Superconductivity induced by oxygen doping in Y{sub 2}O{sub 2}Bi

Energy Technology Data Exchange (ETDEWEB)

Cheng, Xiyue; Deng, Shuiquan [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter (FJIRSM), Chinese Academy of Sciences (CAS), Fuzhou (China); Gordon, Elijah E. [Department of Chemistry, North Carolina State University, Raleigh, NC (United States); Whangbo, Myung-Hwan [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter (FJIRSM), Chinese Academy of Sciences (CAS), Fuzhou (China); Department of Chemistry, North Carolina State University, Raleigh, NC (United States)

2017-08-14

When doped with oxygen, the layered Y{sub 2}O{sub 2}Bi phase becomes a superconductor. This finding raises questions about the sites for doped oxygen, the mechanism of superconductivity, and practical guidelines for discovering new superconductors. We probed these questions in terms of first-principles calculations for undoped and O-doped Y{sub 2}O{sub 2}Bi. The preferred sites for doped O atoms are the centers of Bi{sub 4} squares in the Bi square net. Several Bi 6p x/y bands of Y{sub 2}O{sub 2}Bi are raised in energy by oxygen doping because the 2p x/y orbitals of the doped oxygen make antibonding possible with the 6p x/y orbitals of surrounding Bi atoms. Consequently, the condition necessary for the ''flat/steep'' band model for superconductivity is satisfied in O-doped Y{sub 2}O{sub 2}Bi. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Rose-like I-doped Bi_2O_2CO_3 microspheres with enhanced visible light response: DFT calculation, synthesis and photocatalytic performance

International Nuclear Information System (INIS)

Zai, Jiantao; Cao, Fenglei; Liang, Na; Yu, Ke; Tian, Yuan; Sun, Huai; Qian, Xuefeng

2017-01-01

Highlights: • DFT reveals I"− can partially substitute CO_3"2"−to narrow the bandgap of Bi_2O_2CO_3. • Sodium citrate play a key role on the formation of rose-like I-doped Bi_2O_2CO_3. • Rose-like I-doped Bi_2O_2CO_3 show enhanced visible light response. • The catalyst has enhanced photocatalytic activity to organic and Cr(VI) pollutes. - Abstract: Based on the crystal structure and the DFT calculation of Bi_2O_2CO_3, I"− can partly replace the CO_3"2"−in Bi_2O_2CO_3 to narrow its bandgap and to enhance its visible light absorption. With this in mind, rose-like I-doped Bi_2O_2CO_3 microspheres were prepared via a hydrothermal process. This method can also be extended to synthesize rose-like Cl- or Br-doped Bi_2O_2CO_3 microspheres. Photoelectrochemical test supports the DFT calculation result that I- doping narrows the bandgap of Bi_2O_2CO_3 by forming two intermediate levels in its forbidden band. Further study reveals that I-doped Bi_2O_2CO_3 microspheres with optimized composition exhibit the best photocatalytic activity. Rhodamine B can be completely degraded within 6 min and about 90% of Cr(VI) can be reduced after 25 min under the irradiation of visible light (λ > 400 nm).

Narrow band gap and visible light-driven photocatalysis of V-doped Bi{sub 6}Mo{sub 2}O{sub 15} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Xu, Jian; Qin, Chuanxiang; Huang, Yanlin [State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Wang, Yaorong, E-mail: yrwang@suda.edu.cn [State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Qin, Lin [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of); Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

2017-02-28

Highlights: • V{sup 5+}-doped Bi{sub 6}Mo{sub 2}O{sub 15} was synthesized by the electrospinning preparation. • The band gap energy of Bi{sub 6}Mo{sub 2}O{sub 15} was greatly reduced by V-doping in the lattices. • V-doped Bi{sub 6}Mo{sub 2}O{sub 15} shows high activity in RhB degradation under visible light. • Crystal structure of Bi{sub 6}Mo{sub 2}O{sub 15} is favorable for high photocatalytic capacity. - Abstract: Pure and V{sup 5+}-doped Bi{sub 6}Mo{sub 2}O{sub 15} (3Bi{sub 2}O{sub 3}·2MoO{sub 3}) photocatalysts were synthesized through electrospinning, followed by low-temperature heat treatment. The samples developed into nanoparticles with an average size of approximately 50 nm. The crystalline phases were verified via X-ray powder diffraction measurements (XRD). The surface properties of the photocatalysts were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analyses. The UV–vis spectra showed that V doping in Bi{sub 6}Mo{sub 2}O{sub 15} shifted the optical absorption from the UV region to the visible-light wavelength region. The energy of the band gap of Bi{sub 6}Mo{sub 2}O{sub 15} was reduced by V doping in the lattices. The photocatalytic activities of the pure and V-doped Bi{sub 6}Mo{sub 2}O{sub 15} were tested through photodegradation of rhodamine B (RhB) dye solutions under visible light irradiation. Results showed that 20 mol% V-doped Bi{sub 6}Mo{sub 2}O{sub 15} achieved efficient photocatalytic ability. RhB could be degraded by V-doped Bi{sub 6}Mo{sub 2}O{sub 15} in 2 h. The photocatalytic activities and mechanisms were discussed according to the characteristics of the crystal structure and the results of EIS and XPS measurements.

A comprehensive investigation of tetragonal Gd-doped BiVO{sub 4} with enhanced photocatalytic performance under sun-light

Energy Technology Data Exchange (ETDEWEB)

Luo, Yangyang; Tan, Guoqiang, E-mail: tan3114@163.com; Dong, Guohua; Ren, Huijun; Xia, Ao

2016-02-28

Graphical abstract: - Highlights: • Tetragonal Gd-BiVO{sub 4} with enhanced photocatalytic activity was synthesized. • Gd doping can induce the phase transition from monoclinic to tetragonal BiVO{sub 4}. • GdVO{sub 4} seeds as crystal nucleus dominate the formation of tetragonal Gd-BiVO{sub 4}. • Tetragonal Gd-BiVO{sub 4} exhibits the excellent separation of electrons and holes. • The contribution of high photocatalytic activity under sun-light is from UV-light. - Abstract: Tetragonal Gd-doped BiVO{sub 4} having enhanced photocatalytic activity have been synthesized by a facile microwave hydrothermal method. The structural analysis indicates that Gd doping can induce the phase transition from monoclinic to tetragonal BiVO{sub 4}. The reaction results in precursor solutions imply that tetragonal GdVO{sub 4} seeds as crystal nucleus are the original and determined incentives to force the formation of tetragonal Gd-BiVO{sub 4}. The influences of the surface defect, band structure, and BET surface area on the improved photocatalytic activities of tetragonal Gd-doped BiVO{sub 4} are investigated systematically. The results demonstrate that the more surface oxygen deficiencies as active sites and the excellent mobility and separation of photogenerated electrons and holes are beneficial to the enhancement of the photocatalytic performance of tetragonal Gd-BiVO{sub 4}. The RhB photodegradation experiments indicate that the contribution of high photocatalytic activities under simulated sun-light is mainly from UV-light region due to the tetragonal structure feature. The best photocatalytic performance is obtained for tetragonal 10 at% Gd-BiVO{sub 4}, of which the RhB degradation rate can reach to 96% after 120 min simulated sun-light irradiation. The stable tetragonal Gd-BiVO{sub 4} with efficient mineralization will be a promising photocatalytic material applied in water purification.

Solvothermal syntheses of Bi and Zn co-doped TiO_2 with enhanced electron-hole separation and efficient photodegradation of gaseous toluene under visible-light

International Nuclear Information System (INIS)

Li, Juan-Juan; Cai, Song-Cai; Xu, Zhen; Chen, Xi; Chen, Jin; Jia, Hong-Peng; Chen, Jing

2017-01-01

Highlights: • Bi-Zn co-doped TiO_2 catalysts were prepared by solvothermal route. • The incorporation of Bi doping into the TiO_2 generates intermediate energy levels. • Bi and Zn doping showed the enhanced absorption in visible-light region. • Zn dopant acts as a mediator of interfacial charge transfer. • TiBi_1_._9_%Zn_1_%O_2 exhibited high photocatalytic degradation for toluene. - Abstract: This study investigated the effects of Bi doped and Bi-Zn co-doped TiO_2 on photodegradation of gaseous toluene. The doped TiO_2 with various concentration of metal was prepared using the solvothermal route and characterized by SEM, XRD, Raman, BET, DRS, XPS, PL and EPR. Their photocatalytic activities under visible-light irradiation were drastically influenced by the dopant content. The results showed that moderate metal doping levels were obviously beneficial for the toluene degradation, while high doping levels suppressed the photocatalytic activity. The photocatalytic degradation of toluene over TiBi_1_._9_%O_2 and TiBi_1_._9_%Zn_1_%O_2 can reach to 51% and 93%, respectively, which are much higher than 25% of TiO_2. Bi doping into TiO_2 lattice generates new intermediate energy level of Bi below the CB edge of TiO_2. The electron excitation from the VB to Bi orbitals results in the decreased band gap, extended absorption of visible-light and thus enhances its photocatalytic efficiency. Zn doping not only further enhances the absorption in this visible-light region, but also Zn dopant exists as the form of ZnO crystallites located on the interfaces of TiO_2 agglomerates and acts as a mediator of interfacial charge transfer to suppress the electron-hole recombination. These synergistic effects are responsible for the enhanced photocatalytic performance.

Synergistic effect of oxygen vacancy and nitrogen doping on enhancing the photocatalytic activity of Bi{sub 2}O{sub 2}CO{sub 3} nanosheets with exposed {0 0 1} facets for the degradation of organic pollutants

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yafei [School of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062 (China); Zhu, Gangqiang, E-mail: zgq2006@snnu.edu.cn [School of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062 (China); Hojamberdiev, Mirabbos [School of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062 (China); Department of Natural and Mathematic Sciences, Turin Polytechnic University in Tashkent, Kichik Halqa Yo’li 17, Tashkent 100095 (Uzbekistan); Gao, Jianzhi [School of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062 (China); Hao, Jing [Xi' an Rejee Industry Development Co., Ltd., Xi’an 710016 (China); Zhou, Jianping; Liu, Peng [School of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062 (China)

2016-05-15

Highlights: • Nitrogen-doped Bi{sub 2}O{sub 2}CO{sub 3} flower-like microstructures were synthesized by hydrothermal method. • Surface oxygen vacancy were obtained by irradiating the nitrogen-doped Bi{sub 2}O{sub 2}CO{sub 3} with UV light. • Photocatalytic activity was studied by degrading Rhodamine B. • A synergistic effect between oxygen vacancy and nitrogen doping in Bi{sub 2}O{sub 2}CO{sub 3}. - Abstract: Single-crystalline bare Bi{sub 2}O{sub 2}CO{sub 3} (BOC) nanosheets with exposed {0 0 1} facets and nitrogen-doped Bi{sub 2}O{sub 2}CO{sub 3} (NBOC) flower-like microstructures were synthesized by a simple hydrothermal method. The nitrogen-doped Bi{sub 2}O{sub 2}CO{sub 3} flower-like microstructures with oxygen vacancy (UV-NBOC) were obtained by irradiating the NBOC microstructures with UV light for 2 h in ethanol. The UV–vis diffuse reflectance spectra showed that the NBOC and UV-NBOC nanosheets exhibit an obvious red shift in light absorption band compared with the pure BOC nanosheets. Rhodamine B (RhB) was chosen as a model organic pollutant to verify the influence of oxygen vacancy and nitrogen doping on the photocatalytic activity of Bi{sub 2}O{sub 2}CO{sub 3} under simulated solar light irradiation. Judging from the kinetics of RhB photodegradation over the synthesized samples, a synergistic effect between oxygen vacancy and nitrogen doping was found with a remarkable increase (more than 10 and 2 times) in the photocatalytic activity of UV-NBOC compared with BOC and NBOC, respectively. Moreover, the UV-NBOC also exhibited an excellent cyclability and superior photocatalytic activity toward degradation of other organic pollutants (methylene blue, Congo red, Bisphenol A) under simulated solar light irradiation.

Hydrothermal fabrication of N-doped (BiO){sub 2}CO{sub 3}: Structural and morphological influence on the visible light photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Dong, Fan, E-mail: dfctbu@126.com [Chongqing Key Laboratory of Catalysis and Functional Organic Molecules, College of Environmental and Biological Engineering, Chongqing Technology and Business University, Chongqing 400067 (China); Wang, Rui; Li, Xinwei [Chongqing Key Laboratory of Catalysis and Functional Organic Molecules, College of Environmental and Biological Engineering, Chongqing Technology and Business University, Chongqing 400067 (China); Ho, Wing-Kei [Department of Science and Environmental Studies, The Centre for Education in Environmental Sustainability, The Hong Kong Institute of Education, Hong Kong (China)

2014-11-15

Graphical abstract: - Highlights: • Persimmon-like, flower-like N-doped (BiO){sub 2}CO{sub 3} superstructures were prepared. • The superstructures were fabricated by one-step hydrothermal method. • The hydrothermal temperature controlled the morphological structure. • N-doped (BiO){sub 2}CO{sub 3} superstructure showed enhanced photocatalytic activity. • The high activity can be ascribed to doped nitrogen and hierarchical structure. - Abstract: Various 3D N-doped (BiO){sub 2}CO{sub 3} (N-BOC) hierarchical superstructures self-assembled with 2D nanosheets were fabricated by one-step hydrothermal treatment of bismuth citrate and urea. The as-obtained samples were characterized by XRD, XPS, FT-IR, SEM, N{sub 2} adsorption–desorption isotherms and UV–vis DRS. The hydrothermal temperature plays a crucial role in tuning the crystal and morphological structure of the samples. Adjusting the reaction temperature to 150, 180 and 210 °C, we obtained N-doped (BiO){sub 2}CO{sub 3} samples with corresponding attractive persimmon-like, flower-like and nanoflakes nano/microstructures. The photocatalytic activities of the samples were evaluated by removal of NO under visible and solar light irradiation. The results revealed that the N-doped (BiO){sub 2}CO{sub 3} hierarchical superstructures showed enhanced visible light photocatalytic activity compared to pure (BiO){sub 2}CO{sub 3} and TiO{sub 2}-based visible light photocatalysts. The outstanding photocatalytic performance of N-BOC samples can be ascribed to the doped nitrogen and the special hierarchical structure. The present work could provide new perspectives in controlling the morphological structure and photocatalytic activity of photocatalyst for better environmental pollution control.

Enhanced photocatalytic property of BiFeO_3/N-doped graphene composites and mechanism insight

International Nuclear Information System (INIS)

Li, Pai; Li, Lei; Xu, Maji; Chen, Qiang; He, Yunbin

2017-01-01

Highlights: • A hydrothermal process was used to prepare BiFeO_3/N-doped graphene composites. • BiFeO_3/N-doped graphene exhibits superior photocatalytic activity and stability. • The energy band of BiFeO_3 bends downward by ∼1.0 eV at the composite interface. • Downward band bending leads to rapid electron transfer at the composite interface. • Holes and ·OH are predominant active species in the photo-degradation process. - Abstract: A series of BiFeO_3/(N-doped) graphene composites are prepared by a facile hydrothermal method. BiFeO_3/N-doped graphene shows photocatalytic performance superior to that of BiFeO_3/graphene and pristine BiFeO_3. The enhanced photo-degradation performance of BiFeO_3/N-doped graphene are mainly attributable to the improved light absorbance of the composite, abundant active adsorption sites and high electrical charge mobility of N-doped graphene, and the downward band bending of BiFeO_3 at the composite interface. In particular, X-ray photoelectron spectroscopy analyses reveal that the electron energy band of BiFeO_3 is downward bent by 1.0 eV at the interface of BiFeO_3/N-doped graphene, because of different work functions of both materials. This downward band bending facilitates the transfer of photogenerated electrons from BiFeO_3 to N-doped graphene and prompts the separation of photo-generated electron-hole pairs, leading eventually to the enhanced photocatalytic performance.

Solvothermal syntheses of Bi and Zn co-doped TiO{sub 2} with enhanced electron-hole separation and efficient photodegradation of gaseous toluene under visible-light

Energy Technology Data Exchange (ETDEWEB)

Li, Juan-Juan [Center for Excellence in Regional Atmospheric Environment, and Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Cai, Song-Cai [Center for Excellence in Regional Atmospheric Environment, and Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); University of Chinese Academy of Sciences, Beijing, 100049 (China); Xu, Zhen [Center for Excellence in Regional Atmospheric Environment, and Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Chen, Xi [Center for Excellence in Regional Atmospheric Environment, and Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); University of Chinese Academy of Sciences, Beijing, 100049 (China); Chen, Jin [Center for Excellence in Regional Atmospheric Environment, and Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Jia, Hong-Peng, E-mail: hpjia@iue.ac.cn [Center for Excellence in Regional Atmospheric Environment, and Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Chen, Jing, E-mail: jing.chen@fjirsm.ac.cn [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China)

2017-03-05

Highlights: • Bi-Zn co-doped TiO{sub 2} catalysts were prepared by solvothermal route. • The incorporation of Bi doping into the TiO{sub 2} generates intermediate energy levels. • Bi and Zn doping showed the enhanced absorption in visible-light region. • Zn dopant acts as a mediator of interfacial charge transfer. • TiBi{sub 1.9%}Zn{sub 1%}O{sub 2} exhibited high photocatalytic degradation for toluene. - Abstract: This study investigated the effects of Bi doped and Bi-Zn co-doped TiO{sub 2} on photodegradation of gaseous toluene. The doped TiO{sub 2} with various concentration of metal was prepared using the solvothermal route and characterized by SEM, XRD, Raman, BET, DRS, XPS, PL and EPR. Their photocatalytic activities under visible-light irradiation were drastically influenced by the dopant content. The results showed that moderate metal doping levels were obviously beneficial for the toluene degradation, while high doping levels suppressed the photocatalytic activity. The photocatalytic degradation of toluene over TiBi{sub 1.9%}O{sub 2} and TiBi{sub 1.9%}Zn{sub 1%}O{sub 2} can reach to 51% and 93%, respectively, which are much higher than 25% of TiO{sub 2}. Bi doping into TiO{sub 2} lattice generates new intermediate energy level of Bi below the CB edge of TiO{sub 2}. The electron excitation from the VB to Bi orbitals results in the decreased band gap, extended absorption of visible-light and thus enhances its photocatalytic efficiency. Zn doping not only further enhances the absorption in this visible-light region, but also Zn dopant exists as the form of ZnO crystallites located on the interfaces of TiO{sub 2} agglomerates and acts as a mediator of interfacial charge transfer to suppress the electron-hole recombination. These synergistic effects are responsible for the enhanced photocatalytic performance.

Enhanced sunlight-driven photocatalytic performance of Bi-doped CdMoO4 benefited from efficient separation of photogenerated charge pairs

Science.gov (United States)

Huang, Jiao; Liu, Huanhuan; Zhong, Junbo; Yang, Qi; Chen, Jiufu; Li, Jianzhang; Ma, Dongmei; duan, Ran

2018-06-01

In this paper, to further boost the photocatalytic performance of CdMoO4, Bi3+ was successfully doped into CdMoO4 by a facile microwave hydrothermal method. The Bi-doped CdMoO4 photocatalysts prepared were characterized by Brunauer-Emmett-Teller (BET) method, X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), electron spin-resonance (ESR) and surface photovoltage spectroscopy (SPS). The results exhibit that doping Bi3+ into CdMoO4 remarkably boosts the separation rate of photoinduced charge pairs and the specific surface area, decrease the crystal size, narrows the band gap of the CdMoO4 and induces the binding energy shift of Cd, all these advantageous factors result in the promoted photocatalytic performance of CdMoO4. Using rhodamine B (RhB) as model toxic pollutant, the photocatalytic activities of the photocatalysts were evaluated under a 500 W Xe lamp irradiation. When the molar ratio of Bi/Cd is 0.2%, Bi-CdMoO4 prepared displays the best photocatalytic performance, the photocatalytic performance of the 0.2% sample is more than twice of that of the reference CdMoO4.

Rose-like I-doped Bi{sub 2}O{sub 2}CO{sub 3} microspheres with enhanced visible light response: DFT calculation, synthesis and photocatalytic performance

Energy Technology Data Exchange (ETDEWEB)

Zai, Jiantao; Cao, Fenglei; Liang, Na; Yu, Ke; Tian, Yuan; Sun, Huai; Qian, Xuefeng, E-mail: xfqian@sjtu.edu.cn

2017-01-05

Highlights: • DFT reveals I{sup −} can partially substitute CO{sub 3}{sup 2−}to narrow the bandgap of Bi{sub 2}O{sub 2}CO{sub 3}. • Sodium citrate play a key role on the formation of rose-like I-doped Bi{sub 2}O{sub 2}CO{sub 3}. • Rose-like I-doped Bi{sub 2}O{sub 2}CO{sub 3} show enhanced visible light response. • The catalyst has enhanced photocatalytic activity to organic and Cr(VI) pollutes. - Abstract: Based on the crystal structure and the DFT calculation of Bi{sub 2}O{sub 2}CO{sub 3}, I{sup −} can partly replace the CO{sub 3}{sup 2−}in Bi{sub 2}O{sub 2}CO{sub 3} to narrow its bandgap and to enhance its visible light absorption. With this in mind, rose-like I-doped Bi{sub 2}O{sub 2}CO{sub 3} microspheres were prepared via a hydrothermal process. This method can also be extended to synthesize rose-like Cl- or Br-doped Bi{sub 2}O{sub 2}CO{sub 3} microspheres. Photoelectrochemical test supports the DFT calculation result that I- doping narrows the bandgap of Bi{sub 2}O{sub 2}CO{sub 3} by forming two intermediate levels in its forbidden band. Further study reveals that I-doped Bi{sub 2}O{sub 2}CO{sub 3} microspheres with optimized composition exhibit the best photocatalytic activity. Rhodamine B can be completely degraded within 6 min and about 90% of Cr(VI) can be reduced after 25 min under the irradiation of visible light (λ > 400 nm).

Doping of (Bi,Pb)-2223 with metal oxides

International Nuclear Information System (INIS)

Goehring, D.; Vogt, M.; Wischert, W.; Kemmler-Sack, S.

1997-01-01

The effect of doping on formation, superconductivity and pinning forces of (Bi,Pb)-2223 was studied for several dopants. They can be subdivided into promoters (Cu, Mn at low doping level of x=0.1 and Rh) and inhibitors (Mg, Al, Sn, Co, Y, Pd and high substitution levels of Mn and Ni) of the transformation of the precursor material into (Bi,Pb)-2223. According to X-ray diffraction (XRD) studies the incorporation of the dopant into the 2223 lattice is restricted to a very low doping level. Higher dopant concentrations are accompanied by a segregation of secondary phases. These segregations are not effective in the process of creating flux pinning centres. A depression of T c is observed for 2223 materials with the dopants Co, Ni and Pd. (orig.)

The effect of Bi3+ and Li+ co-doping on the luminescence characteristics of Eu3+-doped aluminum oxide films

International Nuclear Information System (INIS)

Padilla-Rosales, I.; Martinez-Martinez, R.; Cabañas, G.; Falcony, C.

2015-01-01

The incorporation of Bi 3+ and Li + as co-dopants in Eu 3+ -doped aluminum oxide films deposited by the ultrasonic spray pyrolysis technique and its effect on the luminescence characteristics of this material are described. Both Bi 3+ and Li + do not introduce new luminescence features but affect the luminescence intensity of the Eu 3+ related emission spectra as well as the excitation spectra. The introduction of Bi 3+ generates localized states in the aluminum oxide host that result in a quenching of the luminescence intensity, while Li + and Bi 3+ co-doping increase the luminescence intensity of these films. - Highlights: • Li and Bi co-doping increase the luminescence. • Bi creates localized states in the Al 2 O 3 host. • Li was incorporated as a co-activator

Magnetic Doping and Kondo Effect in Bi 2 Se 3 Nanoribbons

KAUST Repository

Cha, Judy J.; Williams, James R.; Kong, Desheng; Meister, Stefan; Peng, Hailin; Bestwick, Andrew J.; Gallagher, Patrick; Goldhaber-Gordon, David; Cui, Yi

2010-01-01

A simple surface band structure and a large bulk band gap have allowed Bi2Se3 to become a reference material for the newly discovered three-dimensional topological insulators, which exhibit topologically protected conducting surface states that reside inside the bulk band gap. Studying topological insulators such as Bi2Se3 in nanostructures is advantageous because of the high surfaceto-volume ratio, which enhances effects from the surface states; recently reported Aharonov-Bohm oscillation in topological insulator nanoribbons by some of us is a good example. Theoretically, introducing magnetic impurities in topological insulators is predicted to open a small gap in the surface states by breaking time-reversal symmetry. Here, we present synthesis of magnetically doped Bi 2Se3 nanoribbons by vapor-liquid-solid growth using magnetic metal thin films as catalysts. Although the doping concentration is less than ∼2 %. low-temperature transport measurements of the Fe-doped Bi2Se3 nanoribbon devices show a clear Kondo effect at temperatures below 30 K, confirming the presence of magnetic impurities in the Bi2Se3 nanoribbons. The capability to dope topological insulator nanostructures magnetically opens up exciting opportunities for spintronics. © 2010 American Chemical Society.

Magnetic Doping and Kondo Effect in Bi 2 Se 3 Nanoribbons

KAUST Repository

Cha, Judy J.

2010-03-10

A simple surface band structure and a large bulk band gap have allowed Bi2Se3 to become a reference material for the newly discovered three-dimensional topological insulators, which exhibit topologically protected conducting surface states that reside inside the bulk band gap. Studying topological insulators such as Bi2Se3 in nanostructures is advantageous because of the high surfaceto-volume ratio, which enhances effects from the surface states; recently reported Aharonov-Bohm oscillation in topological insulator nanoribbons by some of us is a good example. Theoretically, introducing magnetic impurities in topological insulators is predicted to open a small gap in the surface states by breaking time-reversal symmetry. Here, we present synthesis of magnetically doped Bi 2Se3 nanoribbons by vapor-liquid-solid growth using magnetic metal thin films as catalysts. Although the doping concentration is less than ∼2 %. low-temperature transport measurements of the Fe-doped Bi2Se3 nanoribbon devices show a clear Kondo effect at temperatures below 30 K, confirming the presence of magnetic impurities in the Bi2Se3 nanoribbons. The capability to dope topological insulator nanostructures magnetically opens up exciting opportunities for spintronics. © 2010 American Chemical Society.

Experimental evidence of enhanced ferroelectricity in Ca doped BiFeO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Costa, L.V.; Deus, R.C. [Universidade Estadual Paulista, UNESP, Faculdade de Engenharia de Guaratinguetá, Av. Dr. Ariberto Pereira da Cunha, 333, Bairro Portal das Colinas, CEP 12516-410 Guaratinguetá, SP (Brazil); Foschini, C.R.; Longo, E. [Universidade Estadual Paulista, UNESP, Faculdade de Engenharia de Bauru, Dept. de Eng. Mecânica, Av. Eng. Luiz Edmundo C. Coube 14-01, 17033-360 Bauru, SP (Brazil); Cilense, M. [Universidade Estadual Paulista, UNESP, Instituto de Química – Laboratório Interdisciplinar em Cerâmica (LIEC), Rua Professor Francisco Degni s/n, 14800-90 Araraquara, SP (Brazil); Simões, A.Z., E-mail: alezipo@yahoo.com [Universidade Estadual Paulista, UNESP, Faculdade de Engenharia de Guaratinguetá, Av. Dr. Ariberto Pereira da Cunha, 333, Bairro Portal das Colinas, CEP 12516-410 Guaratinguetá, SP (Brazil)

2014-04-01

Calcium (Ca)-doped bismuth ferrite (BiFeO{sub 3}) thin films prepared by using the polymeric precursor method (PPM) were characterized by X-ray diffraction (XRD), field emission gun scanning electron microscopy (FEG-SEM), transmission electron microscopy (TEM), polarization and piezoelectric measurements. Structural studies by XRD and TEM reveal the co-existence of distorted rhombohedral and tetragonal phases in the highest doped BiFeO{sub 3} where enhanced ferroelectric and piezoelectric properties are produced by internal strain. Resistive switching is observed in BFO and Ca-doped BFO which are affected by the barrier contact and work function of multiferroic materials and Pt electrodes. A high coercive field in the hysteresis loop is observed for the BiFeO{sub 3} film. Piezoelectric properties are improved in the highest Ca-doped sample due to changes in the crystal structure of BFO for a primitive cubic perovskite lattice with four-fold symmetry and a large tetragonal distortion within the crystal domain. This observation introduces magnetoelectronics at room temperature by combining electronic conduction with electric and magnetic degrees of freedom which are already present in the multiferroic BiFeO{sub 3}. - Highlights: • Ca doped BiFeO{sub 3} thin films were obtained by the polymeric precursor method. • Co-existence of distorted rhombohedral and tetragonal phases are evident. • Enhanced ferroelectric and piezoelectric properties are produced by the internal strain in the Ca doped BiFeO{sub 3} film.

Effect of Silver Doping on Transport Properties of Bi2Se3: AgxBi2Se3 and Bi2-xAgxSe3

Science.gov (United States)

Zhang, Min; Wei, Zhan-Tao

2018-03-01

Ag-doped Bi2Se3 with the formula AgxBi2Se3 and Bi2-xAgxSe3 were prepared and their electrical and magnetic transport properties have been investigated to study the influence of silver doping on transport properties of Bi2Se3 with different Ag-doped method. All samples exhibited metallic resistivity and the resistivity increased with increasing Ag concentration. The lattice parameter c of Ag-substituted and Ag-intercalated samples displays a contrary change as the Ag concentration increased. For the Ag-intercalated samples, both the resistance upturn were observed in the curves of temperature dependent of resistivity and temperature dependent of magnetoresistance, respectively, indicating that the enhanced surface effect was obtained in those samples. Monotonously, field-induced MR peaks around 200 K were also observed in those samples. Similar behaviors were not observed in the Ag-substituted samples.

Effect of Silver Doping on Transport Properties of Bi2Se3: AgxBi2Se3 and Bi2-xAgxSe3

Science.gov (United States)

Zhang, Min; Wei, Zhan-Tao

2018-05-01

Ag-doped Bi2Se3 with the formula AgxBi2Se3 and Bi2-xAgxSe3 were prepared and their electrical and magnetic transport properties have been investigated to study the influence of silver doping on transport properties of Bi2Se3 with different Ag-doped method. All samples exhibited metallic resistivity and the resistivity increased with increasing Ag concentration. The lattice parameter c of Ag-substituted and Ag-intercalated samples displays a contrary change as the Ag concentration increased. For the Ag-intercalated samples, both the resistance upturn were observed in the curves of temperature dependent of resistivity and temperature dependent of magnetoresistance, respectively, indicating that the enhanced surface effect was obtained in those samples. Monotonously, field-induced MR peaks around 200 K were also observed in those samples. Similar behaviors were not observed in the Ag-substituted samples.

Engineering Topological Surface State of Cr-doped Bi2Se3 under external electric field

Science.gov (United States)

Zhang, Jian-Min; Lian, Ruqian; Yang, Yanmin; Xu, Guigui; Zhong, Kehua; Huang, Zhigao

2017-03-01

External electric field control of topological surface states (SSs) is significant for the next generation of condensed matter research and topological quantum devices. Here, we present a first-principles study of the SSs in the magnetic topological insulator (MTI) Cr-doped Bi2Se3 under external electric field. The charge transfer, electric potential, band structure and magnetism of the pure and Cr doped Bi2Se3 film have been investigated. It is found that the competition between charge transfer and spin-orbit coupling (SOC) will lead to an electrically tunable band gap in Bi2Se3 film under external electric field. As Cr atom doped, the charge transfer of Bi2Se3 film under external electric field obviously decreases. Remarkably, the band gap of Cr doped Bi2Se3 film can be greatly engineered by the external electric field due to its special band structure. Furthermore, magnetic coupling of Cr-doped Bi2Se3 could be even mediated via the control of electric field. It is demonstrated that external electric field plays an important role on the electronic and magnetic properties of Cr-doped Bi2Se3 film. Our results may promote the development of electronic and spintronic applications of magnetic topological insulator.

Effect of Bi doping on morphotropic phase boundary and dielectric properties of PZT

Energy Technology Data Exchange (ETDEWEB)

Joshi, Shraddha; Acharya, Smita, E-mail: saha275@yahoo.com [Advanced Materials Research Laboratory, Department of Physics, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur-440033, M.S. India (India)

2016-05-23

In our present attempt, Pb{sub (1-x)}Bi{sub x}Zr{sub 0.52}Ti{sub 0.48}O{sub 3} [PBZT] {where x = 0, 0.05, 0.1} is synthesized by sol-gel route. Effect of Bi addition on structure, sinterability and dielectric properties are observed. The presence of morphotropic phase boundary (coexistence of tetragonal and rhombohedral symmetry) is confirmed by X-ray diffraction. Enhancement of sinterability after Bi doping is observed through a systematic sintering program. Frequency and temperature dependent dielectric constant are studied. Bi doping in PZT is found to enhance room temperature dielectric constant. However, at high temperature the dielectric constant of pure PZT is more than that of doped PZT.

Study of Bi-2212 phase doped Sn(Pb) by means of pat

International Nuclear Information System (INIS)

Ma Qingzhu; Huang Xiaoqian; Xiong Xiaotao

1997-01-01

Investigation on the effect of Sn/Pb-doped Bi-2212 superconductors has been carried out by the simultaneous measurements of the spectra of positron annihilation lifetime and positron Doppler broadening, together with X-ray diffraction. The results of samples with different doping level show the occupation of Sn atoms on Bi sites. At weak doping level, Sn doping results in a enhancement of cooperation between layers and increment of superconducting transition temperature. At the strong doping level, Sn atoms occupy the sites of Cu-O layers, and at the same time, the other nonsuperconducting phases appear, which results in a decline of the superconducting transition temperature

Synthesis of Er(III)/Yb(III)-doped BiF3 upconversion nanoparticles for use in optical thermometry.

Science.gov (United States)

Du, Peng; Yu, Jae Su

2018-03-23

The authors describe an ethylene glycol assisted precipitation method for synthesis of Er(III)/Yb(III)-doped BiF 3 nanoparticles (NPs) at room temperature. Under 980-nm light irradiation, the NPs emit upconversion (UC) emission of Er(III) ions as a result of a two-photon absorption process. The temperature-dependent green emissions (peaking at 525 and 545 nm) are used to establish an unambiguous relationship between the ratio of fluorescence intensities and temperature. The NPs have a maximum sensitivity of 6.5 × 10 -3  K -1 at 619 K and can be applied over the 291-691 K temperature range. The results indicate that these NPs are a promising candidate for optical thermometry. Graphical abstract Schematic of the room-temperature preparation of Er(III)/Yb(III)-doped BiF 3 nanoparticles with strongly temperature-dependent upconversion emission.

Photoelectrochemical Performance Observed in Mn-Doped BiFeO3 Heterostructured Thin Films

Directory of Open Access Journals (Sweden)

Hao-Min Xu

2016-11-01

Full Text Available Pure BiFeO3 and heterostructured BiFeO3/BiFe0.95Mn0.05O3 (5% Mn-doped BiFeO3 thin films have been prepared by a chemical deposition method. The band structures and photosensitive properties of these films have been investigated elaborately. Pure BiFeO3 films showed stable and strong response to photo illumination (open circuit potential kept −0.18 V, short circuit photocurrent density was −0.023 mA·cm−2. By Mn doping, the energy band positions shifted, resulting in a smaller band gap of BiFe0.95Mn0.05O3 layer and an internal field being built in the BiFeO3/BiFe0.95Mn0.05O3 interface. BiFeO3/BiFe0.95Mn0.05O3 and BiFe0.95Mn0.05O3 thin films demonstrated poor photo activity compared with pure BiFeO3 films, which can be explained by the fact that Mn doping brought in a large amount of defects in the BiFe0.95Mn0.05O3 layers, causing higher carrier combination and correspondingly suppressing the photo response, and this negative influence was more considerable than the positive effects provided by the band modulation.

Defects controlling electrical and optical properties of electrodeposited Bi doped Cu2O

Science.gov (United States)

Brandt, Iuri S.; Tumelero, Milton A.; Martins, Cesar A.; Plá Cid, Cristiani C.; Faccio, Ricardo; Pasa, André A.

2018-04-01

Doping leading to low electrical resistivity in electrodeposited thin films of Cu2O is a straightforward requirement for the construction of efficient electronic and energy devices. Here, Bi (7 at. %) doped Cu2O layers were deposited electrochemically onto Si(100) single-crystal substrates from aqueous solutions containing bismuth nitrate and cupric sulfate. X-ray photoelectron spectroscopy shows that Bi ions in a Cu2O lattice have an oxidation valence of 3+ and glancing angle X-ray diffraction measurements indicated no presence of secondary phases. The reduction in the electrical resistivity from undoped to Bi-doped Cu2O is of 4 and 2 orders of magnitude for electrical measurements at 230 and 300 K, respectively. From variations in the lattice parameter and the refractive index, the electrical resistivity decrease is addressed to an increase in the density of Cu vacancies. Density functional theory (DFT) calculations supported the experimental findings. The DFT results showed that in a 6% Bi doped Cu2O cell, the formation of Cu vacancies is more favorable than in an undoped Cu2O one. Moreover, from DFT data was observed that there is an increase (decrease) of the Cu2O band gap (activation energy) for 6% Bi doping, which is consistent with the experimental results.

Facile synthesis of Sm-doped BiFeO{sub 3} nanoparticles for enhanced visible light photocatalytic performance

Energy Technology Data Exchange (ETDEWEB)

Hu, Zijun; Chen, Da, E-mail: dchen_80@hotmail.com; Wang, Sen; Zhang, Ning; Qin, Laishun, E-mail: qinlaishun@cjlu.edu.cn; Huang, Yuexiang

2017-06-15

Highlights: • Effective Sm doping into BiFeO{sub 3} nanoparticles was obtained by a facile sol-gel route. • Band gap of Sm-doped BiFeO{sub 3} nanoparticles was regulated by the dopant concentration. • Sm-doped BiFeO{sub 3} nanoparticles exhibited superior photocatalytic activities. • The possible photocatalytic mechanism of Sm-doped BiFeO{sub 3} nanospheres was discussed. - Abstract: In this work, the effect of Sm doping on the structural and photocatalytic properties of BiFeO{sub 3} (BFO) was investigated. A series of Sm doped BFO nanoparticles containing different Sm dopant contents (Bi{sub (1−x)}Sm{sub x}FeO{sub 3}, x = 0.00, 0.01, 0.03, 0.05, 0.07, 0.10) were synthesized via a simple sol-gel route. It was revealed that Sm{sup 3+} ions were successfully doped into BFO nanoparticles, and the band gap value was gradually decreased when increasing Sm dopant concentration. The photocatalytic activity of Sm-doped BFO photocatalyst was significantly affected by the Sm doping content. Compared to pure BFO, the Sm-doped BFO samples exhibited much higher photocatalytic activity. The improved photocatalytic activity of Sm-doped BFO could be attributed to the enhanced visible light absorption and the efficient separation of photogenerated electrons and holes derived from Sm dopant trapping level in the Sm-doped BFO samples. In addition, the possible photocatalytic mechanism of Sm-doped BFO photocatalyst was also proposed.

Fe-doping effect on the Bi{sub 3}Ni superconductor microstructure

Energy Technology Data Exchange (ETDEWEB)

Gonsalves, Silvio Henrique; Monteiro, Joao Frederico Haas Leandro; Leal, Adriane Consuelo da Silva; Andrade, Andre Vitor Chaves de; Souza, Gelson Biscaia de; Siqueira, Ezequiel Costa; Serbena, Francisco Carlos; Jurelo, Alcione Roberto, E-mail: arjurelo@uepg.br [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil). Departamento de Fisica

2017-05-15

The substitution effects of Fe ion on the structure of the intermetallic Bi{sub 3}Ni{sub 1-x}Fe{sub x} (0 ≤ x ≤ 0.10) superconductor were studied. The morphology of samples consists of an inhomogeneous laminar slab-like microstructure. The main phase corresponds to Bi{sub 3}Ni{sub 1-x}Fe{sub x} with an orthorhombic structure (Pnma), but with very small quantities of impurities of BiNi and Bi as revealed by X-ray diffraction. SEM and AFM reveal that the Bi3{sub N}i1{sub -x}Fe{sub x} phase consists of two regions. One region is Bi richer and Ni and Fe poorer than the other region.Raman spectroscopy revealed two phonon modes at room temperature. No significant changes were observed in the spectra with Fe doping and in different regions of the Bi{sub 3}Ni{sub 1-x}Fe{sub x} phase. Superconductivity is observed below a transition temperature T{sub C} = 4 K and regardless of iron doping. (author)

Characterization of Bi and Fe co-doped PZT capacitors for FeRAM.

Science.gov (United States)

Cross, Jeffrey S; Kim, Seung-Hyun; Wada, Satoshi; Chatterjee, Abhijit

2010-08-01

Ferroelectric random access memory (FeRAM) has been in mass production for over 15 years. Higher polarization ferroelectric materials are needed for future devices which can operate above about 100 °C. With this goal in mind, co-doping of thin Pb(Zr 40 ,Ti 60 )O 3 (PZT) films with 1 at.% Bi and 1 at.% Fe was examined in order to enhance the ferroelectric properties as well as characterize the doped material. The XRD patterns of PZT-5% BiFeO 3 (BF) and PZT 140-nm thick films showed (111) orientation on (111) platinized Si wafers and a 30 °C increase in the tetragonal to cubic phase transition temperature, often called the Curie temperature, from 350 to 380 °C with co-doping, indicating that Bi and Fe are substituting into the PZT lattice. Raman spectra revealed decreased band intensity with Bi and Fe co-doping of PZT compared to PZT. Polarization hysteresis loops show similar values of remanent polarization, but square-shaped voltage pulse-measured net polarization values of PZT-BF were higher and showed higher endurance to repeated cycling up to 10 10 cycles. It is proposed that Bi and Fe are both in the +3 oxidation state and substituting into the perovskite A and B sites, respectively. Substitution of Bi and Fe into the PZT lattice likely creates defect dipoles, which increase the net polarization when measured by the short voltage pulse positive-up-negative-down (PUND) method.

Thermal growth and cathodoluminescence of Bi doped ZnO nanowires and rods

International Nuclear Information System (INIS)

Aleman, B; Hidalgo, P; Fernandez, P; Piqueras, J

2009-01-01

Bi doped ZnO nanowires and rods have been grown by a catalyst free evaporation-deposition method with precursors containing either ZnO and Bi 2 O 3 or ZnS and Bi 2 O 3 powders. The use of ZnS as a precursor was found to lead to a higher density of nano- and microstructures at lower temperatures than by using ZnO. Energy dispersive x-ray spectroscopy (EDS) shows that the Bi content in the wires and rods is in the range 0.15-0.35 at%. Bi incorporation was found to induce a red shift of the near band gap luminescence but no quantitative correlation between the shift and the amount of Bi, as measured by EDS, was observed. The I-V curves of single Bi doped wires had linear behaviour at low current and non-linear behaviour for high currents, qualitatively similar to that of undoped wires.

Thermal growth and cathodoluminescence of Bi doped ZnO nanowires and rods

Energy Technology Data Exchange (ETDEWEB)

Aleman, B; Hidalgo, P; Fernandez, P; Piqueras, J, E-mail: balemanl@fis.ucm.e [Departamento de Fisica de Materiales, Facultad de Ciencias FIsicas, Universidad Complutense de Madrid, 28040 Madrid (Spain)

2009-11-21

Bi doped ZnO nanowires and rods have been grown by a catalyst free evaporation-deposition method with precursors containing either ZnO and Bi{sub 2}O{sub 3} or ZnS and Bi{sub 2}O{sub 3} powders. The use of ZnS as a precursor was found to lead to a higher density of nano- and microstructures at lower temperatures than by using ZnO. Energy dispersive x-ray spectroscopy (EDS) shows that the Bi content in the wires and rods is in the range 0.15-0.35 at%. Bi incorporation was found to induce a red shift of the near band gap luminescence but no quantitative correlation between the shift and the amount of Bi, as measured by EDS, was observed. The I-V curves of single Bi doped wires had linear behaviour at low current and non-linear behaviour for high currents, qualitatively similar to that of undoped wires.

Structural, magnetic, and electrical properties of Gd-doped BiFeO3 nanoparticles with reduced particle size

International Nuclear Information System (INIS)

Lotey, Gurmeet Singh; Verma, N. K.

2012-01-01

Pure and Gd-doped BiFeO 3 nanoparticles have been synthesized by sol–gel method. The significant effects of size and Gd-doping on structural, electrical, and magnetic properties have been investigated. X-ray diffraction study reveals that the pure BiFeO 3 nanoparticles possess rhombohedral structure, but with 10% Gd-doping complete structural transformation from rhombohedral to orthorhombic has been observed. The particle size of pure and Gd-doped BiFeO 3 nanoparticles, calculated using Transmission electron microscopy, has been found to be in the range 25–15 nm. Pure and Gd-doped BiFeO 3 nanoparticles show ferromagnetic character, and the magnetization increases with decrease in particle size and increase in doping concentration. Scanning electron microscopy study reveals that grain size decreases with increase in Gd concentration. Well-saturated polarization versus electric field loop is observed for the doped samples. Leakage current density decreases by four orders by doping Gd in BiFeO 3 . The incorporation of Gd in BiFeO 3 enhances spin as well as electric polarization at room temperature. The possible origin of enhancement in these properties has been explained on the basis of dopant and its concentration, phase purity, small particle, and grain size.

Enhanced multiferroic properties in scandium doped Bi2Fe4O9

International Nuclear Information System (INIS)

Dutta, Dimple P.; Tyagi, A. K.

2013-01-01

Undoped and Sc 3+ doped Bi 2 Fe 4 O 9 nanoparticles have been synthesized using sonochemical method. The phase purity of the samples was checked using powder X-rau diffraction technique. EDS analysis was done to confirm the extent of Sc 3+ doping in the samples. The size and morphology of the nanoparticles have been analyzed using transmission electron microscopy (TEM). The Bi 2 Fe 4 O 9 nanoparticles show a weak ferromagnetic behavior at room temperature, which is quite different from the linear M–H relationship reported for bulk Bi 2 Fe 4 O 9 . This is mainly attributed to the uncompensated moments at the disordered particle surface resulting from the reduced coordination of the surface spins, arising due to lattice strain or oxygen deficiency. Addition of Sc 3+ dopant in varying concentrations in these Bi 2 Fe 4 O 9 nanoparticles, improves their magnetic as well as ferroelectric properties. The leakage current is considerably reduced and electric polarization increases significantly in case of Bi 2 Fe 4(1-x) Sc x O 9 (x = 0.1) nanoparticles. Hence it can be inferred that Sc 3+ doped Bi 2 Fe 4 O 9 nanoparticles shows promise as good multiferroic materials.

