB2O6were r... A temperature-dependent Raman spectroscopic study on Bi2 Zn OB2O6crystal was carried out to investigate the structure change of the crystal with the increase of temperature. Raman spectra of crystal Bi2 Zn OB2O6were recorded in the spectral range 10–1600 cm-1at room temperature first. Compared with the vibrational spectra of the referred compounds,satisfactory assignment of most of the high-energy modes to vibrations of Bi–O, B–O, and Zn–O bonds was achieved. In particular, the Raman high-frequency peak located at 1344 cm-1was attributed to the B–O vibration in the BO3 triangle.This temperature-dependent Raman spectroscopic study was carried out up to 600°C. It was found that all the Raman lines exhibit decreases in frequency and the widths of the Raman peaks increase with increasing temperature. No phase transition was observed under 600°C. 展开更多
关键词 bi2ZnOB2O6 crystal high temperature Raman spectroscopy vibrational mode
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手掌BIS的特征模型及特征提取算法研究
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作者 吕林涛 王胜 +2 位作者 张胜 黄健 杨宇祥 《传感器与微系统》 CSCD 2020年第1期46-49,共4页
针对现有的生物特征识别技术在特征提取、特征选择、模式分类及身份识别中,存在获取的特征值不是最优解、身份识别误判率高等问题。首次通过手掌生物电阻抗频谱(BIS)数据,建立了一种BIS数据的有效特征椭圆模型(EM);并融合免疫克隆技术... 针对现有的生物特征识别技术在特征提取、特征选择、模式分类及身份识别中,存在获取的特征值不是最优解、身份识别误判率高等问题。首次通过手掌生物电阻抗频谱(BIS)数据,建立了一种BIS数据的有效特征椭圆模型(EM);并融合免疫克隆技术和最小二乘法,提出了一种手掌电阻抗频谱BIS特征选择新算法。实验表明:该算法不仅能充分挖掘免疫克隆快速收敛到全局最优解的分类特性,而且能有效实现了EM特征的提取与选择,使身份识别的正确率提高到95%。因此,所提出的EM特征模型与特征选择算法在信息安全、电子商务等领域应用中具有重要的理论和实用价值。 展开更多
关键词 生物电阻抗频谱 椭圆模型(EM)特征模型 免疫克隆 特征选择
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Possible Nodeless Superconducting Gaps in Bi_2Sr_2CaCu_2O_(8+δ) and YBa_2Cu_3O_(7-x) Revealed by Cross-Sectional Scanning Tunneling Spectroscopy 被引量:2
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作者 任明强 闫亚军 +1 位作者 张童 封东来 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第12期124-128,共5页
Pairing in the cuprate high-temperature superconductors and its origin remain among the most enduring mysteries in condensed matter physics. With cross-sectional scanning tunneling microscopy/spectroscopy, we clearly ... Pairing in the cuprate high-temperature superconductors and its origin remain among the most enduring mysteries in condensed matter physics. With cross-sectional scanning tunneling microscopy/spectroscopy, we clearly reveal the spatial-dependence or inhomogeneity of the superconducting gap structure of Bi2Sr2CaCu2O8+δ (Bi2212) and YBa2Cu3O7-x (YBCO) along their c-axes on a scale shorter than the interlayer spacing. By tunneling into the (100) plane of a Bi2212 single crystal and a YBCO film, we observe both U-shaped tunneling spectra with extended fiat zero-conductance bottoms, and V-shaped gap structures, in different regions of each sample. On the YBCO film, tunneling into a (110) surface only reveals a U-shaped gap without any zero-bias peak. Our analysis suggests that the U-shaped gap is likely a nodeless superconducting gap. The V-shaped gap has a very small amplitude, and is likely proximity-induced by regions having the larger U-shaped gap. 展开更多