Hydrothermal synthesis, structure and photocatalytic properties of La/Bi co-doped NaTaO3

International Nuclear Information System (INIS)

Lan, Nguyen Thi; Huan, Bui Doan; Anh, Trinh Xuan; Chinh, Huynh Dang; Phan, Le Gia; Hoang, Luc Huy; Hong, Le Van

2016-01-01

La/Bi co-doped NaTaO 3 nanomaterials for photocatalytic applications have been successfully synthesized by hydrothermal method at low temperature. The obtained materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and UV-Vis molecular absorption spectroscopy. The results showed that the particle sizes of La/Bi co-doped NaTaO 3 were smaller than that of the pure NaTaO 3 . La/Bi co-doping has extended optical absorption in the visible light region and then successfully increased photocatalytic activity of the La/Bi-codoped NaTaO 3 that were evaluated by degradation of methylene blue (MB). (author)

Magnetic properties of Eu doped BiGdO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Nithya, R., E-mail: nithya@igcar.gov.in; Yadagiri, K. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603 102, TN (India); Shukla, Neeraj [UGC-DAE-CSR Kalpakkam Node, Kokilamedu-603 104, TN (India)

2016-05-23

Bulk Bismuth Gadolinium Oxide, BiGdO{sub 3} and Eu doped BiGdO{sub 3} compounds were synthesized by the conventional solid state reaction in air. Phase formation of these compounds was tracked using powder X-ray characterization technique since single phase formation was found to be sensitive to thermal treatment parameters such as cooling and heating rates. Analysis of X-ray diffraction patterns revealed cubic structure with Pm-3m symmetry. An antiferromagnetic transition around 3.8 K was observed in the pristine compound whereas doped samples showed paramagnetic nature in the whole measured temperature range.

Preparation of Nd-doped BiFeO{sub 3} films and their electrical properties

Energy Technology Data Exchange (ETDEWEB)

Cheng Meng [Key Laboratory of Auxiliary Chemistry and Technology for Chemical Industry, Ministry of Education of China, Shaanxi University of Science and Technology, Weiyang District, Xi' an 710021 (China); Tan Guoqiang, E-mail: tan3114@163.com [Key Laboratory of Auxiliary Chemistry and Technology for Chemical Industry, Ministry of Education of China, Shaanxi University of Science and Technology, Weiyang District, Xi' an 710021 (China); Xue Xu; Xia Ao; Ren Huijun [Key Laboratory of Auxiliary Chemistry and Technology for Chemical Industry, Ministry of Education of China, Shaanxi University of Science and Technology, Weiyang District, Xi' an 710021 (China)

2012-09-01

The Nd-doped BiFeO{sub 3} thin films were prepared on SnO{sub 2}(FTO) substrates spin-coated by the sol-gel method using Nd(NO{sub 3}){sub 3}{center_dot}6H{sub 2}O, Fe(NO{sub 3}){sub 3}{center_dot}9H{sub 2}O and Bi(NO{sub 3}){sub 3}{center_dot}5H{sub 2}O as raw materials. The microstructure and electric properties of the BiFeO{sub 3} thin films were characterized and tested. The results indicate that the diffraction peak of the Nd-doped BiFeO{sub 3} films is shifted towards right as the doping amounts are increased. The structure is transformed from the rhombohedral to pseudotetragonal phase. The crystal grain is changed from an elliptical to irregular polyhedron. Structure transition occurring in the Bi{sub 0.85}Nd{sub 0.15}FeO{sub 3} films gives rise to the largest Pr of 64 {mu}C/cm{sup 2}. The leakage conductance of the Nd doped thin films is reduced. The dielectric constant and dielectric loss of Bi{sub 0.85}Nd{sub 0.15}FeO{sub 3} thin film at 10 kHz are 190 and 0.017 respectively.

Synthesis of carbon-doped nanosheets m-BiVO{sub 4} with three-dimensional (3D) hierarchical structure by one-step hydrothermal method and evaluation of their high visible-light photocatalytic property

Energy Technology Data Exchange (ETDEWEB)

Zhao, Deqiang; Zong, Wenjuan [Chongqing University, Key Laboratory of Three Gorges Reservoir Region’s Eco-Environment Ministry of Education and National Centre for International Research of Low-carbon and Green Buildings (China); Fan, Zihong [School of Environmental and Biological Engineering Chongqing Technology and Business University (China); Fang, Yue-Wen [East China Normal University, Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering (China); Xiong, Shimin; Du, Mao; Wu, Tianhui; Ji, Fangying, E-mail: jfy@cqu.edu.cn; Xu, Xuan, E-mail: xuxuan@cqu.edu.cn [Chongqing University, Key Laboratory of Three Gorges Reservoir Region’s Eco-Environment Ministry of Education and National Centre for International Research of Low-carbon and Green Buildings (China)

2017-04-15

To achieve an efficient visible-light absorption and degradation of bismuth vanadate (BiVO{sub 4}), in this paper, a carbon-doped (C-doped) nanosheets monoclinic BiVO{sub 4} (m-BiVO{sub 4}), with thicknesses within 19.86 ± 8.48 nm, was synthesized using polyvinylpyrrolidone K-30 (PVP) as a template and l-carbonic as the carbon source by one-step hydrothermal synthesis method. This C-doped BiVO{sub 4} in three-dimensional (3D) hierarchical structure enjoys high visible-light photocatalytic property. The samples were characterized using x-ray diffraction, scanning electron microscope, Raman spectra, energy dispersive spectrometer, transmission electron microscope, x-ray photoelectron spectroscopy, UV–Vis diffused reflectance spectroscopy, specific surface area, electron spin resonance, and transient photocurrent response, photoluminescence spectra, and incident-photon-to-current conversion efficiency, respectively. What is more, we studied the C-doping effect on the band-gap energy of BiVO{sub 4} based on First-principles. X-ray diffraction analysis showed that all photocatalysts were in the same single monoclinic scheelite structure. According to the other characterization results, the element C was successfully doped in BiVO{sub 4}, resulting in the 3D hierarchical structure of C-doped BiVO{sub 4} (P-L-BiVO{sub 4}). We speculated that it could be the directional coalescence mechanism by which the l-cysteine promoted the two-dimensional growth and C-doping process of BiVO{sub 4}, thus leading to the formation of nanosheets which were then promoted into 3D self-assembly by PVP and the shortening of the band gap. Among all samples, P-L-BiVO{sub 4} can make the highest removal ratio of rhodamine B under visible-light irradiation. The stability of P-L-BiVO{sub 4} was verified by recycle experiments. It showed that P-L-BiVO{sub 4} had strong visible-light absorption behavior and high electron–hole separation efficiency and stability, making a significant

EPR in non-doped irradiated polyacetylene

International Nuclear Information System (INIS)

Hola, O.; Stasko, A.; Foeldesova, M.

1993-01-01

The influence of γ-irradiation on the paramagnetic properties of non-doped polyacetylene at low and high radiation doses has been studied and summarized. The dependence of the EPR spectra on the radiation dose in irradiated polyacetylene has been measured. No essential changes of the spin mobility as a consequence of irradiation were observed. The measurements of spin concentration confirm the high resistivity of non-doped polyacetylene to radiation. (author) 9 refs

Structural and optical properties of cobalt doped multiferroics BiFeO3 nanostructure thin films

Science.gov (United States)

Prasannakumara, R.; Naik, K. Gopalakrishna

2018-05-01

Bismuth ferrite (BiFeO3) and Cobalt doped BiFeO3 (BiFe1-XCoXO3) nanostructure thin films were deposited on glass substrates by the sol-gel spin coating method. The X-ray diffraction patterns (XRD) of the grown BiFeO3 and BiFe1-XCoXO3 nanostructure thin films showed distorted rhombohedral structure. The shifting of peaks to higher angles was observed in cobalt doped BiFeO3. The surface morphology of the BiFeO3 and BiFe1-XCoXO3 nanostructure thin films were studied using FESEM, an increase in grain size was observed as Co concentration increases. The thickness of the nanostructure thin films was examined using FESEM cross-section. The EDX studies confirmed the elemental composition of the grown BiFeO3 and BiFe1-XCoXO3 nanostructure thin films. The optical characterizations of the grown nanostructure thin films were carried out using FTIR, it confirms the existence of Fe-O and Bi-O bands and UV-Visible spectroscopy shows the increase in optical band gap of the BiFeO3 nanostructure thin films with Co doping by ploting Tauc plot.

Enhanced magnetic and ferroelectric properties in scandium doped nano Bi2Fe4O9

International Nuclear Information System (INIS)

Dutta, Dimple P.; Sudakar, C.; Mocherla, Pavana S.V.; Mandal, Balaji P.; Jayakumar, Onnatu D.; Tyagi, Avesh K.

2012-01-01

In this study we report the synthesis of undoped and Sc 3+ doped Bi 2 Fe 4 O 9 nanoparticles using sonochemical technique. X-ray diffraction reveals that all samples are single phase with no impurities detected. EDS analysis was done to confirm the extent of Sc 3+ doping in the samples. The size and morphology of the nanoparticles have been analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Bi 2 Fe 4 O 9 nanoparticles show a weak ferromagnetic behavior at room temperature, which is quite different from the linear M–H relationship reported for bulk Bi 2 Fe 4 O 9 . A magnetization of 0.144 μB/f.u. is obtained at 300 K, which is mainly attributed to the uncompensated moments at the disordered particle surface resulting from the reduced coordination of the surface spins, arising due to lattice strain or oxygen deficiency. Addition of Sc 3+ dopant in varying concentrations in these Bi 2 Fe 4 O 9 nanoparticles, improves their magnetic as well as ferroelectric properties. The leakage current is considerably reduced and electric polarization increases significantly in case of Bi 2 Fe 4(1−x) Sc x O 9 (x = 0.1) nanoparticles. Thus it can be inferred that Sc 3+ doped Bi 2 Fe 4 O 9 nanoparticles shows promise as good multiferroic materials. -- Graphical abstract: Undoped and Sc 3+ doped Bi 2 Fe 4 O 9 nanoparticles have been synthesized using sonochemical technique. The bi-functionalities of Sc 3+ doped Bi 2 Fe 4 O 9 nanoparticles have been demonstrated. The Bi 2 Fe 4(1−x) Sc x O 9 (x = 0.1) nanoparticles showed enhanced magnetic and ferroelectric properties with considerably less lossy characteristics compared to the bulk Bi 2 Fe 4 O 9 . Highlights: ► Phase pure Bi 2 Fe 4 O 9 nanostructures synthesized using a facile sonochemical technique. ► Nanoparticles show a weak ferromagnetic order at room temperature. ► Sc 3+ doping in Bi 2 Fe 4 O 9 nanoparticles alters their magnetic and ferroelectric properties. ► A

Effects of Bi doping on dielectric and ferroelectric properties

Indian Academy of Sciences (India)

[Pb0.95(La1−Bi)0.05][Zr0.53Ti0.47]O3 (PLBZT) ferroelectric thin films have been synthesized on indium tin oxide (ITO)-coated glass by sol–gel processing. PLBZT thin films were annealed at a relatively low temperature of 550 °C in oxygen ambient. Effects of Bi doping on structure, dielectric and ferroelectric properties of ...

Fe-Doping Effect on Thermoelectric Properties of p-Type Bi0.48Sb1.52Te3

Directory of Open Access Journals (Sweden)

Hyeona Mun

2015-03-01

Full Text Available The substitutional doping approach has been shown to be an effective strategy to improve ZT of Bi2Te3-based thermoelectric raw materials. We herein report the Fe-doping effects on electronic and thermal transport properties of polycrystalline bulks of p-type Bi0.48Sb1.52Te3. After a small amount of Fe-doping on Bi/Sb-sites, the power factor could be enhanced due to the optimization of carrier concentration. Additionally, lattice thermal conductivity was reduced by the intensified point-defect phonon scattering originating from the mass difference between the host atoms (Bi/Sb and dopants (Fe. An enhanced ZT of 1.09 at 300 K was obtained in 1.0 at% Fe-doped Bi0.48Sb1.52Te3 by these synergetic effects.

Stoichiometric transfer of material in the infrared pulsed laser deposition of yttrium doped Bi-2212 films

International Nuclear Information System (INIS)

De Vero, Jeffrey C.; Blanca, Glaiza Rose S.; Vitug, Jaziel R.; Garcia, Wilson O.; Sarmago, Roland V.

2011-01-01

Highlights: → This work describes the stoichiometric transfer of Y-doped Bi-2212 during IR-PLD. → As-deposited films show spheroidal morphology with similar composition as the target. Relatively flat and highly c-axis oriented films were obtained after heat treatment. → IR-PLD can be a viable technique in growing other high Tc superconducting materials. - Abstract: Films of Y-doped Bi-2212 were successfully grown on MgO (1 0 0) substrates by infrared pulsed laser deposition (IR-PLD). With post-heat treatments, smooth and highly c-axis oriented films were obtained. The average compositions of the films have the same stoichiometry as the target. Y content is also preserved on the grown films at all doping levels. The electrical properties of the grown Y-doped Bi-2212 films exhibit the expected electrical properties of the bulk Y-doped Bi-2212. This is attributed to the stoichiometric transfer of material by IR-PLD.

Complex boron redistribution kinetics in strongly doped polycrystalline-silicon/nitrogen-doped-silicon thin bi-layers

Energy Technology Data Exchange (ETDEWEB)

Abadli, S. [Department of Electrical Engineering, University Aout 1955, Skikda, 21000 (Algeria); LEMEAMED, Department of Electronics, University Mentouri, Constantine, 25000 (Algeria); Mansour, F. [LEMEAMED, Department of Electronics, University Mentouri, Constantine, 25000 (Algeria); Pereira, E. Bedel [CNRS-LAAS, 7 avenue du colonel Roche, 31077 Toulouse (France)

2012-10-15

We have investigated the complex behaviour of boron (B) redistribution process via silicon thin bi-layers interface. It concerns the instantaneous kinetics of B transfer, trapping, clustering and segregation during the thermal B activation annealing. The used silicon bi-layers have been obtained by low pressure chemical vapor deposition (LPCVD) method at 480 C, by using in-situ nitrogen-doped-silicon (NiDoS) layer and strongly B doped polycrystalline-silicon (P{sup +}) layer. To avoid long-range B redistributions, thermal annealing was carried out at relatively low-temperatures (600 C and 700 C) for various times ranging between 30 min and 2 h. To investigate the experimental secondary ion mass spectroscopy (SIMS) doping profiles, a redistribution model well adapted to the particular structure of two thin layers and to the effects of strong-concentrations has been established. The good adjustment of the simulated profiles with the experimental SIMS profiles allowed a fundamental understanding about the instantaneous physical phenomena giving and disturbing the complex B redistribution profiles-shoulders. The increasing kinetics of the B peak concentration near the bi-layers interface is well reproduced by the established model. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Complex Boron Redistribution in P+ Doped-polysilicon / Nitrogen Doped Silicon Bi-layers during Activation Annealing

Science.gov (United States)

Abadli, S.; Mansour, F.; Perrera, E. Bedel

We have investigated and modeled the complex phenomenon of boron (B) redistribution process in strongly doped silicon bilayers structure. A one-dimensional two stream transfer model well adapted to the particular structure of bi- layers and to the effects of strong-concentrations has been developed. This model takes into account the instantaneous kinetics of B transfer, trapping, clustering and segregation during the thermal B activation annealing. The used silicon bi-layers have been obtained by low pressure chemical vapor deposition (LPCVD) method, using in-situ nitrogen- doped-silicon (NiDoS) layer and strongly B doped polycrystalline-silicon (P+) layer. To avoid long redistributions, thermal annealing was carried out at relatively lowtemperatures (600 °C and 700 °C) for various times ranging between 30 minutes and 2 hours. The good adjustment of the simulated profiles with the experimental secondary ion mass spectroscopy (SIMS) profiles allowed a fundamental understanding about the instantaneous physical phenomena giving and disturbing the complex B redistribution profiles-shoulders kinetics.

Enhancement of thermoelectric properties of Mg2Si compounds with Bi doping through carrier concentration tuning

Science.gov (United States)

Lee, Ji Eun; Cho, Sang-Hum; Oh, Min-Wook; Ryu, Byungi; Joo, Sung-Jae; Kim, Bong-Seo; Min, Bok-Ki; Lee, Hee-Woong; Park, Su-Dong

2014-07-01

The Bi-doped Mg2Si powder was fabricated with solid state reaction method and consolidated with hot pressing method and then its thermoelectric properties were investigated. The n-type transport properties were measured in all samples and temperature dependence of the electrical properties shows a behavior of degenerate semiconductors for Bi-doped samples. The electrical resistivity and the Seebeck coefficient were greatly reduced with Bi, which was mainly due to the increment of the carrier concentration. The samples have maximum carrier concentration of 8.2 × 1018 cm-3. The largest ZT value of 0.61 was achieve at 873 K for Mg2.04SiBi0.02. The Bi-doping was found to be an effective n-type dopant to adjust carrier concentration. [Figure not available: see fulltext.

The degrees of tri-axial orientation in RE-doped Bi2212 powders aligned in a modulated rotation magnetic field

International Nuclear Information System (INIS)

Nagai, R.; Horii, S.; Maeda, T.; Haruta, M.; Shimoyama, J.

2013-01-01

Highlights: •Tri-axial magnetic alignment of Bi2212 with rare-earth (RE) doping was attempted. •Magnetization axes depended on the type of doped RE ions. •RE-doping increased degrees of inplane orientation and inplane magnetic anisotropy. -- Abstract: We report relationship between the degrees of tri-axial orientation and doping level of rare earth (RE) ions in Bi 2 Sr 2 (Ca 1−x RE x )Cu 2 O y (RE-doped Bi2212; RE = Dy, Ho, Er and Tm) powder samples aligned under a modulated rotation magnetic field (MRF) of 10 T. Tri-axial magnetic alignment of the RE-doped Bi2212 with x = 0–0.5 was achieved by single-ion magnetic anisotropy of RE 3+ and tri-axial magnetic anisotropy induced by modulation microstructure in a grain level. The degrees of in-plane and c-axis orientation with ∼3° were achieved for the case of the Tm-doped Bi2212 with x = 0.5. The findings in the present study give us important information for the fabrication of triaxially oriented Bi-based cuprate superconductor materials by the magneto-scientific process

Gradient Self-Doped CuBi2O4 with Highly Improved Charge Separation Efficiency.

Science.gov (United States)

Wang, Fuxian; Septina, Wilman; Chemseddine, Abdelkrim; Abdi, Fatwa F; Friedrich, Dennis; Bogdanoff, Peter; van de Krol, Roel; Tilley, S David; Berglund, Sean P

2017-10-25

A new strategy of using forward gradient self-doping to improve the charge separation efficiency in metal oxide photoelectrodes is proposed. Gradient self-doped CuBi 2 O 4 photocathodes are prepared with forward and reverse gradients in copper vacancies using a two-step, diffusion-assisted spray pyrolysis process. Decreasing the Cu/Bi ratio of the CuBi 2 O 4 photocathodes introduces Cu vacancies that increase the carrier (hole) concentration and lowers the Fermi level, as evidenced by a shift in the flat band toward more positive potentials. Thus, a gradient in Cu vacancies leads to an internal electric field within CuBi 2 O 4 , which can facilitate charge separation. Compared to homogeneous CuBi 2 O 4 photocathodes, CuBi 2 O 4 photocathodes with a forward gradient show highly improved charge separation efficiency and enhanced photoelectrochemical performance for reduction reactions, while CuBi 2 O 4 photocathodes with a reverse gradient show significantly reduced charge separation efficiency and photoelectrochemical performance. The CuBi 2 O 4 photocathodes with a forward gradient produce record AM 1.5 photocurrent densities for CuBi 2 O 4 up to -2.5 mA/cm 2 at 0.6 V vs RHE with H 2 O 2 as an electron scavenger, and they show a charge separation efficiency of 34% for 550 nm light. The gradient self-doping accomplishes this without the introduction of external dopants, and therefore the tetragonal crystal structure and carrier mobility of CuBi 2 O 4 are maintained. Lastly, forward gradient self-doped CuBi 2 O 4 photocathodes are protected with a CdS/TiO 2 heterojunction and coated with Pt as an electrocatalyst. These photocathodes demonstrate photocurrent densities on the order of -1.0 mA/cm 2 at 0.0 V vs RHE and evolve hydrogen with a faradaic efficiency of ∼91%.

Study of A-site doping of SrBi4Ti4O15 Bi-layered compounds using micro-Raman spectroscopy

International Nuclear Information System (INIS)

Hao, H.; Liu, H.X.; Cao, M.H.; Min, X.M.; Ouyang, S.X.

2006-01-01

The temperature-dependent Raman spectra of Mg- and La-doped SrBi 4 Ti 4 O 15 (SBT) were studied in the range 40-590 C. A quantum chemistry calculation was employed to estimate these two substitution states. It was found that A-site doping in this study not only caused multiplicative substitution states, but also the Raman spectra changed with the substitution amount. In a La-doped perovskite-like layer, La would occupy the Bi site when x>0.10 and the 314 and 550 cm -1 modes related to the rotating and tilting of the TiO 6 octahedron firstly became wide and then became sharp. With the increase of the substitution amount, both substitution states of Mg-doped SBT lead to the widening of 270 and 520 cm -1 peaks. (orig.)

Study of A-site doping of SrBi4Ti4O15 Bi-layered compounds using micro-Raman spectroscopy

Science.gov (United States)

Hao, H.; Liu, H. X.; Cao, M. H.; Min, X. M.; Ouyang, S. X.

2006-10-01

The temperature-dependent Raman spectra of Mg- and La-doped SrBi4Ti4O15 (SBT) were studied in the range 40 590 °C. A quantum chemistry calculation was employed to estimate these two substitution states. It was found that A-site doping in this study not only caused multiplicative substitution states, but also the Raman spectra changed with the substitution amount. In a La-doped perovskite-like layer, La would occupy the Bi site when x>0.10 and the 314 and 550 cm-1 modes related to the rotating and tilting of the TiO6 octahedron firstly became wide and then became sharp. With the increase of the substitution amount, both substitution states of Mg-doped SBT lead to the widening of 270 and 520 cm-1 peaks.

Hydrothermal synthesis of B-doped Bi2MoO6 and its high photocatalytic performance for the degradation of Rhodamine B

Science.gov (United States)

Wang, Min; Han, Jin; Guo, Pengyao; Sun, Mingzhi; Zhang, Yu; Tong, Zhu; You, Meiyan; Lv, Chunmei

2018-02-01

B-doped Bi2MoO6 photocatalysts have been synthesized by a hydrothermal method using HBO3 as the doping source and the effect of B doping content on Bi2MoO6 structure and performance was studied. The samples were characterized with XPS, XRD, SEM, BET, UV-Vis DRS, and PL. The photocatalytic activity was evaluated by photocatalytic degradation of Rhodamine B (RhB) under visible light (λ ≥ 420 nm). The results show that all samples are orthorhombic structure. Doping Bi2MoO6 with B increases the amount of Bi5+ and oxygen vacancies, which led to stronger absorption in visible light region and lower band gap energy of the B-doped Bi2MoO6 but had little impact on morphology. B doping significantly improves the photocatalytic activity of Bi2MoO6 and the highest photocatalytic degradation rate is 89% when the initial molar ratio of B to Bi is 0.01.

An efficient dye-sensitized BiOCl photocatalyst for air and water purification under visible light irradiation.

Science.gov (United States)

Li, Guisheng; Jiang, Bo; Xiao, Shuning; Lian, Zichao; Zhang, Dieqing; Yu, Jimmy C; Li, Hexing

2014-08-01

A photosensitized BiOCl catalyst was found to be effective for photocatalytic water purification and air remediation under visible light irradiation (λ > 420 nm). Prepared by a solvothermal method, the BiOCl crystals possessed a 3D hierarchical spherical structure with the highly active facets exposed. When sensitized by Rhodamine B (RhB), the photocatalyst system was more active than N-doped TiO2 for breaking down 4-chlorophenol (4-CP, 200 ppm) and nitric monoxide (NO, 500 ppb). The high activity could be attributed to the hierarchical structure (supplying feasible reaction tunnels for adsorption and transition of reactants or products) and the efficient exposure of the {001} facets. The former provides an enriched oxygen atom density that promotes adsorption of cationic dye RhB, and creates an oxygen vacancy state. The HO˙ and ˙O2(-) radicals produced from the injected electrons from the excited dye molecule (RhB*) into the conduction band of BiOCl were responsible for the excellent photocatalytic performance of the RhB-BiOCl system.

Doping dependence of low-energy quasiparticle excitations in superconducting Bi2212.

Science.gov (United States)

Ino, Akihiro; Anzai, Hiroaki; Arita, Masashi; Namatame, Hirofumi; Taniguchi, Masaki; Ishikado, Motoyuki; Fujita, Kazuhiro; Ishida, Shigeyuki; Uchida, Shinichi

2013-12-05

: The doping-dependent evolution of the d-wave superconducting state is studied from the perspective of the angle-resolved photoemission spectra of a high-Tc cuprate, Bi2Sr2CaCu2 O8+δ (Bi2212). The anisotropic evolution of the energy gap for Bogoliubov quasiparticles is parametrized by critical temperature and superfluid density. The renormalization of nodal quasiparticles is evaluated in terms of mass enhancement spectra. These quantities shed light on the strong coupling nature of electron pairing and the impact of forward elastic or inelastic scatterings. We suggest that the quasiparticle excitations in the superconducting cuprates are profoundly affected by doping-dependent screening.

Enhanced thermoelectric figure of merit in strained Tl-doped Bi2Se3

KAUST Repository

Saeed, Y.; Singh, Nirpendra; Schwingenschlö gl, Udo

2014-01-01

We explain recent experimental findings on Tl-doped Bi2Se3 by determining the electronic and transport properties by first-principles calculations and semi-classical Boltzmann theory. Though Tl-doping introduces a momentum-dependent spin

Rotational Symmetry Breaking in a Trigonal Superconductor Nb-doped Bi_{2}Se_{3}

Directory of Open Access Journals (Sweden)

Tomoya Asaba

2017-01-01

Full Text Available The search for unconventional superconductivity has been focused on materials with strong spin-orbit coupling and unique crystal lattices. Doped bismuth selenide (Bi_{2}Se_{3} is a strong candidate, given the topological insulator nature of the parent compound and its triangular lattice. The coupling between the physical properties in the superconducting state and its underlying crystal symmetry is a crucial test for unconventional superconductivity. In this paper, we report direct evidence that the superconducting magnetic response couples strongly to the underlying trigonal crystal symmetry in the recently discovered superconductor with trigonal crystal structure, niobium (Nb-doped Bi_{2}Se_{3}. As a result, the in-plane magnetic torque signal vanishes every 60°. More importantly, the superconducting hysteresis loop amplitude is enhanced along one preferred direction, spontaneously breaking the rotational symmetry. This observation indicates the presence of nematic order in the superconducting ground state of Nb-doped Bi_{2}Se_{3}.

Modification of photosensing property of CdS–Bi{sub 2}S{sub 3} bi-layer by thermal annealing and swift heavy ion irradiation

Energy Technology Data Exchange (ETDEWEB)

Shaikh, Shaheed U.; Siddiqui, Farha Y. [Thin Film and Nanotechnology Laboratory, Department of Physics (India); Department of Nanotechnology, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004 (India); Singh, Fouran; Kulriya, Pawan K. [Inter University Accelerator Center, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Phase, D.M. [UGC DAE Consortium for Scientific Research, Khandwa Road, Indore 452017 (India); Sharma, Ramphal, E-mail: ramphalsharma@yahoo.com [Thin Film and Nanotechnology Laboratory, Department of Physics (India); Department of Nanotechnology, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004 (India)

2016-02-01

The CdS–Bi{sub 2}S{sub 3} bi-layer thin films have been deposited on Indium Tin Oxide (ITO) glass substrates at room temperature by Chemical Bath Deposition Technique (CBD) and bi-layer thin films were annealed in air atmosphere for 1 h at 250 {sup °}C. The air annealed sample was irradiated using Au{sup 9+} ions at the fluence 5 × 10{sup 11} ion/cm{sup 2} with 120 MeV energy. Effects of Swift Heavy Ion (SHI) irradiation on CdS–Bi{sub 2}S{sub 3} bi-layer thin films were studied. The results are explained on the basis annealing and high electronic excitation, using X-ray diffraction (XRD), Selective Electron Area Diffraction (SEAD), Atomic Force Microscopy (AFM), Raman Spectroscopy, UV spectroscopy and I–V characteristics. The photosensing property after illumination of visible light over the samples is studied. These as-deposited, annealed and irradiated bi-layer thin films are used to sense visible light at room temperature. - Graphical abstract: Schematic illustration of CdS–Bi{sub 2}S{sub 3} bi-layer thin film (a) As-deposited (b) Annealed (c) irradiated sample respectively (d) Model of bi-layer photosensor device (e) Graph of illumination intensity verses photosensitivity. - Highlights: • CdS–Bi{sub 2}S{sub 3} bi-layer thin film prepared at room temperature. • Irradiated using Au{sup 9+} ions at the fluence of 5 × 10{sup 11} ion/cm{sup 2} with 120 MeV energy. • Study of modification induced by irradiations. • Study of Photosensitivity after annealing and irradiation.

Studying magnetic structure of Bi doped Co2MnO4 cubic spinel by neutron diffraction

International Nuclear Information System (INIS)

Rajeevan, N.E.; Kaushik, S.D.; Kumar, Ravi

2016-01-01

In present work, we studied effect of Bi doped spinel Bi x Co 2-x MnO 4 (x = 0, 0.05, 0.10, 0.15 and 0.20) samples on their crystal as well as magnetic structure by employing neutron diffraction of wavelength 1.48 A using focusing crystal diffractometer of UGC-DAECSR Mumbai Centre at Dhruva, Trombay, Mumbai, India. The analysis of the neutron diffraction using Fullprof program reveals that crystal structure due to Bi doping remains intact and all the samples have been formed in the cubic spinel structure with Fd3m (space group no. 227). The lattice parameter shows the positive thermal expansion upon Bi doping across the temperature range. In order to understand the implication on the spin structure and magnetism in the detail, temperature dependent neutron diffraction study is carried out on some of the samples (x = 0, 0.1) in the series. The ND pattern of x = 0.1 at 2.9K is shown. The experimental finding in terms of modified magnetic structure upon Bi doping are discussed which are understood in terms of variation in the ferroelectric properties, bond lengths and their effect on the CoO 6 polyhedra. Furthermore, Bi substitution in Co 2 MnO 4 spinel brings in the balance of structural distortion, which affects both ferrimagnetism and ferroelectricity

Effects of low-level Ag doping on Bi2Sr2CaCu2O8+x

International Nuclear Information System (INIS)

Deis, T.A.; Eror, N.G.; Krishnaraj, P.; Prorok, B.C.; Lelovic, M.; Balachandran, U.

1995-07-01

Bi 2 Sr 2 CaCu 2 O 8 has been doped with silver, up to 10,000 ppm, in three ways: excess additions, substitution of Ag for Bi, and substitution of Ag for Sr. Effects of doping on the c-axis lattice parameter and critical temperature (T c ) were measured. Effects from doing were only observed in slow-cooled [10 degree/hr] oxygen equilibrated samples. Doping by excess additions caused a small decrease in T c and an increase in the c-axis length of the lattice. Doping by substitution, compared to excess Ag additions, caused a larger decrease in T c and higher c-axis values for doping levels up to 1,000 ppm. Doping by substitution at higher levels (1,000--10,000 ppm) caused T c to increase and the c-axis to decrease. Samples with similar substitutional doping levels exhibited comparable T c values and samples with Ag substituted for Sr consistently exhibited higher c-axis values than samples that had equivalent amounts of Ag substituted for Bi

Ions irradiation on bi-layer coatings

Science.gov (United States)

Tessarolo, Enrico; Corso, Alain Jody; Böttger, Roman; Martucci, Alessandro; Pelizzo, Maria G.

2017-09-01

Future space missions will operate in very harsh and extreme environments. Optical and electronics components need to be optimized and qualified in view of such operational challenges. This work focuses on the effect of low alpha particles irradiation on coatings. Low energy He+ (4 keV and 16 keV) ions have been considered in order to simulate in laboratory the irradiation of solar wind (slow and fast components) alpha particles. Mono- and proper bi-layers coatings have been investigated. The experimental tests have been carried out changing doses as well as fluxes during the irradiation sessions. Optical characterization in the UV-VIS spectral range and superficial morphological analysis have performed prior and after irradiation.

High figure of merit and thermoelectric properties of Bi-doped Mg2Si0.4Sn0.6 solid solutions

International Nuclear Information System (INIS)

Liu, Wei; Zhang, Qiang; Yin, Kang; Chi, Hang; Zhou, Xiaoyuan; Tang, Xinfeng; Uher, Ctirad

2013-01-01

The study of Mg 2 Si 1−x Sn x -based thermoelectric materials has received widespread attention due to a potentially high thermoelectric performance, abundant raw materials, relatively low cost of modules, and non-toxic character of compounds. In this research, Mg 2.16 (Si 0.4 Sn 0.6 ) 1−y Bi y solid solutions with the nominal Bi content of 0≤y≤0.03 are prepared using a two-step solid state reaction followed by spark plasma sintering consolidation. Within this range of Bi concentrations, no evidence of second phase segregation was found. Bi is confirmed to occupy the Si/Sn sites in the crystal lattice and behaves as an efficient n-type dopant in Mg 2 Si 0.4 Sn 0.6 . Similar to the effect of Sb, Bi doping greatly increases the electron density and the power factor, and reduces the lattice thermal conductivity of Mg 2.16 Si 0.4 Sn 0.6 solid solutions. Overall, the thermoelectric figure of merit of Bi-doped Mg 2.16 Si 0.4 Sn 0.6 solid solutions is improved by about 10% in comparison to values obtained with Sb-doped materials of comparable dopant content. This improvement comes chiefly from a marginally higher Seebeck coefficient of Bi-doped solid solutions. The highest ZT∼1.4 is achieved for the y=0.03 composition at 800 K. - Graphical abstract: (a)The relationship between electrical conductivity and power factor for Sb/Bi-doped Mg 2.16 (Si 0.4 Sn 0.6 ) 1−y (Sb/Bi) y (0 2.16 (Si 0.4 Sn 0.6 ) 1−y Bi y (0≤y≤0.03) solid solutions. (c)Temperature dependent dimensionless figure of merit ZT of Mg 2.16 (Si 0.4 Sn 0.6 ) 1−y Bi y (0≤y≤0.03) solid solutions. - Highlights: • Bi doped Mg 2.16 Si 0.4 Sn 0.6 showed 15% enhancement in the power factor as compared to Sb doped samples. • Bi doping reduced κ ph of Mg 2.16 Si 0.4 Sn 0.6 due to stronger point defect scattering. • The highest ZT=1.4 at 800 K was achieved for Mg 2.16 (Si 0.4 Sn 0.6 ) 0.97 Bi 0.03

Types of defect ordering in undoped and lanthanum-doped Bi2201 single crystals

International Nuclear Information System (INIS)

Martovitsky, V. P.

2006-01-01

Undoped and lanthanum-doped Bi2201 single crystals having a perfect average structure have been comparatively studied by x-ray diffraction. The undoped Bi2201 single crystals exhibit very narrow satellite reflections; their half-width is five to six times smaller than that of Bi2212 single crystals grown by the same technique. This narrowness indicates three-dimensional defect ordering in the former crystals. The lanthanumdoped Bi2201 single crystals with x = 0.7 and T c = 8-10 K exhibit very broad satellite reflections consisting of two systems (modulations) misoriented with respect to each other. The modulation-vector components of these two modulations are found to be q 1 = 0.237b* + 0.277c* and q 2 = 0.238b* + 0.037c*. The single crystals having a perfect average structure and a homogeneous average distribution of doping lanthanum consist of 70-to 80-A-thick layers that alternate along the c axis and have two different types of modulated superlattice. The crystals having a less perfect average structure also consist of alternating layers, but they have different lanthanum concentrations. The low value of T c in the undoped Bi2201 single crystals (9.5 K) correlates with three-dimensional defect ordering in them, and an increase in T c to 33 K upon lanthanum doping can be related to a thin-layer structure of these crystals and to partial substitution of lanthanum for the bismuth positions

Enhanced photoluminescence of Sm{sup 3+}/Bi{sup 3+} co-doped Gd{sub 2}O{sub 3} phosphors by combustion synthesis

Energy Technology Data Exchange (ETDEWEB)

Liu Guangsheng; Zhang Ying [Institute of Micro-system Physics, School of Physics and Electronics, Henan University, Kaifeng 475001 (China); Yin Jiang [Department of Physics, Nanjing University, Nanjing 210093 (China); Zhang, W.F. [Institute of Micro-system Physics, School of Physics and Electronics, Henan University, Kaifeng 475001 (China)], E-mail: wfzhang@henu.edu.cn

2008-12-15

Gd{sub 2}O{sub 3}:Sm{sup 3+} and Gd{sub 2}O{sub 3}:Sm{sup 3+},Bi{sup 3+} powders were prepared by a combustion method. Their structures were determined using X-ray diffraction. UV-visible absorption and photoluminescence spectra were investigated for Gd{sub 2}O{sub 3}:Sm{sup 3+} and Gd{sub 2}O{sub 3}:Sm{sup 3+},Bi{sup 3+} at different annealing temperatures and different doping concentrations. The emission spectra of all samples presented the characteristic emission narrow lines arising from the {sup 4}G{sub 5/2}{yields}{sup 6}H{sub J} transitions (J=5/2, 7/2, and 9/2) of Sm{sup 3+} ions upon excitation with UV irradiation. The emission intensity of Sm{sup 3+} ions was largely enhanced with introducing Bi{sup 3+} ions into Gd{sub 2}O{sub 3}:Sm{sup 3+} and the maximum occurred at a Bi{sup 3+} concentration of 0.5 mol%. The relevant mechanisms were discussed with the sensitization theory by Dexter and the aggregation behavior of Bi{sup 3+} ions.

Structural transitions and multiferroic properties of high Ni-doped BiFeO3

Science.gov (United States)

Betancourt-Cantera, L. G.; Bolarín-Miró, A. M.; Cortés-Escobedo, C. A.; Hernández-Cruz, L. E.; Sánchez-De Jesús, F.

2018-06-01

Nickel doped bismuth ferrite powders, BiFe1-x NixO3 (0 ≤ x ≤ 0.5), were synthesized by high-energy ball milling followed by an annealing at 700 °C. A detailed study about the substitution of Fe3+ by Ni2+ on the crystal structure and multiferroic properties is presented. The X-ray diffraction patterns reveal the formation of rhombohedral structure with small amounts of Bi2Fe4O9 as a secondary phase for x behavior indicates the frustration of the G-antiferromagnetic order typical of the un-doped BiFeO3, caused by the presence of small amounts of Ni2+ (x Behavior modifications of electrical conductivity, permittivity and dielectric loss versus frequency are related with crystal structure transformations, when nickel concentration is increased.

High spin state driven magnetism and thermoelectricity in Mn doped topological insulator Bi2Se3

Science.gov (United States)

Maurya, V. K.; Dong, C. L.; Chen, C. L.; Asokan, K.; Patnaik, S.

2018-06-01

We report on the synthesis, and structural - magnetic characterizations of Mn doped Bi2Se3 towards achieving a magnetically doped topological insulator. High quality single crystals of MnxBi2-xSe3 (x = 0, 0.03, 0.05, 0.1) are grown and analysed by X-ray diffraction (XRD), Low Energy Electron Diffraction (LEED), Scanning electron microscopy (SEM), and X-ray absorption near-edge structure spectroscopy (XANES). Magnetic properties of these samples under ZFC-FC protocol and isothermal magnetization confirm ferromagnetic correlation above x = 0.03 value. XANES measurements confirm that the dopant Mn is in Mn2+ state. This is further reconfirmed to be in high spin state by fitting magnetic data with Brillouin function for J = 5/2. Both Hall and Seebeck measurements indicate a sign change of charge carriers above x = 0.03 value of Mn doping. We propose Mn doped Bi2Se3 to be a potential candidate for electromagnetic and thermoelectric device applications involving topological surface states.

Light up conversion effects in Erbium doped CaBi4Ti4O15 ceramics

International Nuclear Information System (INIS)

Bokolia, Renuka; Sreenivas, K.

2013-01-01

In recent years the rare earth doped bismuth layered structured ferroelectric (BLSF) compositions such as CaBi 4 Ti 4 O 15 , SrBi 4 Ti 4 O 15 and BaBi 4 Ti 4 O 15 ceramics have shown interesting light up-conversion emission effects. The observation of such novel effects has generated a lot of scientific interest, and there is a need to further improve their dielectric, piezoelectric and light up-conversion properties. In the present study, Erbium doped CaBi 4 Ti 4 O 15 (CBT), and SrBi 4 Ti 4 O 15 (SBT) ferroelectric ceramic have been prepared by the conventional solid state reaction method. Formation of single phase material is confirmed by X-Ray Diffraction (XRD), and changes occurring in the lattice parameters with Erbium dopant are analysed. Room temperature dielectric studies and ferroelectric studies will be discussed. (author)

Krypton irradiation damage in Nd-doped zirconolite and perovskite

International Nuclear Information System (INIS)

Davoisne, C.; Stennett, M.C.; Hyatt, N.C.; Peng, N.; Jeynes, C.; Lee, W.E.

2011-01-01

Understanding the effect of radiation damage and noble gas accommodation in potential ceramic hosts for plutonium disposition is necessary to evaluate their long-term behaviour during geological disposal. Polycrystalline samples of Nd-doped zirconolite and Nd-doped perovskite were irradiated ex situ with 2 MeV Kr + at a dose of 5 x 10 15 ions cm -2 to simulate recoil of Pu nuclei during alpha decay. The feasibility of thin section preparation of both pristine and irradiated samples by Focused Ion Beam sectioning was demonstrated. After irradiation, the Nd-doped zirconolite revealed a well defined amorphous region separated from the pristine material by a thin (40-60 nm) damaged interface. The zirconolite lattice was lost in the damaged interface, but the fluorite sublattice was retained. The Nd-doped perovskite contained a defined irradiated layer composed of an amorphous region surrounded by damaged but still crystalline layers. The structural evolution of the damaged regions is consistent with a change from orthorhombic to cubic symmetry. In addition in Nd-doped perovskite, the amorphisation dose depended on crystallographic orientation and possibly sample configuration (thin section or bulk). Electron Energy Loss Spectroscopy revealed Ti remained in the 4+ oxidation state but there was a change in Ti coordination in both Nd-doped perovskite and Nd-doped zirconolite associated with the crystalline to amorphous transition.

Effect of Nd-doping on structure and microwave electromagnetic properties of BiFeO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Liu, Sheng [School of Physics and Electronics, Institute of Super-microstructure and Ultrafast Process in Advanced Materials, Central South University, Changsha 410083 (China); Luo, Heng [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Yan, Shuoqing; Yao, Lingling; He, Jun; Li, Yuhan; He, Longhui; Huang, Shengxiang; Deng, Lianwen [School of Physics and Electronics, Institute of Super-microstructure and Ultrafast Process in Advanced Materials, Central South University, Changsha 410083 (China)

2017-03-15

The single-phase Bi{sub 1-x}Nd{sub x}FeO{sub 3} (x=0, 0.05, 0.10, 0.15, 0.20) were synthesized by the sol-gel method. Their crystal structure and microwave electromagnetic property in the frequency range of 2–18 GHz were investigated. The XRD patterns and Raman spectra showed that structural transition from rhombohedral (x=0, 0.05, 0.1) to triclinic (x=0.15) and tetragonal structure (x=0.20) appeared in the Bi{sub 1-x}Nd{sub x}FeO{sub 3}. Electromagnetic measurement suggested that both microwave permeability μ′ and magnetic loss tanδ{sub m} increased remarkably over 2–18 GHz by doping Nd. Strong dielectric loss peak was observed on the samples of Bi{sub 1-x}Nd{sub x}FeO{sub 3} (x=0.15) and Bi{sub 1-x}Nd{sub x}FeO{sub 3} (x=0.2). Results show that Nd substitution is an effective way to push BiFeO{sub 3} to become microwave absorbing materials with high performance. - Highlights: • Single-phase Bi{sub 1-x}Nd{sub x}FeO{sub 3} samples were prepared by a sol-gel method. • Strong dielectric loss peak was observed in BiFeO{sub 3} with high doping content. • Significant enhancement of microwave absorption property was found in Nd-doped BiFeO{sub 3}.

Electronic conduction in doped multiferroic BiFeO3

Science.gov (United States)

Yang, Chan-Ho; Seidel, Jan; Kim, Sang-Yong; Gajek, M.; Yu, P.; Holcomb, M. B.; Martin, L. W.; Ramesh, R.; Chu, Y. H.

2009-03-01

Competition between multiple ground states, that are energetically similar, plays a key role in many interesting material properties and physical phenomena as for example in high-Tc superconductors (electron kinetic energy vs. electron-electron repulsion), colossal magnetoresistance (metallic state vs. charge ordered insulating state), and magnetically frustrated systems (spin-spin interactions). We are exploring the idea of similar competing phenomena in doped multiferroics by control of band-filling. In this paper we present systematic investigations of divalent Ca doping of ferroelectric BiFeO3 in terms of structural and electronic conduction properties as well as diffusion properties of oxygen vacancies.

In-situ synthesis of nanofibers with various ratios of BiOCl{sub x}/BiOBr{sub y}/BiOI{sub z} for effective trichloroethylene photocatalytic degradation

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yifan [Department of Chemistry, Inha University, 100 Inharo, Incheon 402-751 (Korea, Republic of); Park, Mira [Department of Organic Materials and Fiber Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Kim, Hak Yong [Department of BIN Convergence Technology, Chonbuk National University, Jeonju, 561-756 (Korea, Republic of); Ding, Bin [College of Textiles, Donghua University, Shanghai 201620 (China); Park, Soo-Jin, E-mail: sjpark@inha.ac.kr [Department of Chemistry, Inha University, 100 Inharo, Incheon 402-751 (Korea, Republic of)

2016-10-30

Highlights: • BiOCl{sub x}/BiOBr{sub y}/BiOI{sub z}/PAN fibers were synthesized by in-situ method. • Photodegradation behavior of BiOCl{sub x}/BiOBr{sub y}/BiOI{sub z}/PAN fibers was measured under solar light irradiation. • BiOCl{sub 0.3}/BiOBr{sub 0.3}/BiOI{sub 0.4}/PAN fibers exhibited the highest photocatalytic activity. • Photocatalytic mechanism was discussed in detail. - Abstract: In this work, BiOCl{sub x}/BiOBr{sub y}/BiOI{sub z} (x + y + z = 1) composite nanofibers were prepared through electrospinning and the sol-gel methods. Photocatalytic degradation of trichloroethylene (TCE) by BiOCl{sub x}/BiOBr{sub y}/BiOI{sub z}/PAN nanofibers was systematically investigated via gas chromatography (GC). Optimum photocatalytic activity was achieved with BiOCl{sub 0.3}/BiOBr{sub 0.3}/BiOI{sub 0.4} fibers under solar light irradiation. X-ray photoelectron spectroscopy (XPS) peaks due to C−O and C=O were observed at 286.0 and 288.3 eV, respectively, it indicated that the BiOCl{sub x}/BiOBr{sub y}/BiOI{sub z} mixture had been successfully doped on the polyacrylonitrile (PAN) fibers. Furthermore, X-ray diffraction (XRD) results also confirmed that we had synthesized the as-prepared composite nanofibers successfully. Photocatalytic activities of BiOCl{sub 0.3}/BiOBr{sub 0.3}/BiOI{sub 0.4} were up to 3 times higher than the pure BiOCl, BiOBr and BiOI samples, respectively.

Flat Ge-doped optical fibres for food irradiation dosimetry

Energy Technology Data Exchange (ETDEWEB)

Noor, N. Mohd; Jusoh, M. A. [Department of Imaging, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Razis, A. F. Abdull [Food Safety Research Centre, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Laboratory of UPM-MAKNA Cancer Research, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Alawiah, A. [Faculty of Engineering and Technology, Multimedia University, 75450 Malacca (Malaysia); Bradley, D. A. [Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2015-04-24

Exposing food to radiation can improve hygiene quality, germination control, retard sprouting, and enhance physical attributes of the food product. To provide for food safety, radiation dosimetry in irradiated food is required. Herein, fabricated germanium doped (Ge-doped) optical fibres have been used. The fibres have been irradiated using a gamma source irradiator, doses in the range 1 kGy to 10 kGy being delivered. Using Ge-doped optical fibres of variable size, type and dopant concentration, study has been made of linearity, reproducibility, and fading. The thermoluminescence (TL) yield of the fibres were obtained and compared. The fibres exhibit a linear dose response over the investigated range of doses, with mean reproducibility to within 2.69 % to 8.77 %, exceeding the dose range of all commercial dosimeters used in evaluating high doses for the food irradiation industry. TL fading of the Ge-doped flat fibres has been found to be < 13%.

Flat Ge-doped optical fibres for food irradiation dosimetry

International Nuclear Information System (INIS)

Noor, N. Mohd; Jusoh, M. A.; Razis, A. F. Abdull; Alawiah, A.; Bradley, D. A.

2015-01-01

Exposing food to radiation can improve hygiene quality, germination control, retard sprouting, and enhance physical attributes of the food product. To provide for food safety, radiation dosimetry in irradiated food is required. Herein, fabricated germanium doped (Ge-doped) optical fibres have been used. The fibres have been irradiated using a gamma source irradiator, doses in the range 1 kGy to 10 kGy being delivered. Using Ge-doped optical fibres of variable size, type and dopant concentration, study has been made of linearity, reproducibility, and fading. The thermoluminescence (TL) yield of the fibres were obtained and compared. The fibres exhibit a linear dose response over the investigated range of doses, with mean reproducibility to within 2.69 % to 8.77 %, exceeding the dose range of all commercial dosimeters used in evaluating high doses for the food irradiation industry. TL fading of the Ge-doped flat fibres has been found to be < 13%

Molecular Doping the Topological Dirac Semimetal Na3Bi across the Charge Neutrality Point with F4-TCNQ.

Science.gov (United States)

Edmonds, Mark T; Hellerstedt, Jack; O'Donnell, Kane M; Tadich, Anton; Fuhrer, Michael S

2016-06-29

We perform low-temperature transport and high-resolution photoelectron spectroscopy on 20 nm thin film topological Dirac semimetal Na3Bi grown by molecular beam epitaxy. We demonstrate efficient electron depletion ∼10(13) cm(-2) of Na3Bi via vacuum deposition of molecular F4-TCNQ without degrading the sample mobility. For samples with low as-grown n-type doping (1 × 10(12) cm(-2)), F4-TCNQ doping can achieve charge neutrality and even a net p-type doping. Photoelectron spectroscopy and density functional theory are utilized to investigate the behavior of F4-TCNQ on the Na3Bi surface.

Suppression of irradiation effects in gold-doped silicon detectors

International Nuclear Information System (INIS)

McPherson, M.; Sloan, T.; Jones, B.K.

1997-01-01

Two sets of silicon detectors were irradiated with 1 MeV neutrons to different fluences and then characterized. The first batch were ordinary p-i-n photodiodes fabricated from high-resistivity (400 Ω cm) silicon, while the second batch were gold-doped powder diodes fabricated from silicon material initially of low resistivity (20 Ω cm). The increase in reverse leakage current after irradiation was found to be more in the former case than in the latter. The fluence dependence of the capacitance was much more pronounced in the p-i-n diodes than in the gold-doped diodes. Furthermore, photo current generation by optical means was less in the gold doped devices. All these results suggest that gold doping in silicon somewhat suppresses the effects of neutron irradiation. (author)

Origin of broad NIR photoluminescence in bismuthate glass and Bi-doped glasses at room temperature

Energy Technology Data Exchange (ETDEWEB)

Peng, Mingying; Zollfrank, Cordt; Wondraczek, Lothar [Lehrstuhl fuer Glas und Keramik, WW3, Friedrich Alexander Universitaet Erlangen-Nuernberg, Martensstrasse 5, D-91058 Erlangen (Germany)], E-mail: mingying.peng@ww.uni-erlangen.de, E-mail: lothar.wondraczek@ww.uni-erlangen.de

2009-07-15

Bi-doped glasses with broadband photoluminescence in the near-infrared (NIR) spectral range are presently receiving significant consideration for potential applications in telecommunications, widely tunable fiber lasers and spectral converters. However, the origin of NIR emission remains disputed. Here, we report on NIR absorption and emission properties of bismuthate glass and their dependence on the melting temperature. Results clarify that NIR emission occurs from the same centers as it does in Bi-doped glasses. The dependence of absorption and NIR emission of bismuthate glasses on the melting temperature is interpreted as thermal dissociation of Bi{sub 2}O{sub 3} into elementary Bi. Darkening of bismuthate glass melted at 1300 deg. C is due to the agglomeration of Bi atoms. The presence of Bi nanoparticles is confirmed by transmission electron microscopy, high-resolution energy dispersive x-ray spectroscopy and element distribution mapping. By adding antimony oxide as an oxidation agent to the glass, NIR emission centers can be eliminated and Bi{sup 3+} is formed. By comparing with atomic spectral data, absorption bands at {approx}320 , {approx}500 , 700 , 800 and 1000 nm observed in Bi-doped glasses are assigned to Bi{sup 0} transitions {sup 4}S{sub 3/2}{yields}{sup 2}P{sub 3/2}, {sup 4}S{sub 3/2}{yields}{sup 2}P{sub 1/2}, {sup 4}S{sub 3/2}{yields}{sup 2}D{sub 5/2}, {sup 4}S{sub 3/2}{yields}{sup 2}D{sub 3/2}(2) and {sup 4}S{sub 3/2}{yields}{sup 2}D{sub 3/2}(1), respectively, and broadband NIR emission is assigned to the transition {sup 2}D{sub 3/2}(1){yields}{sup 4}S{sub 3/2}.

Tl, Bi, and Pb doping in Ba4BiPb2TlO12-δ

International Nuclear Information System (INIS)

Sutto, T.E.; Averill, B.A.

1992-01-01

To determine the effects of different 6s metal concentrations on the superconducting nature of Ba 4 BiPb 2 TlO 12-δ , materials produced via four doping schemes were examined: Ba 4 Bi(Pb, Tl) 3 O 12-δ , Ba 4 -(BiPb) 3 TlO 12-δ , Ba 4 (Bi,Tl) 2 Pb 2 O 12-δ , and Ba 4 Bi x Pb 4-2x Tl x O 12-δ . For the parent compound a value of δ = 0.91 was observed, indicating that approximately 1/4 oxygen atom was missing per cubic subsection of the unit cell. For all samples, the symmetry of the parent compound changed from orthorhombic to tetragonal as the system moved away from the ideal composition. This was usually accompanied by the loss of superconductivity, which exhibited a maximum T c of 10.5 K for the parent compound Ba 4 BiPb 2 TlO 12-δ . Also reported are high-temperature magnetic susceptibility results, which are used to determine the effect of metal substitution on the density of states at the Fermi level. For each set of variants on the parent composition, the onset of superconductivity was accompanied by a significant decrease in the size of the Pauli paramagnetic signal. 16 refs., 6 figs

Effects of CuO co-doping on γ-ray irradiation resistance of active ions doped phosphate glasses

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zhihuan [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); ENEA-UTTMAT, Via Anguillarese 301, 00123 Rome (Italy); Baccaro, Stefania; Cemmi, Alessia [ENEA-UTTMAT, Via Anguillarese 301, 00123 Rome (Italy); Shen, Wei [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Chen, Guorong, E-mail: grchen@ecust.edu.cn [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China)

2013-09-15

The effect of copper ion doping on the γ-ray irradiation resistance of Mn{sup 2+} and Pr{sup 3+} doped phosphate glasses has been studied. UV–visible transmission spectra and photoluminescence spectra have been measured before and after γ-irradiation to characterize the radiation-induced defects. The electron paramagnetic resonance spectra of the irradiated samples with, and without Cu ions have been compared to show the ability of Cu ions to suppress the generation of radiation-induced color centers. The differential transmission spectra and the radiation-induced absorption coefficients have also been calculated for discussion of the observed phenomena. The much improved γ-irradiation resistance of Mn{sup 2+} and Pr{sup 3+} doped phosphate glasses has been demonstrated through CuO co-doping.

Hydrothermal synthesis of Nd3+-doped heterojunction ms/tz-BiVO4 and its enhanced photocatalytic performance

Science.gov (United States)

Chen, Ruizhi; Wang, Weixuan; Jiang, Dongmei; Chu, Xiaoxuan; Ma, Xueming; Zhan, Qingfeng

2018-06-01

BiVO4 photocatalysts with different Nd3+ doping content were prepared by a hydrothermal method with varied hydrothermal reaction time. The effects of Nd3+ doping on phase transformation, morphology, chemical valence, optical properties and photocatalytic activities were investigated. With different reaction time, phase transformation from tetragonal zircon (tz-BiVO4) to monoclinic scheelite (ms-BiVO4) could be found, and Nd3+ doping played a suppressive role in this process. Scanning electron microscopy showed the morphology evolved from irregular structure to rod-like shapes with phase transformation. The photoluminescence induced by Nd3+ doping could be confirmed by UV-vis diffuse reflectance spectra. Photocatalytic performance tests had been performed under simulated solar conditions and sample with 1 at% Nd3+ doping and 5 h reaction time showed the best performance (89% degradation rate in 90 min). The pH also showed great influence on morphology and phase transformation of samples. Finally, the phyotocatalytic mechanism and effects of Nd3+ in phase transformation were discussed.

Electrical properties of niobium doped Bi4Ti3O12-SrBi4Ti4O15 intergrowth ferroelectrics

International Nuclear Information System (INIS)

Parida, Geetanjali; Bera, J.

2013-01-01

Bismuth layer structured ferroelectrics (BLSFs) have attracted much attention because of their potential applications in non-volatile ferroelectric random access memories and high temperature piezoelectric. They are very attractive for these applications due to their fatigue free nature and environment friendly lead-free composition. BLSF crystal structure has layers of bismuth oxide and pseudo perovskite block stacked alternately along their c-direction, For commercial application, numerous efforts have been made to improve the electrical properties of BLSFs. Some effective approaches are: (i) doping at A-site, (ii) high valentcation doping at B-site and (iii) formation of intergrowth between different BLSFs. The intergrowth BLSFs are consist of regular stacking of one half the unit cell of m-member structure and one half the unit cell of (m+1) member BLSF structure along their c-axis. In this report, Nb-doped Bi 4 Ti 3 O 12 -SrBi 4 Ti 4 O 15 intergrowth ceramics have been prepared by modified oxalate route. XRD phase analysis confirmed the formation of single phase compound. Nb-doping does not affect the basic crystal structure of the intergrowth. SEM micrographs showed that the grain size of the ceramics decreases with Nb-doping. The temperature dependence of dielectric constant and losses was investigated in the temperature range 30 to 800℃ and frequency range 1 kHz to 1 MHz. With Nb-doping, the T c of the ferroelectrics reduces and peak permittivity increases. Doping also introduces small relaxor behaviour in the ferroelectrics. The dc conductivity of the ceramics decreases with doping. The remnant polarization (Pr) of the intergrowth ferroelectrics is increased with Nb doping. (author)

Enhanced magnetic and ferroelectric properties in scandium doped nano Bi{sub 2}Fe{sub 4}O{sub 9}

Energy Technology Data Exchange (ETDEWEB)

Dutta, Dimple P., E-mail: dimpled@barc.gov.in [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Sudakar, C.; Mocherla, Pavana S.V. [Department of Physics, IIT Madras, Chennai 600 036 (India); Mandal, Balaji P.; Jayakumar, Onnatu D. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tyagi, Avesh K., E-mail: aktyagi@barc.gov.in [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

2012-08-15

In this study we report the synthesis of undoped and Sc{sup 3+} doped Bi{sub 2}Fe{sub 4}O{sub 9} nanoparticles using sonochemical technique. X-ray diffraction reveals that all samples are single phase with no impurities detected. EDS analysis was done to confirm the extent of Sc{sup 3+} doping in the samples. The size and morphology of the nanoparticles have been analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Bi{sub 2}Fe{sub 4}O{sub 9} nanoparticles show a weak ferromagnetic behavior at room temperature, which is quite different from the linear M-H relationship reported for bulk Bi{sub 2}Fe{sub 4}O{sub 9}. A magnetization of 0.144 {mu}B/f.u. is obtained at 300 K, which is mainly attributed to the uncompensated moments at the disordered particle surface resulting from the reduced coordination of the surface spins, arising due to lattice strain or oxygen deficiency. Addition of Sc{sup 3+} dopant in varying concentrations in these Bi{sub 2}Fe{sub 4}O{sub 9} nanoparticles, improves their magnetic as well as ferroelectric properties. The leakage current is considerably reduced and electric polarization increases significantly in case of Bi{sub 2}Fe{sub 4(1-x)}Sc{sub x}O{sub 9} (x = 0.1) nanoparticles. Thus it can be inferred that Sc{sup 3+} doped Bi{sub 2}Fe{sub 4}O{sub 9} nanoparticles shows promise as good multiferroic materials. -- Graphical abstract: Undoped and Sc{sup 3+} doped Bi{sub 2}Fe{sub 4}O{sub 9} nanoparticles have been synthesized using sonochemical technique. The bi-functionalities of Sc{sup 3+} doped Bi{sub 2}Fe{sub 4}O{sub 9} nanoparticles have been demonstrated. The Bi{sub 2}Fe{sub 4(1-x)}Sc{sub x}O{sub 9} (x = 0.1) nanoparticles showed enhanced magnetic and ferroelectric properties with considerably less lossy characteristics compared to the bulk Bi{sub 2}Fe{sub 4}O{sub 9}. Highlights: Black-Right-Pointing-Pointer Phase pure Bi{sub 2}Fe{sub 4}O{sub 9} nanostructures synthesized using a facile

Novel and facile synthesis of Ba-doped BiFeO{sub 3} nanoparticles and enhancement of their magnetic and photocatalytic activities for complete degradation of benzene in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Soltani, Tayyebeh; Lee, Byeong-Kyu, E-mail: bklee@ulsan.ac.kr

2016-10-05

Highlights: • An efficient novel visible light photocatalyst was synthesized. • Ba doped BFO showed enhanced surface area, oxygen vacancies, magnetic and photocatalytic activities. • Ba doped BFO can be an economic photocatalyst for benzene degradation. • Complete degradation and high mineralization of benzene were achieved with 60 min irradiation. - Abstract: In this work, Bi{sub 1-x} Ba{sub x} FeO{sub 3} (x = 0.05, 0.1 and 0.2 mol%) multiferroic materials as visible-light photocatalysts were successfully synthesized via a simple and rapid sol-gel method, at a low temperature and with rapid calcination. Ba loading brought about a distorted structure of BiFeO{sub 3} magnetic nanoparticles (BFO MNPs) consisting of small, randomly oriented and non-uniform grains, leading to increased surface area and improved magnetic and photocatalytic activities. Doping of Ba{sup 2+} into pure BFO (Bi{sub 1-x} Ba{sub x} FeO{sub 3}, x = 0.2 mol%) greatly increased magnetic saturation to 3.0 emu/g and significantly decreased the band-gap energy to 1.79 eV, as compared to 2.1 emu/g and 2.1 eV, respectively, for pure BFO. Bi{sub 1-x}Ba {sub x}FeO{sub 3} of x = 0.2 mol% exhibited the greatest photocatalytic degradation effect after 60 min of visible light irradiation, and reached 97% benzene removal efficiency, leading to production of a high concentration of carbon dioxide (CO{sub 2}), with 93% and 82% reductions in chemical oxygen demand (COD) and total organic carbon (TOC), respectively. The identified major intermediate products of photodegradation enabled prediction of the proposed benzene degradation pathway. The enhanced photocatalytic activity of benzene removal is due to both mechanisms, photocatalytic and photo-Fenton catalytic degradation.

Enhancing visible light photocatalytic and photocharge separation of (BiO)_2CO_3 plate via dramatic I"− ions doping effect

International Nuclear Information System (INIS)

Liang, Lei; Cao, Jing; Lin, Haili; Guo, Xiaomin; Zhang, Meiyu; Chen, Shifu

2016-01-01

Highlights: • Novel I-(BiO)_2CO_3 was prepared by a facile chemical precipitation method. • I"− ions impurity level located on the top of valence band of (BiO)_2CO_3. • I"− ions doping largely improved photocatalytic activity of I-(BiO)_2CO_3. • I-(BiO)_2CO_3 displayed excellent photocharge separation efficiency. - Abstract: Novel I"− ions doped (BiO)_2CO_3 (I-(BiO)_2CO_3) photocatalysts were successfully synthesized via a facile chemical precipitation method. Under visible light (λ > 400 nm), I-(BiO)_2CO_3 displayed much higher activity for rhodamine B and dichlorophenol degradation than the undoped (BiO)_2CO_3. The pseudo-first-order rate constant k_a_p_p of RhB degradation over 15.0% I-(BiO)_2CO_3 was 0.54 h"−"1, which is 11.3 times higher than that of (BiO)_2CO_3. The doped I"− ions formed an impurity level on the top of valence band of (BiO)_2CO_3 and induced much more visible light to be absorbed. The enhanced photocurrent and surface photovoltage properties were detected, which strongly ensures the efficient separation of electrons and holes in I-(BiO)_2CO_3 system under visible light. It provides a facile way to improve the photocatalytic activity of the wide-band-gap (BiO)_2CO_3 via intense doping effect of I"− ions.

Physical properties of Bi doped CdTe thin films grown by CSVT and their influence on the CdS/CdTe solar cells PV-properties

International Nuclear Information System (INIS)

Vigil-Galan, O.; Sanchez-Meza, E.; Ruiz, C.M.; Sastre-Hernandez, J.; Morales-Acevedo, A.; Cruz-Gandarilla, F.; Aguilar-Hernandez, J.; Saucedo, E.; Contreras-Puente, G.; Bermudez, V.

2007-01-01

The physical properties of Bi doped CdTe films, grown on glass substrates by the Closed Space Transport Vapour (CSVT) method, from different Bi doped CdTe powders are presented. The CdTe:Bi films were characterized using Photoluminescence, Hall effect, X-Ray diffraction, SEM and Photoconductivity measurements. Moreover, CdS/CdTe:Bi solar cells were made and their characteristics like short circuit current density (J sc ), open circuit voltage (V OC ), fill factor (FF) and efficiency (η) were determined. These devices were fabricated from Bi doped CdTe layers deposited on CdS with the same growth conditions than those used for the single CdTe:Bi layers. A correlation between the CdS/CdTe:Bi solar cell characteristics and the physical properties of the Bi doped CdTe thin films are presented and discussed

Enhanced surface area, high Zn interstitial defects and band gap reduction in N-doped ZnO nanosheets coupled with BiVO{sub 4} leads to improved photocatalytic performance

Energy Technology Data Exchange (ETDEWEB)

Singh, Sonal [Deen Dayal Upadhyaya College, Dwarka, University of Delhi, New Delhi 110078 (India); Sharma, Rishabh, E-mail: rishabh.rammstien@gmail.com [Thin Film Laboratory, Department of Physics, Indian Institute of Technology, New Delhi 110016 (India); Mehta, Bodh Raj [Thin Film Laboratory, Department of Physics, Indian Institute of Technology, New Delhi 110016 (India)

2017-07-31

Highlights: • In this study, we report novel nitrogen doped ZnO (nanosheet)/BiVO{sub 4} nanocomposite with enhanced visible light photocatalytic activity tested on methylene blue dye. • In a typical composite synthesis process, individual metal oxides synthesized by chemical route were mixed through ultrasonication followed by annealing at the temperature of 400 °C. • To understand mechanism of action we carried out XRD, TEM, UV–vis spectroscopy, XPS, BET & PL of the samples. • Enhancement in photocatalytic performance of the composite was due to increased light absorption due to band gap reduction and formation intermediate band. • Also, charge exchange as per Z-scheme at the hetrojunction between N-ZnO and BiVO{sub 4} resulted in reduced charge recombination rate which is further responsible for enhancement in photocatalytic activity. - Abstract: For the first time, a series of Nitrogen-doped-ZnO nanosheet coupled with BiVO{sub 4} (N-ZnO/BiVO{sub 4}) heterojunctioned photocatalysts have been synthesized. The new N-ZnO/BiVO{sub 4} material has been prepared via a simple and effective method of precipitation followed by high temperature annealing process. The photocatalytic activities of the N-ZnO/BiVO{sub 4} composites were evaluated for the degradation of methylene blue (MB) a common organic pollutant under visible-light irradiation. The results revealed that photocatalytic activity of the coupled system was directly influenced by the percentage amount of BiVO{sub 4} in N-ZnO which affected the available exposed surface area for photoreactions. 30% N-ZnO/BiVO{sub 4} system exhibited remarkable performance than 10%N-ZnO/BiVO{sub 4}, 50%N-ZnO/BiVO{sub 4}, and also to their pristine counterparts. The composite demonstrated the degradation efficiency of 90% in 90 min which is 1.76 times the efficiency of pure ZnO for same time duration. This pronounced photocatalytic effect is ascribed to the reduced band gap and lowered recombination rate of ZnO due to

Hydrothermal Synthesis, Characterization, and Optical Properties of Ce Doped Bi2MoO6 Nanoplates

Directory of Open Access Journals (Sweden)

Anukorn Phuruangrat

2014-01-01

Full Text Available Undoped and Ce doped Bi2MoO6 samples were synthesized by hydrothermal reaction at 180°C for 20 h. Phase, morphology, atomic vibration, and optical properties were characterized by X-ray powder diffraction (XRD, X-ray photoelectron spectroscopy (XPS, Raman spectrophotometry, Fourier transform infrared (FTIR spectroscopy, scanning electron microscopy (SEM, transmission electron microscopy (TEM, selected area electron diffraction (SAED, and UV-visible spectroscopy. In this research, the products were orthorhombic Bi2MoO6 nanoplates with the growth direction along the [0b0], including the asymmetric and symmetric stretching and bending modes of Bi–O and Mo–O. Undoped and Ce doped Bi2MoO6 samples show a strong absorption in the UV region.

Bi-Sn alloy catalyst for simultaneous morphology and doping control of silicon nanowires in radial junction solar cells

International Nuclear Information System (INIS)

Yu, Zhongwei; Lu, Jiawen; Qian, Shengyi; Xu, Jun; Xu, Ling; Wang, Junzhuan; Shi, Yi; Chen, Kunji; Misra, Soumyadeep; Roca i Cabarrocas, Pere; Yu, Linwei

2015-01-01

Low-melting point metals such as bismuth (Bi) and tin (Sn) are ideal choices for mediating a low temperature growth of silicon nanowires (SiNWs) for radial junction thin film solar cells. The incorporation of Bi catalyst atoms leads to sufficient n-type doping in the SiNWs core that exempts the use of hazardous dopant gases, while an easy morphology control with pure Bi catalyst has never been demonstrated so far. We here propose a Bi-Sn alloy catalyst strategy to achieve both a beneficial catalyst-doping and an ideal SiNW morphology control. In addition to a potential of further growth temperature reduction, we show that the alloy catalyst can remain quite stable during a vapor-liquid-solid growth, while providing still sufficient n-type catalyst-doping to the SiNWs. Radial junction solar cells constructed over the alloy-catalyzed SiNWs have demonstrated a strongly enhanced photocurrent generation, thanks to optimized nanowire morphology, and largely improved performance compared to the reference samples based on the pure Bi or Sn-catalyzed SiNWs

Thermoluminescence studies of Nd doped Bi_4Ge_3O_1_2 crystals irradiated by UV and beta sources

International Nuclear Information System (INIS)

Karabulut, Y.; Canimoglu, A.; Ekdal, E.; Ayvacikli, M.; Can, N.; Karali, T.

2016-01-01

Thermoluminescence (TL) glow curves of pure and rare earth doped bismuth germanate (BGO) were investigated under UV and beta radiation. The glow curves of pure BGO crystal present different patterns for both kinds of radiation. The TL glow curves of BGO crystals doped with Nd ions are similar to that of pure BGO under UV radiation. The kinetic parameters, kinetic order (b), activation energy (E) and frequency factor (s) of the TL glow curves of pure BGO crystal have been determined by peak shape method. Activation energies of 3 peaks obtained by PS were found to be 1.81, 1.15 and 1.78, respectively. - Highlights: • Thermoluminescence properties of pure and Nd doped BGO crystals. • Irradiated by UV and beta for TL glow curve analysis. • Evaluation of kinetic parameters by PS method.

Tritium-doping enhancement of polystyrene by ultraviolet laser and hydrogen plasma irradiation for laser fusion experiments

Energy Technology Data Exchange (ETDEWEB)

Iwasa, Yuki, E-mail: iwasa-y@ile.osaka-u.ac.jp [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Yamanoi, Kohei; Iwano, Keisuke; Empizo, Melvin John F.; Arikawa, Yasunobu; Fujioka, Shinsuke; Sarukura, Nobuhiko; Shiraga, Hiroyuki; Takagi, Masaru; Norimatsu, Takayoshi; Azechi, Hiroshi [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Noborio, Kazuyuki; Hara, Masanori; Matsuyama, Masao [Hydrogen Isotope Research Center, Organization for Promotion of Research, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan)

2016-11-15

Highlights: • Tritium-doped polystyrene films are fabricated by the Wilzbach method with UV laser and hydrogen plasma irradiation. • The 266-nm laser-irradiated, 355-nm laser-irradiated, and hydrogen plasma-irradiated polystyrene films exhibit higher PSL intensities and specific radioactivities than the non-irradiated sample. • Tritium doping by UV laser irradiation can be largely affected by the laser wavelength because of polystyrene’s absorption. • Hydrogen plasma irradiation results to a more uniform doping concentration even at low partial pressure and short irradiation time. • UV laser and plasma irradiations can be utilized to fabricate tritium-doped polystyrene shell targets for future laser fusion experiments. - Abstract: We investigate the tritium-doping enhancement of polystyrene by ultraviolet (UV) laser and hydrogen plasma irradiation. Tritium-doped polystyrene films are fabricated by the Wilzbach method with UV laser and hydrogen plasma. The 266-nm laser-irradiated, 355-nm laser-irradiated, and hydrogen plasma-irradiated polystyrene films exhibit higher PSL intensities and specific radioactivities than the non-irradiated sample. Tritium doping by UV laser irradiation can be largely affected by the laser wavelength because of polystyrene’s absorption. In addition, UV laser irradiation is more localized and concentrated at the spot of laser irradiation, while hydrogen plasma irradiation results to a more uniform doping concentration even at low partial pressure and short irradiation time. Both UV laser and plasma irradiations can nevertheless be utilized to fabricate tritium-doped polystyrene targets for future laser fusion experiments. With a high doping rate and efficiency, a 1% tritium-doped polystyrene shell target having 7.6 × 10{sup 11} Bq g{sup −1} specific radioactivity can be obtained at a short period of time thereby decreasing tritium consumption and safety management costs.

Enhanced photocatalytic activity of cadmium-doped Bi{sub 2}WO{sub 6} nanoparticles under simulated solar light

Energy Technology Data Exchange (ETDEWEB)

Song, Xu Chun, E-mail: songxuchunfj@163.com; Li, Wen Ting [Fujian Normal University, Department of Chemistry (China); Huang, Wan Zhen; Zhou, Huan [Zhejiang University of Technology, Research Center of Analysis and Measurement (China); Yin, Hao Yong [Hangzhou Dianzi University, Institute of Environmental Science and Engineering (China); Zheng, Yi Fan [Zhejiang University of Technology, Research Center of Analysis and Measurement (China)

2015-03-15

Novel cadmium-doped Bi{sub 2}WO{sub 6} nanoparticles with different Cd contents have been synthesized by a one-step route using ethylene glycol and water as solvents at 180 °C for 12 h. The as-synthesized samples were characterized in detailed by SEM, XRD, EDS, HRTEM, UV–Vis DRS, BET techniques, and so on. The results shown that with the increase of the Cd{sup 2+} addition, the crystal structure, lattice space, and absorption edge were not significantly changed and the calculated band gap value was 2.58 eV. However, the flower-like Bi{sub 2}WO{sub 6} sphere was gradually destroyed. Simultaneously, the surface area and photocurrent responses of the catalysts were greatly increased. Photocatalytic activity of the Cd-doped Bi{sub 2}WO{sub 6} samples was determined by monitoring the change of RhB concentration under simulated solar light. The results revealed that cadmium doping greatly improved the photocatalytic efficiency of Bi{sub 2}WO{sub 6}. The Bi{sub 2}WO{sub 6} sample with R{sub Cd} = 0.05 displayed the highest photocatalytic activity, and the degradation rate is about two times greater than pure Bi{sub 2}WO{sub 6}. Moreover, the Cd–Bi{sub 2}WO{sub 6} photocatalyst remained stable even after five consecutive cycles. A possible mechanism of photocatalytic activity enhancement on basis of the experimental results was proposed.

Electric modulation of conduction in multiferroic Ca-doped BiFeO3 films

Science.gov (United States)

Yang, C.-H.; Seidel, J.; Kim, S. Y.; Rossen, P. B.; Yu, P.; Gajek, M.; Chu, Y. H.; Martin, L. W.; Holcomb, M. B.; He, Q.; Maksymovych, P.; Balke, N.; Kalinin, S. V.; Baddorf, A. P.; Basu, S. R.; Scullin, M. L.; Ramesh, R.

2009-06-01

Many interesting materials phenomena such as the emergence of high-Tc superconductivity in the cuprates and colossal magnetoresistance in the manganites arise out of a doping-driven competition between energetically similar ground states. Doped multiferroics present a tantalizing evolution of this generic concept of phase competition. Here, we present the observation of an electronic conductor-insulator transition by control of band-filling in the model antiferromagnetic ferroelectric BiFeO3 through Ca doping. Application of electric field enables us to control and manipulate this electronic transition to the extent that a p-n junction can be created, erased and inverted in this material. A `dome-like' feature in the doping dependence of the ferroelectric transition is observed around a Ca concentration of ~1/8, where a new pseudo-tetragonal phase appears and the electric modulation of conduction is optimized. Possible mechanisms for the observed effects are discussed on the basis of the interplay of ionic and electronic conduction. This observation opens the door to merging magnetoelectrics and magnetoelectronics at room temperature by combining electronic conduction with electric and magnetic degrees of freedom already present in the multiferroic BiFeO3.

Structural determination of Bi-doped magnetite multifunctional nanoparticles for contrast imaging.

Science.gov (United States)

Laguna-Marco, M A; Piquer, C; Roca, A G; Boada, R; Andrés-Vergés, M; Veintemillas-Verdaguer, S; Serna, C J; Iadecola, A; Chaboy, J

2014-09-14

To determine with precision how Bi atoms are distributed in Bi-doped iron oxide nanoparticles their structural characterization has been carried out by X-ray absorption spectroscopy (XAS) recorded at the K edge of Fe and at the L3 edge of Bi. The inorganic nanoparticles are nominally hybrid structures integrating an iron oxide core and a bismuth oxide shell. Fe K-edge XAS indicates the formation of a structurally ordered, non-stoichiometric magnetite (Fe3-δO4) phase for all the nanoparticles. The XAS spectra show that, in the samples synthesized by precipitation in aqueous media and laser pyrolysis, the Bi atoms neither enter into the iron oxide spinel lattice nor form any other mixed Bi-Fe oxides. No modification of the local structure around the Fe atoms induced by the Bi atoms is observed at the Fe K edge. In addition, contrary to expectations, our results indicate that the Bi atoms do not form a well-defined Bi oxide structure. The XAS study at the Bi L3 edge indicates that the environment around Bi atoms is highly disordered and only a first oxygen coordination shell is observed. Indefinite [BiO6-x(OH)x] units (isolated or aggregated forming tiny amorphous clusters) bonded through hydroxyl bridges to the nanoparticle, rather than a well defined Bi2O3 shell, surround the nanoparticle. On the other hand, the XAS study indicates that, in the samples synthesized by thermal decomposition, the Bi atoms are embedded in a longer range ordered structure showing the first and second neighbors.

Correlation between modulation structure and electronic inhomogeneity on Pb-doped Bi-2212 single crystals

International Nuclear Information System (INIS)

Sugimoto, A.; Kashiwaya, S.; Eisaki, H.; Yamaguchi, H.; Oka, K.; Kashiwaya, H.; Tsuchiura, H.; Tanaka, Y.

2005-01-01

The correlation between nanometer-size electronic states and surface structure is investigated by scanning tunneling microscopy/spectroscopy (STM/S) on Pb-doped Bi 2-x Pb x Sr 2 CaCu2O 8+y (Pb-Bi-2212) single crystals. The advantage of the Pb-Bi-2212 samples is that the modulation structure can be totally or locally suppressed depending on the Pb contents and annealing conditions. The superconducting gap (Δ) distribution on modulated Pb-Bi-2212 samples showed the lack of correlation with modulation structure except a slight reduction of superconducting island size for the b-axis direction. On the other hand, the optimal doped Pb-Bi-2212 (x = 0.6) samples obtained by reduced-annealing showed totally non-modulated structure in topography, however, the spatial distribution of Δ still showed inhomogeneity of which features were quite similar to those of modulated samples. These results suggest that the modulation structure is not the dominant origin of inhomogeneity although it modifies the streaky Δ structure sub-dominantly. From the gap structure variation around the border of narrow gap and broad gap regions, a trend of the coexistence of two separated phases i.e., superconducting phase and pseudogap like phase, is detected

Bi-tangential hybrid IMRT for sparing the shoulder in whole breast irradiation.

Science.gov (United States)

Farace, P; Deidda, M A; Iamundo de Cumis, I; Iamundo de Curtis, I; Deiana, E; Farigu, R; Lay, G; Porru, S

2013-11-01

A bi-tangential technique is proposed to reduce undesired doses to the shoulder produced by standard tangential irradiation. A total of 6 patients affected by shoulder pain and reduced functional capacity after whole-breast irradiation were retrospectively analysed. The standard tangential plan used for treatment was compared with (1) a single bi-tangential plan where, to spare the shoulder, the lateral open tangent was split into two half-beams at isocentre, with the superior portion rotated by 10-20° medially with respect to the standard lateral beam; (2) a double bi-tangential plan, where both the tangential open beams were split. The planning target volume (PTV) coverage and the dose to the portion of muscles and axilla included in the standard tangential beams were compared. PTV95 % of standard plan (91.9 ± 3.8) was not significantly different from single bi-tangential plan (91.8 ± 3.4); a small but significant (p < 0.01) decrease was observed with the double bi-tangential plan (90.1 ± 3.7). A marked dose reduction to the muscle was produced by the single bi-tangential plan around 30-40 Gy. The application of the double bi-tangential technique further reduced the volume receiving around 20 Gy, but did not markedly affect the higher doses. The dose to the axilla was reduced both in the single and the double bi-tangential plans. The single bi-tangential technique would have been able to reduce the dose to shoulder and axilla, without compromising target coverage. This simple technique is valuable for irradiation after axillary lymph node dissection or in patients without dissection due to negative or low-volume sentinel lymph node disease.

Bi-tangential hybrid IMRT for sparing the shoulder in whole breast irradiation

Energy Technology Data Exchange (ETDEWEB)

Farace, P.; Deidda, M. A.; Iamundo de Curtis, I.; Deiana, E.; Farigu, R.; Lay, G.; Porru, S. [Regional Oncological Hospital, Cagliari (Italy). Dept. of Radio-Oncology

2013-11-15

Background and purpose: A bi-tangential technique is proposed to reduce undesired doses to the shoulder produced by standard tangential irradiation. Patients and methods: A total of 6 patients affected by shoulder pain and reduced functional capacity after whole-breast irradiation were retrospectively analysed. The standard tangential plan used for treatment was compared with (1) a single bi-tangential plan where, to spare the shoulder, the lateral open tangent was split into two half-beams at isocentre, with the superior portion rotated by 10-20 medially with respect to the standard lateral beam; (2) a double bi-tangential plan, where both the tangential open beams were split. The planning target volume (PTV) coverage and the dose to the portion of muscles and axilla included in the standard tangential beams were compared. Results: PTV95 % of standard plan (91.9 {+-} 3.8) was not significantly different from single bi-tangential plan (91.8 {+-} 3.4); a small but significant (p < 0.01) decrease was observed with the double bi-tangential plan (90.1 {+-} 3.7). A marked dose reduction to the muscle was produced by the single bi-tangential plan around 30-40 Gy. The application of the double bi-tangential technique further reduced the volume receiving around 20 Gy, but did not markedly affect the higher doses. The dose to the axilla was reduced both in the single and the double bi-tangential plans. Conclusion: The single bi-tangential technique would have been able to reduce the dose to shoulder and axilla, without compromising target coverage. This simple technique is valuable for irradiation after axillary lymph node dissection or in patients without dissection due to negative or low-volume sentinel lymph node disease. (orig.)

Bi-tangential hybrid IMRT for sparing the shoulder in whole breast irradiation

International Nuclear Information System (INIS)

Farace, P.; Deidda, M.A.; Iamundo de Curtis, I.; Deiana, E.; Farigu, R.; Lay, G.; Porru, S.

2013-01-01

Background and purpose: A bi-tangential technique is proposed to reduce undesired doses to the shoulder produced by standard tangential irradiation. Patients and methods: A total of 6 patients affected by shoulder pain and reduced functional capacity after whole-breast irradiation were retrospectively analysed. The standard tangential plan used for treatment was compared with (1) a single bi-tangential plan where, to spare the shoulder, the lateral open tangent was split into two half-beams at isocentre, with the superior portion rotated by 10-20 medially with respect to the standard lateral beam; (2) a double bi-tangential plan, where both the tangential open beams were split. The planning target volume (PTV) coverage and the dose to the portion of muscles and axilla included in the standard tangential beams were compared. Results: PTV95 % of standard plan (91.9 ± 3.8) was not significantly different from single bi-tangential plan (91.8 ± 3.4); a small but significant (p < 0.01) decrease was observed with the double bi-tangential plan (90.1 ± 3.7). A marked dose reduction to the muscle was produced by the single bi-tangential plan around 30-40 Gy. The application of the double bi-tangential technique further reduced the volume receiving around 20 Gy, but did not markedly affect the higher doses. The dose to the axilla was reduced both in the single and the double bi-tangential plans. Conclusion: The single bi-tangential technique would have been able to reduce the dose to shoulder and axilla, without compromising target coverage. This simple technique is valuable for irradiation after axillary lymph node dissection or in patients without dissection due to negative or low-volume sentinel lymph node disease. (orig.)

Synthesis and photocatalytic properties of MgBi2O6 with Ag additions

Science.gov (United States)

Zhong, Liansheng; Hu, Chaohao; Zhu, Binqing; Zhong, Yan; Zhou, Huaiying

2018-02-01

Ag-doped MgBi2O6 photocatalysts were synthesized by the low temperature hydrothermal method in combination with heat treatment reaction using NaBiO3·2H2O, MgCl2·6H2O, and AgNO3 as raw materials. The products were characterized by using power X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Energy dispersive X-ray detector (EDS), and UV-Vis diffusion reflectance spectra. The photocatalytic activity of MgBi2O6 with Ag additions was evaluated by degrading MB (10 mg/L) under visible light irradiation (λ > 420 nm). The results showed that in comparison with pure MgBi2O6, the photocatalytic activity of MgBi2O6 with about 5% Ag concentration is increased by about 24% after 120 min reaction. The enhancement of catalytic activity of Ag-doped MgBi2O6 photocatalysts should be related to the band structure, morphology and larger specific surface area.

Preparation of La{sup 3+}/Zn{sup 2+}-doped BiVO{sub 4} nanoparticles and its enhanced visible photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Hou, Yanhui; Yuan, Huili; Chen, Hang; Feng, Jiantao; Ding, Yan; Li, Liangchao [Zhejiang Normal University, Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Department of Chemistry, Jinhua (China)

2017-10-15

BiVO{sub 4} samples doped with different amounts of La{sup 3+} or Zn{sup 2+} ions have been synthesized successfully by a hydrothermal method, and their composition, microstructure and photocatalytic activity were characterized by means of modern analytical techniques. The results illustrated that these doped BiVO{sub 4} samples presented a better photocatalytic performance than the undoped BiVO{sub 4} sample, among which Bi{sub 0.92}La{sub 0.08}VO{sub 4} and Bi{sub 0.92}Zn{sub 0.08}VO{sub 4} exhibited the highest degradation efficiency. Under visible light illumination, their photocatalytic degradation on RhB was up to 95.4 and 98.56% in 60 min, respectively. In particular, the Bi{sub 0.92}La{sub 0.08}VO{sub 4} and Bi{sub 0.92}Zn{sub 0.08}VO{sub 4} had a good stability and still retained the photocatalytic activity of 93.7 and 94% after five cycling test. These results confirmed that the La{sup 3+}/Zn{sup 2+}-doped BiVO{sub 4} samples were a kind of efficient and stable visible-light-driven photocatalysts and had a promising application for the degradation of organic contaminant. (orig.)

Microscopic effects of Dy doping in the topological insulator Bi2Te3

Science.gov (United States)

Duffy, L. B.; Steinke, N.-J.; Krieger, J. A.; Figueroa, A. I.; Kummer, K.; Lancaster, T.; Giblin, S. R.; Pratt, F. L.; Blundell, S. J.; Prokscha, T.; Suter, A.; Langridge, S.; Strocov, V. N.; Salman, Z.; van der Laan, G.; Hesjedal, T.

2018-05-01

Magnetic doping with transition metal ions is the most widely used approach to break time-reversal symmetry in a topological insulator (TI)—a prerequisite for unlocking the TI's exotic potential. Recently, we reported the doping of Bi2Te3 thin films with rare-earth ions, which, owing to their large magnetic moments, promise commensurately large magnetic gap openings in the topological surface states. However, only when doping with Dy has a sizable gap been observed in angle-resolved photoemission spectroscopy, which persists up to room temperature. Although disorder alone could be ruled out as a cause of the topological phase transition, a fundamental understanding of the magnetic and electronic properties of Dy-doped Bi2Te3 remained elusive. Here, we present an x-ray magnetic circular dichroism, polarized neutron reflectometry, muon-spin rotation, and resonant photoemission study of the microscopic magnetic and electronic properties. We find that the films are not simply paramagnetic but that instead the observed behavior can be well explained by the assumption of slowly fluctuating, inhomogeneous, magnetic patches with increasing volume fraction as the temperature decreases. At liquid helium temperatures, a large effective magnetization can be easily introduced by the application of moderate magnetic fields, implying that this material is very suitable for proximity coupling to an underlying ferromagnetic insulator or in a heterostructure with transition-metal-doped layers. However, the introduction of some charge carriers by the Dy dopants cannot be excluded at least in these highly doped samples. Nevertheless, we find that the magnetic order is not mediated via the conduction channel in these samples and therefore magnetic order and carrier concentration are expected to be independently controllable. This is not generally the case for transition-metal-doped topological insulators, and Dy doping should thus allow for improved TI quantum devices.

Synthesis, Property Characterization and Photocatalytic Activity of the Novel Composite Polymer Polyaniline/Bi2SnTiO7

Directory of Open Access Journals (Sweden)

Yunjun Yang

2012-03-01

Full Text Available A novel polyaniline/Bi2SnTiO7 composite polymer was synthesized by chemical oxidation in-situ polymerization method and sol-gel method for the first time. The structural properties of novel polyaniline/Bi2SnTiO7 have been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray spectrometry. The lattice parameter of Bi2SnTiO7 was found to be a = 10.52582(8 Å. The photocatalytic degradation of methylene blue was realized under visible light irradiation with the novel polyaniline/Bi2SnTiO7 as catalyst. The results showed that novel polyaniline/Bi2SnTiO7 possessed higher catalytic activity compared with Bi2InTaO7 or pure TiO2 or N-doped TiO2 for photocatalytic degradation of methylene blue under visible light irradiation. The photocatalytic degradation of methylene blue with the novel polyaniline/Bi2SnTiO7 or N-doped TiO2 as catalyst followed first-order reaction kinetics, and the first-order rate constant was 0.01504 or 0.00333 min−1. After visible light irradiation for 220 minutes with novel polyaniline/Bi2SnTiO7 as catalyst, complete removal and mineralization of methylene blue was observed. The reduction of the total organic carbon, the formation of inorganic products, SO42− and NO3−, and the evolution of CO2 revealed the continuous mineralization of methylene blue during the photocatalytic process. The possible photocatalytic degradation pathway of methylene blue was obtained under visible light irradiation.

Proton irradiation induced defects in Cd and Zn doped InP

International Nuclear Information System (INIS)

Rybicki, G.C.; Williams, W.S.

1993-01-01

Proton irradiation induced defects in Zn and Cd doped InP have been studied by deep level transient spectroscopy, (DLTS). After 2 MeV proton irradiation the defects H4 and H5 were observed in lightly Zn doped InP, while the defects H3 and H5 were observed in more heavily Zn and Cd doped InP. The defect properties were not affected by the substitution of Cd for Zn, but the introduction rate of H5 was lower in Cd doped InP. The annealing rate of defects was also higher in Cd doped InP. The use of Cd doped InP may thus result in an InP solar cell with even greater radiation resistance

Improved ferroelectric and pyroelectric properties of Pb-doped SrBi4Ti4O15 ceramics for high temperature applications

International Nuclear Information System (INIS)

Venkata Ramana, E.; Graça, M.P.F.; Valente, M.A.; Bhima Sankaram, T.