关键词 of is in Revealed by Cross-Sectional Scanning Tunneling spectroscopy and YBa2Cu3O Possible Nodeless Superconducting Gaps in bi2Sr2CaCu2O by DOS on bi Cu Sr
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Optical Spectroscopy of Er^(3+) and Er^(3+)/Yb^(3+)Co-doped Bi_2O_3-GeO_2-B_2O_3-ZnO Glasses 被引量:1
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作者 夏海平 章践立 +1 位作者 王金浩 张约品 《Journal of Rare Earths》 SCIE EI CAS CSCD 2006年第4期408-412,共5页
The (60 - x)Bi2O3 - xGeO2-30B2O3-10ZnO (x = 5, 10, 20, 30 molar percent) glasses doped with Er^3+ and Er^3+/Yb^3+ were fabricated using the melting method. The thermal stability of the glasses was studied with ... The (60 - x)Bi2O3 - xGeO2-30B2O3-10ZnO (x = 5, 10, 20, 30 molar percent) glasses doped with Er^3+ and Er^3+/Yb^3+ were fabricated using the melting method. The thermal stability of the glasses was studied with their DTA curves. The results show that the difference between the glass transition temperature and the crystallization onset temperature increases with the increase of GeO2 content, indicating that the thermal stability of the glass has become better. The absorption spectra were recorded and the stimulated emission cross sections were calculated using the McCumber theory. The Ω2, O4, and Ω6 parameters,the transition probability, the radiative lifetime, and the fluorescence branch ratio of Er^3+ for optical transition were calculated from their absorption spectra in terms of reduced matrix U^(t)(λ = 2, 4, 6) character for optical transitions. The infrared emission of Er^3+ was measured upon excitation with 970 nm light and the full width at half-maximum (FWHM) was estimated from the emission spectra. The pumping efficiency and the intensity of the emission at the 1.54 μm band of Er^3+ were enhanced considerably by co-doping Yb^3+ . 展开更多
关键词 bi-based glass GeO2 Er^3+ Er^3+/Yb^3+ thermal stability optical spectroscopy rare earths
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Structure, ferroelectric and dielectric properties of Bi_2 WO_6 with different bismuth content
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作者 王晓娟 龚志强 +1 位作者 朱骏 陈小兵 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第2期803-809,共7页
This paper reports that the Bi2WO6 ferroelectric ceramics with excess Bi2O3 of 0.0, 2.0, 3.5 and 5.0wt.% of the stoichiometric composition are prepared by the conventional solid-state reaction method. Their microstruc... This paper reports that the Bi2WO6 ferroelectric ceramics with excess Bi2O3 of 0.0, 2.0, 3.5 and 5.0wt.