2014-01-01

Highlights: • Sr 1−x Pb x Bi 4 Ti 4 O 15 (SPBT, x = 0 − 0.4) ceramics were synthesized by soft chemical method. • X-ray diffraction analysis confirmed the formation of bismuth layered structure. • SEM images showed plate like grain morphology with random orientation of plate faces. • Pb-doping resulted in improved ferroelectricity of SrBi 4 Ti 4 O 15 ceramics. • Pb-doped SrBi 4 Ti 4 O 15 exhibited improved pyroelectric properties with high T C . -- Abstract: Ferroelectric properties of Pb-modified strontium bismuth titanate ceramics with chemical formula Sr 1−x Pb x Bi 4 Ti 4 O 15 (x = 0–0.4) were investigated. Polycrystalline ceramics were synthesized by soft chemical method to study the effect of Pb-doping on its physical properties. X-ray diffraction analysis revealed a bismuth layered structure for all the compounds. The doping resulted in an increased tetragonal strain and improved ferroelectric properties. Scanning electron microscope images showed plate like grain morphology with random orientation of platelets. The ferroelectric transition temperature of the ceramics increased systematically from 525 °C to 560 °C with the increase of doping concentration. The piezoelectric coefficient (d 33 ) of the ceramics was enhanced significantly with Pb doping, exhibiting a maximum value of 21.8 pC/N for 40 mol.% Pb-doped SBT. Pyroelectric studies carried out using the Byer–Roundy method indicated that the modified SBT ceramics are promising candidates for high temperature pyroelectric applications

Effect of bismuth doping on the ZnO nanocomposite material and study of its photocatalytic activity under UV-light

International Nuclear Information System (INIS)

Chandraboss, V.L.; Natanapatham, L.; Karthikeyan, B.; Kamalakkannan, J.; Prabha, S.; Senthilvelan, S.

2013-01-01

Graphical abstract: The hetero-junctions that are formed between the ZnO and the Bi provide an internal electric field that facilitates separation of the electron-hole pairs and induces faster carrier migration. Thus they often enhanced photocatalytic reaction. - Highlights: • Bi-doped ZnO nanocomposite material was prepared by precipitation method. • Characterized by XRD, HR-SEM with EDX, UV–visible DRS and FT-RAMAN analysis. • Bi-doped ZnO nanocomposite material was used to photodegradation of Congo red. • Mechanism and photocatalytic effect of nanocomposite material have been discussed. - Abstract: Bismuth (Bi)-doped ZnO nanocomposite material was prepared by precipitation method with doping precursors of bismuth nitrate pentahydrate and oxalic acid, characterized by X-ray diffraction (XRD), High Resolution-Scanning Electron Microscopy (HR-SEM) with Energy Dispersive X-ray (EDX) analysis, UV–visible Diffuse Reflectance Spectroscopy (UV–visible DRS) and Fourier Transform-Raman (FT-RAMAN) analysis. The enhanced photocatalytic activity of the Bi-doped ZnO is demonstrated through photodegradation of Congo red under UV-light irradiation. The mechanism of photocatalytic effect of Bi-doped ZnO nanocomposite material has been discussed

Chalcogen doping of silicon via intense femtosecond-laser irradiation

International Nuclear Information System (INIS)

Sheehy, Michael A.; Tull, Brian R.; Friend, Cynthia M.; Mazur, Eric

2007-01-01

We have previously shown that doping silicon with sulfur via femtosecond-laser irradiation leads to near-unity absorption of radiation from ultraviolet wavelengths to below band gap short-wave infrared wavelengths. Here, we demonstrate that doping silicon with two other group VI elements (chalcogens), selenium and tellurium, also leads to near-unity broadband absorption. A powder of the chalcogen dopant is spread on the silicon substrate and irradiated with femtosecond-laser pulses. We examine and compare the resulting morphology, optical properties, and chemical composition for each chalcogen-doped substrate before and after thermal annealing. Thermal annealing reduces the absorption of below band gap radiation by an amount that correlates with the diffusivity of the chalcogen dopant used to make the sample. We propose a mechanism for the absorption of below band gap radiation based on defects in the lattice brought about by the femtosecond-laser irradiation and the presence of a supersaturated concentration of chalcogen dopant atoms. The selenium and tellurium doped samples show particular promise for use in infrared photodetectors as they retain most of their infrared absorptance even after thermal annealing-a necessary step in many semiconductor device manufacturing processes

Enhanced thermoelectric figure of merit in strained Tl-doped Bi2Se3

KAUST Repository

Saeed, Y.

2014-07-21

We explain recent experimental findings on Tl-doped Bi2Se3 by determining the electronic and transport properties by first-principles calculations and semi-classical Boltzmann theory. Though Tl-doping introduces a momentum-dependent spin-orbit splitting, the effective mass of the carriers is essentially not modified, while the band gap is reduced. Tl is found to be exceptional in this respect as other dopants modify the dispersion, which compromises thermoelectricity. Moreover, we demonstrate that only after Tl-doping strain becomes an efficient tool for enhancing the thermoelectric performance. A high figure of merit of 0.86 is obtained for strong p-doping (7 × 10^20 cm^(−3), maximal power factor) at 500 K under 2% tensile strain.

Effects of (La, Sr) co-doping on electrical conduction and magnetic properties of BiFeO3 nanoparticles

International Nuclear Information System (INIS)

Liu Li; Wang Shouyu; Yin Zi; Zhang Chuang; Li Xiu; Yang Jiabin; Liu Weifang; Xu Xunling

2016-01-01

Multiferroic material as a photovoltaic material has gained considerable attention in recent years. Nanoparticles (NPs) La 0.1 Bi 0.9−x Sr x FeO y (LBSF, x = 0, 0.2, 0.4) with dopant Sr 2+ ions were synthesized by the sol–gel method. A systematic change in the crystal structure from rhombohedral to tetragonal upon increasing Sr doping was observed. There is an obvious change in the particle size from 180 nm to 50 nm with increasing Sr substitution into LBFO. It was found that Sr doping effectively narrows the band gap from ∼ 2.08 eV to ∼ 1.94 eV, while it leads to an apparent enhancement in the electrical conductivity of LBSF NPs, making a transition from insulator to semiconductor. This suggests an effective way to modulate the conductivity of BiFeO 3 -based multiferroic materials with pure phase by co-doping with La and Sr at the A sites of BiFeO 3 . (paper)

Structural, magnetic and dielectric properties of Y doped BiFeO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Zhong, Min [School of Materials Science and Engineering, Shanghai University, Shanghai, 200072 (China); Kumar, N. Pavan [Departmant of Physics, Osmania University, Hyderabad, 500 007 (India); Department of Physics, National Institute of Technology, Warangal, 506002 (India); Sagar, E. [Departmant of Physics, Osmania University, Hyderabad, 500 007 (India); Jian, Zhu; Yemin, Hu [School of Materials Science and Engineering, Shanghai University, Shanghai, 200072 (China); Reddy, P. Venugopal, E-mail: paduruvenugopalreddy@gmail.com [Departmant of Physics, Osmania University, Hyderabad, 500 007 (India); Vidya Jyothi Institute of Technology, Aziz Nagar Gate, C.B. Post, Hyderabad, 500075 (India)

2016-04-15

With a view to understand the influence of doping Bismuth ferrite with Yttrium on structural, magnetic and dielectric behavior, a series of samples were prepared by the solid state reaction technique. After characterizing the samples with XRD and SEM studies, magnetic and dielectric measurements were carried out. The impurity phase of Bismuth ferrite is found to disappear with increasing Y doping concentration and finally the sample with x = 0.2 is found to be free from secondary phases. The dielectric constant is also found to exhibit two transitions and efforts were made to explain the observed behavior. - Highlights: • The doping of Y helped in reducing the impurity phase of BiFeO{sub 3}. • All the Y doped samples are found to exhibit peaks in magnetization. • Y doped BFO might be considered for future device applications.

Accuracy and Transferability of Ab Initio Electronic Band Structure Calculations for Doped BiFeO3

Science.gov (United States)

Gebhardt, Julian; Rappe, Andrew M.

2017-11-01

BiFeO3 is a multiferroic material and, therefore, highly interesting with respect to future oxide electronics. In order to realize such devices, pn junctions need to be fabricated, which are currently impeded by the lack of successful p-type doping in this material. In order to guide the numerous research efforts in this field, we recently finished a comprehensive computational study, investigating the influence of many dopants onto the electronic structure of BiFeO3. In order to allow for this large scale ab initio study, the computational setup had to be accurate and efficient. Here we discuss the details of this assessment, showing that standard density-functional theory (DFT) yields good structural properties. The obtained electronic structure, however, suffers from well-known shortcomings. By comparing the conventional DFT results for alkali and alkaline-earth metal doping with more accurate hybrid-DFT calculations, we show that, in this case, the problems of standard DFT go beyond a simple systematic error. Conventional DFT shows bad transferability and the more reliable hybrid-DFT has to be chosen for a qualitatively correct prediction of doping induced changes in the electronic structure of BiFeO3.

Effects of Lu and Tm Doping on Thermoelectric Properties of Bi2Te3 Compound

Science.gov (United States)

Yaprintsev, Maxim; Lyubushkin, Roman; Soklakova, Oxana; Ivanov, Oleg

2018-02-01

The Bi2Te3, Bi1.9Lu0.1Te3 and Bi1.9Tm0.1Te3 thermoelectrics of n-type conductivity have been prepared by the microwave-solvothermal method and spark plasma sintering. These compounds behave as degenerate semiconductors from room temperature up to temperature T d ≈ 470 K. Within this temperature range the temperature behavior of the specific electrical resistivity is due to the temperature changes of electron mobility determined by acoustic and optical phonon scattering. Above T d, an onset of intrinsic conductivity takes place when electrons and holes are present. At the Lu and Tm doping, the Seebeck coefficient increases, while the specific electrical resistivity and total thermal conductivity decrease within the temperature 290-630 K range. The increase of the electrical resistivity is related to the increase of electron concentration since the Tm and Lu atoms are donor centres in the Bi2Te3 lattice. The increase of the density-of-state effective mass for conduction band can be responsible for the increase of the Seebeck coefficient. The decrease of the total thermal conductivity in doped Bi2Te3 is attributed to point defects like the antisite defects and Lu or Tm atoms substituting for the Bi sites. In addition, reducing the electron thermal conductivity due to forming a narrow impurity (Lu or Tm) band having high and sharp density-of-states near the Fermi level can effectively decrease the total thermal conductivity. The thermoelectric figure-of-merit is enhanced from ˜ 0.4 for undoped Bi2Te3 up to ˜ 0.7 for Bi1.9Tm0.1Te3 and ˜ 0.9 for Bi1.9Lu0.1Te3.

Electrical conduction and thermal properties of Bi-doped Pr0·7Sr0 ...

Indian Academy of Sciences (India)

mal conductivity and thermo-power measurements show that larger Bi-ion, in place of smaller Pr ion, enhances ... correlated electron system and technological applications because of ..... doping level (c) indicate the reliability of fitting with this.

Structural, magnetic and electric properties of Nd and Ni co-doped BiFeO3 materials

Directory of Open Access Journals (Sweden)

Dao Viet Thang

2017-09-01

Full Text Available Multiferroic Bi1−xNdxFe0.975Ni0.025O3 (x = 0.00, 0.05, 0.10, 0.125, and 0.15 (BNFNO and BiFeO3 (BFO materials were synthesized by a sol-gel method. Crystal structure, ferromagnetic and ferroelectric properties of the as-synthesized materials were investigated. Results showed that Nd3+ and Ni2+ co-doping affected to the electrical leakage, enhanced ferroelectric polarization and magnetization of BiFeO3. Co-doped sample with 12.5 mol% of Nd3+ and 2.5 mol% of Ni2+ exhibited an enhancement in both ferromagnetism and ferroelectric properties up to MS ~ 0.528 emu/g and PS ~ 18.35 μC/cm2 with applied electric field at 5 kV/cm, respectively. The origins of ferromagnetism and ferroelectricity enhancement were discussed in the paper.

380 keV proton irradiation effects on photoluminescence of Eu-doped GaN

International Nuclear Information System (INIS)

Okada, Hiroshi; Nakanishi, Yasuo; Wakahara, Akihiro; Yoshida, Akira; Ohshima, Takeshi

2008-01-01

The effect of 380 keV proton irradiation on the photoluminescence (PL) properties has been investigated for undoped and Eu-doped GaN. As the proton irradiation exceeds 1x10 13 cm -2 , a drastic decrease of PL intensity of the near band-edge emission of undoped GaN was observed. On the other hand, for Eu-doped GaN, the PL emission corresponding to the 5 D 0 → 7 F 2 transition in Eu 3+ kept the initial PL intensity after the proton irradiation up to 1x10 14 cm -2 . Present results, together with our previous report on electron irradiation results, suggest that Eu-doped GaN is a strong candidate for light emitting devices in high irradiation environment

Enhancing visible light photocatalytic and photocharge separation of (BiO){sub 2}CO{sub 3} plate via dramatic I{sup −} ions doping effect

Energy Technology Data Exchange (ETDEWEB)

Liang, Lei [College of Chemistry and Materials Science, Huaibei Normal University, Huaibei, 235000, Anhui (China); Cao, Jing [College of Chemistry and Materials Science, Huaibei Normal University, Huaibei, 235000, Anhui (China); Anhui Collaborative Innovation Center of Advanced Functional Composite, Huaibei, 235000, Anhui (China); Lin, Haili, E-mail: linhaili@mail.ipc.ac.cn [College of Chemistry and Materials Science, Huaibei Normal University, Huaibei, 235000, Anhui (China); Guo, Xiaomin; Zhang, Meiyu [College of Chemistry and Materials Science, Huaibei Normal University, Huaibei, 235000, Anhui (China); Chen, Shifu, E-mail: chshifu@chnu.edu.cn [College of Chemistry and Materials Science, Huaibei Normal University, Huaibei, 235000, Anhui (China); College of Chemistry and Materials Engineering, Anhui Science and Technology University, Fengyang, 233100, Anhui (China)

2016-08-15

Highlights: • Novel I-(BiO){sub 2}CO{sub 3} was prepared by a facile chemical precipitation method. • I{sup −} ions impurity level located on the top of valence band of (BiO){sub 2}CO{sub 3}. • I{sup −} ions doping largely improved photocatalytic activity of I-(BiO){sub 2}CO{sub 3}. • I-(BiO){sub 2}CO{sub 3} displayed excellent photocharge separation efficiency. - Abstract: Novel I{sup −} ions doped (BiO){sub 2}CO{sub 3} (I-(BiO){sub 2}CO{sub 3}) photocatalysts were successfully synthesized via a facile chemical precipitation method. Under visible light (λ > 400 nm), I-(BiO){sub 2}CO{sub 3} displayed much higher activity for rhodamine B and dichlorophenol degradation than the undoped (BiO){sub 2}CO{sub 3}. The pseudo-first-order rate constant k{sub app} of RhB degradation over 15.0% I-(BiO){sub 2}CO{sub 3} was 0.54 h{sup −1}, which is 11.3 times higher than that of (BiO){sub 2}CO{sub 3}. The doped I{sup −} ions formed an impurity level on the top of valence band of (BiO){sub 2}CO{sub 3} and induced much more visible light to be absorbed. The enhanced photocurrent and surface photovoltage properties were detected, which strongly ensures the efficient separation of electrons and holes in I-(BiO){sub 2}CO{sub 3} system under visible light. It provides a facile way to improve the photocatalytic activity of the wide-band-gap (BiO){sub 2}CO{sub 3} via intense doping effect of I{sup −} ions.

Condensation energy density in Bi-2212 superconductors

International Nuclear Information System (INIS)

Matsushita, Teruo; Kiuchi, Masaru; Haraguchi, Teruhisa; Imada, Takeki; Okamura, Kazunori; Okayasu, Satoru; Uchida, Satoshi; Shimoyama, Jun-ichi; Kishio, Kohji

2006-01-01

The relationship between the condensation energy density and the anisotropy parameter, γ a , has been derived for Bi-2212 superconductors in various anisotropic states by analysing the critical current density due to columnar defects introduced by heavy ion irradiation. The critical current density depended on the size of the defects, determined by the kind and irradiation energy of the ions. A significantly large critical current density of 17.0 MA cm -2 was obtained at 5 K and 0.1 T even for the defect density of a matching field of 1 T in a specimen irradiated with iodine ions. The dependence of the critical current density on the size of the defects agreed well with the prediction from the summation theory of pinning forces, and the condensation energy density could be obtained consistently from specimens irradiated with different ions. The condensation energy density obtained increased with decreasing γ a over the entire range of measurement temperature, and reached about 60% of the value for the most three-dimensional Y-123 observed by Civale et al at 5 K. This gives the reason for the very strong pinning in Bi-2212 superconductors at low temperatures. The thermodynamic critical field obtained decreased linearly with increasing temperature and extrapolated to zero at a certain characteristic temperature, T * , lower than the critical temperature, T c . T * , which seems to be associated with the superconductivity in the block layers, was highest for the optimally doped specimen. This shows that the superconductivity becomes more inhomogeneous as the doped state of a superconductor deviates from the optimum condition

Proton irradiation effects on optical attenuation in doped- and pure-silica fibers

International Nuclear Information System (INIS)

Sakasai, Kaoru; Bueker, H.; Haesing, F.W.; Pfeiffer, F.

1999-05-01

Optical attenuation in doped- and pure-silica fibers was measured at wavelengths of 470 nm, 660 nm, and 850 nm during and after 20 MeV proton irradiation. In the experiment the fibers were arranged on a holder to make one layer' so that uniform proton irradiation can be achieved to them. The induced loss of the doped-silica fiber increased strongly at the beginning of the first irradiation, and decreased slowly after stopping of the beam. In the second irradiation, however, the developed loss was not so large. On the other hand, the loss of the pure-silica fiber increased gradually in the first irradiation, and decreased very quickly after the beam stopped. The loss increased stepwise at the very beginning of the second irradiation. Small luminescence from the fibers during irradiation was observed also. The luminescence of the pure-silica fiber was slightly larger than that of the doped-silica fiber. The induced loss of HCP fibers was also measured when a SiO 2 plate was set in front of the fibers. It may be possible to estimate the proton dose in materials using fiber-optic technique. Proton sensitivities of doped- and pure-silica fibers were, respectively, 1.0 x 10 -10 at 660 nm and 5.5 x 10 -12 at 470 nm in units of (dB/m)/(protons/cm 2 ), where the values were estimated from the slope of the loss growth curves at the beginning of the first irradiation. (author)

The effects of Zn doping on magnetic properties of Cu3Bi(SeO3)2O2Cl

Science.gov (United States)

Yang, Pei-Ying; Tseng, Wu-Jyun; Wu, Hung-Cheng; Kakarla, D. Chandrasekhar; Yang, Hung-Duen; Department of Physics, Natl Sun Yat Sen Univ Team

Recently, layered spin-frustrated Cu3Bi(SeO3)2 O2Cl has received considerable research attention due to its unusual magnetic properties. Two inequivalent Cu2 + ions form a pseudo-kagome lattice that invokes spin frustration and anisotropic magnetic properties. In this study, the influence of Zn doping on the complex magnetic properties has been explored. Polycrystalline (Cu1-xZnx) Bi(SeO3)2 O2Cl (0 x 0.5) samples were synthesized using solid-state reaction and characterized by X-ray diffraction and magnetic measurements. The Zn doping strongly modulates the magnetic ground state of the system. The antiferromagnetic transition temperature TN = 24 K and magnetic field-induced hysteresis observed for x = 0 at low field are systematically shifted to lower temperature and reduced with Zn doping. These results can illustrate the insight of the occurrence of field-induced spin-flip type multiferroics in Cu3Bi(SeO3)2 O2Cl.

Enhancement of magnetic and ferroelectric properties of BiFeO3 by Er and transition element (Mn, Co) co-doping

International Nuclear Information System (INIS)

Han, Yumin; Mao, Weiwei; Quan, Chuye; Wang, Xingfu; Yang, Jianping; Yang, Tao; Li, Xing’ao

2014-01-01

Highlights: • BiFeO 3 , Bi 0.8 Er 0.2 FeO 3 , Bi 0.8 Er 0.2 Fe 0.9 Mn 0.1 O 3 and Bi 0.8 Er 0.2 Fe 0.9 Co 0.1 O 3 nanoparticles were prepared by sol–gel method. • The introduction of Er and Mn, Co into BiFeO 3 leads into a phase transition with reduced grain size. • The phase transformation combined with size reduction has significantly increased saturated polarization (Ps), remanent polarization (Pr) and saturated magnetization (Ms), remanent magnetization (Mr) behaviors of the doped samples with the same variation trend. • The formation of dipolar defect complexes (DDCs) in the doped samples may also contribute to the improved ferroelectric property. • Bi 0.8 Er 0.2 Fe 0.9 Mn 0.1 O 3 exhibits significantly improved ferroelectric and ferromagnetic properties. - Abstract: BiFeO 3 (BFO), Bi 0.8 Er 0.2 FeO 3 (BEFO), Bi 0.8 Er 0.2 Fe 0.9 Mn 0.1 O 3 (BEFMO) and Bi 0.8 Er 0.2 Fe 0.9 Co 0.1 O 3 (BEFCO) nanoparticles were prepared by sol–gel method having an average size of 200 nm for BFO, under100 nm for BEFO and under 60 nm for BEFMO and BEFCO. Phase transition from a rhombohedral symmetry (R3c) for BFO to an orthorhombic symmetry (Ibmm) for BEFO, BEFMO and BEFCO has been observed. The phase transformation combined with size reduction has significantly improved both ferroelectric and ferromagnetic behaviors of the doped samples in a similar way. The formation of dipolar defect complexes (DDCs) in the doped samples also contributes to the improved ferroelectric property with saturated polarization (Ps) of 0.375 μC/cm 2 and remanent polarization (Pr) of 0.244 μC/cm 2 for BEFMO. Size effect may also impact the simultaneously developed Pr for BEFMO and BEFCO. Owning to the interactions between the ferromagnetic and antiferromagnetic microdomains, improved saturated magnetization (Ms) and remanent magnetization (Mr) are also observed in BEFMO

Optical, mechanical and TEM assessment of titania-doped Bi2V1 ...

Indian Academy of Sciences (India)

2016-08-26

Aug 26, 2016 ... Home; Journals; Bulletin of Materials Science; Volume 37; Issue 7. Optical, mechanical and TEM assessment of titania-doped Bi2V1−TiO5.5−δ bismuth vanadate oxides. Gurbinder Kaur Gary Pickrell Vishal Kumar Om Prakash Pandey Kulvir Singh Daniel Homa. Volume 37 Issue 7 December 2014 pp ...

Preparation of a Leaf-Like BiVO4-Reduced Graphene Oxide Composite and Its Photocatalytic Activity

Directory of Open Access Journals (Sweden)

Shimin Xiong

2017-01-01

Full Text Available We prepared a unique leaf-like BiVO4-reduced graphene oxide (BiVO4-rGO composite with prominent adsorption performance and photocatalytic ability by a single-step method. Multiple characterization results showed that the leaf-like BiVO4 with average diameter of about 5 um was well dispersed on the reduced graphene oxide sheet, which enhanced the transportation of photogenerated electrons into BiVO4, thereby leading to efficient separation of photogenerated carriers in the coupled graphene-nanocomposite system. The characterization and experiment results also indicated that the outstanding adsorption ability of such composite was closely associated with the rough surface of the leaf-like BiVO4 and doped rGO. The surface photocurrent spectroscopy and transient photocurrent density measurement results demonstrated that the doped rGO enhanced separation efficiency and transfer rate of photogenerated charges. As a result, the BiVO4-rGO exhibited higher photocatalytic capacity toward the degradation of rhodamine B dye under visible-light irradiation compared with pure BiVO4 and P25.

Enhanced photocatalytic performance of BiVO_4 in aqueous AgNO_3 solution under visible light irradiation

International Nuclear Information System (INIS)

Huang, Chien-Kai; Wu, Tsunghsueh; Huang, Chang-Wei; Lai, Chi-Yung; Wu, Mei-Yao; Lin, Yang-Wei

2017-01-01

Graphical abstract: Ag"+ ions enhanced photocatalytic activity of BiVO_4 under visible light irradiation. - Highlights: • The presence of Ag"+ ions enhanced the photodegradation activity of BiVO_4. • Photoreduction of Ag deposited on the BiVO_4 surface was obtained. • Luminescence and electrochemical results elucidated the photocatalytic mechanism. • Holes and oxygen radicals were the main reactive species generated by BiVO_4/Ag"+. • Used BiVO_4/Ag"+ exhibited photocatalytic antibacterial activity toward E. coli. - Abstract: Monoclinic-phase bismuth vanadate (BiVO_4) with a 2.468 eV band gap exhibited enhanced synergic photodegradation activity toward methylene blue (MB) when combined with silver ions (Ag"+) in an aqueous solution under visible light irradiation. The mass ratio of AgNO_3 to BiVO_4 and the calcination temperature were discovered to considerably affect the degradation activity of BiVO_4/Ag"+. Superior photocatalytic performance was obtained when BiVO_4 was mixed with 0.01%(w/v) AgNO_3 solution, and complete degradation of MB was achieved after 25 min visible light irradiation, outperforming BiVO_4 or AgNO_3 solution alone. The enhanced photodegradation was investigated using systematic luminescence measurements, electrochemical impedance spectroscopy, and scavenger addition, after which a photocatalytic mechanism for MB degradation under visible light irradiation was identified that involved oxygen radicals and holes. This study also discovered the two dominating processes involved in enhancing the electron–hole separation efficiency and reducing their recombination rate, namely photoreduction of Ag"+ and the formation of a BiVO_4/Ag heterojunction. The synergic effect between BiVO_4 and Ag"+ was discovered to be unique. BiVO_4/Ag"+ was successfully used to degrade two other dyes and disinfect Escherichia Coli. A unique fluorescent technique using BiVO_4 and a R6G solution to detect Ag"+ ions in water was discovered.

Fe(Ⅲ) ions enhanced catalytic properties of (BiO)2CO3 nanowires and mechanism study for complete degradation of xanthate.

Science.gov (United States)

Guo, Yujiao; Cui, Kuixin; Hu, Mingyi; Jin, Shengming

2017-08-01

The wire-like Fe 3+ -doped (BiO) 2 CO 3 photocatalyst was synthesized by a hydrothermal method. The photocatalytic property of Fe 3+ -doped (BiO) 2 CO 3 nanowires was evaluated through degradation of sodium isopropyl xanthate under UV-visible light irradiation. The as-prepared Fe 3+ -doped (BiO) 2 CO 3 nanowires were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV-visible diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) in detail. The results of XRD showed that the crystallinity of (BiO) 2 CO 3 nanowires decreased when Fe 3+ ions were introduced into the solution system. XPS results illustrated that xanthate could be absorbed on the surface of Fe 3+ -doped (BiO) 2 CO 3 nanowires to produce BiS bond at the beginning of the reaction, which could broaden the visible light absorption. FTIR spectra confirmed the formation of SO 4 2- after photocatalytic decomposition of xanthate solution. The Fe 3+ -doped (BiO) 2 CO 3 nanowires showed an enhanced photocatalytic activity for decomposition of xanthate due to the narrower band gap and larger BET surface area, comparing with pure (BiO) 2 CO 3 nanowires. By the results of UV-vis spectra of the solution and FTIR spectra of recycled Fe 3+ -doped (BiO) 2 CO 3 , the xanthate was oxidized completely into CO 2 and SO 4 2- . The photocatalytic degradation process of xanthate followed a pseudo-second-order kinetics model. The mechanism of enhanced photocatalytic activity was proposed as well. Copyright © 2017 Elsevier Ltd. All rights reserved.

Co-doping induced coexistence of superconductivity and ferromagnetism in Bi{sub 3.9}Co{sub 0.1}O{sub 4}S{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Yu, Chuan [Department of Physics, Shanghai University, Shanghai 200444 (China); Feng, Zhenjie, E-mail: fengzhenjie@t.shu.edu.cn [Department of Physics, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of High Temperature Superconductors, Shanghai 200444 (China); Yin, Xunqing; Li, Qing; Kang, Baojuan [Department of Physics, Shanghai University, Shanghai 200444 (China); Lu, Bo [Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China); Jing, Chao; Cao, Shixun [Department of Physics, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of High Temperature Superconductors, Shanghai 200444 (China); Zhang, Jincang [Department of Physics, Shanghai University, Shanghai 200444 (China); Materials Genome Institute, Shanghai University, Shanghai 200444 (China)

2016-09-15

Highlights: • Bi{sub 4}O{sub 4}S{sub 3} is a new discovered layered superconductor. Some doping effects, such as Ag, Cu, and Pb, are studied, the superconductivity is suppressed in these doping samples. We doped the Ni magnetic ions to the system, it is interesting that the superconductivity is not suppressed in x = 0.1 sample. Meanwhile, the coexistence of the superconductivity and magnetism is observed in the samples from the M-vs. –H loops. - Abstract: The effects of Co doping on the physical properties of the Bi{sub 4}O{sub 4}S{sub 3} system was studied. We discovered that stable Bi{sub 3.9}Co{sub 0.1}O{sub 4}S{sub 3} compound exhibits both long-range ferromagnetism and enhanced superconductivity with thermodynamic evidences for Tc ∼ 5.5 K. We found that there is an anomalous feature which represents superconducting transition in the hysteretic M-vs.-H loops for Bi{sub 3.9}Co{sub 0.1}O{sub 4}S{sub 3} at T = 3 K.

Enhanced magnetic and dielectric behavior in Co doped BiFeO{sub 3} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Chakrabarti, Kaushik; Sarkar, Babusona; Ashok, Vishal Dev [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032 (India); Chaudhuri, Sheli Sinha [Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata-700032 (India); De, S.K., E-mail: msskd@iacs.res.in [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032 (India)

2015-05-01

Magnetic and dielectric properties of Co doped BiFeO{sub 3} (BFO) nanoparticles (13 nm) have been investigated. The dopant Co{sup 2+} converts spherical morphology to cubic nanostructures. The significant changes in temperature dependence of magnetization may be due to magnetic disorder phase induced by divalent Co. The substitution of Fe by Co disrupts cycloidal spin structure of BFO and improves the ferromagnetic property. Enhancement of the saturation magnetization and coercivity by about 10 times in doped BFO are due to changes in morphology. High dielectric constant of about 670 and low loss at room temperature show Co doped BFO as promising material for multifunctional devices.

A model of knock-out of oxygen by charged particle irradiation of Bi-2212

International Nuclear Information System (INIS)

Bandyopadhyay, S.K.; Sen, Pintu; Barat, P.; Mukherjee, P.; Das, S.K.; Ghosh, B.

1996-01-01

A model of knock-out of oxygen by charged particle (α and proton) irradiation of Bi 2 Sr 2 CaCu 2 O 8+x (Bi-2212) is proposed on the basis of Monte Carlo TRIM calculations. In Bi-2212, the loosely bound excess oxygen is vulnerable to be displaced by particle irradiation. Binding energy and hence, displacement energy of this loosely bound excess oxygen is less compared to that of stoichiometric lattice bound oxygen and other atoms. The displaced or knocked out oxygen goes to pores or intergranular region and generates large pressure inside the sample. Because of porosity of the material, this displaced oxygen diffuses out and there is a net reduction of oxygen content of the sample. The irradiation induced oxygen knock-out is dominant in the bulk where nonionizing energy loss is maximum. (author). 29 refs., 1 fig., 3 tabs

BiVO4–graphene catalyst and its high photocatalytic performance under visible light irradiation

International Nuclear Information System (INIS)

Fu Yongsheng; Sun Xiaoqiang; Wang Xin

2011-01-01

Highlights: ► A facile strategy is designed to deposit leaf-like BiVO 4 lamellas on graphene sheet. ► Graphene oxide is reduced to graphene in the hydrothermal reaction process. ► BiVO 4 –graphene system shows high catalytic effects under visible light irradiation. - Abstract: A BiVO 4 –graphene photocatalyst was prepared by a facile one-step hydrothermal method and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectra (XPS), and transmission electron microscopy (TEM) techniques. The results show that the graphene sheets in this catalyst are exfoliated and decorated by leaf-like BiVO 4 lamellas. In comparison with the pure BiVO 4 catalyst, the BiVO 4 –graphene system reveals much higher photocatalytic activity for degradation of methyl orange (MO), methylene blue (MB), Rhodamine B (RhB) and active black BL-G in water under visible light irradiation due to the concerted effects of BiVO 4 and graphene sheets or their integrated properties.

Radiation stability of nanocrystalline ZrN coatings irradiated with high energy Xe and Bi ions

International Nuclear Information System (INIS)

Skuratov, V.A.; Sokhatsky, A.S.; Uglov, V.V.; Zlotski, S.V.; Van Vuuren, A.J.; Neethling, Jan; O'Connell, J.

2011-01-01

Swift Xe and Bi ion irradiation effects in nanocrystalline ZrN coatings as a function of ion fluence are reported. Zirconium nitride films of different thickness (0.1, 3, 10 and 20 micrometers) synthesized by vacuum arc-vapour deposition in nanocrystalline state (average size of crystallites is ∼4 nm) were irradiated with 167 MeV Xe and 695 MeV Bi ions to fluences in the range 3x10 12 ÷2.6x10 15 cm -2 (Xe) and 10 12 x10 13 cm -2 (Bi) and studied using XRD and TEM techniques. No evidence of amorphization due to high level ionizing energy losses has been found. The measurements of lattice parameter have revealed nonmonotonic dependence of the stress level in irradiated samples on ion fluence. (authors)

Magnetic and dielectric properties of alkaline earth Ca2+ and Ba2+ ions co-doped BiFeO3 nanoparticles

International Nuclear Information System (INIS)

Yang, C.; Liu, C.Z.; Wang, C.M.; Zhang, W.G.; Jiang, J.S.

2012-01-01

Ca 2+ and Ba 2+ ions co-doped BiFeO 3 nanoparticles, Bi 0.8 Ca 0.2−x Ba x FeO 3 (x=0–0.20), were prepared by a sol–gel method. The phase structure, grain size, dielectric and magnetic properties of the prepared samples were investigated. The results showed that the lattice structure of the nanoparticles transformed from rhombohedral (x=0) to orthorhombic (x=0.07–0.19) and then to tetragonal (x=0.20) with x increased. The dielectric properties of the nanoparticles were affected by the properties of the substitutional ions as well as the crystalline structure of the samples. The magnetic properties of the nanoparticles were greatly improved and the T N of the nanoparticles was obviously increased. All the Ca 2+ and Ba 2+ ions co-doped BiFeO 3 nanoparticles presented the high ratio of M r /M from 0.527 to 0.571 and large coercivity from 4.335 to 5.163 KOe. - Highlights: ► Ca 2+ and Ba 2+ ions co-doped BiFeO 3 nanoparticles were prepared using a sol–gel method. ► The magnetic properties of the nanoparticles are greatly improved. ► The Neel temperature (T N ) of the nanoparticles is greatly increased. ► Doped ions and crystal structure affect the dielectric properties of the nanoparticles.

Enhanced photoelectrochemical water splitting performance using morphology-controlled BiVO4 with W doping

Directory of Open Access Journals (Sweden)

Xin Zhao

2017-12-01

Full Text Available Nanostructures exhibit numerous merits to improve the efficiency in solar-to-energy conversion. These include shortened carrier collection pathways, an increased volume ratio between depletion layer and bulk, enhanced light capture due to multiple light scattering in nanostructures, and a high surface area for photochemical conversion reactions. In this study, we describe the synthesis of morphology-controlled W-doped BiVO4 by simply tuning the solvent ratio in precursor solutions. Planar and porous W-doped BiVO4 thin films were prepared and compared. The porous film, which exhibits increased surface area and enhanced light absorption, has displayed enhanced charge separation and interfacial charge injection. Our quantitative analysis showed an enhancement of about 50% of the photoelectrochemical performance for the porous structure compared to the planar structure. This enhancement is attributed to improved light absorption (13% increase, charge separation (14% increase, and interfacial charge injection (20% increase.

The oxidation states of elements in pure and Ca-doped BiCuSeO thermoelectric oxides

International Nuclear Information System (INIS)

Hsiao, Chun-Lung; Qi, Xiaoding

2016-01-01

Bi 1−x Ca x CuSeO (x = 0–0.3) was synthesized at 650 °C in an air-tight system flowing with pure argon. The Ca doping resulted in an increase in the thermoelectric figure of merit (ZT) as the consequence of increased carrier concentration. X-ray photoelectron spectroscopy (XPS) was carried out to check the oxidation states in Bi 1−x Ca x CuSeO. The results indicated that in addition to the expected Bi 3+ and Cu 1+ , there existed Bi 2+ and Cu 2+ in the undoped BiCuSeO, whereas in the Ca-doped BiCuSeO, Bi 4+ , Cu 3+ and Cu 2+ were observed. The Ca dopant was confirmed to be in the 2+ oxidation state. Two broad peaks centered at 54.22 and 58.59 eV were recorded in the vicinity around the binding energy of Se 3d. The former is often observed in the Se-containing intermetallics while the latter is often found in the Se-containing oxides, indicating that along with the expected Se–Cu bonding, a bonding between Se and O may also exist. Based on the XPS results, the charge compensation mechanisms were proposed for Bi 1−x Ca x CuSeO, which may shed some light on the origins of charge carriers. BiCuSeO based oxides have recently be discovered to have a large ZT comparable to the best alloys currently in use, because of the large Seebeck coefficient and small thermal conductivity. However, their electrical conductivity is lower compared to the best thermoelectrics. This work may provide some hints for the further improvement of ZT in BiCuSeO based oxides. - Graphical abstract: The oxidation states, charge compensation mechanisms, and origins of charge carriers in Bi 1−x Ca x CuSeO thermoelectrics. Display Omitted

Beginning point of metal to insulator transition for Bi-2223 superconducting matrix doped with Eu nanoparticles

International Nuclear Information System (INIS)

Yildirim, G.

2013-01-01

Highlights: •Standard measurements such as bulk density, ρ-T, J ct , XRD, SEM and EDX examinations for characterization of the samples. •Role of Eu inclusions on the microstructural, electrical and superconducting properties of Bi-2223 phase. •Determination of metal to insulator transition due to Eu impurities in the Bi-2223 superconducting matrix. •From the Eu content level of x = 0.5 onwards, destruction of the superconducting phases. •Constant retrogression of the microstructural and superconducting properties with the Eu individuals. -- Abstract: This comprehensive study examines the change of the microstructural, electrical and superconducting properties of the Eu doped Bi 1.8 Pb 0.4 Eu x Sr 2 Ca 2.2 Cu 3.0 O y ceramic cuprates (with x ⩽ 0.7) produced by the conventional solid state reaction method at the constant annealing temperature of 840 °C for 24 h with the aid of the standard characterization measurements such as bulk density, dc resistivity (ρ-T), transport critical current density (J c ), X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron dispersive X-ray (EDX) examinations. For the full characterization of the pure and Eu doped Bi-2223 samples, the degree of granularity (from the bulk density and porosity measurements); the room temperature resistivity, onset–offset critical transition temperature, variation of transition temperature, hole carrier concentration, spin-gap opening temperature and thermodynamic fluctuations (from the dc resistivity experiments); the texturing, crystal structure, crystallite size, phase purity and cell parameters (from the XRD investigations); the variation of the flux pinning centers and the boundary weak-links between the superconducting grains (from the critical current density values); the crystallinity, specimen surface morphology, grain connectivity between the superconducting grains and grain size distribution (from the SEM examinations), the elemental compositions and

Synthesis, structural and luminescence properties of Bi3+ co-doped Y2Sn2O7:Tb nanoparticles

International Nuclear Information System (INIS)

Nigam, S.; Sudarsan, V.; Vatsa, R.K.

2010-01-01

Full text: In recent years, advanced materials derived from Pyrochlore-type oxides (A 2 B 2 O 7 ) have been of extensive scientific and technological interest. Chemical substitution of A or B sites of pyrochlore oxide by rare earth ions is a widely used approach to prepare thermally stable, lanthanide ion doped luminescent materials. Due to the higher symmetry around the A and B sites in the lattice lanthanide ions like Eu 3+ and Tb 3+ when incorporated at the A or B sites give very poor luminescence. This problem can be avoided by incorporating other ions like Bi 3+ in the lattice so that the lattice gets distorted and luminescent intensity from the lanthanide ions increases. The present study deals with the synthesis and characterization of Bi 3+ co-doped Y 2 Sn 2 O 7 :Tb nanoparticles. For the preparation of Tb 3+ and Bi 3+ doped Y 2 Sn 2 O 7 nano-materials, Sn metal, Bi(NO 3 ) 3 , Tb 4 O 7 , Y 2 CO 3 , were used as starting materials. The solution containing Y 3+ , Sn 4+ ,and Bi 3+ -Tb 3+ in ethylene glycol medium was slowly heated up to 120 deg C and then subjected to urea hydrolysis. The obtained precipitate after washing was heated to 700 deg C. As prepared samples are amorphous in nature and 700 deg C heated sample showed well crystalline pyrochlore structure as revealed by the XRD studies. Average particles size is calculated from the width of the X-ray diffraction peaks and found to be ∼ 5 nm. TEM images of the nanoparticles obtained at 700 deg C shows very fine spherical particles having a diameter in the range of 2-5 nm. Luminescence measurements were carried out for as prepared and 700 deg C heated samples of 2.5%Tb doped Y 2 Sn 2 O 7 nanoparticles. Green emission characteristic 5 D 4 7 F 5 transition of Tb 3+ has been observed from as prepared sample but on heating to 700 deg C the emission characteristic of Tb 3+ ions got completely removed . However, there is a significant improvement in Tb 3+ emission from 2.5% Bi 3+ co-doped Y 2 Sn 2 O 7 :Tb 3

Doping of silicon by laser-induced diffusion

International Nuclear Information System (INIS)

Pretorius, R.; Allie, M.S.

1986-01-01

This report gives information on the doping of silicon by laser-induced diffusion, modelling and heat-flow calculation, doping from evaporated layers and silicon self-diffusion during pulsed laser irradiation. In order to tailor dopant profiles accurately a knowledge of the heat flow and the melt depths attained as a function of laser energy and material type is crucial. The heat flow calculations described can be used in conjuntion with most diffusion equations in order to predict the redistribution of the deposited dopant which occurs as a result of liquid phase diffusion during the melting period. Doping of Si was carried out by evaporating this films of Sb, In and Bi 10 to 300 A thick, onto the substrates. During pulsed laser irradiation the dopant film and underlying silicon substrate is melted and the dopant incorporated into the crystal lattice during recrystallization. Radioactive 31 Si(T1/2=2,62h) was used as a tracer to measure the self-diffusion of silicon in silicon during pulsed laser (pulsewidth = 30ns, wavelength = 694nm) irradiation

Space growth studies of Ce-doped Bi12SiO20 single crystal

International Nuclear Information System (INIS)

Zhou, Y.F.; Wang, J.C.; Tang, L.A.; Pan, Z.L.; Chen, N.F.; Chen, W.C.; Huang, Y.Y.; He, W.

2004-01-01

Ce-doped Bi 12 SiO 20 (BSO) single crystal was grown on board of the Chinese Spacecraft-Shenzhou No. 3. A cylindrical crystal, 10 mm in diameter and 40 mm in length, was obtained. The morphology of crystals is significantly different for ground- and space-grown portions. The space- and ground-grown crystals have been characterized by Ce concentration distribution, X-ray rocking curve absorption spectrum and micro-Raman spectrum. The results show that the quality of Ce-doped BSO crystal grown in space is more homogeneous and more perfect than that of ground grown one

First-principles study on doping and temperature dependence of thermoelectric property of Bi2S3 thermoelectric material

International Nuclear Information System (INIS)

Guo, Donglin; Hu, Chenguo; Zhang, Cuiling

2013-01-01

Graphical abstract: The direction-induced ZT is found. At ZZ direction and n = 1.47 × 10 19 cm −3 , the ZT can reach maximal value, 0.36, which is three times as much as maximal laboratorial value. This result matches well the analysis of electron effective mass. Highlights: ► Electrical transportations of Bi 2 S 3 depend on the concentration and temperature. ► The direction-induced ZT is found. ► At ZZ direction and n = 1.47 × 10 19 cm −3 , the ZT can reach maximal value, 0.36. ► The maximal ZT value is three times as much as maximal laboratorial value. ► By doping and temperature tuning, Bi 2 S 3 is a promising thermoelectric material. - Abstract: The electronic structure and thermoelectric property of Bi 2 S 3 are investigated. The electron and hole effective mass of Bi 2 S 3 is analyzed in detail, from which we find that the thermoelectric transportation varies in different directions in Bi 2 S 3 crystal. Along ac plane the higher figure of merit (ZT) could be achieved. For n-type doped Bi 2 S 3 , the optimal doping concentration is found in the range of (1.0–5.0) × 10 19 cm −3 , in which the maximal ZT reaches 0.21 at 900 K, but along ZZ direction, the maximal ZT reaches 0.36. These findings provide a new understanding of thermoelectricity-dependent structure factors and improving ZT ways. The donor concentration N increases as T increases at one bar of pressure under a suitable chemical potential μ, but above this chemical potential μ, the donor concentration N keeps a constant

The semiconductor doping with radiation defects via proton and alpha-particle irradiation. Review

CERN Document Server

Kozlov, V A

2001-01-01

Paper presents an analytical review devoted to semiconductor doping with radiation defects resulted from irradiation by light ions, in particular, by protons and alpha-particles. One studies formation of radiation defects in silicon, gallium arsenide and indium phosphide under light ion irradiation. One analyzes effect of proton and alpha-particle irradiation on electric conductivity of the above-listed semiconducting materials. Semiconductor doping with radiation defects under light ion irradiation enables to control their electrophysical properties and to design high-speed opto-, micro- and nanoelectronic devices on their basis

Growth of nucleation sites on Pb-doped Bi2Sr2Ca1Cu2O8+δ

International Nuclear Information System (INIS)

Finnemore, D.K.; Xu, M.; Kouzoudis, D.; Bloomer, T.; Kramer, M.J.; McKernan, S.; Balachandran, U.; Haldar, P.