% of the stoichiometric composition are prepared by the conventional solid-state reaction method. Their microstructure, ferroelectric properties, the concentration and mobility of the defects have been analysed systematically. With increasing Bi content, the remnant polarization decreases, and the broken-down voltage increases. The optimum Bi excess, 3.5, lowers the oxygen vacancy concentration, while further Bi-addition brings about more defects. The activation energies fitted from cole-cole plots are 0.97 eV, 1.07 eV, 1.18 eV, and 1.33 eV, respectively. This suggests that the mobility of the defects is weakened by Bi-addition, which may be due to the increase of the ratio of the number of Bi2O2 layers to that of the oerovskite blocks. 展开更多
关键词 ferroelectric ceramics bi2WO6 oxygen vacancy x-ray photoemission spectroscopy
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Synthesis and Characterization of Cr(III) &Fe(II) Bis(2-Methoxybenzylidene)Biphenyl-4,4'-Diamine Complexes
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作者 Younis O. Ben Amer Rehab N. El-Daghare +2 位作者 Ahmed N. Hammouda Rashd M. El-Ferjani Fatin M. Elmagbari 《Open Journal of Inorganic Chemistry》 2020年第1期6-14,共9页
Bis(2-methoxybenzylidene)biphenyl-4,4'-diamine Schiff base was prepared by the reaction of benzidine and O-methoxy benzaldehyde 1:2 reaction. Two complexes of this ligand with Cr(III) and Fe(II) were prepared. All... Bis(2-methoxybenzylidene)biphenyl-4,4'-diamine Schiff base was prepared by the reaction of benzidine and O-methoxy benzaldehyde 1:2 reaction. Two complexes of this ligand with Cr(III) and Fe(II) were prepared. All prepared compounds were analysed using elemental analysis, IR, 1H NMR and mass spectroscopy. The formation of proposed structures, including the free ligand and complexes were confirmed. 展开更多
关键词 Schiff Base Complexes spectroscopy bis(2-Methoxybenzylidene)biphenyl-4 4'-Diamine
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X-ray Photoemission Spectroscopy Studies of the Semiconducting Molybdenum Purple Bronze Bi_(0.2)MoO_3
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作者 Rui XIONG Chang LUO +1 位作者 Wufeng TANG Jing SHI 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2006年第4期487-490,共4页
The electronic structure of the quasi-two-dimensional (2D) semiconducting molybdenum purple bronze Bio.2MoO3 was presented by X-ray photoemission spectroscopy. The valence band of Bio.2MoO3 is made up of Opπ nonbon... The electronic structure of the quasi-two-dimensional (2D) semiconducting molybdenum purple bronze Bio.2MoO3 was presented by X-ray photoemission spectroscopy. The valence band of Bio.2MoO3 is made up of Opπ nonbonding level, π and a bonding bands. The peak at 1.5 eV and the shoulder at 0.5 eV in the forbidden band may be formed from the non-bonding dxy orbitals of some Mo atoms. The O1s core-level spectrum demonstrates the presence of two inequivalent bonds of oxygen ions in Bio.2MoO3. Bi4f core-level spectrum shows two bonding characters of Bi atoms in bismuth molybdenum single crystal. Mo3d core-level spectrum confirms two kinds of valence states of Molybdenum (Mo^+5 and Mo^+6). Ar^+ ion irradiation induces more significant distortion of MoO6 octahedra. 展开更多