1996-01-01

In the growth of Bi 2 Sr 2 Ca 2 Cu 3 O 10+δ from mixed powders of Pb-doped Bi 2 Sr 2 Ca 1 Cu 2 O 8+δ and other oxides, it has been discovered that a dense array of hillocks or mesas grow at the interface between a Ag overlay and Pb-doped Bi 2 Sr 2 Ca 1 Cu 2 O 8+δ grains during the ramp up to the reaction temperature. As viewed in an environmental scanning electron microscope, the Ag coated grains develop a texture that looks like open-quote open-quote chicken pox close-quote close-quote growing on the grains at about 700 degree C. These hillocks are about 100 nm across and are spaced at about 500 to 1000 nm. If there is no Ag, this texture does not develop. Preliminary measurements indicate that the hillocks are a recrystallization of (Bi,Pb) 2 Sr 2 Ca 1 Cu 2 O 8+δ , and are definitely not a Pb rich phase. copyright 1996 American Institute of Physics

Bi3+–Pr3+ energy transfer processes and luminescent properties of LuAG:Bi,Pr and YAG:Bi,Pr single crystalline films

International Nuclear Information System (INIS)

Zorenko, Y.; Gorbenko, V.; Savchyn, V.; Zorenko, T.; Nikl, M.; Mares, J.A.; Beitlerova, A.; Jary, V.

2013-01-01

Absorption, cathodoluminescence, excitation spectra of photoluminescence (PL) and PL decay kinetics were studied at 300 K for the double doped with Bi 3+ –Pr 3+ and separately doped with Bi 3+ and Pr 3+ Lu 3 Al 5 O 12 (LuAG) and Y 3 Al 5 O 12 (YAG) single crystalline film (SCF) phosphors grown by the liquid phase epitaxy method. The emission bands in the UV range arising from the intrinsic radiative transitions of Bi 3+ based centers, and emission bands in the visible range, related to the luminescence of excitons localized around Bi 3+ based centers, were identified both in Bi–Pr and Bi-doped LuAG and YAG SCFs. The energy transfer processes from the host lattice simultaneously to Bi 3+ and Pr 3+ ions and from Bi 3+ to Pr 3+ ions were investigated. Competition between Pr 3+ and Bi 3+ ions in the energy transfer processes from the LuAG and YAG hosts was evidenced. The strong decrease of the intensity of Pr 3+ luminescence both in LuAG:Pr and YAG:Pr SCFs phosphors, grown from Bi 2 O 3 flux, is observed due to the quenching influence of Bi 3+ flux related impurity. Due to overlap of the UV emission band of Bi 3+ centers with the f–d absorption bands of Pr 3+ ions in the UV range and the luminescence of excitons localized around Bi ions with the f–f absorption bands of Pr 3+ ions in the visible range, an effective energy transfer from Bi 3+ ions to Pr 3+ ions takes place in LuAG:Bi,Pr and YAG:Bi,Pr SCFs, resulting in the appearance of slower component in the decay kinetics of the Pr 3+ d–f luminescence. -- Highlights: • Bi and Pr doped film phosphor grown by liquid phase epitaxy method. • Energy transfer from Bi 3+ to Pr 3+ ions. • Strong quenching of the Pr 3+ luminescence by Bi 3+ co-dopant

Pyroelectric properties and electrical conductivity in samarium doped BiFeO 3 ceramics

KAUST Repository

Yao, Yingbang

2012-06-01

Samarium (Sm 3+) doped BiFeO 3 (BFO) ceramics were prepared by a modified solid-state-reaction method which adopted a rapid heating as well as cooling during the sintering process. The pyroelectric coefficient increased from 93 to 137 μC/m 2 K as the Sm 3+ doping level increased from 1 mol% to 8 mol%. Temperature dependence of the pyroelectric coefficient showed an abrupt decrease above 80 °C in all samples, which was associated with the increase of electrical conductivity with temperature. This electrical conduction was attributed to oxygen vacancy existing in the samples. An activation energy of ∼0.7 eV for the conduction process was found to be irrespective of the Sm 3+ doping level. On the other hand, the magnetic Néel temperature (T N) decreased with increasing Sm 3+ doping level. On the basis of our results, the effects of Sm doping level on the pyroelectric and electrical properties of the BFO were revealed. © 2011 Elsevier Ltd. All rights reserved.

Evidence of chemical-potential shift with hole doping in Bi2Sr2CaCu2O8+δ

International Nuclear Information System (INIS)

Shen, Z.; Dessau, D.S.; Wells, B.O.; Olson, C.G.; Mitzi, D.B.; Lombado, L.; List, R.S.; Arko, A.J.

1991-01-01

We have performed photoemission studies on high-quality Bi 2 Sr 2 CaCu 2 O 8+δ samples with various δ. Our results show a clear chemical-potential shift (0.15--0.2 eV) as a function of doping. This result and the existing angle-resolved-photoemission data give a rather standard doping behavior of this compound in its highly doped regime

Experimental and density functional study of Mn doped Bi2Te3 topological insulator

Directory of Open Access Journals (Sweden)

A. Ghasemi

2016-12-01

Full Text Available We present a nanoscale structural and density functional study of the Mn doped 3D topological insulator Bi2Te3. X-ray absorption near edge structure shows that Mn has valency of nominally 2+. Extended x-ray absorption fine structure spectroscopy in combination with electron energy loss spectroscopy (EELS shows that Mn is a substitutional dopant of Bi and Te and also resides in the van der Waals gap between the quintuple layers of Bi2Te3. Combination of aberration-corrected scanning transmission electron microscopy and EELS shows that Mn substitution of Te occurs in film regions with increased Mn concentration. First-principles calculations show that the Mn dopants favor octahedral sites and are ferromagnetically coupled.

Thermoelectric Properties of Cu-Doped n-Type Bi2Te2.85Se0.15 Prepared by Liquid Phase Growth Using a Sliding Boat

Science.gov (United States)

Kitagawa, Hiroyuki; Matsuura, Tsukasa; Kato, Toshihito; Kamata, Kin-ya

2015-06-01

N-type Bi2Te2.85Se0.15 thermoelectric materials were prepared by liquid phase growth (LPG) using a sliding boat, a simple and short fabrication process for Bi2Te3-related materials. Cu was selected as a donor dopant, and its effect on thermoelectric properties was investigated. Thick sheets and bars of Cu x Bi2 Te2.85Se0.15 ( x=0-0.25) of 1-2mm in thickness were obtained using the process. X-ray diffraction patterns and scanning electron micrographs showed that the in-plane direction tended to correspond to the hexagonal c-plane, which is the preferred direction for thermoelectric conversion. Cu-doping was effective in controlling conduction type and carrier (electron) concentration. The conduction type was p-type for undoped Bi2Te2.85Se0.15 and became n-type after Cu-doping. The Hall carrier concentration was increased by Cu-doping. Small resistivity was achieved in Cu0.02Bi2Te2.85Se0.15 owing to an optimized amount of Cu-doping and high crystal orientation. As a result, the maximum power factor near 310K for Cu0.02Bi2Te2.85Se0.15 was approximately 4×10-3W/K2m and had good reproducibility. Furthermore, the thermal stability of Cu0.02Bi2Te2.85Se0.15 was also confirmed by thermal cycling measurements of electrical resistivity. Thus, n-type Bi2Te2.85Se0.15 with a large power factor was prepared using the present LPG process.

Thermoelectric properties of I-doped n-type Bi2Te3-based material prepared by hydrothermal and subsequent hot pressing

Directory of Open Access Journals (Sweden)

Fang Wu

2017-04-01

Full Text Available I-doped Bi2Te3−xIx (x=0, 0.05, 0.1, 0.2 flower-like nanoparticles were synthesized by a hydrothermal method through a careful adjustment of the amount of ethylenediamine tetraacetic acid surfactant. The nanopowders of flower-like nanoparticles were hot-pressed into bulk pellets and the thermoelectric properties of the pellets were investigated. The results showed that I-doping decreased the electrical resistivity effectively, and the thermal conductivitives of the Bi2Te3−xIx bulk samples was lower because of the closer atomic mass of I compared to Te. As a result, a ZT value of 1.1 was attained at 448 K for the Bi2Te2.9I0.1 sample.

Fluctuating Charge-Order in Optimally Doped Bi- 2212 Revealed by Momentum-resolved Electron Energy Loss Spectroscopy

Science.gov (United States)

Husain, Ali; Vig, Sean; Kogar, Anshul; Mishra, Vivek; Rak, Melinda; Mitrano, Matteo; Johnson, Peter; Gu, Genda; Fradkin, Eduardo; Norman, Michael; Abbamonte, Peter

Static charge order is a ubiquitous feature of the underdoped cuprates. However, at optimal doping, charge-order has been thought to be completely suppressed, suggesting an interplay between the charge-ordering and superconducting order parameters. Using Momentum-resolved Electron Energy Loss Spectroscopy (M-EELS) we show the existence of diffuse fluctuating charge-order in the optimally doped cuprate Bi2Sr2CaCu2O8+δ (Bi-2212) at low-temperature. We present full momentum-space maps of both elastic and inelastic scattering at room temperature and below the superconducting transition with 4meV resolution. We show that the ``rods'' of diffuse scattering indicate nematic-like fluctuations, and the energy width defines a fluctuation timescale of 160 fs. We discuss the implications of fluctuating charge-order on the dynamics at optimal doping. This work was supported by the Gordon and Betty Moore Foundation's EPiQS Initiative through Grant GBMF-4542. An early prototype of the M-EELS instrument was supported by the DOE Center for Emergent Superconductivity under Award No. DE-AC02-98CH10886.

Degradation mechanisms of optoelectric properties of GaN via highly-charged 209Bi33+ ions irradiation

Science.gov (United States)

Zhang, L. Q.; Zhang, C. H.; Xian, Y. Q.; Liu, J.; Ding, Z. N.; Yan, T. X.; Chen, Y. G.; Su, C. H.; Li, J. Y.; Liu, H. P.

2018-05-01

N-type gallium nitride (GaN) epitaxial layers were subjected to 990-keV Bi33+ ions irradiation to various fluences. Optoelectric properties of the irradiated-GaN specimens were studied by means of Raman scattering and variable temperature photoluminescence (PL) spectroscopy. Raman spectra reveal that both the free-carrier concentration and its mobility generally decrease with a successive increase in ion fluence. Electro-optic mechanisms dominated the electrical transport to a fluence of 1.061 × 1012 Bi33+/cm2. Above this fluence, electrical properties were governed by the deformation potential. The appearance of vacancy-type defects results in an abrupt degradation in electrical transports. Varying temperature photoluminescence (PL) spectra display that all emission lines of 1.061 × 1012 Bi33+/cm2-irradiated specimen present a general remarkable thermal redshift, quenching, and broadening, including donor-bound-exciton peak, yellow luminescence band, and LO-phonon replicas. Moreover, as the temperature rises, a transformation from excitons (donor-acceptor pairs' luminescence) to band-to-band transitions (donor-acceptor combinations) was found, and the shrinkage effect of the band gap dominated the shift of the peak position gradually, especially the temperature increases above 150 K. In contrast to the un-irradiated specimen, a sensitive temperature dependence of all photoluminescence (PL) lines' intensity obtained from 1.061 × 1012 Bi33+/cm2-irradiated specimen was found. Mechanisms underlying were discussed.

Effect of swift heavy ion irradiation on structural and opto-electrical properties of bi-layer CdS-Bi2S3 thin films prepared by solution growth technique at room temperature

Science.gov (United States)

Shaikh, Shaheed U.; Siddiqui, Farha Y.; Desale, Deepali J.; Ghule, Anil V.; Singh, Fouran; Kulriya, Pawan K.; Sharma, Ramphal

2015-01-01

CdS-Bi2S3 bi-layer thin films have been deposited by chemical bath deposition method on Indium Tin Oxide glass substrate at room temperature. The as-deposited thin films were annealed at 250 °C in an air atmosphere for 1 h. An air annealed thin film was irradiated using Au9+ ions with the energy of 120 MeV at fluence 5×1012 ions/cm2 using tandem pelletron accelerator. The irradiation induced modifications were studied using X-ray diffraction (XRD), Atomic Force Microscopy (AFM), Raman spectroscopy, UV spectroscopy and I-V characteristics. XRD study reveals that the as-deposited thin films were nanocrystalline in nature. The decrease in crystallite size, increase in energy band gap and resistivity were observed after irradiation. Results are explained on the basis of energy deposited by the electronic loss after irradiation. The comparative results of as-deposited, air annealed and irradiated CdS-Bi2S3 bi-layer thin films are presented.

Hierarchical nitrogen doped bismuth niobate architectures: Controllable synthesis and excellent photocatalytic activity

International Nuclear Information System (INIS)

Hou, Jungang; Cao, Rui; Wang, Zheng; Jiao, Shuqiang; Zhu, Hongmin

2012-01-01

Graphical abstract: Efficient visible-light-driven photocatalysts of peony-like nitrogen doped Bi 3 NbO 7 hierarchical architectures and silver-layered Bi 3 NbO 7−x Nx heterostructures were successfully synthesized in this discovery. Highlights: ► N-Bi 3 NbO 7 architectures were synthesized via two-step hydrothermal process. ► Electronic structure calculations indicated that N replaced O in samples. ► Growth mechanism is proposed for transformation of nanoparticles to microflowers. ► Excellent activities of N-Bi 3 NbO 7 architectures were obtained for degradation. ► Enhanced photocatalytic performance was observed for Ag/N-Bi 3 NbO 7 architectures. - Abstract: Nitrogen doped bismuth niobate (N-Bi 3 NbO 7 ) hierarchical architectures were synthesized via a facile two-step hydrothermal process. XRD patterns revealed that the defect fluorite-type crystal structure of Bi 3 NbO 7 remained intact upon nitrogen doping. Electron microscopy showed the N-Bi 3 NbO 7 architecture has a unique peony-like spherical superstructure composed of numerous nanosheets. UV–vis spectra indicated that nitrogen doping in the compound results in a red-shift of the absorption edge from 450 nm to 470 nm. XPS indicated that [Bi/Nb]-N bonds were formed by inducing nitrogen to replace a small amount of oxygen in Bi 3 NbO 7−x N x , which is explained by electronic structure calculations including energy band and density of states. Based on observations of architectures formation, a possible growth mechanism was proposed to explain the transformation of polyhedral-like nanoparticles to peony-like microflowers via an Ostwald riping mechanism followed by self-assembly. The N-Bi 3 NbO 7 architectures due to the large specific surface area and nitrogen doping exhibited higher photocatalytic activities in the decomposition of organic pollutant under visible-light irradiation than Bi 3 NbO 7 nanoparticles. Furthermore, an enhanced photocatalytic performance was also observed for Ag/N-Bi

The irradiation induced creep of graphite under accelerated damage produced by boron doping

International Nuclear Information System (INIS)

Brocklehurst, J.E.

1975-01-01

The presence of boron enhances fast neutron irradiation damage in graphite by providing nucleation sites for interstitial loop formation. Doping with 11 B casues an increase in the irradiation induced macroscopic dimensional changes, which have been shown to result from an acceleration in the differential crystal growth rate for a given carbon atom displacement rate. Models of irradiation induced creep in graphite have centred around those in which creep is induced by internal stresses due to the anisotopic crystal growth, and those in which creep is activated by atomic displacements. A creep test on boron doped graphite has been performed in an attempt to establish which of these mechanisms is the determining factor. An isotropic nuclear graphite was doped to a 11 B concentration of 0.27 wt.%. The irradiation induced volume shrinkage rate at 750 0 C increased by a factor of 3 over that of the virgin graphite, in agreement with predictions from the earlier work, but the total creep strains were comparable in both doped and virgin samples. This observation supports the view that irradiation induced creep is dependent only on the carbon atom displacement rate and not on the internal stress level determined by the differential crystal growth rate. The implications of this result on the irradiation behaviour of graphite containing significant concentrations of boron are briefly discussed. (author)

Facile synthesis of surface N-doped Bi_2O_2CO_3: Origin of visible light photocatalytic activity and in situ DRIFTS studies

International Nuclear Information System (INIS)

Zhou, Ying; Zhao, Ziyan; Wang, Fang; Cao, Kun; Doronkin, Dmitry E.; Dong, Fan; Grunwaldt, Jan-Dierk

2016-01-01

Graphical abstract: Surfactant (CTAB) can induce nitrogen interstitially doping in the Bi_2O_2CO_3 surface, leading to the formation of localized states from N−O bond, which probably account for the origin of the visible light activity. Moreover, the photocatalytic NO oxidation processes over Bi_2O_2CO_3 were successfully monitored for the first time by in situ DRIFTS. - Highlights: • Interstitially doping N in the Bi_2O_2CO_3 surface was achieved at room temperature. • N-doped Bi_2O_2CO_3 exhibited significantly enhanced visible light photocatalytic activity compared to the pristine Bi_2O_2CO_3. • The formation of localized states from N−O bond could account for the visible light activity of Bi_2O_2CO_3. • The photocatalytic NO oxidation process was monitored by in situ DRIFTS. - Abstract: Bi_2O_2CO_3 nanosheets with exposed {001} facets were prepared by a facile room temperature chemical method. Due to the high oxygen atom density in {001} facets of Bi_2O_2CO_3, the addition of cetyltrimethylammonium bromide (CTAB) does not only influence the growth of crystalline Bi_2O_2CO_3, but also modifies the surface properties of Bi_2O_2CO_3 through the interaction between CTAB and Bi_2O_2CO_3. Nitrogen from CTAB as dopant interstitially incorporates in the Bi_2O_2CO_3 surface evidenced by both experimental and theoretical investigations. Hence, the formation of localized states from N−O bond improves the visible light absorption and charge separation efficiency, which leads to an enhancement of visible light photocatalytic activity toward to the degradation of Rhodamine B (RhB) and oxidation of NO. In addition, the photocatalytic NO oxidation over Bi_2O_2CO_3 nanosheets was successfully monitored for the first time using in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS). Both bidentate and monodentate nitrates were identified on the surface of catalysts during the photocatalytic reaction process. The application of this strategy to

Thermoelectric properties and thermal stability of Bi-doped PbTe single crystal

Science.gov (United States)

Chen, Zhong; Li, Decong; Deng, Shuping; Tang, Yu; Sun, Luqi; Liu, Wenting; Shen, Lanxian; Yang, Peizhi; Deng, Shukang

2018-06-01

In this study, n-type Bi-doped single-crystal PbTe thermoelectric materials were prepared by melting and slow cooling method according to the stoichiometric ratio of Pb:Bi:Te = 1-x:x:1 (x = 0, 0.1, 0.15, 0.2, 0.25). The X-ray diffraction patterns of Pb1-xBixTe samples show that all main diffraction peaks are well matched with the PbTe matrix, which has a face-centered cubic structure with the space group Fm 3 bar m . Electron probe microanalysis reveals that Pb content decreases gradually, and Te content remains invariant basically with the increase of Bi content, indicating that Bi atoms are more likely to replace Pb atoms. Thermal analysis shows that the prepared samples possess relatively high thermal stability. Simultaneously, transmission electron microscopy and selected area electron diffraction pattern indicate that the prepared samples have typical single-crystal structures with good mechanical properties. Moreover, the electrical conductivity of the prepared samples improved significantly compared with that of the pure sample, and the maximum ZT value of 0.84 was obtained at 600 K by the sample with x = 0.2.

Study of Ho-doped Bi{sub 2}Te{sub 3} topological insulator thin films

Energy Technology Data Exchange (ETDEWEB)

Harrison, S. E. [Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom); Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Collins-McIntyre, L. J.; Zhang, S. L.; Chen, Y. L.; Hesjedal, T., E-mail: Thorsten.Hesjedal@physics.ox.ac.uk [Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom); Baker, A. A. [Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom); Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE (United Kingdom); Figueroa, A. I.; Laan, G. van der [Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE (United Kingdom); Kellock, A. J.; Pushp, A.; Parkin, S. S. P. [IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (United States); Harris, J. S. [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)

2015-11-02

Breaking time-reversal symmetry through magnetic doping of topological insulators has been identified as a key strategy for unlocking exotic physical states. Here, we report the growth of Bi{sub 2}Te{sub 3} thin films doped with the highest magnetic moment element Ho. Diffraction studies demonstrate high quality films for up to 21% Ho incorporation. Superconducting quantum interference device magnetometry reveals paramagnetism down to 2 K with an effective magnetic moment of ∼5 μ{sub B}/Ho. Angle-resolved photoemission spectroscopy shows that the topological surface state remains intact with Ho doping, consistent with the material's paramagnetic state. The large saturation moment achieved makes these films useful for incorporation into heterostructures, whereby magnetic order can be introduced via interfacial coupling.

Structural and morphological study of Fe-doped Bi-based superconductor

Science.gov (United States)

Singh, Yadunath; Kumar, Rohitash

2018-05-01

In the present work, we report the study of iron-doped Bi-based superconductor sample with stoichiometric composition of Bi2Sr2Can-1(Cu1-x Fex)3O2n+4 where n=3 and x = 0.7. This sample was prepared by grinding the precursor oxides in the Ball mill for 6 hours continuous at the rate of 400 rpm for a proper mixing and to obtain the required grain size. Then the solid-state reaction method was used to prepare the sample. X-ray diffraction (XRD) and scanning electron microscopy (SEM) in combination with energy dispersive X-ray fluorescence analysis (EDX) were performed for determination of the crystal structure, surface morphology and trace the material elements of samples, respectively. The surface microscopy data were collected over a selected area of the surface of the material and a two-dimensional image generated that displays spatial variations in properties including chemical characterization and orientation of materials.

Enhanced photocatalytic performance of BiVO{sub 4} in aqueous AgNO{sub 3} solution under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Huang, Chien-Kai [Department of Chemistry, National Changhua University of Education, Changhua City, Taiwan (China); Wu, Tsunghsueh [Department of Chemistry, University of Wisconsin-Platteville, Platteville (United States); Huang, Chang-Wei [Department of Chemistry, National Changhua University of Education, Changhua City, Taiwan (China); Lai, Chi-Yung [Department of Biology, National Changhua University of Education, Changhua, Taiwan (China); Wu, Mei-Yao, E-mail: meiyaowu0919@gmail.com [Research Centre for Traditional Chinese Medicine, Department of Medical Research, China Medical University Hospital, Taichung City, Taiwan (China); Lin, Yang-Wei, E-mail: linywjerry@cc.ncue.edu.tw [Department of Chemistry, National Changhua University of Education, Changhua City, Taiwan (China)

2017-03-31

Graphical abstract: Ag{sup +} ions enhanced photocatalytic activity of BiVO{sub 4} under visible light irradiation. - Highlights: • The presence of Ag{sup +} ions enhanced the photodegradation activity of BiVO{sub 4}. • Photoreduction of Ag deposited on the BiVO{sub 4} surface was obtained. • Luminescence and electrochemical results elucidated the photocatalytic mechanism. • Holes and oxygen radicals were the main reactive species generated by BiVO{sub 4}/Ag{sup +}. • Used BiVO{sub 4}/Ag{sup +} exhibited photocatalytic antibacterial activity toward E. coli. - Abstract: Monoclinic-phase bismuth vanadate (BiVO{sub 4}) with a 2.468 eV band gap exhibited enhanced synergic photodegradation activity toward methylene blue (MB) when combined with silver ions (Ag{sup +}) in an aqueous solution under visible light irradiation. The mass ratio of AgNO{sub 3} to BiVO{sub 4} and the calcination temperature were discovered to considerably affect the degradation activity of BiVO{sub 4}/Ag{sup +}. Superior photocatalytic performance was obtained when BiVO{sub 4} was mixed with 0.01%(w/v) AgNO{sub 3} solution, and complete degradation of MB was achieved after 25 min visible light irradiation, outperforming BiVO{sub 4} or AgNO{sub 3} solution alone. The enhanced photodegradation was investigated using systematic luminescence measurements, electrochemical impedance spectroscopy, and scavenger addition, after which a photocatalytic mechanism for MB degradation under visible light irradiation was identified that involved oxygen radicals and holes. This study also discovered the two dominating processes involved in enhancing the electron–hole separation efficiency and reducing their recombination rate, namely photoreduction of Ag{sup +} and the formation of a BiVO{sub 4}/Ag heterojunction. The synergic effect between BiVO{sub 4} and Ag{sup +} was discovered to be unique. BiVO{sub 4}/Ag{sup +} was successfully used to degrade two other dyes and disinfect Escherichia Coli. A

Novel electrical conductivity properties in Ca-doped BiFeO3 nanoparticles

International Nuclear Information System (INIS)

Wang, X.; Wang, S. Y.; Liu, W. F.; Xi, X. J.; Zhang, H.; Guo, F.; Xu, X. L.; Li, M.; Liu, L.; Zhang, C.; Li, X.; Yang, J. B.

2015-01-01

The charge defective structure in Bi 1−x Ca x FeO 3 (CBFO, x = 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3) nanoparticles (NPs) ranging from 140 to 25 nm as well as their relations to band gap and leakage current behavior are investigated. It is demonstrated that Ca doping effectively narrows the band gap from ∼2.16 to ∼2.02 eV, due to the appearance and accumulation of oxygen vacancy. Subsequently, enhanced electrical conductivity was obtained in these CBFO NPs, which leads to the appearance of a distinct threshold switching behavior in Ca-doped BFO NPs with higher conductivity at room temperature. Possible mechanisms for Ca doping effects on the electric conduction were discussed upon the interplay of NPs’ size effect and mobile charged defects on the basis of reduced particle size and the increased density of oxygen vacancy analyzed through X-ray photoelectron spectrum

Effects of iron deficiency on anisotropy and ferromagnetic resonance linewidth in Bi-doped LiZn ferrite

Directory of Open Access Journals (Sweden)

Xiaona Jiang

2017-05-01

Full Text Available Bi-doped LiZn ferrites with different iron deficiencies were fabricated by a conventional ceramic method. Anisotropy constant (K1 was calculated and ferromagnetic resonance (FMR linewidth (ΔH was investigated. Crystalline anisotropy broadening linewidth (ΔHa and porosity broadening linewidth (ΔHp were derived by an approximate calculation based on dipolar narrowing theory, which play a significant role in contributions to FMR linewidth and occupy more than 90 % of ΔH. Physical and static magnetic properties of LiZn ferrite with iron deficiency are presented, which supports a decline in linewidths with increasing iron deficiency. Iron deficiency makes K1, ΔHa and ΔHp reduce. The results also show that ΔHp is the majority of contributions to ΔH in Bi-doped LiZn ferrite and densification is an effective method to decrease ΔH.

Structural, magnetic and dielectric properties of Sr and V doped BiFeO{sub 3} multiferroics

Energy Technology Data Exchange (ETDEWEB)

Dahiya, Reetu; Agarwal, Ashish, E-mail: aagju@yahoo.com; Sanghi, Sujata; Hooda, Ashima; Godara, Priyanka

2015-07-01

Bi{sub 0.85}Sr{sub 0.15}FeO{sub 3} (BSFO), Bi{sub 0.85}Sr{sub 0.15}Fe{sub 0.97}V{sub 0.03}O{sub 3} (BSFVO1) and Bi{sub 0.85}Sr{sub 0.15}Fe{sub 0.95}V{sub 0.05}O{sub 3} (BSFVO2) ceramics were synthesized by solid state reaction method. X-ray diffraction studies and Rietveld refinement results indicate that all the samples crystallized in rhombohedrally distorted perovskite structure. The remnant magnetization and coercive field of BSFVO2 were greatly enhanced in comparison with BSFO. The enhancement of remnant magnetization was attributed to collapse of the spiral spin structure caused by change in bond length and bond angles of BSFO on V substitution. The enhanced value of coercive field might be attributed to decreased grain size with V substitution. BSFO sample shows dispersion in dielectric constant (έ) and dielectric loss (tan δ) values in lower frequency region. With V doping this dispersion is reduced resulting in frequency independent region. Dielectric anomaly peak due to charge defects in BSFO sample is also suppressed significantly on V substitution. BSFVO2 sample shows almost temperature stable behavior in έ and tan δ in the studied temperature range. Temperature dependence of index ‘s’ of power law suggests that overlapping large polaron tunneling model is applicable for describing the conduction mechanism in BSFO sample while small polaron tunneling model is appropriate for BSFVO1 and BSFVO2 samples in the studied temperature range. - Highlights: • Sr and V doped BiFeO{sub 3} multiferroics were synthesized by solid state reaction. • Ceramics crystallized in rhombohedrally distorted perovskite structure. • Remnant magnetization and coercive field were improved with V doping.

Luminescence properties of Y2O3:Bi3+, Yb3+ co-doped phosphor for application in solar cells

Science.gov (United States)

Lee, E.; Kroon, R. E.; Terblans, J. J.; Swart, H. C.

2018-04-01

Bismuth (Bi3+) and ytterbium (Yb3+) co-doped yttrium oxide (Y2O3) phosphor powder was successfully synthesised using the co-precipitation technique. The X-ray diffraction (XRD) patterns confirmed that a single phase cubic structure with a Ia-3 space group was formed. The visible emission confirmed the two symmetry sites, C2 and S6, found in the Y2O3 host material and revealed that Bi3+ ions preferred the S6 site as seen the stronger emission intensity. The near-infrared (NIR) emission of Yb3+ increased significantly by the presence of the Bi3+ ions when compared to the singly doped Y2O3:Yb3+ phosphor with the same Yb3+ concentration. An increase in the NIR emission intensity was also observed by simply increasing the Yb3+ concentration in the Y2O3:Bi3+, Yb3+ phosphor material where the intensity increased up to x = 5.0 mol% of Yb3+ before decreasing due to concentration quenching.

Electrical characterization of 10B doped diamond irradiated with low thermal neutron fluence

International Nuclear Information System (INIS)

Reed, M.L.; Reed, M.J.; Jagannadham, K.; Verghese, K.; Bedair, S.M.; El-Masry, N.; Butler, J.E.

2004-01-01

A sample of 10 B isotope doped diamond was neutron irradiated to a thermal fluence of 1.3x10 19 neutron cm -2 . The diamond sample was cooled continuously during irradiation in a nuclear reactor. 7 Li is formed by nuclear transmutation reaction from 10 B. Characterization for electrical conductance in the temperature range of 160 K 10 B doped sample and the 10 B doped and irradiated sample. The unirradiated diamond sample showed p-type conductance at higher temperature (T>200 K) and p-type surface conductance at lower temperature (T 7 Li that is formed by nuclear transmutation reaction from 10 B atoms. Also, compensation of n-type carriers from 7 Li by p-type carriers from 10 B is used to interpret the conductance above 400 K. A low concentration of radiation induced defects, absence of defect complexes, and the low activation energy of n-type 7 Li are thought responsible for the observed variation of conductance in the irradiated diamond. The present results illustrate that neutron transmutation from 10 B doped diamond is a useful method to achieve n-type conductivity in diamond

Structural, electric and dielectric properties of Eu-doped SrBi2Nb2O9 ceramics obtained by co-precipitation route

Directory of Open Access Journals (Sweden)

Mohamed Afqir

2018-03-01

Full Text Available This paper presents a study of the structure and dielectric properties of Eu-doped SrBi2Nb2O9 ceramics prepared by co-precipitation route and sintered at 850 °C. The materials were examined using XRD and FTIR methods. XRD data indicated the formation of well crystallized structure of the pure and doped SrBi2Nb2O9, without the presence of undesirable phases. FTIR spectra do not bring a significant shift in the band positions. Moreover, the AC conductivity, dielectric constant and dielectric loss of the ceramics were determined through the frequency range [50 kHz–1 MHz]. In particular, the dielectric constant (ε′ and dielectric losses (tan δ of the SrBi2Nb2O9 and SrBi1.6Eu0.4Nb2O9 ceramics were measured as a function of temperature at various frequencies.

Synthesis of chemically bonded BiOCl@Bi{sub 2}WO{sub 6} microspheres with exposed (0 2 0) Bi{sub 2}WO{sub 6} facets and their enhanced photocatalytic activities under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Ma, Yongchao [Qingdao Agricultural University, Qingdao 266109 (China); Chen, Zhiwei [School of Life Sciences, Shandong University of Technology, Zibo 255049 (China); Qu, Dan [Qingdao Agricultural University, Qingdao 266109 (China); Shi, Jinsheng, E-mail: jsshiqn@aliyun.com [Qingdao Agricultural University, Qingdao 266109 (China)

2016-01-15

Graphical abstract: - Highlights: • BiOCl@Bi{sub 2}WO{sub 6} composites were prepared via a controlled anion exchange method. • The shell of composites was composed of Bi{sub 2}WO{sub 6} sheets with exposed (0 2 0) facets. • The BiOCl@Bi{sub 2}WO{sub 6} composites showed efficient photocatalytic activity. • A possible photocatalytic degradation mechanism is proposed. - Abstract: Bi{sub 2}WO{sub 6} photocatalysts has been extensively studied for its photocatalytic activity. However, few works have been conducted on hierarchical Bi{sub 2}WO{sub 6} composite photocatalysts with specifically exposed facets. In this work, we report a facile method to synthesize BiOCl@Bi{sub 2}WO{sub 6} hierarchical composite microspheres. Bi{sub 2}WO{sub 6} nanosheets with specifically exposed (0 2 0) facet were directly formed on the surface of BiOCl precursor microspheres via a controlled anion exchange route between BiOCl and Na{sub 2}WO{sub 4}. The visible-light photocatalytic activity of the BiOCl@Bi{sub 2}WO{sub 6} heterojunction with exposed (0 2 0) facets (denoted as BiOCl@Bi{sub 2}WO{sub 6}) was investigated by degradation of Rhodamine B (RhB) and ciprofloxacin (CIP) aqueous solution under visible light irradiation. The experimental results indicated that the BiOCl@Bi{sub 2}WO{sub 6} composite microsphere with intimate interfacial contacts exhibited improved efficiency for RhB photodegradation in comparison with pure BiOCl and Bi{sub 2}WO{sub 6}. The BiOCl@Bi{sub 2}WO{sub 6} composite microsphere also shows high photocatalytic activity for degradation of CIP under visible light irradiation. The enhanced photocatalytic performance of BiOCl@Bi{sub 2}WO{sub 6}-020 hierarchical microspheres can be ascribed to the improved visible light harvesting ability, high charge separation and transfer. This work will make significant contributions toward the exploration of novel heterostructures with high potential in photocatalytic applications.

Influence of cobalt doping on structural and magnetic properties of BiFeO3 nanoparticles

Science.gov (United States)

Khan, U.; Adeela, N.; Javed, K.; Riaz, S.; Ali, H.; Iqbal, M.; Han, X. F.; Naseem, S.

2015-11-01

Nanocrystalline cobalt-doped bismuth ferrites with general formula of BiFe1- δ Co δ O3 (0 ≤ δ ≤ 0.1) have been synthesized using solution evaporation method. Structure and phase identification was performed with X-ray diffraction (XRD) technique. The results confirm the formation of rhombohedral-distorted Perovskite structure with R3c symmetry. A decrease in lattice parameters and an increase in X-ray density have been observed with increasing cobalt concentration in BiFeO3. Particle size determined by transmission electron microscope was in good agreement with XRD, i.e., 39 nm. Room-temperature coercivity and saturation magnetization of nanoparticles were increased up to 7.5 % of cobalt doping. Low-temperature magnetic measurements of selected sample showed increasing behavior in saturation magnetization, coercivity, effective magnetic moments, and anisotropy constant. An increase in coercivity with decrease in temperature followed theoretical model of Kneller's law, while modified Bloch's model was employed for saturation magnetization in temperature range of 5-300 K.

Spin-Glass Transition and Giant Paramagnetism in Heavily Hole-Doped Bi2Sr2Co2Oy

Science.gov (United States)

Hsu, Hung Chang; Lee, Wei-Li; Lin, Jiunn-Yuan; Young, Ben-Li; Kung, Hsiang-Hsi; Huang, Jian; Chou, Fang Cheng

2014-02-01

Hole-doped single crystals of misfit-layered cobaltate Bi2-xPbxSr2-zCo2Oy (x = 0-0.61, y = 8.28-8.62, and z = 0.01-0.22) have been successfully grown using the optical floating-zone method. Heavier hole doping has been achieved through both Pb substitution in the Bi site and the more effective Sr vacancy formation. The Co4+ : Co3+ ratio can be raised significantly from its original ˜1 : 1 to 4.5 : 1, as confirmed by iodometric titration. A spin-glass transition temperature of Tg ˜ 70 K is confirmed by ac susceptibility measurement when the Co4+ : Co3+ ratio becomes higher than 2 : 1, presumably owing to the significantly increased probability of triangular geometrical frustration among antiferromagnetically coupled localized Co4+ spins.

Surface chemical and photocatalytic consequences of Ca-doping of BiFeO{sub 3} as probed by XPS and H{sub 2}O{sub 2} decomposition studies

Energy Technology Data Exchange (ETDEWEB)

Zaki, Mohamed I., E-mail: mizaki@link.net [Chemistry Department, Faculty of Science, Minia University, El-Minia 61519 (Egypt); Ramadan, Wegdan [Physics Department, Faculty of Science, Alexandria University, Alexandria 21511 (Egypt); Katrib, Ali [Chemistry Department, Faculty of Science, Kuwait University, P.O. Box 5969, Safat 13060 (Kuwait); Rabee, Abdallah I.M. [Chemistry Department, Faculty of Science, Minia University, El-Minia 61519 (Egypt)

2014-10-30

Graphical abstract: - Highlights: • BiFeO{sub 3} is a modest visible-light heterogeneous photocatalyst for H{sub 2}O{sub 2} decomposition. • The ferrite activity is promoted with Ca-doping up to 10 wt%-Ca. • Favourable consequences are enhanced surface metal redoxability and oxide basicity. • Furthering doping to >10 wt%-Ca retrogresses the ferrite photocatalytic activity. • A retrogressive doping consequence is bulk phase separation of α(γ)-Fe{sub 2}O{sub 3}. - Abstract: Pure and Ca-doped Bi{sub 1−x}Ca{sub x}FeO{sub 3} samples were prepared with x = 0.0–0.2, adopting a sol–gel method. Previously reported studies performed on similarly composed and prepared samples revealed that Ca-doping, above solubility limit (namely at ≥10%-Ca), results in phase separation and formation of BiFeO{sub 3}/α(γ)-Fe{sub 2}O{sub 3} nanocomposite particles. Hetero p/n nanojunctions thus established were considered to help separating photo-generated electron–hole pairs and, therefore, explain consequent promotion of photo-Fenton catalytic activity of BiFeO{sub 3} towards methylene blue degradation in presence of H{sub 2}O{sub 2} additive. However, the encompassed decomposition of H{sub 2}O{sub 2} was not addressed. To bridge this gap of knowledge, the present investigation was designed to assess Ca-doping-effected surface chemical modifications and gauge its impact on the heterogeneous photo-/thermo-catalytic activity of BiFeO{sub 3} towards H{sub 2}O{sub 2} decomposition, by means of X-ray photoelectron spectroscopy (XPS) and H{sub 2}O{sub 2} decomposition gravimetry. XPS results revealed generation of high binding energy Bi 4f and Fe 2p states, as well as enhancement of the surface basicity, upon doping to 10%-Ca. These surface chemical consequences are rendered hardly detectable upon further increase of the dopant magnitude to 20%-Ca. In parallel, the H{sub 2}O{sub 2} decomposition activity of the ferrite, under natural visible light, is enhanced to optimize

Large power factor and anomalous Hall effect and their correlation with observed linear magneto resistance in Co-doped Bi2Se3 3D topological insulator

Science.gov (United States)

Singh, Rahul; Shukla, K. K.; Kumar, A.; Okram, G. S.; Singh, D.; Ganeshan, V.; Lakhani, Archana; Ghosh, A. K.; Chatterjee, Sandip

2016-09-01

Magnetoresistance (MR), thermo power, magnetization and Hall effect measurements have been performed on Co-doped Bi2Se3 topological insulators. The undoped sample shows that the maximum MR as a destructive interference due to a π-Berry phase leads to a decrease of MR. As the Co is doped, the linearity in MR is increased. The observed MR of Bi2Se3 can be explained with the classical model. The low temperature MR behavior of Co doped samples cannot be explained with the same model, but can be explained with the quantum linear MR model. Magnetization behavior indicates the establishment of ferromagnetic ordering with Co doping. Hall effect data also supports the establishment of ferromagnetic ordering in Co-doped Bi2Se3 samples by showing the anomalous Hall effect. Furthermore, when spectral weight suppression is insignificant, Bi2Se3 behaves as a dilute magnetic semiconductor. Moreover, the maximum power factor is observed when time reversal symmetry (TRS) is maintained. As the TRS is broken the power factor value is decreased, which indicates that with the rise of Dirac cone above the Fermi level the anomalous Hall effect and linearity in MR increase and the power factor decreases.

Some structural characteristics of gamma-irradiated pure and Li2O-doped NiO solids

International Nuclear Information System (INIS)

Ramadan, A.A.; Dessouki, A.M.

1989-01-01

The induced structural changes, due to Li 2 O-doping (2.5 mol%) and γ-irradiation (10-80 Mrad), of NiO were investigated by XRD analyses. The results obtained revealed that lithium-doping resulted in a significant increase in the internal strain and a decrease in lattice parameter. These changes were explained in terms of creation of Ni 3+ ions in the doped solids. γ-Irradiation of pure and doped solids effected a decrease in both crystallite size and microstrain upon subjecting to doses of 20 and 30 Mrad. Higher doses induced an increase in both parameters in the case of pure NiO and a further decrease in case of the doped solid. These results were attributed to splitting of the large strained crystallites and to an activated sintering of the small strained ones. γ-Irradiation effected also an increase in the lattice parameters of pure and doped solids due to removal of some excess oxygen with subsequent decrease in the concentration of Ni 3+ ions. (author)

Phase separation in Sr doped BiMnO3

International Nuclear Information System (INIS)

Li Guan-Nan; Gao Qing-Qing; Luo Jun; Liu Guang-Yao; Liang Jing-Kui; Rao Guang-Hui; Huang Qing-Zhen; Li Jing-Bo

2014-01-01

Phase separation in Sr doped BiMnO 3 (Bi 1−x Sr x MnO 3 , x = 0.4−0.6) was studied by means of temperature-dependent high-resolution neutron powder diffraction (NPD), high resolution X-ray powder diffraction (XRD), and physical property measurements. All the experiments indicate that a phase separation occurs at the temperature coinciding with the reported charge ordering temperature (T CO ) in the literature. Below the reported T CO , both the phases resulting from the phase separation crystallize in the orthorhombically distorted perovskite structure with space group Imma. At lower temperature, these two phases order in the CE-type antiferromagnetic structure and the A-type antiferromagnetic structure, respectively. However, a scrutiny of the high-resolution NPD and XRD data at different temperatures and the electron diffraction experiment at 300 K did not manifest any evidence of a long-range charge ordering (CO) in our investigated samples, suggesting that the anomalies of physical properties such as magnetization, electric transport, and lattice parameters at the T CO might be caused by the phase separation rather than by a CO transition

Optical temperature sensing by upconversion luminescence of Er doped Bi5TiNbWO15ferroelectric materials

Directory of Open Access Journals (Sweden)

Hua Zou

2014-12-01

Full Text Available The Er3+ doped Bi5TiNbWO15 ceramics have been synthesized using conventional solid-state reaction techniques. The crystal structure, ferroelectric properties, UC emission properties and especially the temperature sensing behaviors were systematically studied. With increasing Er3+ content, the investigation of XRD pattern, the ferroelectric loop and the UC emission indicated that the Er3+ ions dopants preferentially substituted the A sites of Bi3TiNbO9 and then Bi2WO6. Based on fluorescence intensity ratio (FIR technique, the observed results implied the ceramics were promising candidates for temperature sensors in the temperature range of 175 K −550 K. More importantly, this study provided a contrast of temperature sensitivity between emission from the same part (Bi3TiNbO9 in bismuth layered-structure and emission from the different part (Bi3TiNbO9 and Bi2WO6 in bismuth layered-structure for the first time.

Surface morphology and physical properties of partially melt textured Mn doped Bi-2223

Directory of Open Access Journals (Sweden)

Indu Verma

2011-09-01

Full Text Available The samples of Bi2Sr2Ca2Cu3-xMnxO10+δ (x = 0.0 to 0.30 were prepared by the standard solid-state reaction method. The phase identification characteristics of synthesized (HTSC materials were explored through powder X-ray diffractometer reveals that all the samples crystallize in orthorhombic structure with lattice parameters a = 5.4053 Å, b = 5.4110 Å and c = 37.0642 Å up to Mn concentration of x = 0.30. The critical temperature (Tc measured by standard four probe method has been found to depress from 108 K to 70 K as Mn content (x increases from 0.00 to 0.30. The effects of sintering temperature on the surface morphology of Bi2Sr2Ca2Cu3-xMnxO10+δ have also been investigated. The surface morphology investigated through scanning electron microscope and atomic force microscopy (SEM & AFM results that voids are decreasing but grains size increases as the Mn concentration increases besides, nanosphere like structures on the surface of the Mn doped Bi2Sr2Ca2Cu3-xMnxO10+δ (Bi-2223 samples.

Andreev Reflection Spectroscopy of Nb-doped Bi2Se3 Topological Insulator

Science.gov (United States)

Kurter, C.; Finck, A. D. K.; Qiu, Y.; Huemiller, E.; Weis, A.; Atkinson, J.; Medvedeva, J.; Hor, Y. S.; van Harlingen, D. J.

2015-03-01

Doped topological insulators are speculated to realize p-wave superconductivity with unusual low energy quasiparticles, such as surface Andreev bound states. We present point contact spectroscopy of thin exfoliated flakes of Nb-doped Bi2Se3 where superconductivity persists up to ~ 1 K, compared to 3.2 K in bulk crystals. The critical magnetic field is strongly anisotropic, consistent with quasi-2D behavior. Andreev reflection measurements of devices with low resistance contacts result in prominent BTK-like behavior with an enhanced conductance plateau at low bias. For high resistance contacts, we observe a split zero bias conductance anomaly and additional features at the superconducting gap. Our results suggest that this material is a promising platform for studying topological superconductivity. We acknowledge support from Microsoft Project Q.

Defect formation in heavily doped Si upon irradiation

International Nuclear Information System (INIS)

Gubskaya, V.I.; Kuchinskii, P.V.; Lomako, V.M.

1981-01-01

The rates of the carrier removal and radiation defect introduction into n- and p-Si in the concentration range of 10 14 to 10 17 cm -3 upon 7-MeV-electron irradiation have been studied. The spectrum of the vacancy-type defects, defining the carrier removal rate in lightly doped crystals has been found. With doping level increase the carrier removal rate grows irrespective of conductivity type, and at n 0 , p 0 > 10 17 cm -3 is close to the total displacement number. At the same time a decrease in the introduction rate of the known vacancy-type defects is observed. x It is shown that a considerable growth of the carrier removal rate is defined neither by introduction of shallow compensating centers, nor by change in the primary defect charge state. It is suggested that at high doping impurity concentrations compensation in Si is due to the introduction of complexes doping impurity-interstitial or (impurity atom-interstitial) + vacancy, which give deep levels. (author)

Structural phase transition and magnetic properties of Er-doped BiFeO3 nanoparticles

International Nuclear Information System (INIS)

Li, Y T; Zhang, H G; Dong, X G; Li, Q; Mao, W W; Dong, C L; Ren, S L; Li, X A; Wei, S Q

2013-01-01

The structural phase transition and local structural distortion of Er-doped BiFeO 3 nanoparticles have been discussed in order to understand the variation of magnetic properties in this system. The X-ray diffraction patterns and X-ray absorption fine structure of these samples demonstrate that there is structural phase transition and no obvious local structural distortion with the increasing of doping concentration. Unfortunately, no ferromagnetic properties have been observed even at a lower temperature. And the X-ray absorption spectra of Fe 2p core level of these samples are totally same, especially the energy positions do not shift which means the consistent valence states of Fe ions.