关键词 bi0.2MoO3 single crystal X-ray photoemission spectroscopy Core-electron spectrum
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Optical Spectroscopy of Er^(3+), Er^(3+)/Yb^(3+) Co-doped Bi_2O_3-GeO_2-B_2O_3-ZnO Glasses
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作者 Xia Haiping Zhang Jianli Wang Jinhao Zhang Yuepin 《Journal of Rare Earths》 SCIE EI CAS CSCD 2005年第5期550-550,共1页
The (60 - x) Bi2O3-xGeO2-30B2O3-10ZnO (x = 5, 10, 20, 30 molar percent) glasses doped with Er^3+ and Er^3+/Yb^3+ were fabricated by melting method. The thermal stability of the glasses was studied by their DTA ... The (60 - x) Bi2O3-xGeO2-30B2O3-10ZnO (x = 5, 10, 20, 30 molar percent) glasses doped with Er^3+ and Er^3+/Yb^3+ were fabricated by melting method. The thermal stability of the glasses was studied by their DTA curves. The results indicate that the difference between the glass transition temperature and the crystallization onset temperature increase as increase of GeO2 content, indicating that the thermal stability of the glass becomes better. The absorption spectra were recorded. The stimulated emission cross sections were calculated by McCumber theory. The Ω2, Ω4, and Ω6 parameters, transition probability, radiative lifetime, fluorescence branch ratio of Er^3+ for optical transition were calculated from their absorption spectra in terms of reduced matrix U^(1)(λ = 2, 4, 6) character for optical transitions. The infrared emission was measured by excitation with 970 nm light and the FWHM was estimated from their emission spectra. The pumping efficiency and the intensity of emission at the band of 1.54 μm are enhanced greatly by addition of Y2O3. 展开更多
关键词 bi-based glass GeO2 Er^3 Er^3 +/Yb^3+ thermal stability optical spectroscopy rare earths
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Mg和RE合金化对Al-Zn-Bi合金阳极组织和电化学性能的影响 被引量:4
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作者 文九巴 郝庆国 +1 位作者 贺俊光 马景灵 《材料热处理学报》 EI CAS CSCD 北大核心 2011年第11期99-104,共6页
针对Al-Zn-Bi合金,分别单独及复合添加Mg、RE元素进行微合金化,利用金相、扫描电镜及X射线能谱等分析了该合金添加不同元素前后的微观组织特征;采用恒电流法测定了该系列合金在人造海水中的开路电位、工作电位和电流效率,利用极化曲线... 针对Al-Zn-Bi合金,分别单独及复合添加Mg、RE元素进行微合金化,利用金相、扫描电镜及X射线能谱等分析了该合金添加不同元素前后的微观组织特征;采用恒电流法测定了该系列合金在人造海水中的开路电位、工作电位和电流效率,利用极化曲线和电化学阻抗谱,分析了微合金化对Al-Zn-Bi阳极材料电化学性能的影响。结果表明:单独添加Mg、RE可以细化晶粒、改善偏析相的组成和分布,将电流效率提高15.93%和4.12%;二者复合添加虽电流效率稍有降低,但可促使基体均匀溶解,减小腐蚀电流密度,从而有效提高其综合性能。 展开更多
关键词 Al-Zn-bi合金 微观组织 电化学性能 电化学阻抗谱
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Er^(3+)单掺与Er^(3+)/Yb^(3+)双掺杂Bi_2O_3-GeO_2-B_2O_3-ZnO玻璃的光谱研究 被引量:7
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作者 夏海平 章践立 +1 位作者 王金浩 张约品 《中国稀土学报》 CAS CSCD 北大核心 2005年第5期524-528,共5页