Considerable photoluminescence enhancement of LiEu(MoO4)2 red phosphors via Bi and/or Si doping for white LEDs

International Nuclear Information System (INIS)

Wang, Qing-Feng; Liu, Ying; Wang, Yu; Wang, Wenxi; Wan, Yi; Wang, Gui-Gen; Lu, Zhou-Guang

2015-01-01

Graphical abstract: Doping of Bi and Si into the lattice leads to an considerable increase of the excitation efficiency and luminous intensity, and obvious movement of the CIE chromaticity coordinates to the NTSC standard values of the LiEu(MoO 4 ) 2 , a promising red phosphors suitable for near UV excited white-light emitting diodes. - Highlights: • High performance red phosphors for near UV light excited white LEDs. • Lithium lanthanide molybdate red phosphors. • Bi and Si substitution. • Considerable enhancement of luminescence intensity and excitation efficiency. • CIE chromaticity coordinates very close to the NTSC standard values. - Abstract: Novel Bi and/or Si substituted LiEu(MoO 4 ) 2 phosphors, where Bi was used as sensitizer to enhance the emission intensity and Si was used as substitution to improve the excitation efficiency, were prepared using the sol–gel method, and the photoluminescent properties of the resulting phosphors were intensively investigated. All samples can be excited efficiently by UV (395 nm) light and emit bright red light at 614 nm, which are coupled well with the characteristic emission from a UV-LED. In the Bi 3+ -doped samples, the intensities of the main emission line ( 5 D 0 – 7 F 2 transition at 614 nm) are strengthened because of the energy transition from Bi 3+ to Eu 3+ . With the substitution of Mo 4+ by Si 4+ , there are no significant changes in the emission peak positions, but the emission intensity was significantly enhanced under 395 nm excitation. Particularly, the LiEu 0.9 Bi 0.1 (Mo 0.97 Si 0.03 O 4 ) 2 phosphor doped with both Bi and Si demonstrates superior comprehensive photoluminescence properties with an excellent combination of easy excitation in the near UV range, bright emission intensity, high PL quantum efficiency as well as suitable decay time, which are very suitable for application as red phosphor for near UV type LEDs

Novel electrical conductivity properties in Ca-doped BiFeO{sub 3} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Wang, X.; Wang, S. Y., E-mail: shouyu.wang@yahoo.com [Tianjin Normal University, College of Physics and Materials Science (China); Liu, W. F., E-mail: wfliu@tju.edu.cn [Tianjin University, Department of Applied Physics, Institute of Advanced Materials Physics, Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Faculty of Science (China); Xi, X. J. [Tianjin Normal University, College of Physics and Materials Science (China); Zhang, H. [Tianjin University, Department of Applied Physics, Institute of Advanced Materials Physics, Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Faculty of Science (China); Guo, F. [Tianjin Normal University, College of Physics and Materials Science (China); Xu, X. L. [Tianjin University, Department of Applied Physics, Institute of Advanced Materials Physics, Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Faculty of Science (China); Li, M.; Liu, L.; Zhang, C.; Li, X.; Yang, J. B. [Tianjin Normal University, College of Physics and Materials Science (China)

2015-05-15

The charge defective structure in Bi{sub 1−x}Ca{sub x}FeO{sub 3} (CBFO, x = 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3) nanoparticles (NPs) ranging from 140 to 25 nm as well as their relations to band gap and leakage current behavior are investigated. It is demonstrated that Ca doping effectively narrows the band gap from ∼2.16 to ∼2.02 eV, due to the appearance and accumulation of oxygen vacancy. Subsequently, enhanced electrical conductivity was obtained in these CBFO NPs, which leads to the appearance of a distinct threshold switching behavior in Ca-doped BFO NPs with higher conductivity at room temperature. Possible mechanisms for Ca doping effects on the electric conduction were discussed upon the interplay of NPs’ size effect and mobile charged defects on the basis of reduced particle size and the increased density of oxygen vacancy analyzed through X-ray photoelectron spectrum.

Photoluminescence and excited state structure in Bi3+-doped Y2SiO5 single crystalline films

International Nuclear Information System (INIS)

Babin, V.; Gorbenko, V.; Krasnikov, A.; Mihokova, E.; Nikl, M.; Zazubovich, S.; Zorenko, Yu.

2013-01-01

Single crystalline films of Bi-doped Y 2 SiO 5 are studied at 4.2–350 K by the time-resolved luminescence methods under excitation in the 3.8–6.2 eV energy range. Ultraviolet luminescence of Y 2 SiO 5 :Bi (≈3.6 eV) is shown to arise from the radiative decay of the metastable and radiative minima of the triplet relaxed excited state (RES) of Bi 3+ centers which are related to the 3 P 0 and 3 P 1 levels of a free Bi 3+ ion, respectively. The lowest-energy excitation band of this emission, located at ≈4.5 eV, is assigned to the 1 S 0 → 3 P 1 transitions of a free Bi 3+ ion. The phenomenological model is proposed to describe the excited-state dynamics of Bi 3+ centers in Y 2 SiO 5 :Bi, and parameters of the triplet RES are determined. -- Highlights: •Luminescence of Y 2 SiO 5 :Bi is investigated for the first time. •Ultraviolet emission arises from Bi 3+ ions located in Y lattice sites. •The triplet relaxed excited states parameters of Bi 3+ centers are determined

M-line spectroscopic, spectroscopic ellipsometric and microscopic measurements of optical waveguides fabricated by MeV-energy N{sup +} ion irradiation for telecom applications

Energy Technology Data Exchange (ETDEWEB)

Bányász, I., E-mail: banyasz@sunserv.kfki.hu [Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O.B. 49, H-1525, Budapest (Hungary); Berneschi, S. [“Enrico Fermi” Center for Study and Research, Piazza del Viminale 2, 00184 Roma (Italy); MDF-Lab, “Nello Carrara” Institute of Applied Physics, IFAC-CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Italy); Fried, M.; Lohner, T. [Institute of Technical Physics and Materials Science, Research Centre for Natural Sciences, Hungarian Academy of Sciences, P.O.B. 49, H-1525, Budapest (Hungary); Conti, G. Nunzi; Righini, G.C.; Pelli, S. [MDF-Lab, “Nello Carrara” Institute of Applied Physics, IFAC-CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Italy); Zolnai, Z. [Institute of Technical Physics and Materials Science, Research Centre for Natural Sciences, Hungarian Academy of Sciences, P.O.B. 49, H-1525, Budapest (Hungary)

2013-08-31

Irradiation with N{sup +} ions of the 1.5–3.5 MeV energy range was applied to optical waveguide formation. Planar and channel waveguides have been fabricated in an Er-doped tungsten–tellurite glass, and in both types of bismuth germanate (BGO) crystals: Bi{sub 4}Ge{sub 3}O{sub 12} (eulytine) and Bi{sub 12}GeO{sub 20} (sillenite). Multi-wavelength m-line spectroscopy and spectroscopic ellipsometry were used for the characterisation of the ion beam irradiated waveguides. Planar waveguides fabricated in the Er-doped tungsten–tellurite glass using irradiation with N{sup +} ions at 3.5 MeV worked even at the 1550 nm telecommunication wavelength. 3.5 MeV N{sup +} ion irradiated planar waveguides in eulytine-type BGO worked up to 1550 nm and those in sillenite-type BGO worked up to 1330 nm. - Highlights: ► Waveguides were fabricated in glass and crystals using MeV energy N{sup +} ions. ► SRIM simulation and spectroscopic ellipsometry yielded similar waveguide structures. ► Multi-wavelength m-line spectroscopy was used to study the waveguides. ► Waveguides fabricated in an Er-doped tungsten–tellurite glass worked up to 1.5 μm. ► Waveguides in Bi{sub 12}GeO{sub 20} remained operative up to 1.5 μm.

Scintillation properties of Er-doped Y3Al5O12 single crystals

International Nuclear Information System (INIS)

Yamaji, Akihiro; Ogino, Hiraku; Fujimoto, Yutaka; Suzuki, Akira; Yanagida, Takayuki; Yokota, Yuui; Kurosawa, Shunsuke; Yoshikawa, Akira

2013-01-01

Er-doped Y 3 Al 5 O 12 single crystals with different Er concentrations of 0.1, 1.0, 10, 30, and 50% were grown by the micro-pulling down method. There were several absorption lines due to the Er 3+ 4f-4f transitions in the transmittance spectra and these lines correspond to the transitions from the ground state of 4 I 15/2 to the excited states. The photo- and radio-luminescence spectra showed Er 3+ 4f-4f emissions. Relative light yield under 5.5 MeV alpha-ray irradiation of Er 0.1%:Y 3 Al 5 O 12 was estimated to be 63% of that of Bi 4 Ge 3 O 12 . -- Highlights: •Er doped Y 3 Al 5 O 12 single crystal scintillators were grown with different Er concentrations. •Optical properties associated with 4f-4f transition were evaluated. •Radio luminescence spectra measurements were performed under 5.5 MeV alpha-ray irradiation. •The highest light yield was estimated to be 63% of that of Bi 4 Ge 3 O 12 under 5.5 MeV alpha-ray irradiation

The defects produced by electron irradiation in tellurium-doped germanium

International Nuclear Information System (INIS)

Fukuoka, Noboru; Saito, Haruo

1989-01-01

The nature of the irradiation induced defects in a germanium single crystal doped with tellurium was studied by DLTS and electrical measurements. The E c -0.21 eV level produced by irradiation with 1.5 MeV electrons was studied using the DLTS technique. It was found that the defect associated with this level is a divacancy. The E-center like defect (group V impurity-vacancy pair) introduces the E c -0.20 eV level in samples doped with a group V impurity. The level introduced by a tellurium (group VI impurity)-vacancy pair is deeper. The E c -0.16 eV level was generated by annealing at 430 K. A tellurium-vacancies complex is proposed as the defect associated with this level. (author)

Comparison of Sn-doped and nonstoichiometric vertical-Bridgman-grown crystals of the topological insulator Bi2Te2Se

International Nuclear Information System (INIS)

Kushwaha, S. K.; Gibson, Q. D.; Cava, R. J.; Xiong, J.; Ong, N. P.; Pletikosic, I.; Weber, A. P.; Fedorov, A. V.; Valla, T.

2014-01-01

A comparative study of the properties of topological insulator Bi 2 Te 2 Se (BTS) crystals grown by the vertical Bridgeman method is described. Two defect mechanisms that create acceptor impurities to compensate for the native n-type carriers are compared: Bi excess, and light Sn doping. Both methods yield low carrier concentrations and an n-p crossover over the length of the grown crystal boules, but lower carrier concentrations and higher resistivities are obtained for the Sn-doped crystals, which reach carrier concentrations as low as 8 × 10 14  cm −3 . Further, the temperature dependent resistivities for the Sn-doped crystals display strongly activated behavior at high temperatures, with a characteristic energy of half the bulk band gap. The (001) cleaved Sn-doped BTS crystals display high quality Shubnikov de Haas (SdH) quantum oscillations due to the topological surface state electrons. Angle resolved photoelectron spectroscopy (ARPES) characterization shows that the Fermi energy (E F ) for the Sn-doped crystals falls cleanly in the surface states with no interference from the bulk bands, which the Dirac point for the surface states lies approximately 60 meV below the top of the bulk valence band maximum, and allows for a determination of the bulk and surface state carrier concentrations as a function of Energy near E F . Electronic structure calculations that compare Bi excess and Sn dopants in BTS demonstrate that Sn acts as a special impurity, with a localized impurity band that acts as a charge buffer occurring inside the bulk band gap. We propose that the special resonant level character of Sn in BTS gives rise to the exceptionally low carrier concentrations and activated resistivities observed

Doping influence by some transition elements on the irradiation effects in nuclear waste glasses

International Nuclear Information System (INIS)

Florent, Olivier

2006-06-01

High-level waste glasses are submitted to auto-irradiation. Modelling it using external irradiations on simple glasses revealed defects production and non negligible structural changes. This thesis aims at determining the impact of a more complex composition on these effects, especially the influence of adding polyvalent transition metals. Silicate, soda-lime and alumino-borosilicate glasses are doped with different iron, chromium and manganese concentrations then β irradiated at different doses up to 10 9 Gy. Non doped glasses show an increase of their density and polymerisation coupled with a molecular oxygen and point defects production. Adding 0.16 mol% Fe decreases the amount of defects by 85 % and all irradiation effects. A Fe 3+ reduction is also observed by EPR, optical absorption and indirectly by Raman spectroscopy. A higher than 0.32 mol% Fe concentration causes complete blockage of the evolution of polymerisation, density and defect production. The same results are obtained on chromium or manganese doped glasses. An original in situ optical absorption device shows the quick decrease of Fe 3+ amount to a 25 % lower level during irradiation. Stopping irradiation causes a lower decrease of 65 %, suggesting a dynamic (h 0 /e-) consuming equilibrium. He + and Kr 3+ ions and γ irradiated glasses tend to confirm these phenomena for all kind of irradiation with electronic excitations. (author)

Size dependent magnetic and electrical properties of Ba-doped nanocrystalline BiFeO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Hasan, Mehedi, E-mail: mhrizvi@gce.buet.ac.bd; Hakim, M. A.; Zubair, M. A.; Hussain, A.; Islam, Md. Fakhrul [Department of Glass and Ceramic Engineering, Bangladesh University of Engineering and Technology, Dhaka 1000 (Bangladesh); Basith, M. A., E-mail: mabasith@phy.buet.ac.bd [Department of Physics, Bangladesh University of Engineering and Technology, Dhaka-1000 (Bangladesh); Hossain, Md. Sarowar [S. N. Bose National Centre for Basic Sciences, Salt Lake City, Kolkata, West Bengal 700098 (India); Ahmmad, Bashir [Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510 (Japan)

2016-03-15

Improvement in magnetic and electrical properties of multiferroic BiFeO{sub 3} in conjunction with their dependence on particle size is crucial due to its potential applications in multifunctional miniaturized devices. In this investigation, we report a study on particle size dependent structural, magnetic and electrical properties of sol-gel derived Bi{sub 0.9}Ba{sub 0.1}FeO{sub 3} nanoparticles of different sizes ranging from ∼ 12 to 49 nm. The substitution of Bi by Ba significantly suppresses oxygen vacancies, reduces leakage current density and Fe{sup 2+} state. An improvement in both magnetic and electrical properties is observed for 10 % Ba-doped BiFeO{sub 3} nanoparticles compared to its undoped counterpart. The saturation magnetization of Bi{sub 0.9}Ba{sub 0.1}FeO{sub 3} nanoparticles increase with reducing particle size in contrast with a decreasing trend of ferroelectric polarization. Moreover, a first order metamagnetic transition is noticed for ∼ 49 nm Bi{sub 0.9}Ba{sub 0.1}FeO{sub 3} nanoparticles which disappeared with decreasing particle size. The observed strong size dependent multiferroic properties are attributed to the complex interaction between vacancy induced crystallographic defects, multiple valence states of Fe, uncompensated surface spins, crystallographic distortion and suppression of spiral spin cycloid of BiFeO{sub 3}.

Enhanced Photoluminescence of Sm3+/Bi3+ Co-Doped La2O3 Nanophosphors by Combustion Synthesis

Science.gov (United States)

Zhang, Ying; Wu, Muying; Zhang, W. F.

Nanosized La2O3:Sm3+ and La2O3:Sm3+, Bi3+ phosphor powders were prepared via combustion synthesis. The structures and morphology were examined using powder X-ray diffraction and transmission electron microscope, respectively. The photoluminescence spectra were investigated at different doping concentrations of Sm3+ and Bi3+ ions. The results indicate that La2O3:Sm3+ (Bi3+) exhibited good crystallinity and spherical-like particles. All phosphors give emission bands centered at 564, 608 and 650 nm corresponding to 4G5/2→6HJ (J=5/2, 7/2 and 9/2) transitions of Sm3+ ions, respectively. Interestingly, the emission intensity of Sm3+ ions is significantly enhanced with the addition of Bi3+ ions to La2O3:Sm3+ and the maximum occurs at a Bi3+ concentration of 0.8 mol%. The La2O3:Sm3+, Bi3+ phosphor with highly enhanced luminescence is very encouraging for applications in display and tunable solid lasers.

H+ irradiation effect in Co-doped BaFe2As2 single crystals

International Nuclear Information System (INIS)

Nakajima, Y.; Tsuchiya, Y.; Taen, T.; Tamegai, T.; Kitamura, H.; Murakami, T.

2011-01-01

The effect of H + irradiation on the suppression of Tc in Co-doped BaFe 2 As 2 . H + irradiation introduces nonmagnetic scattering centers. Critical Scattering rate is much higher than that expected in s±-pairing scenario. We report the suppression of the critical temperature T c in single crystalline Ba(Fe 1-x Co x ) 2 As 2 at under-, optimal-, and over-doping levels by 3 MeV proton irradiation. T c decreases and residual resistivity increases monotonically with increasing the dose. The low-temperature resistivity does not show the upturn in contrast with the α-particle irradiated NdFeAs(O,F), which suggests that proton irradiation introduces nonmagnetic scattering centers. Critical scattering rates for all samples obtained by three different ways are much higher than that expected in s±-pairing scenario based on inter-band scattering due to antiferro-magnetic spin fluctuations.

Evidence for charge transfer in Bi-based superconductors studied by positron annihilation

International Nuclear Information System (INIS)

Tang, Z.; Wang, S.J.; Gao, X.H.; Ce, G.C.; Zhao, Z.X.

1993-01-01

We have measured Doppler-broadening annihilation radiation (DBAR) spectra and positron lifetimes in normal and superconducting states for three kinds of Bi-based superconductors: Bi2212, Pb-doped Bi2223, Pb- and F-doped Bi2223. The difference spectra after deconvolution between two states show a sharpening effect with increasing temperature; the F-doped sample has the greatest amplitude in difference spectra but nearly the same positron lifetimes as the Pb-doped sample. The results are interpreted in terms of charge transfer between the Cu-O and Bi-O planes. The role of oxygen defects in charge transfer is discussed. (orig.)

Distinct effects of Cr bulk doping and surface deposition on the chemical environment and electronic structure of the topological insulator Bi{sub 2}Se{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Yilmaz, Turgut, E-mail: yilmaz@phys.uconn.edu [Department of Physics, University of Connecticut, Storrs, CT 06269 (United States); Hines, William [Department of Physics, University of Connecticut, Storrs, CT 06269 (United States); Sun, Fu-Chang [Department of Materials Science and Engineering, University of Connecticut, Storrs, CT 06269 (United States); Pletikosić, Ivo [Department of Physics, Princeton University, Princeton, NJ 08544 (United States); Budnick, Joseph [Department of Physics, University of Connecticut, Storrs, CT 06269 (United States); Valla, Tonica [Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Sinkovic, Boris [Department of Physics, University of Connecticut, Storrs, CT 06269 (United States)

2017-06-15

Highlights: • Cr doping into the bulk of Bi{sub 2}Se{sub 3} opens an energy gap at the Dirac point which is observable in the non-magnetic state. • Cr surface deposition does not lead to open an energy gap at the Dirac point of Bi{sub 2}Se{sub 3}. • Formation of two distinct Bi and Cr core level peaks was observed upon the deposition of Cr on the surface of Bi{sub 2}Se{sub 3}. - Abstract: In this report, it is shown that Cr doped into the bulk and Cr deposited on the surface of Bi{sub 2}Se{sub 3} films produced by molecular beam epitaxy (MBE) have strikingly different effects on both the electronic structure and chemical environment. Angle resolved photoemission spectroscopy (ARPES) shows that Cr doped into the bulk opens a surface state energy gap which can be seen at room temperature; much higher than the measured ferromagnetic transition temperature of ≈10 K. On the other hand, similar ARPES measurements show that the surface states remain gapless down to 15 K for films with Cr surface deposition. In addition, core-level photoemission spectroscopy of the Bi 5d, Se 3d, and Cr 3p core levels show distinct differences in the chemical environment for the two methods of Cr introduction. Surface deposition of Cr results in the formation of shoulders on the lower binding energy side for the Bi 5d peaks and two distinct Cr 3p peaks indicative of two Cr sites. These striking differences suggests an interesting possibility that better control of doping at only near surface region may offer a path to quantum anomalous Hall states at higher temperatures than reported in the literature.

Influence of Ga-doping on the thermoelectric properties of Bi(2−xGaxTe2.7Se0.3 alloy

Directory of Open Access Journals (Sweden)

Xingkai Duan

2015-02-01

Full Text Available Bi(2−xGaxTe2.7Se0.3 (x=0, 0.04, 0.08, 0.12 alloys were fabricated by vacuum melting and hot pressing technique. The structure of the samples was evaluated by means of X-ray diffraction. The peak shift toward higher angle can be observed by Ga-doping. The effects of Ga substitution for Bi on the electrical and thermal transport properties were investigated in the temperature range of 300–500 K. The power factor values of the Ga-doped samples are obviously improved in the temperature range of 300–440 K. Among all the samples, the Bi(2−xGaxTe2.7Se0.3 (x=0.04 sample showed the lowest thermal conductivity near room temperature and the maximum ZT value reached 0.82 at 400 K.

Luminescence and electron degradation properties of Bi doped CaO phosphor

Energy Technology Data Exchange (ETDEWEB)

Yousif, A. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Department of Physics, Faculty of Education, University of Khartoum, P.O. Box 321, 11115 Omdurman (Sudan); Kroon, R.E.; Coetsee, E.; Ntwaeaborwa, O.M. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Seed Ahmed, H.A.A. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Department of Physics, Faculty of Education, University of Khartoum, P.O. Box 321, 11115 Omdurman (Sudan); Swart, H.C., E-mail: swarthc@ufs.ac.za [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa)

2015-11-30

Graphical abstract: - Highlights: • Blue emitting Ca{sub 1−x}O:Bi{sub x=0.5%} phosphor powder was successfully prepared. • Strong blue near-UV emission was obtained. • Electron beam induced cathodoluminescence intensity degradation occurred. • XPS was successfully used to explain the degradation process. - Abstract: Ca{sub 1−x}O:Bi{sub x=0.5%} phosphor powder was successfully synthesized by the sol-gel combustion method. The structure, morphology and luminescent properties of the phosphor were characterized by X-ray diffraction, scanning electron microscopy, photoluminescence and cathodoluminescence (CL) spectroscopy. The results showed that the Ca{sub 1−x}O:Bi{sub x=0.5%} consisted of single face-centred cubic crystals and that the phosphor particles were uniformly distributed. When the phosphor was excited by a xenon lamp at 355 nm, or a 325 nm He–Cd laser, or electron beam, it emitted strongly in the blue near-UV range with a wavelength of 395 nm ({sup 3}P{sub 1} → {sup 1}S{sub 0} transition of Bi{sup 3+}). The CL intensity was monitored as a function of the accelerating voltage and also as a function of the beam current. The powder was also subjected to a prolonged electron beam irradiation to study the electron beam induced CL intensity degradation. X-ray photoelectron spectroscopy was used to analyze the Ca{sub 1−x}O:Bi{sub x=0.5%} phosphor sample surface before and after degradation.

Luminescence and excited state dynamics in Bi3+-doped LiLaP4O12 phosphates

International Nuclear Information System (INIS)

Babin, V.; Chernenko, K.; Demchenko, P.; Mihokova, E.; Nikl, M.; Pashuk, I.; Shalapska, T.; Voloshinovskii, A.; Zazubovich, S.

2016-01-01

Photo- and X-ray-excited luminescence characteristics of Bi-doped LiLaP 4 O 12 phosphates with different bismuth contents (from 1 to 25 at% in the melt) are investigated in the 4.2–300 K temperature range and compared with the characteristics of the undoped LiLaP 4 O 12 phosphate. The broad 2.95 eV emission band of LiLaP 4 O 12 :Bi excited around 5.4 eV is found to arise from the bismuth dopant. Relatively large FWHM and Stokes shift of the emission band and especially the data on the low-temperature decay kinetics of the 2.95 eV emission and its temperature dependence, indicating a very small spin-orbit splitting energy of the corresponding excited state, allow the conclusion that this emission arises from the radiative decay of the triplet state of an exciton localized around a Bi 3+ ion. No spectral bands are observed, arising from the electron transitions between the energy levels of Bi 3+ ions. Phenomenological model is proposed for the description of the excited state dynamics of the Bi 3+ -related localized exciton in LiLaP 4 O 12 :Bi and the parameters of the triplet localized exciton state are determined. Keywords: Photoluminescence; Time-resolved spectroscopy; Excited states; Bi 3+ centers; LiLaP 4 O 12 :Bi powders

Dosimetric properties of dysprosium doped lithium borate glass irradiated by 6 MV photons

International Nuclear Information System (INIS)

Ab Rasid, A.; Wagiran, H.; Hashim, S.; Ibrahim, Z.; Ali, H.

2015-01-01

Undoped and dysprosium doped lithium borate glass system with empirical formula (70–x) B 2 O 3 –30 Li 2 O–(x) Dy 2 O 3 (x=0.1, 0.3, 0.5, 0.7, 1.0 mol%) were prepared using the melt-quenching technique. The dosimetric measurements were performed by irradiating the samples to 6 MV photon beam using linear accelerator (LINAC) over a dose range of 0.5–5.0 Gy. The glass series of dysprosium doped lithium borate glass produced the best thermoluminescence (TL) glow curve with the highest intensity peak from sample with 1.0 mol% Dy 2 O 3 concentration. Minimum detectable dose was detected at 2.24 mGy, good linearity of regression coefficient, high reproducibility and high sensitivity compared to the undoped glass are from 1.0 mol% dysprosium doped lithium borate glass. The results indicated that the series of dysprosium doped lithium glasses have a great potential to be considered as a thermoluminescence dosimetry (TLD). - Highlights: • TL response of undoped and dysprosium doped lithium borate glass subjected to 6 MV photons irradiation at low dose range. • TL linear response of dysprosium doped lithium borate glass. • The sensitivity of dysprosium doped lithium borate glass is approximately 93 times higher than undoped glass

Study on superstructure in ion co-doped BiFeO3 by using transmission electron microscopy

Science.gov (United States)

Pu, Shi-Zhou; Guo, Chao; Li, Mei-Ya; Chen, Zhen-Lian; Zou, Hua-Min

2015-04-01

La3+ and V5+ co-doped BiFeO3 ceramics are synthesized by rapid liquid sintering technique. The modulated structure in Bi0.85La0.15Fe0.97V0.03O3 is investigated by using transmission electron microscopy (TEM). Two kinds of superstructures are observed in the samples. One is the component modulated superstructure and twin-domain, which is generated by La3+ ordered substitution for Bi3+ and frequently appears. The chemical composition of the superstructure is explored by x-ray energy dispersive spectroscopy (EDS). The model of the ordered structure is proposed. Simulation based on the model is conducted. The second is the fluorite-type δ-Bi2O3 related superstructure. The relation between the ferroelectric property and the microstructure of the sample is also discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 51372174, 11074193, and 51132001) and the Fundamental Research Funds for the Central Universities.

Fabrication of ZnS-Bi-TiO2 Composites and Investigation of Their Sunlight Photocatalytic Performance

Directory of Open Access Journals (Sweden)

Xuewei Dong

2014-01-01

Full Text Available The ZnS-Bi-TiO2 composites were prepared by the sol-gel method and were characterized by X-ray photoelectron spectroscopy (XPS, transmission electron microscopy (TEM, X-ray diffraction (XRD and UV-visible diffuse reflectance spectroscopy (UV-Vis DRS. It is found that the doped Bi as Bi4+/Bi3+ species existed in composites, and the introducing of ZnS enhanced further the light absorption ability of TiO2 in visible region and reduced the recombination of photogenerated electrons and holes. As compared to pure TiO2, the ZnS-Bi-TiO2 exhibited enhanced photodegradation efficiency under xenon lamp irradiation, and the kinetic constant of methyl orange removal with ZnS-Bi-Ti-0.005 (0.0141 min−1 was 3.9 times greater than that of pure TiO2 (0.0029 min−1, which could be attributed to the existence of Bi4+/Bi3+ species, the ZnS/TiO2 heterostructure.

Microstructural and thermoelectric properties of p-type Te-doped Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} and n-type SbI{sub 3}-doped Bi{sub 2}Te{sub 2.85}Se{sub 0.15} compounds

Energy Technology Data Exchange (ETDEWEB)

Seo, J; Park, K; Lee, C; Kim, J

1997-07-01

The p-type Te-doped Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} and n-type SbI{sub 3}-doped Bi{sub 2}Te{sub 2.85}Se{sub 0.15} thermoelectric compounds were fabricated by hot pressing in the temperature range of 380 to 440 C under 200 MPa in Ar. Both the compounds were highly dense and showed high crystalline quality. The grains of the compounds were preferentially oriented and contained many dislocations through the hot pressing. The fracture path followed the transgranular cleavage planes, which are perpendicular to the c-axis. In addition, with increasing the pressing temperature, the figure of merit was increased. The highest values of figure of merit for the p- and n-type compounds, which were obtained at 420 C, were 2.69 x 10{sup {minus}3}/K and 2.35 x 10{sup {minus}3}/K, respectively.

Visible-light-induced Ag/BiVO4 semiconductor with enhanced photocatalytic and antibacterial performance

Science.gov (United States)

Regmi, Chhabilal; Dhakal, Dipesh; Wohn Lee, Soo

2018-02-01

An Ag-loaded BiVO4 visible-light-driven photocatalyst was synthesized by the microwave hydrothermal method followed by photodeposition. The photocatalytic performance of the synthesized samples was evaluated on a mixed dye (methylene blue and rhodamine B), as well as bisphenol A in aqueous solution. Similarly, the disinfection activities of synthesized samples towards the Gram-negative Escherichia coli (E. coli) in a model cell were investigated under irradiation with visible light (λ ≥ 420 nm). The synthesized samples have monoclinic scheelite structure. Photocatalytic results showed that all Ag-loaded BiVO4 samples exhibited greater degradation and a higher mineralization rate than the pure BiVO4, probably due to the presence of surface plasmon absorption that arises due to the loading of Ag on the BiVO4 surface. The optimum Ag loading of 5 wt% has the highest photocatalytic performance and greatest stability with pseudo-first-order rate constants of 0.031 min-1 and 0.023 min-1 for the degradation of methylene blue and rhodamine B respectively in a mixture with an equal volume and concentration of each dye. The photocatalytic degradation of bisphenol A reaches 76.2% with 5 wt% Ag-doped BiVO4 within 180 min irradiation time. Similarly, the Ag-loaded BiVO4 could completely inactivate E. coli cells within 30 min under visible light irradiation. The disruption of the cell membrane as well as degradation of protein and DNA exhibited constituted evidence for antibacterial activity towards E. coli. Moreover, the bactericidal mechanisms involved in the photocatalytic disinfection process were systematically investigated.

Influence of La doping on structural and dielectric properties of SrBi2Nb2O9 ceramics

Science.gov (United States)

Verma, Maya; Sreenivas, K.; Gupta, Vinay

2009-01-01

Lanthanum doped SrBi2Nb2O9 ceramics with the chemical formula SrBi2-xLaxNb2O9 (SBLN) (x =0-0.5) have been prepared through conventional solid state route. X-ray diffraction reveals the shrinkage of unit cell of strontium bismuth niobate with incorporation of La3+ dopant, having no lone pair electrons. Shifting of Raman phonon modes indicates the reduced rattling space of NbO6 octahedra with increase in La doping concentration. Further, the softening of lowest frequency phonon mode with increasing x in SBLN shows the transition from ferroelectric to paraelectric at room temperature. The dielectric properties for all the compositions are studied as a function of temperature (25 to 500 °C) over the frequency range of 10 kHz-1 MHz. With increase in lanthanum doping concentration the phase transition becomes diffused and transition temperature gets shifted toward lower temperature. A phase transition from normal ferroelectric to paraelectric has been observed via relaxor-type ferroelectrics with increase in x. The frequency dependence of transition temperature was studied in terms of Vogel-Fulcher relation for SBLN (x =0.4).

Influence of La doping on structural and dielectric properties of SrBi2Nb2O9 ceramics

International Nuclear Information System (INIS)

Verma, Maya; Sreenivas, K.; Gupta, Vinay

2009-01-01

Lanthanum doped SrBi 2 Nb 2 O 9 ceramics with the chemical formula SrBi 2-x La x Nb 2 O 9 (SBLN) (x=0-0.5) have been prepared through conventional solid state route. X-ray diffraction reveals the shrinkage of unit cell of strontium bismuth niobate with incorporation of La 3+ dopant, having no lone pair electrons. Shifting of Raman phonon modes indicates the reduced rattling space of NbO 6 octahedra with increase in La doping concentration. Further, the softening of lowest frequency phonon mode with increasing x in SBLN shows the transition from ferroelectric to paraelectric at room temperature. The dielectric properties for all the compositions are studied as a function of temperature (25 to 500 deg. C) over the frequency range of 10 kHz-1 MHz. With increase in lanthanum doping concentration the phase transition becomes diffused and transition temperature gets shifted toward lower temperature. A phase transition from normal ferroelectric to paraelectric has been observed via relaxor-type ferroelectrics with increase in x. The frequency dependence of transition temperature was studied in terms of Vogel-Fulcher relation for SBLN (x=0.4)

Effect of 520 MeV Kr{sup 20+} ion irradiation on the critical current density of Bi-2212 single crystals

Energy Technology Data Exchange (ETDEWEB)

Terai, Takayuki; Ito, Yasuyuki [Tokyo Univ. (Japan). Faculty of Engineering; Kishio, Kouji

1996-10-01

Change in magnetic properties of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+y} (Bi-2212) single crystals due to Kr{sup 20+} ion irradiation is reported, focused on critical current density and irreversibility magnetic field. The Bi-2212 single crystal specimens (3x3x0.3 mm{sup 3}) were prepared by the floating zone method. Each specimen was irradiated with 520 MeV Kr{sup 20+} ions of 10{sup 10}-10{sup 11} cm{sup -2} in the fluence. Magnetic hysteresis was measured at 4.2K-60K with a vibrating sample magnetometer before and after irradiation. Very large enhancement was observed in critical current density and irreversibility magnetic field above 20K. (author)

Influence of cobalt doping on structural and magnetic properties of BiFeO{sub 3} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Khan, U. [Chinese Academy of Sciences, Institute of Physics (China); Adeela, N., E-mail: adeela16@gmail.com [Centre for High Energy Physics, University of the Punjab (Pakistan); Javed, K. [Chinese Academy of Sciences, Institute of Physics (China); Riaz, S. [Centre for Solid State Physics, University of the Punjab (Pakistan); Ali, H. [Chinese Academy of Sciences, Institute of Physics (China); Iqbal, M. [Centre for High Energy Physics, University of the Punjab (Pakistan); Han, X. F. [Chinese Academy of Sciences, Institute of Physics (China); Naseem, S., E-mail: shahzad-naseem@yahoo.com [Centre for Solid State Physics, University of the Punjab (Pakistan)

2015-11-15

Nanocrystalline cobalt-doped bismuth ferrites with general formula of BiFe{sub 1−δ}Co{sub δ}O{sub 3} (0 ≤ δ ≤ 0.1) have been synthesized using solution evaporation method. Structure and phase identification was performed with X-ray diffraction (XRD) technique. The results confirm the formation of rhombohedral-distorted Perovskite structure with R3c symmetry. A decrease in lattice parameters and an increase in X-ray density have been observed with increasing cobalt concentration in BiFeO{sub 3}. Particle size determined by transmission electron microscope was in good agreement with XRD, i.e., 39 nm. Room-temperature coercivity and saturation magnetization of nanoparticles were increased up to 7.5 % of cobalt doping. Low-temperature magnetic measurements of selected sample showed increasing behavior in saturation magnetization, coercivity, effective magnetic moments, and anisotropy constant. An increase in coercivity with decrease in temperature followed theoretical model of Kneller’s law, while modified Bloch’s model was employed for saturation magnetization in temperature range of 5–300 K.Graphical Abstract.

Characterization of standard reference material 2944, Bi-ion-doped glass, spectral correction standard for red fluorescence

International Nuclear Information System (INIS)

DeRose, Paul C.; Smith, Melody V.; Anderson, Jeffrey R.; Kramer, Gary W.

2013-01-01

Standard Reference Material (SRM) 2944 is a cuvette-shaped, Bi-ion-doped glass, recommended for optimal use for relative spectral correction of emission from 590 nm to 805 nm and day-to-day performance verification of steady-state fluorescence spectrometers. Properties of this standard that influence its effective use or contribute to the uncertainty in its certified emission spectrum were explored here. These properties include its photostability, absorbance, dissolution rate in water, anisotropy and temperature coefficient of fluorescence intensity. The expanded uncertainties (k=2) in the certified spectrum are about 4% around the nominal peak maximum at 704 nm and increase to about 6% at the wings, using an excitation wavelength of 515 nm. -- Highlights: ► The fluorescence emission spectrum of SRM 2944 was determined for spectral correction. ► This Bi-ion-doped glass has been certified in the fluorescence region from 530 nm to 830 nm. ► Fluorescence properties of the glass were determined, e.g., anisotropy, lifetime. ► SRM 2944 is photostable under common visible lamp excitation, when UV light is not present

Facile synthesis of surface N-doped Bi{sub 2}O{sub 2}CO{sub 3}: Origin of visible light photocatalytic activity and in situ DRIFTS studies

Energy Technology Data Exchange (ETDEWEB)

Zhou, Ying, E-mail: yzhou@swpu.edu.cn [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Xindu Rd. 8, Chengdu 610500 (China); The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Xindu Rd. 8, Chengdu 610500 (China); Insititute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe (Germany); Zhao, Ziyan [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Xindu Rd. 8, Chengdu 610500 (China); The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Xindu Rd. 8, Chengdu 610500 (China); Wang, Fang; Cao, Kun [The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Xindu Rd. 8, Chengdu 610500 (China); Doronkin, Dmitry E. [Insititute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe (Germany); Dong, Fan [College of Environmental and Biological Engineering, Chonqing Technology and Business University, Chongqing 400067 (China); Grunwaldt, Jan-Dierk, E-mail: grunwaldt@kit.edu [Insititute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe (Germany)

2016-04-15

Graphical abstract: Surfactant (CTAB) can induce nitrogen interstitially doping in the Bi{sub 2}O{sub 2}CO{sub 3} surface, leading to the formation of localized states from N−O bond, which probably account for the origin of the visible light activity. Moreover, the photocatalytic NO oxidation processes over Bi{sub 2}O{sub 2}CO{sub 3} were successfully monitored for the first time by in situ DRIFTS. - Highlights: • Interstitially doping N in the Bi{sub 2}O{sub 2}CO{sub 3} surface was achieved at room temperature. • N-doped Bi{sub 2}O{sub 2}CO{sub 3} exhibited significantly enhanced visible light photocatalytic activity compared to the pristine Bi{sub 2}O{sub 2}CO{sub 3}. • The formation of localized states from N−O bond could account for the visible light activity of Bi{sub 2}O{sub 2}CO{sub 3}. • The photocatalytic NO oxidation process was monitored by in situ DRIFTS. - Abstract: Bi{sub 2}O{sub 2}CO{sub 3} nanosheets with exposed {001} facets were prepared by a facile room temperature chemical method. Due to the high oxygen atom density in {001} facets of Bi{sub 2}O{sub 2}CO{sub 3}, the addition of cetyltrimethylammonium bromide (CTAB) does not only influence the growth of crystalline Bi{sub 2}O{sub 2}CO{sub 3}, but also modifies the surface properties of Bi{sub 2}O{sub 2}CO{sub 3} through the interaction between CTAB and Bi{sub 2}O{sub 2}CO{sub 3}. Nitrogen from CTAB as dopant interstitially incorporates in the Bi{sub 2}O{sub 2}CO{sub 3} surface evidenced by both experimental and theoretical investigations. Hence, the formation of localized states from N−O bond improves the visible light absorption and charge separation efficiency, which leads to an enhancement of visible light photocatalytic activity toward to the degradation of Rhodamine B (RhB) and oxidation of NO. In addition, the photocatalytic NO oxidation over Bi{sub 2}O{sub 2}CO{sub 3} nanosheets was successfully monitored for the first time using in situ diffuse reflectance infrared Fourier

Considerable photoluminescence enhancement of LiEu(MoO{sub 4}){sub 2} red phosphors via Bi and/or Si doping for white LEDs

Energy Technology Data Exchange (ETDEWEB)

Wang, Qing-Feng [Department of Materials Science and Engineering, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen, Guangdong 518055 (China); Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China); Liu, Ying [Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China); Wang, Yu [Department of Physics and Materials Science, City University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong); Wang, Wenxi; Wan, Yi [Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China); Wang, Gui-Gen [Department of Materials Science and Engineering, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen, Guangdong 518055 (China); Lu, Zhou-Guang [Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China)

2015-03-15

Graphical abstract: Doping of Bi and Si into the lattice leads to an considerable increase of the excitation efficiency and luminous intensity, and obvious movement of the CIE chromaticity coordinates to the NTSC standard values of the LiEu(MoO{sub 4}){sub 2}, a promising red phosphors suitable for near UV excited white-light emitting diodes. - Highlights: • High performance red phosphors for near UV light excited white LEDs. • Lithium lanthanide molybdate red phosphors. • Bi and Si substitution. • Considerable enhancement of luminescence intensity and excitation efficiency. • CIE chromaticity coordinates very close to the NTSC standard values. - Abstract: Novel Bi and/or Si substituted LiEu(MoO{sub 4}){sub 2} phosphors, where Bi was used as sensitizer to enhance the emission intensity and Si was used as substitution to improve the excitation efficiency, were prepared using the sol–gel method, and the photoluminescent properties of the resulting phosphors were intensively investigated. All samples can be excited efficiently by UV (395 nm) light and emit bright red light at 614 nm, which are coupled well with the characteristic emission from a UV-LED. In the Bi{sup 3+}-doped samples, the intensities of the main emission line ({sup 5}D{sub 0}–{sup 7}F{sub 2} transition at 614 nm) are strengthened because of the energy transition from Bi{sup 3+} to Eu{sup 3+}. With the substitution of Mo{sup 4+} by Si{sup 4+}, there are no significant changes in the emission peak positions, but the emission intensity was significantly enhanced under 395 nm excitation. Particularly, the LiEu{sub 0.9}Bi{sub 0.1}(Mo{sub 0.97}Si{sub 0.03}O{sub 4}){sub 2} phosphor doped with both Bi and Si demonstrates superior comprehensive photoluminescence properties with an excellent combination of easy excitation in the near UV range, bright emission intensity, high PL quantum efficiency as well as suitable decay time, which are very suitable for application as red phosphor for near UV

Facile synthesis of Bi/BiOCl composite with selective photocatalytic properties

International Nuclear Information System (INIS)

Chen, Dongling; Zhang, Min; Lu, Qiuju; Chen, Junfang; Liu, Bitao; Wang, Zhaofeng

2015-01-01

This paper presents a novel and facile method to fabricate Bi/BiOCl composites with dominant (001) facets in situ via a microwave reduction route. Different characterization techniques, including X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission scanning electron microscopy (TEM), UV–vis diffuse reflectance spectrometry (DRS), X-ray photoelectron spectroscopy (XPS), electron spin resonance spectroscopy (ESR), cathodoluminescence spectrum (CL), and lifetime, have been employed to investigate the structure, optical and electrical properties of the Bi/BiOCl composites. The experimental results show that the introduction of Bi particles can efficiently enhance the photocatalytic performance of BiOCl for the degradation of several dyes under ultraviolet (UV) light irradiation, especially for negative charged methyl orange (MO). Unlike the UV photocatalytic performance, such Bi/BiOCl composite shows higher degradation efficiency towards rhodamine B (RhB) than MO and methylene blue (MB) under visible light irradiation. This special photocatalytic performance can be ascribed to the synergistic effect between oxygen vacancies and Bi particles. This work provides new insights about the photodegradation mechanisms of MO, MB and RhB under UV and visible light irradiation, which would be helpful to guide the selection of an appropriate catalyst for other pollutants. - Highlights: • Bi/BiOCl composites were synthesized via a microwave reduction. • Tunable selectivity photocatalytic activity can be achieved. • Photodegradation mechanism under UV and visible light were proposed

Luminescence properties of pure and doped CaSO4 nanorods irradiated by 15 MeV e-beam

International Nuclear Information System (INIS)

Salah, Numan; Alharbi, Najlaa D.; Enani, Mohammad A.

2014-01-01

Calcium sulfate (CaSO 4 ) doped with proper activators is a highly sensitive phosphor used in different fields mainly for radiation dosimetry, lighting and display applications. In this work pure and doped nanorods of CaSO 4 were produced by the co-precipitation technique. Samples from this material doped with Ag, Cu, Dy, Eu and Tb were exposed to different doses of 15 MeV e-beam and studied for their thermoluminesence (TL) and photoluminescence (PL) properties. Color center formation leading to PL emissions were investigated before and after e-beam irradiation. The samples doped with rare earths elements (i.e. Dy, Eu and Tb) were observed to have thinner nanorods than the other samples and have higher absorption in the UV region. The Ag and Tb doped samples have poor TL response to e-beam, while those activated by Cu, Dy and Eu have strong glow peaks at around 123 °C. Quite linear response curves in the whole studied exposures i.e. 0.1–100 Gy were also observed in Cu and Dy doped samples. The PL results show that pure CaSO 4 nanorods have active color centers without irradiation, which could be enriched/modified by these impurities mainly rare earths and further enhanced by e-beam irradiation. Eu 3+ → Eu 2+ conversion is clearly observed in Eu doped sample after e-beam irradiation. These results show that these nanorods might be useful in lighting and display devices development

Doping evolution of the electronic structure in the single-layer cuprates Bi2Sr2−xLaxCuO6 delta: Comparison with other single-layer cuprates

Energy Technology Data Exchange (ETDEWEB)

Hashimoto, M.