用高温融熔法制备了Er3+单掺与Er3+/Yb3+双掺杂的(60-x)Bi2O3-xGeO2-30B2O3-10ZnO(x=5,10,20,30)系统玻璃。用差热曲线(DTA)研究了该玻璃系统的热稳定性。结果表明,GeO2的掺入,使得玻璃的软化温度与结晶起始温度的差增加,玻璃的稳定性... 用高温融熔法制备了Er3+单掺与Er3+/Yb3+双掺杂的(60-x)Bi2O3-xGeO2-30B2O3-10ZnO(x=5,10,20,30)系统玻璃。用差热曲线(DTA)研究了该玻璃系统的热稳定性。结果表明,GeO2的掺入,使得玻璃的软化温度与结晶起始温度的差增加,玻璃的稳定性与料性增加。测定了玻璃的吸收光谱。应用McCumber理论计算了Er3+离子的受激发射截面及Er3+离子4I13/2-4I15/2发射光谱的荧光半高宽。从吸收光谱特性出发,应用J-O理论计算了玻璃中Er3+离子的强度参数(Ω2,Ω4,Ω6),Er3+离子的自发跃迁几率、荧光分支比以及辐射寿命。在970 nm波长的激发下,研究了样品在红外波段的荧光光谱。Yb2O3的掺入,大幅度地提高了970 nm波长的抽运效率以及在1.54μm波段的发光强度。 展开更多
关键词 铋基玻璃 GeO2 Er^3+单掺 Er^3+/Yb^3+双掺 热稳定性 光谱 稀土
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NaTaO_3及NaTaO_3∶Bi^(3+)光催化剂的光致发光光谱研究 被引量:1
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作者 石建英 陈涛 +3 位作者 周国华 冯兆池 应品良 李灿 《高等学校化学学报》 SCIE EI CAS CSCD 北大核心 2007年第4期692-695,共4页
采用光致发光光谱技术对一系列不同条件下制备的NaTaO3及不同掺杂量的NaTaO3∶Bi3+进行了研究.结果表明,NaTaO3的发光性质与其制备条件密切相关在钠离子不足的条件下合成的样品,其发光带主要位于515和745nm左右;而在钠离子充足条件下合... 采用光致发光光谱技术对一系列不同条件下制备的NaTaO3及不同掺杂量的NaTaO3∶Bi3+进行了研究.结果表明,NaTaO3的发光性质与其制备条件密切相关在钠离子不足的条件下合成的样品,其发光带主要位于515和745nm左右;而在钠离子充足条件下合成的样品,其发光带位于460nm左右,随着n(Na)/n(Ta)的降低,发光带向长波长方向移动;掺入Bi3+之后,其发光峰由515nm移至455nm,随着Bi3+掺入量的增加,455nm的发光带强度减弱.515nm的发光带与替位缺陷Ta.N.a..相关;745nm的发光带与VN`a缺陷相关;而460nm的发光带与本征TaO6基团相关.将Bi3+掺入到钽酸钠样品,TaN..a..由BiN..a替代,相应的发光带向高的n(Na)/n(Ta)方向移动,从而呈现出本征TaO6基团的发光带. 展开更多
关键词 光致发光光谱 NaTaO3 NaTaO3:bi^3+
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退火温度对Al-Zn-Bi-Mg-RE合金电化学性能的影响 被引量:2
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作者 郝庆国 文九巴 +1 位作者 贺俊光 马景灵 《热加工工艺》 CSCD 北大核心 2011年第22期146-148,共3页
采用金相显微镜、恒电流法、动电位极化法和电化学阻抗谱(EIS)技术研究了退火温度对Al-Zn-Bi-Mg-RE阳极合金微观组织和电化学性能的影响。结果表明:随退火温度的升高,合金的晶粒有长大的趋势,体积也逐渐球化,第二相弥散均匀分布于晶界... 采用金相显微镜、恒电流法、动电位极化法和电化学阻抗谱(EIS)技术研究了退火温度对Al-Zn-Bi-Mg-RE阳极合金微观组织和电化学性能的影响。结果表明:随退火温度的升高,合金的晶粒有长大的趋势,体积也逐渐球化,第二相弥散均匀分布于晶界和晶内;合金的电流效率提高,开路电位正移,工作电位更加稳定;在一定热处理温度范围内,随温度的升高,合金的电化学性能有所改善,经510℃×4 h保温并炉冷后的试样综合性能最好。 展开更多
关键词 Al-Zn-bi-Mg-RE合金 热处理温度 电化学性能 电化学阻抗谱
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皮肤肿瘤早期筛查的快速无创电阻抗检测方法
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作者 彭俊文 胡松佩 +3 位作者 洪志扬 王莉莉 刘凯 姚佳烽 《生物化学与生物物理进展》 SCIE CAS CSCD 北大核心 2024年第5期1161-1173,共13页
目的随着环境问题和臭氧层空洞化的加剧,皮肤肿瘤的患病率也大幅增加,但是皮肤肿瘤前期隐蔽性高、症状不明显,导致大部分病例都是在中晚期发现的。因此,本文基于生物阻抗谱(bioimpedance spectroscopy,BIS)技术,提出一种皮肤肿瘤早期筛... 目的随着环境问题和臭氧层空洞化的加剧,皮肤肿瘤的患病率也大幅增加,但是皮肤肿瘤前期隐蔽性高、症状不明显,导致大部分病例都是在中晚期发现的。因此,本文基于生物阻抗谱(bioimpedance spectroscopy,BIS)技术,提出一种皮肤肿瘤早期筛查的快速无创电阻抗检测方法。方法首先,建立四层皮肤模型,采用数值分析方法研究角质层对BIS测量的阻碍作用。其次,使用去除角质层的皮肤模型研究混有不同半径和浸润深度的皮肤肿瘤组织电学特性。最后,使用凝胶处理后的猪皮组织实验验证肿瘤浸润深度(h)的影响。结果角质层仿真结果表明,去除角质层的皮肤对激励信号的响应更明显。皮肤肿瘤模型仿真表明,当肿瘤半径(R_(tumor))及h>1.5 mm时能够区分肿瘤组织与正常组织。同时根据实验结果中正常组织与肿瘤组织虚部弛豫阻抗(Z_(imag-relax))定义了组织病变度(ε_(worse),为肿瘤组织虚部阻抗相对于正常组织虚部阻抗变化的百分比),并绘制了肿瘤组织浸润深度(Depth)与Z_(imag-relax)的拟合曲线。当ε_(worse)=0.4920时,BIS即可识别微浸润肿瘤组织,且拟合曲线修正决定系数为0.9468,拟合效果良好。结论基于BIS技术的方法具有实时、便捷、无创的优点,有望应用于皮肤肿瘤的检测。 展开更多
关键词 皮肤癌检测 无创/实时 肿瘤早筛应用 生物阻抗谱
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Bi-Sr-Ca-Cu-O系超导体制备过程中化学组成的选择性挥发
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作者 赵良仲 胡玉秀 +3 位作者 王俊茹 杨德亮 张金彪 朱道本 《无机材料学报》 SCIE EI CAS CSCD 北大核心 1990年第4期346-348,共3页
实验表明,在烧制 Bi-Sr-Ca-Cu-O 超导体时,压片两面用银片覆盖后热处理有利于110K 超导相生成,制得的超导体有较高的零电阻温度。XPS 分析表明,在烧制超导材料时 Bi 能优先挥发,其次是 Ca。有银片覆盖可减轻 Bi 等成份的挥发程度,因此... 实验表明,在烧制 Bi-Sr-Ca-Cu-O 超导体时,压片两面用银片覆盖后热处理有利于110K 超导相生成,制得的超导体有较高的零电阻温度。XPS 分析表明,在烧制超导材料时 Bi 能优先挥发,其次是 Ca。有银片覆盖可减轻 Bi 等成份的挥发程度,因此有银片覆盖的超导体中 Bi、Sr、Ca 和 O 的相对浓度比无银片覆盖的超导体中的要高。 展开更多
关键词 超导体 制备 化学组成
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插入Bi层对NiFe/Cu/NiFe/FeMn自旋阀多层膜交换耦合的影响
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作者 朱逢吾 于广华 +2 位作者 李明华 姜宏伟 赖武彦 《金属学报》 SCIE EI CAS CSCD 北大核心 2002年第6期617-620,共4页
对于Ta/NiFe/Cu/NiFe/FeMn/Ta自旋阀多层膜,Cu原子偏聚到NiFe/FeMn界面将导致自旋阀多层膜中NiFe/FeMn的交换耦合场Hex下降.然而,少量的表面活化原子Bi被沉积到Cu层和被钉扎NiFe层之间... 对于Ta/NiFe/Cu/NiFe/FeMn/Ta自旋阀多层膜,Cu原子偏聚到NiFe/FeMn界面将导致自旋阀多层膜中NiFe/FeMn的交换耦合场Hex下降.然而,少量的表面活化原子Bi被沉积到Cu层和被钉扎NiFe层之间,Cu原子在NiFe/FeMn界面的偏聚可以被抑制:而且,更重要的是Ta/NiFe/Cu/NiFe/FeMn/Ta自旋阀多层膜中的交换耦合场Hex可以被有效地提高. 展开更多
关键词 层间偏聚 交换耦合场 表面活化原子 bi XPS
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Facile synthesis of Bi_(12)O_(17)Br_2 and Bi_4O_5Br_2 nanosheets:In situ DRIFTS investigation of photocatalytic NO oxidation conversion pathway 被引量:6
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作者 Wendong Zhang Xiaoli Liu +2 位作者 Xing’an Dong Fan Dong Yuxin Zhang 《Chinese Journal of Catalysis》 CSCD 北大核心 2017年第12期2030-2038,共9页
Bi12O17Br2and Bi4O5Br2visible‐light driven photocatalysts,were respectively fabricated by hydrothermal and room‐temperature deposition methods with the use of BiBr3and NaOH as precursors.Both Bi12O17Br2and Bi4O5Br2w... Bi12O17Br2and Bi4O5Br2visible‐light driven photocatalysts,were respectively fabricated by hydrothermal and room‐temperature deposition methods with the use of BiBr3and NaOH as precursors.Both Bi12O17Br2and Bi4O5Br2were composed of irregular nanosheets.The Bi4O5Br2nanosheets exhibited high and stable visible‐light photocatalytic efficiency for ppb‐level NO removal.The performance of Bi4O5Br2was markedly higher than that of the Bi12O17Br2nanosheets.The hydroxyl radical(?OH)was determined to be the main reactive oxygen species for the photo‐degradation processes of both Bi12O17Br2and Bi4O5Br2.However,in situ diffuse reflectance infrared Fourier transform spectroscopy analysis revealed that Bi12O17Br2and Bi4O5Br2featured different conversion pathways for visible light driven photocatalytic NO oxidation.The excellent photocatalytic activity of Bi4O5Br2resulted from a high surface area and large pore volumes,which facilitated the transport of reactants and intermediate products,and provided more active sites for photochemical reaction.Furthermore,the Bi4O5Br2nanosheets produced more?OH and presented stronger valence band holeoxidation.In addition,the oxygen atoms of NO could insert into oxygen‐vacancies of Bi4O5Br2,whichprovided more active sites for the reaction.This work gives insight into the photocatalytic pollutant‐degradation mechanism of bismuth oxyhalide. 展开更多
关键词 bi12O17Br2 bi4O5Br2 In situ diffuse reflectance infrared Fourier transform spectroscopy investigation Conversion pathway NO oxidation