2010-04-30

We have performed angle-resolved photoemission and core-level x-ray photoemission studies of the single-layer cuprate Bi{sub 2}Sr{sub 2-x}La{sub x}CuO{sub 6+{delta}} (Bi2201) and revealed the doping evolution of the electronic structure from the lightly-doped to optimally-doped regions. We have observed the formation of the dispersive quasi-particle band, evolution of the Fermi 'arc' into the Fermi surface and the shift of the chemical potential with hole doping as in other cuprates. The doping evolution in Bi2201 is similar to that in Ca{sub 2-x}Na{sub x}CuO{sub 2}Cl{sub 2} (Na-CCOC), where a rapid chemical potential shift toward the lower Hubbard band of the parent insulator has been observed, but is quite different from that in La{sub 2-x}Sr{sub x}CuO{sub 4} (LSCO), where the chemical potential does not shift, yet the dispersive band and the Fermi arc/surface are formed around the Fermi level already in the lightly-doped region. The (underlying) Fermi surface shape and band dispersions are quantitatively analyzed using tightbinding fit, and the deduced next-nearest-neighbor hopping integral t also confirm the similarity to Na-CCOC and the difference from LSCO.

Structural, Raman, and dielectric studies on multiferroic Mn-doped Bi 1-xLax FeO 3 ceramics

KAUST Repository

Xing, Zhibiao

2014-04-03

Multiferroic Bi1-xLaxFeO3 [BLFO (x)] ceramics with x = 0.10-0.50 and Mn-doped BLFO (x = 0.30) ceramics with different doping contents (0.1-1.0 mol%) were prepared by solid-state reaction method. They were crystallized in a perovskite phase with rhombohedral symmetry. In the BLFO (x) system, a composition (x)-driven structural transformation (R3c→C222) was observed at x = 0.30. The formation of Bi2Fe 4O9 impure phase was effectively suppressed with increasing the x value, and the rhombohedral distortion in the BLFO ceramics was decreased, leading to some Raman active modes disappeared. A significant red frequency shift (~13 cm-1) of the Raman mode of 232 cm-1 in the BLFO ceramics was observed, which strongly perceived a significant destabilization in the octahedral oxygen chains, and in turn affected the local FeO6 octahedral environment. In the Mn-doped BLFO (x = 0.30) ceramics, the intensity of the Raman mode near 628 cm-1 was increased with increasing the Mn-doping content, which was resulted from an enhanced local Jahn-Teller distortions of the (Mn,Fe)O6 octahedra. Electron microscopy images revealed some changes in the ceramic grain sizes and their morphologies in the Mn-doped samples at different contents. Wedge-shaped 71° ferroelectric domains with domain walls lying on the {110} planes were observed in the BLFO (x = 0.30) ceramics, whereas in the 1.0 mol% Mn-doped BLFO (x = 0.30) samples, 71° ferroelectric domains exhibited a parallel band-shaped morphology with average domain width of 95 nm. Dielectric studies revealed that high dielectric loss of the BLFO (x = 0.30) ceramics was drastically reduced from 0.8 to 0.01 (measured @ 104 Hz) via 1.0 mol% Mn-doping. The underlying mechanisms can be understood by a charge disproportion between the Mn4+ and Fe2+ in the Mn-doped samples, where a reaction of Mn4+ + Fe2+→Mn3+ + Fe3+ is taken place, resulting in the reduction in the oxygen vacancies and a suppression of the electron hopping from Fe3+ to Fe2+ ions

Structural, Raman, and dielectric studies on multiferroic Mn-doped Bi 1-xLax FeO 3 ceramics

KAUST Repository

Xing, Zhibiao; Zhu, Xinhua; Zhu, Jianmin; Liu, Zhiguo; Al-Kassab, Talaat

2014-01-01

Multiferroic Bi1-xLaxFeO3 [BLFO (x)] ceramics with x = 0.10-0.50 and Mn-doped BLFO (x = 0.30) ceramics with different doping contents (0.1-1.0 mol%) were prepared by solid-state reaction method. They were crystallized in a perovskite phase with rhombohedral symmetry. In the BLFO (x) system, a composition (x)-driven structural transformation (R3c→C222) was observed at x = 0.30. The formation of Bi2Fe 4O9 impure phase was effectively suppressed with increasing the x value, and the rhombohedral distortion in the BLFO ceramics was decreased, leading to some Raman active modes disappeared. A significant red frequency shift (~13 cm-1) of the Raman mode of 232 cm-1 in the BLFO ceramics was observed, which strongly perceived a significant destabilization in the octahedral oxygen chains, and in turn affected the local FeO6 octahedral environment. In the Mn-doped BLFO (x = 0.30) ceramics, the intensity of the Raman mode near 628 cm-1 was increased with increasing the Mn-doping content, which was resulted from an enhanced local Jahn-Teller distortions of the (Mn,Fe)O6 octahedra. Electron microscopy images revealed some changes in the ceramic grain sizes and their morphologies in the Mn-doped samples at different contents. Wedge-shaped 71° ferroelectric domains with domain walls lying on the {110} planes were observed in the BLFO (x = 0.30) ceramics, whereas in the 1.0 mol% Mn-doped BLFO (x = 0.30) samples, 71° ferroelectric domains exhibited a parallel band-shaped morphology with average domain width of 95 nm. Dielectric studies revealed that high dielectric loss of the BLFO (x = 0.30) ceramics was drastically reduced from 0.8 to 0.01 (measured @ 104 Hz) via 1.0 mol% Mn-doping. The underlying mechanisms can be understood by a charge disproportion between the Mn4+ and Fe2+ in the Mn-doped samples, where a reaction of Mn4+ + Fe2+→Mn3+ + Fe3+ is taken place, resulting in the reduction in the oxygen vacancies and a suppression of the electron hopping from Fe3+ to Fe2+ ions

Leakage current phenomena in Mn-doped Bi(Na,K)TiO_3-based ferroelectric thin films

International Nuclear Information System (INIS)

Walenza-Slabe, J.; Gibbons, B. J.

2016-01-01

Mn-doped 80(Bi_0_._5Na_0_._5)TiO_3-20(Bi_0_._5K_0_._5)TiO_3 thin films were fabricated by chemical solution deposition on Pt/TiO_2/SiO_2/Si substrates. Steady state and time-dependent leakage current were investigated from room temperature to 180 °C. Undoped and low-doped films showed space-charge-limited current (SCLC) at high temperatures. The electric field marking the transition from Ohmic to trap-filling-limited current increased monotonically with Mn-doping. With 2 mol. % Mn, the current was Ohmic up to 430 kV/cm, even at 180 °C. Modeling of the SCLC showed that all films exhibited shallow trap levels and high trap concentrations. In the regime of steady state leakage, there were also observations of negative differential resistivity and positive temperature coefficient of resistivity near room temperature. Both of these phenomena were confined to relatively low temperatures (below ∼60 °C). Transient currents were observed in the time-dependent leakage data, which was measured out to several hundred seconds. In the undoped films, these were found to be a consequence of oxygen vacancy migration modulating the electronic conductivity. The mobility and thermal activation energy for oxygen vacancies was extracted as μ_i_o_n ≈ 1.7 × 10"−"1"2 cm"2 V"−"1 s"−"1 and E_A_,_i_o_n ≈ 0.92 eV, respectively. The transient current displayed different characteristics in the 1 mol. % Mn-doped films which were not readily explained by oxygen vacancy migration.

Dielectric and magnetic properties of Ba-, La- and Pb-doped Bi0.8Gd0.1M0.1Fe0.9Ti0.1O3 perovskite ceramics

Directory of Open Access Journals (Sweden)

Radheshyam Rai

2014-04-01

Full Text Available The multiferroic Bi0.8Gd0.1M0.1Fe0.9Ti0.1O3, (where M = Ba (DB, La (DL and Pb (DP has been synthesized by using solid-state reaction technique. Effects of Ba, La and Pb substitution on the structure, electrical and ferroelectric properties of Bi0.8Gd0.1M0.1Fe0.9Ti0.1O3 samples have been studied by performing X-ray diffraction, dielectric and magnetic measurements. The crystal structures of the ceramic samples have a tetragonal phase. The vibrating sample magnetometer (VSM measurement shows a significant change in the magnetic properties of Ba-doped Bi0.8Gd0.1M0.1Fe0.9Ti0.1O3 as compared to La- and Pb-doped ceramics. It is seen that coercive field (HC and remanent magnetization (MR increases with Ba-doped ceramics but decreases for La- and Pb-doped ceramics.

Comparison of Sn-doped and nonstoichiometric vertical-Bridgman-grown crystals of the topological insulator Bi{sub 2}Te{sub 2}Se

Energy Technology Data Exchange (ETDEWEB)

Kushwaha, S. K., E-mail: kushwaha@princeton.edu; Gibson, Q. D.; Cava, R. J. [Department of Chemistry, Princeton University, Princeton, New Jersey 08544 (United States); Xiong, J.; Ong, N. P. [Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States); Pletikosic, I. [Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States); Condensed Matter Physics and Materials Science Department, Brookhaven National Lab, Upton, New York 11973 (United States); Weber, A. P. [National Synchrotron Light Source, Brookhaven National Lab, Upton, New York 11973 (United States); Fedorov, A. V. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Valla, T. [Condensed Matter Physics and Materials Science Department, Brookhaven National Lab, Upton, New York 11973 (United States)

2014-04-14

A comparative study of the properties of topological insulator Bi{sub 2}Te{sub 2}Se (BTS) crystals grown by the vertical Bridgeman method is described. Two defect mechanisms that create acceptor impurities to compensate for the native n-type carriers are compared: Bi excess, and light Sn doping. Both methods yield low carrier concentrations and an n-p crossover over the length of the grown crystal boules, but lower carrier concentrations and higher resistivities are obtained for the Sn-doped crystals, which reach carrier concentrations as low as 8 × 10{sup 14} cm{sup −3}. Further, the temperature dependent resistivities for the Sn-doped crystals display strongly activated behavior at high temperatures, with a characteristic energy of half the bulk band gap. The (001) cleaved Sn-doped BTS crystals display high quality Shubnikov de Haas (SdH) quantum oscillations due to the topological surface state electrons. Angle resolved photoelectron spectroscopy (ARPES) characterization shows that the Fermi energy (E{sub F}) for the Sn-doped crystals falls cleanly in the surface states with no interference from the bulk bands, which the Dirac point for the surface states lies approximately 60 meV below the top of the bulk valence band maximum, and allows for a determination of the bulk and surface state carrier concentrations as a function of Energy near E{sub F}. Electronic structure calculations that compare Bi excess and Sn dopants in BTS demonstrate that Sn acts as a special impurity, with a localized impurity band that acts as a charge buffer occurring inside the bulk band gap. We propose that the special resonant level character of Sn in BTS gives rise to the exceptionally low carrier concentrations and activated resistivities observed.

Gamma-ray irradiation resistance of silver doped GeS2–Ga2S3–AgI chalcohalide glasses

International Nuclear Information System (INIS)

Shen, W.; Baccaro, S.; Cemmi, A.; Ren, J.; Zhang, Z.; Zhou, Y.; Yang, Y.; Chen, G.

2014-01-01

Highlights: • The γ-ray irradiation resistance of Ag doped chalcohalide glasses (GeS 2 –Ga 2 S 3 –AgI) has been investigated. • The introduction of silver ions plays a specific role in the modification of the gamma-ray irradiation resistance of glasses. • The sulfur exerts an important effect on the photo-sensitivity of chalcogenide glasses. - Abstract: In the present work, series of silver doped Ge–Ga–S–AgI chalcohalide glasses have been prepared and their optical transmission spectra are compared before and after γ-ray irradiation at different doses. The differential transmission spectra of the irradiated samples with and without Ag doping have been compared to characterize the γ-ray irradiation induced red-shift of electronic absorption and formation of color centers. Ag doping plays an important role in increasing γ-ray irradiation resistance of the chalcohalide glasses due to its specific effect on the valence band and the network structure of glasses

Ultra-low carrier concentration and surface-dominant transport in antimony-doped Bi2Se3 topological insulator nanoribbons

KAUST Repository

Hong, Seung Sae; Cha, Judy J.; Kong, Desheng; Cui, Yi

2012-01-01

A topological insulator is the state of quantum matter possessing gapless spin-locking surface states across the bulk band gap, which has created new opportunities from novel electronics to energy conversion. However, the large concentration of bulk residual carriers has been a major challenge for revealing the property of the topological surface state by electron transport measurements. Here we report the surface-state-dominant transport in antimony-doped, zinc oxide-encapsulated Bi2Se3 nanoribbons with suppressed bulk electron concentration. In the nanoribbon with sub-10-nm thickness protected by a zinc oxide layer, we position the Fermi levels of the top and bottom surfaces near the Dirac point by electrostatic gating, achieving extremely low two-dimensional carrier concentration of 2×10 11cm-2. The zinc oxide-capped, antimony-doped Bi 2Se3 nanostructures provide an attractive materials platform to study fundamental physics in topological insulators, as well as future applications. © 2012 Macmillan Publishers Limited. All rights reserved.

Ultra-low carrier concentration and surface-dominant transport in antimony-doped Bi2Se3 topological insulator nanoribbons

KAUST Repository

Hong, Seung Sae

2012-03-27

A topological insulator is the state of quantum matter possessing gapless spin-locking surface states across the bulk band gap, which has created new opportunities from novel electronics to energy conversion. However, the large concentration of bulk residual carriers has been a major challenge for revealing the property of the topological surface state by electron transport measurements. Here we report the surface-state-dominant transport in antimony-doped, zinc oxide-encapsulated Bi2Se3 nanoribbons with suppressed bulk electron concentration. In the nanoribbon with sub-10-nm thickness protected by a zinc oxide layer, we position the Fermi levels of the top and bottom surfaces near the Dirac point by electrostatic gating, achieving extremely low two-dimensional carrier concentration of 2×10 11cm-2. The zinc oxide-capped, antimony-doped Bi 2Se3 nanostructures provide an attractive materials platform to study fundamental physics in topological insulators, as well as future applications. © 2012 Macmillan Publishers Limited. All rights reserved.

High multi-photon visible upconversion emissions of Er3+ singly doped BiOCl microcrystals: A photon avalanche of Er3+ induced by 980 nm excitation

International Nuclear Information System (INIS)

Li, Yongjin; Song, Zhiguo; Li, Chen; Wan, Ronghua; Qiu, Jianbei; Yang, Zhengwen; Yin, Zhaoyi; Yang, Yong; Zhou, Dacheng; Wang, Qi

2013-01-01

Under 980 nm excitation, high multi-photon upconversion (UC) emission from the 2 H 11/2 / 4 S 3/2 (green) and 4 F 9/2 (red) levels of Er 3+ ions were observed from Er 3+ singly doped BiOCl microcrystals. These high-energy excited states were populated by a three to ten photon UC process conditionally, which depended on the pump power density and the Er 3+ ion doping concentration, characterizing as a hetero-looping enhanced energy transfer avalanche UC process. UC emission lifetime and Raman analysis suggest that the unusual UC phenomena are initiated by the new and intense phonon vibration modes of BiOCl lattices due to Er 3+ ions doping

Structural study, photoluminescence, and photocatalytic activity of semiconducting BaZrO{sub 3}:Bi nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Borja-Urby, R. [Grupo de Espectroscopia de Materiales Avanzados y Nanoestructurados (EMANA), Centro de Investigaciones en Optica A.C., Leon, Gto 37150 (Mexico); Diaz-Torres, L.A., E-mail: ditlacio@cio.mx [Grupo de Espectroscopia de Materiales Avanzados y Nanoestructurados (EMANA), Centro de Investigaciones en Optica A.C., Leon, Gto 37150 (Mexico); Salas, P. [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, A.P. 1-1010, Queretaro 76000 (Mexico); Moctezuma, E. [Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi, Av. Manuel Nava 6, San Luis Potosi, S.L.P., Mexico 78290 (Mexico); Vega, M. [Centro de Geociencias-UNAM, A.P. 1-1010, Queretaro 76000 (Mexico); Angeles-Chavez, C. [Instituto Mexicano del Petroleo, Ciudad de Mexico, D.F. 07730 (Mexico)

2011-10-25

Wide band gap nanocrystalline bismuth doped barium zirconate is synthesized by a facile hydrothermal method at 100 deg. C. The obtained cubic perovskites are characterized by powder X-ray diffraction (XRD), UV-VIS diffuse reflectance spectroscopy, photoluminescence (PL) spectroscopy, and photocatalytic activity. The estimated band gap in the 2.4-4.9 eV range, depending on Bi concentration, suggests nanocrystalline BaZrO{sub 3}:Bi as a useful visible-light activated photocatalyst under excitation wavelengths <800 nm. Displacement of main XRD pattern peaks suggest that bismuth ion mostly substitutes into Zr{sup 4+} sites within the BaZrO{sub 3} host lattice. It is found that BaZrO{sub 3}:Bi decomposes methylene blue (MB) under both UV and visible light irradiation. The photocatalyst efficiency depends strongly on Bi content and induced defects.

Polymorphism and properties of Bi{sub 2}WO{sub 6} doped with pentavalent antimony

Energy Technology Data Exchange (ETDEWEB)

Kharitonova, E.P.; Belov, D.A. [M.V. Lomonosov Moscow State University, Leninskie Gory, 119991 Moscow (Russian Federation); Gagor, A.B.; Pietraszko, A.P. [W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-950 Wrocław (Poland); Alekseeva, O.A. [Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninsky pr. 59, 119333 Moscow (Russian Federation); Voronkova, V.I., E-mail: voronk@polly.phys.msu.ru [M.V. Lomonosov Moscow State University, Leninskie Gory, 119991 Moscow (Russian Federation)

2014-04-05

Highlights: • The limit of Bi{sub 2}W{sub 1−x}Sb{sub x}O{sub 6−y} solid solutions is at x = 0.05. • Bi{sub 2}W{sub 1−x}Sb{sub x}O{sub 6−y} does not fully transform into high-temperature monoclinic phase. • Sb{sup 5+} has a weak effect on the temperatures of the ferroelectric transitions. • γ→γ{sup ‴} transition near 650 °C was observed as strong permittivity peak at 0.01–8 Hz. • The conductivity of Bi{sub 2}W{sub 0.96}Sb{sub 0.04}O{sub 6−y} at 800 °C reaches 0.02 S/cm. -- Abstract: Antimony-containing solid solutions isostructural with bismuth tungstate, Bi{sub 2}WO{sub 6}, have been prepared in air as polycrystalline samples by solid-state reactions and as single crystals by unseeded flux growth. The antimony in the solid solutions is in a pentavalent state and substitutes for tungsten in the structure of Bi{sub 2}WO{sub 6}. The Bi{sub 2}W{sub 1−x}Sb{sub x}O{sub 6−y} solid solutions have been shown to exist in the composition range 0 ⩽ x ⩽ 0.05. We have examined the effect of Sb{sup 5+} doping on the polymorphism and properties of Bi{sub 2}WO{sub 6}. In contrast to undoped Bi{sub 2}WO{sub 6}, antimony-substituted bismuth tungstate does not completely transform into its high-temperature, monoclinic phase at 960 °C and remains two-phase up to temperatures approaching its melting point. Antimony substitution for tungsten has a weak effect on the temperatures of the ferroelectric phase transitions. Heterovalent substitution of Sb{sup 5+} for W{sup 6+} is accompanied by the formation of extra oxygen vacancies and an increase in the electrical conductivity of the solid solutions by one to two orders of magnitude relative to undoped Bi{sub 2}WO{sub 6}.

High energy electron irradiation effects on Ga-doped ZnO thin films for optoelectronic space applications

Science.gov (United States)

Serrao, Felcy Jyothi; Sandeep, K. M.; Bhat, Shreesha; Dharmaprakash, S. M.

2018-03-01

Gallium-doped ZnO (GZO) thin films of thickness 394 nm were prepared by a simple, cost-effective sol-gel spin coating method. The effect of 8 MeV electron beam irradiation with different irradiation doses ranging from 0 to 10 kGy on the structural, optical and electrical properties was investigated. Electron irradiation influences the changes in the structural properties and surface morphology of GZO thin films. X-ray diffraction analysis showed that the polycrystalline nature of the GZO films is unaffected by the high energy electron irradiation. The grain size and the surface roughness were found maximum for the GZO film irradiated with 10 kGy electron dosage. The average transmittance of GZO thin films decreased after electron irradiation. The optical band gap of Ga-doped ZnO films was decreased with the increase in the electron dosage. The electrical resistivity of GZO films decreased from 4.83 × 10-3 to 8.725 × 10-4 Ω cm, when the electron dosage was increased from 0 to 10 kGy. The variation in the optical and electrical properties in the Ga-doped ZnO thin films due to electron beam irradiation in the present study is useful in deciding their compatibility in optoelectronic device applications in electron radiation environment.

Growth and properties of oxygen- and ion-doped Bi2Sr2CaCu2O8+δ single crystals

Science.gov (United States)

Mitzi, D. B.; Lombardo, L. W.; Kapitulnik, A.; Laderman, S. S.; Jacowitz, R. D.

1990-04-01

A directional solidification method for growing large single crystals in the Bi2Sr2CaCu2O8+δ system is reported. Ion doping, with replacement of La for Sr and Y for Ca, as well as oxygen doping in these crystals has been explored. Doped and undoped crystals have been characterized using microprobe analysis, x-ray diffraction, thermogravimetric analysis, and magnetic and Hall measurements. Ion doping results in little change of the superconducting transition for substitution levels below 20-25%, while beyond this level the Meissner signal broadens and the low-temperature Meissner signal decreases. Microprobe analysis and x-ray diffraction performed on these more highly substituted single crystals provide evidence for inhomogeneity and phase segregation into regions of distinct composition. Annealing unsubstituted crystals in increasing partial pressures of oxygen reversibly depresses the superconducting transition temperature from 90 (as made) to 77 K (oxygen pressure annealed), while the carrier concentrations, as determined from Hall effect measurements, increase from n=3.1(3)×1021 cm-3 (0.34 holes per Cu site) to 4.6(3)×1021 cm-3 (0.50 holes per Cu site). No degradation of the Meissner transition or other indications of inhomogeneity or phase segregation with doping are noted, suggesting that oxygen-doped Bi2Sr2CaCu2O8+δ is a suitable system for pursuing doping studies. The decrease in Tc with concentration for 0.34<=n<=0.50 indicates that a high-carrier-concentration regime exists in which Tc decreases with n and suggests that this decrease does not arise from material inhomogeneity or other materials problems. An examination of the variation of Tc with the density of states and lattice constants for all of the doped and undoped superconducting samples considered here indicates that changes in Tc with doping are primarily affected by changes in the density of states (or carrier concentration) rather than by structural variation induced by the doping.

Hydrocracking of cumene over Ni/Al 2O 3 as influenced by CeO 2 doping and γ-irradiation

Science.gov (United States)

El-Shobaky, G. A.; Doheim, M. M.; Ghozza, A. M.

2004-01-01

Cumene hydrocracking was carried out over pure and doped Ni/Al 2O 3 solids and also, on these solids after exposure to different doses of γ-rays between 0.4 and 1.6 MGy. The dopant concentration was varied between 1 and 4 mol% CeO 2. Pure and doped samples were subjected to heat treatment at 400°C and cumene hydrocracking reaction was carried out using various solids at temperatures between 250°C and 400°C by means of micropulse technique. The results showed that both CeO 2 doping and γ-irradiation of the investigated system brought about an increase in its specific surface area. γ-irradiation of pure samples increased their catalytic activities effectively. However, the doping caused a decrease in the catalytic activity. γ-irradiation of the doped samples brought about a net decrease in the catalytic activity. The catalytic reaction products over different investigated solids were ethylbenzene as a major product together with different amounts of toluene, benzene and C 1-C 3 gaseous hydrocarbons. The selectivity towards the formation of various reaction products varies with the reaction temperature, doping and γ-irradiation.

Investigations on Raman and X-ray photoemission scattering patterns of vanadium-doped SrBi4Ti4O15 ferroelectric ceramics

International Nuclear Information System (INIS)

Zhu, Jun; Chen, Xiao-Bing; He, Jun-hui; Shen, Jian-Cang

2007-01-01

Vanadium incorporation in SrBi 4 Ti 4 O 15 results in an improvement of electric properties. Raman scattering reveals that V-addition brings about the local disorders of structure, charge, and internal stress. The chemical valence of Bi and Ti does not increase after V-doping. The electric property improvement is originated from the restraint of oxygen vacancies, mobility weakening of the defects, and the vacancies produced at A-site

Photoelectrochemical performance of multi-layered BiOx–TiO2/Ti electrodes for degradation of phenol and production of molecular hydrogen in water

International Nuclear Information System (INIS)

Park, Hyunwoong; Bak, Ayoung; Ahn, Yong Yoon; Choi, Jina; Hoffmannn, Michael R.

2012-01-01

Highlights: ► We demonstrated that the electrocatalytic performance of BiO x –TiO 2 anodes for the degradation of aqueous phenol could be highly boosted by light irradiation. ► Although BiO x –TiO 2 anodes have been originally developed as the electrocatalytic anodes that operate in the absence of light by degeneratively doping Bi in TiO 2 , the presence of TiO 2 made them retain photoelectrocatalytic activity as well. ► Such dual functionality of BiO x –TiO 2 electrodes with high synergy effects may be directly used for water treatment with simultaneous hydrogen production from water. - Abstract: Multi-layered BiO x –TiO 2 electrodes were used for the oxidation of chemical contaminants coupled with the production of H 2 characterized by a synergistic enhancement. The BiO x –TiO 2 electrodes were composed of a mixed-metal oxide array involving an under layer of TaO x –IrO x , a middle layer of BiO x –SnO 2 , and a top layer of BiO x –TiO 2 deposited in a series on both sides of Ti foil. Cyclic voltammograms showed that the BiO x –TiO 2 electrodes had an electrocatalytic activity for oxidation of phenol that was enhanced by 70% under illumination with AM 1.5 light. When the BiO x –TiO 2 anode was coupled with a stainless steel cathode in a Na 2 SO 4 electrolyte with phenol and irradiated with UV light at an applied DC voltage, the anodic phenol oxidation rate and the cathodic H 2 production rates were enhanced by factors of four and three, respectively, as compared to the sum of each light irradiation and direct DC electrolysis. These synergistic effects depend on the specific electrode composition and decrease on TaO x –IrO x and BiO x –SnO 2 anodes in the absence of a top layer of BiO x –TiO 2 . These results indicate that the BiO x –TiO 2 layer functions as the key photo-electrocatalyst. The heavy doping level of Bi (25 mol%) in TiO 2 increases the electric conductivity of the parent TiO 2 .

Influence of Co doping on structural, optical and magnetic properties of BiFeO3 films deposited on quartz substrates by sol-gel method

Science.gov (United States)

Peng, Lin; Deng, Hongmei; Tian, Jianjun; Ren, Qing; Peng, Cheng; Huang, Zhipeng; Yang, Pingxiong; Chu, Junhao

2013-03-01

Multiferroic BiFe1-xCoxO3 (x = 0, 0.03, 0.05, 0.1) thin films have been prepared on quartz substrates using a sol-gel technique. X-ray diffraction data confirms that Co atoms have been successfully incorporated into the host lattice. The scanning electron microscopy (SEM) exhibits that the surface morphologies of BiFe0.97Co0.03O3 and BiFe0.95Co0.05O3 thin films become more compact and uniform. With increasing Co dopant, the position of A1-1 and E-4 modes shift towards the lower wavenumber indicates that Co doping induces structural distortion of BiFeO3. With increasing Co composition, the fundamental absorption edges of BiFe1-xCoxO3 films show red shift. Furthermore, transmittance spectra demonstrates that the optical band gap of BiFe1-xCoxO3 films decreases from 2.66 eV to 2.53 eV with the increase of Co from x = 0 to 0.1. At the wavelength of 720 nm, the refractive index decreases and the extinction coefficient increases with increasing the amount of Co. Optical properties reveal that Co doping in BiFeO3 provides preliminary research for optoelectronic devices and infrared detectors. Compared with BiFeO3 prepared under similar conditions, the remanent magnetization Mr of BiFe1-xCoxO3 (x = 0.03, 0.05, 0.1) thin films significantly enhanced, which provides potential applications in information storage.

Scintillation properties and X-ray irradiation hardness of Ce3+-doped Gd2O3-based scintillation glass

International Nuclear Information System (INIS)

Liu, Liwan; Shao, Chongyun; Zhang, Yu; Liao, Xili; Yang, Qiuhong; Hu, Lili; Chen, Danping

2016-01-01

Ce 3+ -doped Gd 2 O 3 -based scintillation glasses are prepared within an air or CO atmosphere. The effects of fluorine, lutetium, barium, and the melting atmosphere on the optical properties, scintillation properties and irradiation hardness are studied. Absorption spectra, luminescence spectra under UV and X-ray excitation, and the X-ray radiation-induced spectra are presented. The results show that the density can be increased by doping with fluorine, lutetium and barium. The luminescence intensity decreases after X-ray irradiation. Because of charge transfer quenching, fluorine and lutetium enhance the UV-excited and X-ray excited luminescence intensity, but barium decreases. Moreover, fluorine and lutetium are advantageous to irradiation hardness while barium is not. In addition, a non-reducing atmosphere provides a higher irradiation hardness than a reducing atmosphere. Fluorine-doped glass is promising to enhance luminescence intensity, promote irradiation hardness, and increase the density.

Red, yellow, blue and green emission from Eu3+, Dy3+ and Bi3+ doped Y2O3 nanophosphors

International Nuclear Information System (INIS)

Loitongbam, Romeo Singh; Rameshwor Singh, W.

2014-01-01

Rare earth elements (RE = Eu 3+ and Dy 3+ ) and Bi 3+ doped Y 2 O 3 nanoparticles were synthesized by urea hydrolysis method in ethylene glycol, which acts as reaction medium as well as capping agent, at a low temperature (140℃), followed by calcination of the obtained product. Scanning electron microscopy (SEM) images reveal that a highly uniform ovoid shaped Y 2 O 3 nanoparticles of around 100 nm size range were obtained in this method. The respective RE and Bi 3+ doped Y 2 O 3 precursor nanoparticles when heated at 600 and 750℃, retains the same shape as that of the as-synthesized Y 2 O 3 precursor samples. XRD pattern reveals the crystalline nature of the heated nanoparticles and indicate the absence of any impurity phase other than cubic Y 2 O 3

Defect properties of Sb- and Bi-doped CuInSe{sub 2}: The effect of the deep lone-pair s states

Energy Technology Data Exchange (ETDEWEB)

Park, Ji-Sang; Yang, Ji-Hui; Ramanathan, Kannan; Wei, Su-Huai, E-mail: Suhuai.Wei@nrel.gov [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)

2014-12-15

Bi or Sb doping has been used to make better material properties of polycrystalline Cu{sub 2}(In,Ga)Se{sub 2} as solar cell absorbers, including the experimentally observed improved electrical properties. However, the mechanism is still not clear. Using first-principles method, we investigate the stability and electronic structure of Bi- and Sb-related defects in CuInSe{sub 2} and study their effects on the doping efficiency. Contrary to previous thinking that Bi or Sb substituted on the anion site, we find that under anion-rich conditions, the impurities can substitute on cation sites and are isovalent to In because of the formation of the impurity lone pair s states. When the impurities substitute for Cu, the defects act as shallow double donors and help remove the deep In{sub Cu} level, thus resulting in the improved carrier life time. On the other hand, under anion-poor conditions, impurities at the Se site create amphoteric deep levels that are detrimental to the device performance.

Tailoring the piezoelectric and relaxor properties of (Bi1/2 Na1/2) TiO3- BaTiO3 via zirconium doping

DEFF Research Database (Denmark)

Glaum, Julia; Simons, Hugh; Acosta, Matias

2013-01-01

This article details the influence of zirconium doping on the piezoelectric properties and relaxor characteristics of 94(Bi1/2Na1/2)TiO3-6Ba(ZrxTi1-x)O3 (BNT-6BZT) bulk ceramics. Neutron diffraction measurements of BNT-6BZT doped with 0%-15% Zr revealed an electric-field-induced transition...

Room temperature ferromagnetism with large magnetic moment at low field in rare-earth-doped BiFeO₃ thin films.

Science.gov (United States)

Kim, Tae-Young; Hong, Nguyen Hoa; Sugawara, T; Raghavender, A T; Kurisu, M

2013-05-22

Thin films of rare earth (RE)-doped BiFeO3 (where RE=Sm, Ho, Pr and Nd) were grown on LaAlO3 substrates by using the pulsed laser deposition technique. All the films show a single phase of rhombohedral structure with space group R3c. The saturated magnetization in the Ho- and Sm-doped films is much larger than the values reported in the literature, and is observed at quite a low field of 0.2 T. For Ho and Sm doping, the magnetization increases as the film becomes thinner, suggesting that the observed magnetism is mostly due to a surface effect. In the case of Nd doping, even though the thin film has a large magnetic moment, the mechanism seems to be different.

Polar-antipolar transition and weak ferromagnetism in Mn-doped Bi0.86La0.14FeO3

Science.gov (United States)

Khomchenko, V. A.; Karpinsky, D. V.; Troyanchuk, I. O.; Sikolenko, V. V.; Többens, D. M.; Ivanov, M. S.; Silibin, M. V.; Rai, R.; Paixão, J. A.

2018-04-01

Having been considered as a prime example of a room-temperature magnetoelectric multiferroic, BiFeO3 continues to attract much interest. Since functional properties of this material can be effectively influenced by chemical, electrical, magnetic, mechanical and thermal stimuli, it can serve as a model for the investigation of cross-coupling phenomena in solids. Special attention is currently paid to the study of chemical pressure-driven magneto-structural transformations. In this paper, we report on the effect of the Mn doping on the crystal structure and magnetic behavior of the Bi1‑x La x FeO3 multiferroics near their polar-antipolar (antiferromagnetic-weak ferromagnetic) phase boundary. Synchrotron x-ray and neutron powder diffraction measurements of the Bi0.86La0.14Fe1‑x Mn x O3 (x  =  0.05, 0.1, 0.15) compounds have been performed. The diffraction data suggest that the Mn substitution results in the suppression of the ferroelectric polarization and gives rise to the appearance of the antiferroelectric (generally, PbZrO3-related) phase characteristic of the phase diagrams of the Bi1‑x RE x FeO3 (RE  =  rare-earth) systems. Depending on the Mn concentration (determining phase composition of the Bi0.86La0.14Fe1‑x Mn x O3 samples at room temperature), either complete or partial revival of the polar phase can be observed with increasing temperature. Magnetic measurements of the samples indicate that the Mn doping affects the stability of the cycloidal antiferromagnetic order specific to the polar phase, thus resulting in the formation of a ferroelectric and weak ferromagnetic state.

Effect of alkaline earth metal doping on thermal, optical, magnetic and dielectric properties of BiFeO3 nanoparticles

International Nuclear Information System (INIS)

Bhushan, B; Das, D; Basumallick, A; Bandopadhyay, S K; Vasanthacharya, N Y

2009-01-01

Substrate-free pure-phase BiFeO 3 (BFO) nanoparticles doped with alkaline earth metals (Ba, Sr and Ca) have been synthesized by a sol-gel route and their thermal, optical, dielectric and magnetic properties are discussed. The characteristic structural phase transitions of BFO nanoparticles are found to occur at much lower temperatures. A reduction of the Neel temperature has been observed in the doped samples in comparison with the pristine one, whereas the band gap shows a reverse trend. Iron was found to be only in the Fe 3+ valence state in all the doped samples. Magnetoelectric coupling is seen in our samples. Weak ferromagnetism is observed at room temperature in all of the doped and undoped BFO nanoparticles with the largest value of coercive field ∼1.78 kOe and saturation magnetization ∼2.38 emu g -1 for Ba and Ca doped BFO nanoparticles, respectively.

Effect of yttrium doping on structural and electrical properties of Bi2Sr1.9Ca0.1−xYxCu2O7+δ (Bi-2202 cuprate ceramics

Directory of Open Access Journals (Sweden)

Yazid Boudjadja

2016-09-01

Full Text Available In this work, we report on the effect of Y3+ doping on structural, mechanical and electrical properties of Bi-2202 phase. Samples of Bi2Sr1.9Ca0.1−xYxCu2O7+δ with x = 0, 0.025, 0.05, 0.075 and 0.10 are elaborated in air by conventional solid state reaction and characterized by X-ray diffraction (XRD, scanning electronic microscopy (SEM combined with EDS spectroscopy, density, Vickers microhardness and resistivity measurements. A good correlation between the variations of the bulk density and the Vickers microhardness with doping is obtained. The SEM photograph shows that the samples are composed of grains with a flat shape that characterizes the Bi-based cuprates. Quantitative EDS analysis confirms the reduction of Ca content and the increase of Y content when x is increased. The variation of resistivity with temperature shows that only samples with x = 0, 0.025 and 0.05 present an onset transition to the superconducting state. The higher onset transition temperature is obtained for x = 0.025 and is about 93.62 K. The transition is wide and is realized in two steps confirming then the presence of the low Tc Bi-2201 phase in the samples. For x = 0.075 and 0.10, a transition to a semiconducting state is seen at low temperatures. Some physical parameters are extracted from these curves and discussed.

Germanium-doped gallium phosphide obtained by neutron irradiation

Science.gov (United States)

Goldys, E. M.; Barczynska, J.; Godlewski, M.; Sienkiewicz, A.; Heijmink Liesert, B. J.

1993-08-01

Results of electrical, optical, electron spin resonance and optically detected magnetic resonance studies of thermal neutron irradiated and annealed at 800 °C n-type GaP are presented. Evidence is found to support the view that the main dopant introduced via transmutation of GaP, germanium, occupies cation sites and forms neutral donors. This confirms the possibility of neutron transmutation doping of GaP. Simultaneously, it is shown that germanium is absent at cation sites. Presence of other forms of Ge-related defects is deduced from luminescence and absorption data. Some of them are tentatively identified as VGa-GeGa acceptors leading to the self-compensation process. This observation means that the neutron transmutation as a doping method in application to GaP is not as efficient as for Si.

Shielding behavior of V2O5 doped lead borate glasses towards gamma irradiation

International Nuclear Information System (INIS)

Ghoneim, N.A.; ElBatal, H.A.; Abdelghany, A.M.; Ali, I.S.

2011-01-01

Highlights: → Base lead borate glass together with samples of the same composition doped with varying V 2 O 5 contents were prepared. → UV-visible and infrared spectroscopy were measured before and after successive gamma irradiation. → Glass samples are observed to absorb strongly in the UV. → Infrared absorption spectra indicate the presence of both triangular and tetrahedral borate groups besides the sharing of lead ions in network forming and network modifying sites. - Abstract: Undoped lead borate glass of the composition PbO 70%-B 2 O 3 30% together with samples of the same composition and doped with varying V 2 O 5 contents were prepared. UV-visible absorption spectra were measured out in the range 200-1500 nm before and after successive gamma irradiation. Infrared absorption measurements within the range 4000-400 cm -1 were carried out for the undoped and V 2 O 5 doped samples before gamma irradiation and after being irradiated with a dose of 6 Mrad. All the glass samples are observed to absorb strongly in the UV region due to the combined contributions of absorption due to trace iron impurities and that from the divalent lead Pb 2+ ions. The V 2 O 5 -doped glasses reveal extra visible absorption bands which are attributed to the existence of V 3+ ions in measurable content but not neglecting the other valence states of vanadium ions (V 4+ , V 5+ ). Infrared absorption spectra indicate the presence of both triangular and tetrahedral borate groups besides the sharing of lead ions in network forming and network modifying sites.

Thermoluminescence properties of undoped and Tb3+ and Ce3+ doped YAG nanophosphor under UV-, X- and β-ray irradiation

International Nuclear Information System (INIS)

Rosa, E. de la; Rodriguez, R.A.; Melendrez, R.; Salas, P.; Diaz-Torres, L.A.; Barboza-Flores, M.

2007-01-01

The thermoluminescence (TL) properties of undoped, Ce 3+ and Tb 3+ doped Y 3 Al 5 O 12 (YAG) nanocrystals under UV-, X- and β-rays irradiation is reported. The TL signal of undoped and doped samples indicates a high sensitivity to UV-, X- and β-ray irradiation. The introduction of the doping ions induces changes in the trapping processes and the TL efficiency. The results show that both undoped and doped YAG nanocrystalline phosphor present good TL efficiency as well as good dose response which qualify them as a potential UV-, X- and β-ray dosimeter. A linear response under X-ray irradiation is observed for low doses level in the 0.02-1.02 μGy range and for relatively high doses level of β-ray irradiation in the range from 10 to 600 Gy

Thermoelectric transport properties of BaBiTe{sub 3}-based materials

Energy Technology Data Exchange (ETDEWEB)

Zhou, Yiming; Zhao, Li-Dong, E-mail: zhaolidong@buaa.edu.cn

2017-05-15

BaBiTe{sub 3}, a material with low thermal conductivity, is an inferior thermoelectric material due to the poor electrical properties originated from its narrow band gap. We choose two types of dopants, K and La, trying to optimize its electrical transport properties. The minority carriers, which harm the Seebeck coefficient in this system, are suppressed by La doping. With the increase of both electrical conductivity and Seebeck coefficient, the power factor of 3% La doped BaBiTe{sub 3} reaches 3.7 μW cm{sup −1} K{sup −2} which increased by 40% from undoped BaBiTe{sub 3}. Besides high power factor, the thermal conductivity is also reduced in it. Eventually, a high ZT value, 0.25 at 473 K, for n-type BaBiTe{sub 3} is achieved in 3% La doped BaBiTe{sub 3}. - Graphical abstract: BaBiTe{sub 3} possesses a low thermal conductivity. However, it is an inferior thermoelectric material due to the poor electrical properties originated from its narrow band gap. A high ZT value of 0.25 at 473 K for n-type BaBiTe{sub 3} can be achieved through optimizing electrical transport properties via La doping. - Highlights: • BaBiTe{sub 3} is an analogue of these promising thermoelectric materials: such as CsBi{sub 4}Te{sub 6} and K{sub 2}Bi{sub 8}Se{sub 13}, etc. • BaBiTe{sub 3} possesses a low thermal conductivity. • La is an effective dopant to enhance electrical transport properties. • A high ZT value of 0.25 at 473 K can be achieved in n-type La-doped BaBiTe{sub 3}.

Morphological effect of BiVO4 catalysts on degradation of aqueous paracetamol under visible light irradiation.

Science.gov (United States)

Hu, Changying; Xu, Jie; Zhu, Yaqi; Chen, Acong; Bian, Zhaoyong; Wang, Hui

2016-09-01

Morphological effect of bismuth vanadate (BiVO4) on visible light-driven catalytic degradation of aqueous paracetamol was carefully investigated using four monoclinic BiVO4 catalysts. The catalysts with different morphologies were controllably prepared by a hydrothermal method without any additions. The prepared catalysts were fully characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis diffuse reflectance spectroscopy (DRS). Under the visible light irradiation, these catalysts with different morphology were investigated to degrade aqueous paracetamol contaminant. The degradation effects were evaluated based on the catalyst morphology, solution pH, initial paracetamol concentration, and catalyst dosage. Cube-like BiVO4 powders exhibited excellent photocatalytic performance. The optimal photocatalytic performance of the cube-like BiVO4 in degrading paracetamol was achieved.

Luminescence properties of pure and doped CaSO{sub 4} nanorods irradiated by 15 MeV e-beam

Energy Technology Data Exchange (ETDEWEB)

Salah, Numan, E-mail: nsalah@kau.edu.sa [Center of Nanotechnology, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Alharbi, Najlaa D. [Sciences Faculty for Girls, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Enani, Mohammad A. [Dept. of Nuclear Engineering, Faculty of Engineering, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

2014-01-15

Calcium sulfate (CaSO{sub 4}) doped with proper activators is a highly sensitive phosphor used in different fields mainly for radiation dosimetry, lighting and display applications. In this work pure and doped nanorods of CaSO{sub 4} were produced by the co-precipitation technique. Samples from this material doped with Ag, Cu, Dy, Eu and Tb were exposed to different doses of 15 MeV e-beam and studied for their thermoluminesence (TL) and photoluminescence (PL) properties. Color center formation leading to PL emissions were investigated before and after e-beam irradiation. The samples doped with rare earths elements (i.e. Dy, Eu and Tb) were observed to have thinner nanorods than the other samples and have higher absorption in the UV region. The Ag and Tb doped samples have poor TL response to e-beam, while those activated by Cu, Dy and Eu have strong glow peaks at around 123 °C. Quite linear response curves in the whole studied exposures i.e. 0.1–100 Gy were also observed in Cu and Dy doped samples. The PL results show that pure CaSO{sub 4} nanorods have active color centers without irradiation, which could be enriched/modified by these impurities mainly rare earths and further enhanced by e-beam irradiation. Eu{sup 3+} → Eu{sup 2+} conversion is clearly observed in Eu doped sample after e-beam irradiation. These results show that these nanorods might be useful in lighting and display devices development.

Effect of electron irradiation exposure on phase formation, microstructure and mechanical strength of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} superconductor prepared via co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Mohiju, Zaahidah ' Atiqah; Hamid, Nasri A., E-mail: Nasri@uniten.edu.my; Kannan, V. [Center for Nuclear Energy, College of Engineering, Universiti Tenaga Nasional, Jalan IKRAM-UNITEN, 43000 Kajang, Selangor (Malaysia); Abdullah, Yusof [Materials Technology Group, Industrial Technology Division, Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia)

2015-04-29

In this work the effect of electron irradiation on the mechanical properties of Bi2Sr2CaCu2O8 (Bi-2212) superconductor was studied by exposing the Bi-2212 superconductor with different doses of electron irradiation. Bi-2212 samples were prepared by using co-precipitation method. Irradiation was performed with irradiation dose of 100 kGray and 200 kGray, respectively. Characterization of the samples was performed by using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Instron Universal Testing machine was used to measure the strength of the samples. The XRD patterns for the non-irradiated and irradiated samples show well-defined peaks of which could be indexed on the basis of a Bi-2212 phase structure. XRD patterns also indicate that electron irradiation did not affect the Bi-2212 superconducting phase. SEM micrographs show disorientation in the texture of the microstructure for irradiated samples. Sample exposed to 200 kGray electron irradiation dose shows enhancement of grain size. Their grain growth and texture improved slightly compared to other sample. The results also show that enlargement of grain size resulted in higher mechanical strength.

Thermoelectric Properties of Cu-doped Bi2-xSbxTe3 Prepared by Encapsulated Melting and Hot Pressing

Science.gov (United States)

Jung, Woo-Jin; Kim, Il-Ho

2018-03-01

P-type Bi2-xSbxTe3:Cum (x = 1.5-1.7 and m = 0.002-0.003) solid solutions were synthesized using encapsulated melting and were consolidated using hot pressing. The effects of Sb substitution and Cu doping on the charge transport and thermoelectric properties were examined. The lattice constants decreased with increasing Sb and Cu contents. As the amount of Sb substitution and Cu doping was increased, the electrical conductivity increased, and the Seebeck coefficient decreased owing to the increase in the carrier concentration. All specimens exhibited degenerate semiconductor characteristics and positive Hall and Seebeck coefficients, indicating p-type conduction. The increased Sb substitution caused a shift in the onset temperature of the intrinsic transition and bipolar conduction to higher temperatures. The electronic thermal conductivity increased with increasing Sb and Cu contents owing to the increase in the carrier concentration, while the lattice thermal conductivity slightly decreased due to alloy scattering. A maximum figure of merit, ZTmax = 1.25, was achieved at 373 K for Bi0.4Sb1.6Te3:Cu0.003.