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Electrical analysis of inter-growth structured Bi_4Ti_3O_(12)-Na_(0.5)Bi_(4.5)Ti_4O_(15) ceramics 被引量:1
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作者 江向平 江亚林 +3 位作者 江兴安 陈超 涂娜 陈云婧 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第7期386-392,共7页
Inter-growth bismuth layer-structured ferroelectrics(BLSFs), Bi_4Ti_3O_(12)-Na_(0.5)Bi_(4.5)Ti_4O_(15)(BIT-NBT), were successfully synthesized using the traditional solid-state reaction method. X-ray diffr... Inter-growth bismuth layer-structured ferroelectrics(BLSFs), Bi_4Ti_3O_(12)-Na_(0.5)Bi_(4.5)Ti_4O_(15)(BIT-NBT), were successfully synthesized using the traditional solid-state reaction method. X-ray diffraction(XRD) Rietveld refinements were conducted using GSAS software. Good agreement and low residual are obtained. The XRD diffraction peaks can be well indexed into I2 cm space group. The inter-growth structure was further observed in the high-resolution TEM image. Dielectric and impedance properties were measured and systematically analyzed. At the temperature range 763-923 K(below T_c), doubly ionized oxygen vacancies(OVs) are localized and the short-range hopping leads to the relaxation processes with an activation energy of 0.79-1.01 eV. Above T_c, the doubly charged OVs are delocalized and become free ones, which contribute to the long-range dc conduction. The reduction in relaxation species gives rise to a higher relaxation activation energy ~ 1.6 eV. 展开更多
关键词 bi4Ti3O12-Na0.5bi4.5Ti4O15 impedance spectroscopy oxygen vacancies-related defect dipoles electrical analysis
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Evolution of incommensurate superstructure and electronic structure with Pb substitution in(Bi2-xPbx)Sr2CaCu2O8+δ superconductors
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作者 Jing Liu Lin Zhao +24 位作者 Qiang Gao Ping Ai Lu Zhang Tao Xie( Jian-Wei Huang Ying Ding Cheng Hu Hong-Tao Yan Chun-Yao Song Yu Xu Cong Li Yong-Qing Cai Hong-Tao Rong Ding-Song Wu Guo-Dong Liu Qing-Yan Wang Yuan Huang Feng-Feng Zhang Feng Yang Qin-Jun Peng Shi-Liang Li Huai-Xin Yang Jian-Qi Li Zu-Yan Xu Xing-Jiang Zhou 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第7期102-110,共9页
High-quality Bi2-xPbxSr2 CaCu2O8+δ(Bi2212) single crystals have been successfully grown by the traveling solvent floating zone technique with a wide range of Pb substitution(x = 0–0.8).The samples are characterized ... High-quality Bi2-xPbxSr2 CaCu2O8+δ(Bi2212) single crystals have been successfully grown by the traveling solvent floating zone technique with a wide range of Pb substitution(x = 0–0.8).The samples are characterized by transmission electron microscope(TEM) and measured by high resolution laser-based angle-resolved photoemission spectroscopy(ARPES) with different photon energies.A systematic evolution of the electronic structure and superstructure with Pb substitution has been revealed for the first time.The superstructure shows a significant change with Pb substitution and the incommensurate modulation vector(Q) decreases with increasing Pb substitution.In the meantime, the superstructure intensity from ARPES measurements also decreases dramatically with increasing Pb concentration.The superstructure in Bi2212 can be effectively suppressed by Pb substitution and it nearly disappears with a Pb substitution of x = 0.8.We also find that the superstructure bands in ARPES measurements depend sensitively on the photon energy of lasers used;they can become even stronger than the main band when using a laser photon energy of 10.897 eV.These results provide important information on the origin of the incommensurate superstructure and its control and suppression in bismuth-based high temperature superconductors. 展开更多
关键词 bi2-xPbxSr2CaCu2O8+δ SUPERSTRUCTURE electronic structure angle-resolved PHOTOEMISSION spectroscopy(ARPES) modulation
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Electronic spectroscopy and photochromic mechanism of bis-Schiff bases, N, N'-bis(2-hydroxy-1-naphthylidene)-1,4-phenyldiamine 被引量:2
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作者 明阳福 黄震年 +3 位作者 樊美公 许宝安 金声 姚思德 《Science China Chemistry》 SCIE EI CAS 1997年第4期373-379,共7页
The steady state and transient state absorption spectra and fluorescence spectra of N,N’-bis(2-hy-droxy-1-napbthylidcne)-1,4-phenyldiamme ( BNP ) in cyclohexane and acetonitrile were determined.The pho-tochromic mech... The steady state and transient state absorption spectra and fluorescence spectra of N,N’-bis(2-hy-droxy-1-napbthylidcne)-1,4-phenyldiamme ( BNP ) in cyclohexane and acetonitrile were determined.The pho-tochromic mechanism was discussed In nonpolar solvents,BNP exists mainly in the enol form and has the absorption maximum in the UV region In polar solvents,however,both the enol and proton transfer tautomer are formed,but the farmer is the main one Fluorescence emissions result from the excited state of proton transfer product. 展开更多
关键词 absorption spectroscopy FLUORESCENCE spectroscopy N N’-bis(2-hydroxy-l-naphthylidene)-1 4-phenyldiamine
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一种多频率同步信号激励电流源设计 被引量:11
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作者 杨宇祥 乔洋 《仪器仪表学报》 EI CAS CSCD 北大核心 2013年第4期908-913,共6页
生物电阻抗频谱(BIS)多频率同步快速测量系统中的激励电流源必须满足频谱宽、谱能量均衡、相位同步、输出阻抗高等特殊要求。基于Walsh函数设计了一种周期、二值的九频率同步信号f(9,t),它在1、2、4、8、16、32、64、128和256次等9个主... 生物电阻抗频谱(BIS)多频率同步快速测量系统中的激励电流源必须满足频谱宽、谱能量均衡、相位同步、输出阻抗高等特殊要求。基于Walsh函数设计了一种周期、二值的九频率同步信号f(9,t),它在1、2、4、8、16、32、64、128和256次等9个主谐波上相位同步,能量分布均衡,功率总和占到了平均总功率的65.52%。介绍了f(9,t)的FPGA实现方法和电压控制电流源(VCCS)驱动电路设计。负载实验表明,VCCS的负载电压理论仿真波形与实测波形高度一致,且具有较高的输出阻抗。确立了一种比较理想的多频率同步激励电流源,为BIS的多频率同步快速测量奠定基础。 展开更多
关键词 生物电阻抗频谱 多频率同步信号 FPGA 电压控制电流源
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