Investigation of crystal structure, dielectric and magnetic properties in La and Nd co-doped BiFeO{sub 3} multiferroics

Energy Technology Data Exchange (ETDEWEB)

Singh, Ompal [Department of Physics, Guru Jambheshwar University of Science & Technology, Hisar 125001, Haryana (India); Agarwal, Ashish, E-mail: aagju@yahoo.com [Department of Physics, Guru Jambheshwar University of Science & Technology, Hisar 125001, Haryana (India); Sanghi, Sujata [Department of Physics, Guru Jambheshwar University of Science & Technology, Hisar 125001, Haryana (India); Das, Amitabh [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Anju [Department of Physics, Chaudhary Devi Lal University, Sirsa 125025, Haryana (India)

2017-03-15

For the investigation of the crystal structure, dielectric properties and magnetic properties of La and Nd co-doped BiFeO{sub 3} multiferroics; Bi{sub 0.8}La{sub 0.2−x}Nd{sub x}FeO{sub 3} (x=0.075, 0.1, 0.125) samples were prepared through solid state reaction method. Rietveld refinement of the obtained XRD patterns shows that there is change in crystal structure in these samples. At higher concentration of La (at x=0.075), the crystal structure was found to have mixed symmetry with rhombohedral and triclinic phases, while with equal concentration of both the dopants (at x=0.1), the structure changes to mixed symmetry having rhombohedral and orthorhombic phases. At higher concentration of Nd (at x=0.125), again mixed symmetry was established having both phases of the previous composition but approximately in reverse fraction. In dielectric analysis, x=0.1 sample showed the highest values of dielectric constant (ε′) and dielectric loss (tan δ). For x=0.125 sample, it was observed that the dielectric constant and dielectric loss response are improved. The magnetic characterization (M–H loops) indicates the significant enhancement in magnetisation with increasing concentration of Nd. Nd doping leads to the destruction of spiral modulation, forming the antiferromagnets, and visualisation of improved magnetisation via canting of spins. - Highlights: • La and Nd co-doped BiFeO{sub 3} were synthesized. • Change in crystal structure is observed. • Significant enhancement in magnetisation is observed.

Effect of (Nd, Ni) co-doped on the multiferroic and photocatalytic properties of BiFeO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Vanga, Pradeep Reddy [Nanomaterials Laboratory, Department of Physics, National Institute of Technology, Tiruchirapalli 620 015 (India); Mangalaraja, R.V. [Department of Materials Engineering, University of Concepcion, Concepcion (Chile); Ashok, M., E-mail: ashokm@nitt.edu [Nanomaterials Laboratory, Department of Physics, National Institute of Technology, Tiruchirapalli 620 015 (India)

2015-12-15

Highlights: • Sol–gel synthesis. • Saturation magnetization and ferroelectricity increases in Ni co-doped samples. • Conduction mechanism is different in Nd doped and (Nd, Ni) co-doped samples. • Samples show good photocatalytic activity in the presence of H{sub 2}O{sub 2}. - Abstract: Bi{sub 0.95}Nd{sub 0.05}Fe{sub 1−x}Ni{sub x}O{sub 3} (x = 0, 0.01, 0.03 and 0.05) samples are synthesized by solgel method. The phase and crystal structure of the samples are confirmed by X-ray diffraction studies, Rietveld refinement is performed to calculate the structural parameters. The reflectance spectra show bands in UV and visible region and the optical band gap is calculated using Kulbeka–Munk function. The magnetization and leakage current density are strongly influenced by doping. Different conduction mechanisms are observed in Nd doped and Ni co-doped samples. All the samples exhibit ferroelectric nature at various frequencies. Photocatalytic activities of the samples are determined by the degradation of methylene blue dye in the presence of visible light and H{sub 2}O{sub 2} which shows samples are good photo-Fenton like catalyst.

Study of SrBi4Ti4O15 (SBTi) dielectric properties of doped PbO

International Nuclear Information System (INIS)

Rodrigues Junior, C.A.; Silva Filho, J.M.; Freitas, D.B.; Oliveira, R.G.M.; Sombra, B.; Sales, J.C.

2012-01-01

The ceramic SrBi 4 Ti 4 O 15 (SBTI), cation-deficient perovskite A 5 B 4 O 15 , was prepared by the method of solid state reaction and then doped with PbO (in the range 2-10% by weight). The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and impedance spectroscopy at room temperature. The X-ray analysis was performed by the Rietveld refinement. The micrographs of the samples show globular-shaped grains (doped PbO). The dielectric properties: dielectric constant (Κ' or έ) and dielectric loss tangent (tan δ), were measured at room temperature in the frequency range 100 Hz - 1 MHz dielectric properties of these 1 MHz sample doped with 10 % PbO showed the dielectric constant Κ'= 168.34 and dielectric loss tangent tanδ, = 7,1.10 -2 . These results show a good possibility of miniaturization of electronic devices such as capacitors. (author)

Deep level centers in electron-irradiated silicon crystals doped with copper at different temperatures

Energy Technology Data Exchange (ETDEWEB)

Yarykin, Nikolai [Institute of Microelectronics Technology, RAS, Chernogolovka (Russian Federation); Weber, Joerg [Technische Universitaet Dresden (Germany)

2017-07-15

The effect of bombardment with energetic particles on the deep-level spectrum of copper-contaminated silicon wafers is studied by space charge spectroscopy methods. The p-type FZ-Si wafers were doped with copper in the temperature range of 645-750 C and then irradiated with the 10{sup 15} cm{sup -2} fluence of 5 MeV electrons at room temperature. Only the mobile Cu{sub i} species and the Cu{sub PL} centers are detected in significant concentrations in the non-irradiated Cu-doped wafers. The properties of the irradiated samples are found to qualitatively depend on the copper in-diffusion temperature T{sub diff}. For T{sub diff} > 700 C, the irradiation partially reduces the Cu{sub i} concentration and introduces additional Cu{sub PL} centers while no standard radiation defects are detected. If T{sub diff} was below ∝700 C, the irradiation totally removes the mobile Cu{sub i} species. Instead, the standard radiation defects and their complexes with copper appear in the deep-level spectrum. A model for the defects reaction scheme during the irradiation is derived and discussed. DLTS spectrum of the Cu-contaminated and then irradiated silicon qualitatively depends on the copper in-diffusion temperature. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Unusual Concentration Induced Antithermal Quenching of the Bi(2+) Emission from Sr2P2O7:Bi(2.).

Science.gov (United States)

Li, Liyi; Peng, Mingying; Viana, Bruno; Wang, Jing; Lei, Bingfu; Liu, Yingliang; Zhang, Qinyuan; Qiu, Jianrong

2015-06-15

The resistance of a luminescent material to thermal quenching is essential for the application in high power LEDs. Usually, thermal luminescence quenching becomes more and more serious as the activator concentration increases. Conversely, we found here that a red phosphor Sr2P2O7:Bi(2+) is one of the exceptions to this as we studied the luminescence properties at low (10-300 K) and high (300-500 K) temperatures. As Bi(2+) ions are incorporated into Sr2P2O7, they exhibit the emissions at ∼660 and ∼698 nm at room temperature and are encoded, hereafter, as Bi(1) and Bi(2) due to the substitutions for two different crystallographic sites Sr(1) and Sr(2), respectively, in the compound. However, they will not substitute for these sites equally. At lower dopant concentration, they will occupy preferentially Sr(2) sites partially due to size match. As the concentration increases, more Bi(2+) ions start to occupy the Sr(1) sites. This can be verified by the distinct changes of emission intensity ratio of Bi(2) to Bi(1). As environment temperature increases, the thermal quenching happens, but it can be suppressed by the Bi(2+) concentration increase. This becomes even more pronounced in Bi(2+) heavily doped sample as we decompose the broad emission band into separated Bi(1) and Bi(2) Gaussian peaks. For the sample, the Bi(1) emission at ∼660 nm even shows antithermal-quenching particularly at higher temperatures. This phenomenon is accompanied by the blue shift of the overall emission band and almost no changes of lifetimes. A mechanism is proposed due to volume expansion of the unit cell, the increase of Bi(1) content, and temperature dependent energy transfer between Bi(2) and Bi(1). This work helps us better understand the complex luminescent behavior of Bi(2+) doped materials, and it will be helpful to design in the future the heavily doped phosphor for WLEDs with even better resistance to thermal quenching.

Ferroelectric relaxor behaviour and impedance spectroscopy of Bi2O3-doped barium zirconium titanate ceramics

International Nuclear Information System (INIS)

Mahajan, Sandeep; Thakur, O P; Bhattacharya, D K; Sreenivas, K

2009-01-01

Bi 2 O 3 -doped barium zirconate titanate ceramics, Ba 1-x Bi x (Zr 0.05 Ti 0.95 )O 3 , have been prepared by the conventional solid-state reaction method. The ferroelectric relaxor behaviour and dielectric properties have been investigated in detail. By XRD analysis, it is suggested that up to x = 0.04, Bi 3+ substitutes A-site ion, and thereafter with higher Bi 3+ content, it enters the B-site sub lattice. Substitution of Bi 3+ ions induces ferroelectric relaxor behaviour and the degree of relaxation behaviour increases with bismuth concentration. The remanent polarization and strain behaviour show a slight increase with the substitution level. The degree of hysteresis (strain versus electric field) also reduces from 21.4% to 4.6% with bismuth substitution. Impedance measurements were made on the prepared sample over a wide range of temperatures (300-723 K) and frequencies (40 Hz-1 MHz), which show the presence of both bulk and grain boundary effects in the material. The bulk and grain boundary conductivities determined from impedance study indicate the Arrhenius-type thermally activated process. Impedance spectroscopy is shown to be an efficient method capable of detecting the contributions of the resistances of grains and grain boundaries to the complex impedance of a ceramic system, accurately estimating its electrical conductivity as well as its corresponding activation energies and drawing conclusions on its structural properties.

Influence of B4C-doping and high-energy ball milling on phase formation and critical current density of (Bi,Pb)-2223 HTS

Science.gov (United States)

Margiani, N. G.; Mumladze, G. A.; Adamia, Z. A.; Kuzanyan, A. S.; Zhghamadze, V. V.

2018-05-01

In this paper, the combined effects of B4C-doping and planetary ball milling on the phase evolution, microstructure and transport properties of Bi1.7Pb0.3Sr2Ca2Cu3Oy(B4C)x HTS with x = 0 ÷ 0.125 were studied through X-ray diffraction (XRD), scanning electron microscopy (SEM), resistivity and critical current density measurements. Obtained results have shown that B4C additive leads to the strong acceleration of high-Tc phase formation and substantial enhancement in Jc. High-energy ball milling seems to produce a more homogeneous distribution of refined doped particles in the (Bi,Pb)-2223 HTS which results in an improved intergranular flux pinning and better self-field Jc performance.

X-ray magnetic spectroscopy of MBE-grown Mn-doped Bi2Se3 thin films

Directory of Open Access Journals (Sweden)

L. J. Collins-McIntyre

2014-12-01

Full Text Available We report the growth of Mn-doped Bi2Se3 thin films by molecular beam epitaxy (MBE, investigated by x-ray diffraction (XRD, atomic force microscopy (AFM, SQUID magnetometry and x-ray magnetic circular dichroism (XMCD. Epitaxial films were deposited on c-plane sapphire substrates by co-evaporation. The films exhibit a spiral growth mechanism typical of this material class, as revealed by AFM. The XRD measurements demonstrate a good crystalline structure which is retained upon doping up to ∼7.5 atomic-% Mn, determined by Rutherford backscattering spectrometry (RBS, and show no evidence of the formation of parasitic phases. However an increasing interstitial incorporation of Mn is observed with increasing doping concentration. A magnetic moment of 5.1 μB/Mn is obtained from bulk-sensitive SQUID measurements, and a much lower moment of 1.6 μB/Mn from surface-sensitive XMCD. At ∼2.5 K, XMCD at the Mn L2,3 edge, reveals short-range magnetic order in the films and indicates ferromagnetic order below 1.5 K.

Microstructure and electrical properties of (1−x)[0.8Bi_0_._5Na_0_._5TiO_3-0.2Bi_0_._5K_0_._5TiO_3]-xBiCoO_3 lead-free ceramics

International Nuclear Information System (INIS)

Wang, Ting; Chen, Xiao-ming; Qiu, Yan-zi; Lian, Han-li; Chen, Wei-ting

2017-01-01

The (1−x)[0.8Bi_0_._5Na_0_._5TiO_3-0.2Bi_0_._5K_0_._5TiO_3]-xBiCoO_3 (x = 0, 0.02, 0.05, abbreviated as BNKT, BNKT-002Co, BNKT-005Co, respectively) lead-free ferroelectric ceramics were prepared via the solid state reaction method. The phase structure, microstructure, dielectric, ferroelectric, pyroelectric, and piezoelectric properties of the ceramics were investigated comparatively by using a combination of characterization techniques. All the samples exhibit typical X-ray diffraction peaks of ABO_3 perovskite structure. The doping of BiCoO_3 causes a decrease in lattice parameters and an increase in grain size of the ceramics. The Raman spectroscopy results suggest a lattice distortion due to the doping. It is found that BNKT-002Co and BNKT-005Co have higher depolarization temperatures compared with BNKT. The Curie-Weiss law and modified Curie-Weiss law explored a diffuse phase transition character for all the samples. The results of ultraviolet–visible diffuse reflectance suggests that BiCoO_3-doped ceramics possess higher defect concentration. The impedance analysis shows a temperature dependent relaxation behavior, and the activation energy for the electrical responses varies with the change of BiCoO_3 amount. The ferroelectric and piezoelectric properties of the ceramics decrease due to the doping of BiCoO_3. Based on the results of the Rayleigh analysis, it was suggested that the differences in the electrical properties among the ceramics are closely related to the change in oxygen vacancy concentration. - Highlights: • BNKT-xCo ceramics were prepared by solid-state reaction method. • Electrical properties of BNKT ceramics are changed by the doping of BiCoO_3. • The doping causes a decrease in lattice parameters and an increase in grain size. • T_d of the ceramics increases with increasing x. • Oxygen vacancies play key role in determining electrical properties of the ceramics.

Thermoluminescence response of Ge-, Al- and Nd- doped optical fibers by 6 MeV - electron and 6 MeV - photon irradiations

International Nuclear Information System (INIS)

Hossain, I.; Moburak, A. A.; Saeed, M.A.; Wagiran, H.; Hida, N.; Yaakob, H.N.

2015-01-01

In this paper, we report the prediction of thermoluminescence responses of Neodymium-doped SiO 2 optical fibre with various dose ranges from 0.5 Gy to 4.0 Gy by 6 MeV - electron irradiations without requirement for experimental measurements. A technique has been developed to calculate prediction of 6 MeV - electron response of Neodymium-doped SiO 2 optical fibre by observing the measured TL response of 6 MV - photon and the ratio of known measured photon/electron yield ratio distribution for Ge-doped, Al-doped optical fibre and standard TLD 100 dosimeter. The samples were kept in gelatin capsule an irradiated with 6 MV - photon at the dose range from 0.5 Gy to 4.0 Gy. Siemens model Primus 3368 linear accelerator located at Hospital Sultan Ismail, Johor Bahru has been used to deliver the photon beam to the samples. We found the average response ratio of 6 MV - photon and 6 MeV - electron in Ge-doped, Al-doped optical fibre and standard TLD-100 dosimeter are 0.83(3). Observing the measured value of 6 MV - photon irradiation this average ratio is useful to find the prediction of thermoluminescence responses by 6 MeV - electron irradiation of Neodymium-doped SiO 2 optical fibre by the requirement for experimental measurements with various dose ranges from 0.5 Gy to 4.0 Gy by 6 MV - photon irradiations.

Topotactic synthesis of a new BiS2-based superconductor Bi2(O,F)S2

OpenAIRE

Okada, Tomoyuki; Ogino, Hiraku; Shimoyama, Jun-ichi; Kishio, Kohji

2015-01-01

A new BiS2-based superconductor Bi2(O,F)S2 was discovered. This is a layered compound consisting of alternate stacking structure of rock-salt-type BiS2 superconducting layer and fluorite-type Bi(O,F) blocking layer. Bi2(O,F)S2 was obtained as the main phase by topotactic fluorination of undoped Bi2OS2 using XeF2, which is the first topotactic synthesis of an electron-doped superconductor via reductive fluorination. With increasing F-content, a- and c-axis length increased and decreased, respe...

Orthorhombic polar Nd-doped BiFeO3 thin film on MgO substrate

International Nuclear Information System (INIS)

Leontyev, I N; Janolin, P-E; Dkhil, B; Yuzyuk, Yu I; El-Marssi, M; Chernyshov, D; Dmitriev, V; Golovko, Yu I; Mukhortov, V M

2011-01-01

A Nd-doped BiFeO 3 thin film deposited on MgO substrate was studied by synchrotron diffraction. The ferroelectric nature of the film is proven by in-plane remanent polarization measurement. The highest possible symmetry of the film is determined to be orthorhombic, within the Fm2m space group. Such a structure is rotated by 45 0 with respect to the substrate and is consistent with tilts of oxygen octahedra doubling the unit cell. This polar structure presents a rather unusual strain-accommodation mechanism. (fast track communication)

Superconducting and normal state properties of carbon doped and neutron irradiated MgB2

International Nuclear Information System (INIS)

Wilke, R.H.T.; Samuely, P.; Szabo, P.; Holanova, Z.; Bud'ko, S.L.; Canfield, P.C.; Finnemore, D.K.

2007-01-01

Current research in MgB 2 focuses on the effects various types of perturbations have on the superconducting properties of this novel two-gap superconductor. In this article we summarize the effects of carbon doping and neutron irradiation in bulk MgB 2 . Low levels of carbon doping and light neutron irradiation result in significant enhancements in H c2 . At high fluences, where superconductivity is nearly fully suppressed, superconductivity can be restored through post exposure annealing. However, this results in a change in the interdependencies of the normal state and superconducting properties (ρ 0 , T c , H c2 ), with little or no enhancement in H c2

Comparative study of neutron irradiation and carbon doping in MgB2 single crystals

International Nuclear Information System (INIS)

Krutzler, C.; Zehetmayer, M.; Eisterer, M.; Weber, H. W.; Zhigadlo, N. D.; Karpinski, J.

2007-01-01

We compare the reversible and irreversible magnetic properties of superconducting carbon doped and undoped MgB 2 single crystals before and after neutron irradiation. A large number of samples with transition temperatures between 38.3 and 22.8 K allows us to study the effects of disorder systematically. Striking similarities are found in the modification of the reversible parameters by irradiation and doping, which are discussed in terms of impurity scattering and changes of the Fermi surface. The irreversible properties are influenced by two counteracting mechanisms: they are enhanced by the newly introduced pinning centers but degraded by changes in the thermodynamic properties. Accordingly, the large neutron induced defects and the small defects from carbon doping lead to significantly different effects on the irreversible properties. Finally, the fishtail effect caused by all kinds of disorder is discussed in terms of an order-disorder transition of the flux-line lattice

Specific features of nonlinear optical properties of Eu{sup 3+} doped BiFeO{sub 3} nanopowders near antiferromagnetic transition

Energy Technology Data Exchange (ETDEWEB)

El Bahraoui, T.; Sekkati, M. [University of Mohammed V, Materials Physics Laboratory, P.B. 1014 Rabat (Morocco); Taibi, M. [University of Mohammed V, LPCMIO, Ecole Normale Supérieure, Rabat (Morocco); Abd-Lefdil, M. [University of Mohammed V, Materials Physics Laboratory, P.B. 1014 Rabat (Morocco); El-Naggar, A.M. [Research chair of Exploitation of Renewable Energy Applications in Saudi Arabia, Physics & Astronomy Department, College of Science, King Saud University, P.O.Box 2455, Riyadh 11451 (Saudi Arabia); Physics Department, Faculty of Science, Ain Shams University, Abassia, Cairo 11566 (Egypt); AlZayed, N.S. [Physics & Astronomy Department, College of Science, King Saud University, P.O.Box 2455, Riyadh 11451, Saudi Arabi (Saudi Arabia); Albassam, A.A. [Research chair of Exploitation of Renewable Energy Applications in Saudi Arabia, Physics & Astronomy Department, College of Science, King Saud University, P.O.Box 2455, Riyadh 11451 (Saudi Arabia); Kityk, I.V., E-mail: iwank74@gmail.com [Faculty of Electrical Engineering, Czestochowa University Technology, Armii Krajowej 17, PL-42201 Czestochowa (Poland); Maciag, A. [Faculty of Electrical Engineering, Czestochowa University Technology, Armii Krajowej 17, PL-42201 Czestochowa (Poland)

2016-01-15

The monitoring of the Eu{sup 3+} doped BiFeO{sub 3} nanopowders was performed near the antiferromagnetic transformation by photoinduced optical second harmonic generation. As photoinduced laser beams we have used bicolor coherent excitations of the Er:glass laser emitting at 1540 nm with frequency repetition about 15 ns. The studies of the photoinduced SHG were performed versus temperature including the temperature range of ferromagnetic–ferroelectric transition (350 °C…390 °C). The optimal light polarization and intensity ratio were chosen; the sensitivity of the photoinduced SHG to the multiferroic phase transitions was explored. - Highlights: • The photoinduced optical second harmonic generation for the Eu{sup 3+} doped BiFeO{sub 3} nanopowders which use two bicolor coherent laser beams incident under different angles gives some enhancement of the SHG. • The photoinduced SHG may be used as sensitive tools for detection of multiferroelectricity. • The nonlinear optical scattering processes play here principal role.

Dopant activation mechanism of Bi wire-δ-doping into Si crystal, investigated with wavelength dispersive fluorescence x-ray absorption fine structure and density functional theory.

Science.gov (United States)

Murata, Koichi; Kirkham, Christopher; Shimomura, Masaru; Nitta, Kiyofumi; Uruga, Tomoya; Terada, Yasuko; Nittoh, Koh-Ichi; Bowler, David R; Miki, Kazushi

2017-04-20

We successfully characterized the local structures of Bi atoms in a wire-δ-doped layer (1/8 ML) in a Si crystal, using wavelength dispersive fluorescence x-ray absorption fine structure at the beamline BL37XU, in SPring-8, with the help of density functional theory calculations. It was found that the burial of Bi nanolines on the Si(0 0 1) surface, via growth of Si capping layer at 400 °C by molecular beam epitaxy, reduced the Bi-Si bond length from [Formula: see text] to [Formula: see text] Å. We infer that following epitaxial growth the Bi-Bi dimers of the nanoline are broken, and the Bi atoms are located at substitutional sites within the Si crystal, leading to the shorter Bi-Si bond lengths.

Heterovalent Cation Substitutional and Interstitial Doping in Semiconductor Sensitizers for Quantum Dot Cosensitized Solar Cell

Directory of Open Access Journals (Sweden)

Ningning Zhang

2015-01-01

Full Text Available Doped films of TiO2/PbS/CdS have been prepared by successive ionic layer adsorption and reaction (SILAR method. Bi- and Ag-doped-PbS quantum dot (QD were produced by admixing Bi3+ or Ag+ during deposition and the existing forms of the doping element in PbS QD were analyzed. The results show that Bi3+ entered the cube space of PbS as donor yielding interstitial doping Bi-doped-PbS QD, while Ag+ replaced Pb2+ of PbS as acceptor yielding substitutional doping Ag-doped-PbS QD. The novel Bi-doped-PbS/CdS and Ag-doped-PbS/CdS quantum dot cosensitized solar cell (QDCSC were fabricated and power conversion efficiency (PCE of 2.4% and 2.2% was achieved, respectively, under full sun illumination.

High multi-photon visible upconversion emissions of Er{sup 3+} singly doped BiOCl microcrystals: A photon avalanche of Er{sup 3+} induced by 980 nm excitation

Energy Technology Data Exchange (ETDEWEB)

Li, Yongjin; Song, Zhiguo, E-mail: songzg@kmust.edu.cn; Li, Chen; Wan, Ronghua; Qiu, Jianbei; Yang, Zhengwen; Yin, Zhaoyi; Yang, Yong; Zhou, Dacheng; Wang, Qi [School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China)

2013-12-02

Under 980 nm excitation, high multi-photon upconversion (UC) emission from the {sup 2}H{sub 11/2}/{sup 4}S{sub 3/2} (green) and {sup 4}F{sub 9/2} (red) levels of Er{sup 3+} ions were observed from Er{sup 3+} singly doped BiOCl microcrystals. These high-energy excited states were populated by a three to ten photon UC process conditionally, which depended on the pump power density and the Er{sup 3+} ion doping concentration, characterizing as a hetero-looping enhanced energy transfer avalanche UC process. UC emission lifetime and Raman analysis suggest that the unusual UC phenomena are initiated by the new and intense phonon vibration modes of BiOCl lattices due to Er{sup 3+} ions doping.

X-ray and optical study on point defect formation and interaction under irradiation adn doping of KCl

Energy Technology Data Exchange (ETDEWEB)

Braude, I S; Rogozyanskaya, L M [AN Ukrainskoj SSR, Kharkov. Fiziko-Tekhnicheskij Inst. Nizkikh Temperatur

1978-08-01

Optical and X-ray diffuse scattering methods have been applied to investigate structural changes, taking place in KCl crystals during irradiation with ..gamma..-quanta and doping with barium. It is shown that ..gamma..-irradiation of ''pure'' and doped KCl crystals mainly leads to formation of F-centers and spherical vacancy complexes. F-center concentration in irradiated addition crystals (3x10/sup -6/) has turned out to be 25% lower, than in irradiated pure ones (4x10/sup -6/), which is connected with interaction of radiation and addition defects. The type of defects, causing assymetry in the distribution of diffuse scattering has been determined. Appearance of scattering ability modulation over direction < 100 > during irradiation of KCl pure crystals has been found. Critical radius of spherical complexes formed during irradiation has been estimated, it appeared to be 2.5 a, where a is a lattice period.

Monitoring of the Irradiated Neutron Fluence in the Neutron Transmutation Doping Process of Hanaro

Science.gov (United States)

Kim, Myong-Seop; Park, Sang-Jun

2009-08-01

Neutron transmutation doping (NTD) for silicon is a process of the creation of phosphorus impurities in intrinsic or extrinsic silicon by neutron irradiation to obtain silicon semiconductors with extremely uniform dopant distribution. HANARO has two vertical holes for the NTD, and the irradiation for 5 and 6 inch silicon ingots has been going on at one hole. In order to achieve the accurate neutron fluence corresponding to the target resistivity, the real time neutron flux is monitored by self-powered neutron detectors. After irradiation, the total irradiation fluence is confirmed by measuring the absolute activity of activation detectors. In this work, a neutron fluence monitoring method using zirconium foils with the mass of 10 ~ 50 mg was applied to the NTD process of HANARO. We determined the proportional constant of the relationship between the resistivity of the irradiated silicon and the neutron fluence determined by using zirconium foils. The determined constant for the initially n-type silicon was 3.126 × 1019 n·Ω/cm. It was confirmed that the difference between this empirical value and the theoretical one was only 0.5%. Conclusively, the practical methodology to perform the neutron transmutation doping of silicon was established.

Effect of Substitutional Pb Doping on Bipolar and Lattice Thermal Conductivity in p-Type Bi0.48Sb1.52Te₃.

Science.gov (United States)

Kim, Hyun-Sik; Lee, Kyu Hyoung; Yoo, Joonyeon; Youn, Jehun; Roh, Jong Wook; Kim, Sang-Il; Kim, Sung Wng

2017-07-06

Cation substitutional doping is an effective approach to modifying the electronic and thermal transports in Bi₂Te₃-based thermoelectric alloys. Here we present a comprehensive analysis of the electrical and thermal conductivities of polycrystalline Pb-doped p-type bulk Bi 0.48 Sb 1.52 Te₃. Pb doping significantly increased the electrical conductivity up to ~2700 S/cm at x = 0.02 in Bi 0.48-x Pb x Sb 1.52 Te₃ due to the increase in hole carrier concentration. Even though the total thermal conductivity increased as Pb was added, due to the increased hole carrier concentration, the thermal conductivity was reduced by 14-22% if the contribution of the increased hole carrier concentration was excluded. To further understand the origin of reduction in the thermal conductivity, we first estimated the contribution of bipolar conduction to thermal conductivity from a two-parabolic band model, which is an extension of the single parabolic band model. Thereafter, the contribution of additional point defect scattering caused by Pb substitution (Pb in the cation site) was analyzed using the Debye-Callaway model. We found that Pb doping significantly suppressed both the bipolar thermal conduction and lattice thermal conductivity simultaneously, while the bipolar contribution to the total thermal conductivity reduction increased at high temperatures. At Pb doping of x = 0.02, the bipolar thermal conductivity decreased by ~30% from 0.47 W/mK to 0.33 W/mK at 480 K, which accounts for 70% of the total reduction.

Synthesis, thermal and electrical properties of Al-doped Bi{sub 4}V{sub 1.8}Cu{sub 0.2}O{sub 10.7}

Energy Technology Data Exchange (ETDEWEB)

Essalim, R.; Ammar, A.; Tanouti, B. [Laboratoire des Sciences des Matériaux Inorganiques et leurs Applications (LASMIA), Equipe Matériaux à Faible Dimensionnalité(EMAFAD), Faculté des Sciences, Semlalia, Av. My Abdellah, B.P. 2390 Marrakech (Morocco); Mauvy, F., E-mail: fabrice.mauvy@cnrs.fr [Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB) CNRS UPR 9048, Université de Bordeaux, 87, Av. Dr A. Schweitzer, 33608 Pessac (France)

2016-08-15

Partial substitution of copper with aluminum in Bi{sub 4}V{sub 1.8}Cu{sub 0.2}O{sub 10.7} has led to the Bi{sub 4}V{sub 1.8}Cu{sub 0.2−x}Al{sub x}O{sub 10.7+x/2} solid solution. X-ray diffraction and thermal analysis have shown that the compounds with x=0.05 and x=0.10 are tetragonal with γ′ form of Bi{sub 4}V{sub 2}O{sub 11}, while the compound with x=0.15 is of β polymorph. The effect of Al{sup 3+} doping on electrical conductivity has been studied using Electrochemical Impedance Spectroscopy. The electrical conductivity of doped samples along with the amount of Al{sup 3+} has been studied by electrochemical impedance spectroscopy in the temperature range 250–700 °C. The slope changes observed in the Arrhenius plots agree with the microstructural transitions occurring in these compounds. The highest ionic conductivity values are obtained for the sample with x=0.05. - Graphical abstract: Arrhenius plots of the electrical conductivity of the of Bi{sub 4}V{sub 1.8}Cu{sub 0.2−x}Al{sub x}O{sub 10.7+x/2} compounds. Display Omitted.

Crystal structure and magnetic properties of the Cr-doped spiral antiferromagnet BiMnFe2O6

International Nuclear Information System (INIS)

Batuk, Dmitry; De Dobbelaere, Christopher; Tsirlin, Alexander A.; Abakumov, Artem M.; Hardy, An; Van Bael, Marlies K.; Greenblatt, Martha; Hadermann, Joke

2013-01-01

Graphical abstract: - Highlights: • The substitution of Cr for Mn in BiMnFe 2 O 6 is possible by the solution–gel method. • The BiCr x Mn 1−x Fe 2 O 6 solid solution is obtained for the x values up to 0.3. • Increasing Cr content lowers the temperature of the antiferromagnetic ordering. - Abstract: We report the Cr 3+ for Mn 3+ substitution in the BiMnFe 2 O 6 structure. The BiCr x Mn 1−x Fe 2 O 6 solid solution is obtained by the solution–gel synthesis technique for the x values up to 0.3. The crystal structure investigation using a combination of X-ray powder diffraction and transmission electron microscopy demonstrates that the compounds retain the parent BiMnFe 2 O 6 structure (for x = 0.3, a = 5.02010(6)Å, b = 7.06594(7)Å, c = 12.6174(1)Å, S.G. Pbcm, R I = 0.036, R P = 0.011) with only a slight decrease in the cell parameters associated with the Cr 3+ for Mn 3+ substitution. Magnetic susceptibility measurements suggest strong similarities in the magnetic behavior of BiCr x Mn 1−x Fe 2 O 6 (x = 0.2; 0.3) and parent BiMnFe 2 O 6 . Only T N slightly decreases upon Cr doping that indicates a very subtle influence of Cr 3+ cations on the magnetic properties at the available substitution rates

Photocatalytic degradation of methylene blue on Fe3+-doped TiO2 nanoparticles under visible light irradiation

Institute of Scientific and Technical Information of China (English)

SU Bitao; WANG Ke; BAI Jie; MU Hongmei; TONG Yongchun; MIN Shixiong; SHE Shixiong; LEI Ziqiang

2007-01-01

Fe3+-doped TiO2 composite nanoparticles with different doping amounts were successfully synthesized using sol-gel method and characterized by X-ray diffraction (XRD),transmission electron microscopy (TEM) and ultraviolet-visible spectroscopy (UV-Vis) diffuse reflectance spectra (DRS). The photocatalytic degradation of methylene blue was used as a model reaction to evaluate the photocatalytic activity of Fe3+/TiO2 nanoparticles under visible light irradia-tion. The influence of doping amount of Fe3+ (ω: 0.00%-3.00%) on photocatalytic activities of TiO2 was investigated.Results show that the size of Fe3+/TiO2 particles decreases with the increase of the amount of Fe3+ and their absorptionspectra are broaden and absorption intensities are also increased. Doping Fe3+ can control the conversion of TiO2 from anatase to rutile. The doping amount of Fe3+ remarkably affects the activity of the catalyst, and the optimum efficiency occurs at about the doping amount of 0.3%. The appropriate doping of Fe3+ can markedly increase the catalytic activity of TiO2 under visible light irradiation.

Electron irradiation response on Ge and Al-doped SiO 2 optical fibres

Science.gov (United States)

Yaakob, N. H.; Wagiran, H.; Hossain, I.; Ramli, A. T.; Bradley, D. A.; Hashim, S.; Ali, H.

2011-05-01

This paper describes the thermoluminescence response, sensitivity, stability and reproducibility of SiO 2 optical fibres with various electron energies and doses. The TL materials that comprise Al- and Ge-doped silica fibres were used in this experiment. The TL results are compared with those of the commercially available TLD-100. The doped SiO 2 optical fibres and TLD-100 are placed in a solid phantom and irradiated with 6, 9 and 12 MeV electron beams at doses ranging from 0.2 to 4.0 Gy using the LINAC at Hospital Sultan Ismail, Johor Bahru, Malaysia. It was found that the commercially available Al- and Ge-doped optical fibres have a linear dose-TL signal relationship. The intensity of TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre.

Electron irradiation response on Ge and Al-doped SiO2 optical fibres

International Nuclear Information System (INIS)

Yaakob, N.H.; Wagiran, H.; Hossain, I.; Ramli, A.T.; Bradley, D.A; Hashim, S.; Ali, H.

2011-01-01

This paper describes the thermoluminescence response, sensitivity, stability and reproducibility of SiO 2 optical fibres with various electron energies and doses. The TL materials that comprise Al- and Ge-doped silica fibres were used in this experiment. The TL results are compared with those of the commercially available TLD-100. The doped SiO 2 optical fibres and TLD-100 are placed in a solid phantom and irradiated with 6, 9 and 12 MeV electron beams at doses ranging from 0.2 to 4.0 Gy using the LINAC at Hospital Sultan Ismail, Johor Bahru, Malaysia. It was found that the commercially available Al- and Ge-doped optical fibres have a linear dose-TL signal relationship. The intensity of TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre.

BiVO4 /N-rGO nano composites as highly efficient visible active photocatalyst for the degradation of dyes and antibiotics in eco system.

Science.gov (United States)

Appavu, Brindha; Thiripuranthagan, Sivakumar; Ranganathan, Sudhakar; Erusappan, Elangovan; Kannan, Kathiravan

2018-04-30

Herein, we report the synthesis of novel nitrogen doped reduced graphene oxide/ BiVO 4 photo catalyst by single step hydrothermal method. The physicochemical properties of the catalysts were characterized using XRD, N 2 adsorption-desorption, Raman, XPS, SEM TEM, DRS-UV and EIS techniques. The synthesized catalysts were tested for their catalytic activity in the photo degradation of some harmful textile dyes (methylene blue & congo red) and antibiotics (metronidazole and chloramphenicol) under visible light irradiation. Reduced charge recombination and enhanced photocatalytic activity were observed due to the concerted effect between BiVO 4 and nitrogen-rGO. The degradation efficiency of BiVO 4 /N-rGO in the degradation of CR and MB was remarkably high i.e 95% and 98% under visible light irradiation. Similarly 95% of MTZ and 93% of CAP were degraded under visible light irradiation. HPLC studies implied that both the dyes and antibiotics were degraded to the maximum extent. The plausible photocatalytic mechanism on the basis of experimental results was suggested. Copyright © 2018 Elsevier Inc. All rights reserved.

Coloration dependence in the thermoluminescence properties of the double doped NaCl single crystals under gamma irradiation

International Nuclear Information System (INIS)

Sanchez-Mejorada, G.; Gelover-Santiago, A.L.; Frias, D.

2006-01-01

In this work the behaviour of calcium manganese doped NaCl single crystals under gamma irradiation is reported. Various single crystals of NaCl doped with Ca and Mn have been irradiated at different doses with ionising radiation. The production of defects has been correlated to the increase in the intensity of the thermo luminescent glow curve as a function of doses. The glow curves intensity as a function of doses shows the potential use of these materials as dosimeters. Optical properties of such crystals after irradiation with gamma rays have also been studied; results have shown their potentiality as a good detector and optical store memory devices. Since the creations of colour centres by photons with energy less than the band gap energy has been detected also in ns 2 -ion doped alkali halides. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

In situ synthesis and characterization of fine-patterned La and Mn co-doped BiFeO{sub 3} film

Energy Technology Data Exchange (ETDEWEB)

Yan, Fuxue, E-mail: yanfuxue@126.com; Zhao, Gaoyang, E-mail: zhaogy@xaut.edu.cn; Song, Na; Zhao, Nana; Chen, Yuanqing

2013-09-05

Highlights: •La and Mn co-doped BiFeO{sub 3} film was prepared by a photosensitive sol–gel method. •XRD and Raman spectra confirmed single-phase rhombohedral structure with space group R3c. •Fine-patterned BLFMO film was obtained by a direct-patterning technique. •The saturation magnetization and Pr were enhanced in the fine-patterned BLFMO film. -- Abstract: La and Mn co-doped BiFeO{sub 3} (BLFMO) film was prepared by a photosensitive sol–gel method utilizing bismuth nitrate, lanthanum nitrate, manganese nitrate and ferric nitrate as starting materials. After a chelating reaction between benzoylacetone (BzAcH) and metallic ions, the precursor solution presented photosensitivity. Through a direct patterning process, a fine-patterned BLFMO film was obtained. The phase constituents, morphology, electric and magnetic properties of the as-prepared BLFMO film were characterized by X-ray diffractometer (XRD), Raman spectroscopy, scanning electron microscopy (SEM), ferroelectric testing unit, LCR Meter and vibrating sample magnetometer (VSM). The Mn dopant enhanced the saturation magnetization and remnant polarization of the BLFMO film.

Magnetic and structural properties of Mn-doped Bi.sub.2./sub.Se.sub.3./sub. topological insulators

Czech Academy of Sciences Publication Activity Database

Tarasenko, R.; Vališka, M.; Vondráček, Martin; Horáková, Kateřina; Tkáč, V.; Carva, K.; Baláž, P.; Holý, V.; Springholz, G.; Sechovský, V.; Honolka, Jan

2016-01-01

Roč. 481, Jan (2016), 262-267 ISSN 0378-4363 R&D Projects: GA ČR(CZ) GA14-30062S; GA MŠk LO1409; GA MŠk(CZ) LM2011029 Grant - others:AV ČR(CZ) Fellowship J. E. Purkyně Institutional support: RVO:68378271 Keywords : topological insulator * Mn-doped Bi 2 Se 3 * X-ray diffraction * X-ray photoemission * spectroscopy * ferromagnetism Subject RIV: BM - Solid Matter Physics ; Magnetism

Topotactic synthesis of a new BiS2-based superconductor Bi2(O,F)S2

Science.gov (United States)

Okada, Tomoyuki; Ogino, Hiraku; Shimoyama, Jun-ichi; Kishio, Kohji

2015-02-01

A new BiS2-based superconductor, Bi2(O,F)S2, was discovered. It is a layered compound consisting of alternately stacked structure of rock-salt-type BiS2 superconducting layers and fluorite-type Bi(O,F) blocking layers. Bi2(O,F)S2 was obtained as the main phase by topotactic fluorination of undoped Bi2OS2 using XeF2. This is the first topotactic synthesis of an electron-doped superconductor via reductive fluorination. With increasing F-content, a- and c-axis lengths increased and decreased, respectively, and Tc increased to 5.1 K.

Co-doped sodium chloride crystals exposed to different irradiation temperature

Energy Technology Data Exchange (ETDEWEB)

Ortiz-Morales, A. [Unidad Profesional Interdisciplinaria de Ingenieria y Tecnologias Avanzadas, IPN, Av. Instituto Politecnico Nacional 2580, Col. La Laguna Ticoman, 07340 Mexico D.F., Mexico and Unidad de Irradiacion y Segurid (Mexico); Cruz-Zaragoza, E.; Furetta, C. [Unidad de Irradiacion y Seguridad Radiologica, Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, A.P. 70-543, 04510 Mexico D.F (Mexico); Kitis, G. [Nuclear Physics Laboratory, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Flores J, C.; Hernandez A, J.; Murrieta S, H. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, AP. 20-364, 01000 Mexico D.F (Mexico)

2013-07-03

Monocrystals of NaCl:XCl{sub 2}:MnCl{sub 2}(X = Ca,Cd) at four different concentrations have been analyzed. The crystals were exposed to different irradiation temperature, such as at room temperature (RT), solid water (SW), dry ice (DI) and liquid nitrogen (LN). The samples were irradiated with photon from {sup 60}Co irradiators. The co-doped sodium chloride crystals show a complex structure of glow curves that can be related to different distribution of traps. The linearity response was analyzed with the F(D) index. The F(D) value was less than unity indicating a sub-linear response was obtained from the TL response on the function of the dose. The glow curves were deconvoluted by using the CGCD program based on the first, second and general order kinetics.

Upconversion luminescence, ferroelectrics and piezoelectrics of Er Doped SrBi{sub 4}Ti{sub 4}O{sub 15}

Energy Technology Data Exchange (ETDEWEB)

Peng Dengfeng [Functional Materials Research Laboratory, Tongji University, 1239 Siping Road, Shanghai 200092 (China); National Institute of Advanced Industrial Science and Technology, Kyushu, 807-1 Shuku, Tosu, Saga 841-0052 (Japan); Zou Hua; Wang Xusheng; Yao Xi [Functional Materials Research Laboratory, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Xu Chaonan [National Institute of Advanced Industrial Science and Technology, Kyushu, 807-1 Shuku, Tosu, Saga 841-0052 (Japan); Lin Jian; Sun Tiantuo [School of Material Science and Engineering, Tongji University, 4800 Cao' an Highway, Shanghai 201804 (China)

2012-12-15

Er{sup 3+} doped SrBi{sub 4}Ti{sub 4}O{sub 15} (SBT) bismuth layered-structure ferroelectric ceramics were synthesized by the traditional solid-state method, and their upconversion photoluminescent (UC) properties were investigated as a function of Er{sup 3+} concentration and incident pump power. Green (555 nm) and red (670 nm) emission bands were obtained under 980 nm excitation at room temperature, which corresponded to the radiative transitions from {sup 4}S{sub 3/2}, and {sup 4}F{sub 9/2} to {sup 4}I{sub 15/2}, respectively. The emission color of the samples could be changed with moderating the doping concentrations. The dependence of UC intensity on pumping power indicated a two-photon emission process. Studies on dielectric properties indicated that the introduction of Er increased the ferroelectric-paraelectric phase transition temperature (Tc) of SBT, thus making this ceramic suitable for piezoelectric sensor applications at higher temperatures. Piezoelectric measurement showed that the doped SBT had a relative higher piezoelectric constant d{sub 33} compared with the non-doped ceramics. The thermal annealing behaviors of the doped sample revealed a stable piezoelectric property. The doped SBT showed bright UC emission while simultaneously having increased Tc and d{sub 33}. As a multifunctional material, Er doped SBT ferroelectric oxide showed great potential in application of sensor, future optical-electro integration and coupling devices.

Luminescence and excited state dynamics in Bi{sup 3+}-doped LiLaP{sub 4}O{sub 12} phosphates

Energy Technology Data Exchange (ETDEWEB)

Babin, V. [Institute of Physics AS CR, Cukrovarnicka 10, 16200 Prague (Czech Republic); Chernenko, K., E-mail: nuclearphys@yandex.ru [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Peter the Great Saint-Petersburg Polytechnic University, Polytekhnicheskaya 29, 195251 St.Petersburg (Russian Federation); Demchenko, P. [Ivan Franko National University of Lviv, Kyryla i Mefodiya 8a, 79005 Lviv (Ukraine); Mihokova, E.; Nikl, M. [Institute of Physics AS CR, Cukrovarnicka 10, 16200 Prague (Czech Republic); Pashuk, I. [Ivan Franko National University of Lviv, Kyryla i Mefodiya 8a, 79005 Lviv (Ukraine); Shalapska, T. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Voloshinovskii, A. [Ivan Franko National University of Lviv, Kyryla i Mefodiya 8a, 79005 Lviv (Ukraine); Zazubovich, S. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia)

2016-08-15

Photo- and X-ray-excited luminescence characteristics of Bi-doped LiLaP{sub 4}O{sub 12} phosphates with different bismuth contents (from 1 to 25 at% in the melt) are investigated in the 4.2–300 K temperature range and compared with the characteristics of the undoped LiLaP{sub 4}O{sub 12} phosphate. The broad 2.95 eV emission band of LiLaP{sub 4}O{sub 12}:Bi excited around 5.4 eV is found to arise from the bismuth dopant. Relatively large FWHM and Stokes shift of the emission band and especially the data on the low-temperature decay kinetics of the 2.95 eV emission and its temperature dependence, indicating a very small spin-orbit splitting energy of the corresponding excited state, allow the conclusion that this emission arises from the radiative decay of the triplet state of an exciton localized around a Bi{sup 3+} ion. No spectral bands are observed, arising from the electron transitions between the energy levels of Bi{sup 3+} ions. Phenomenological model is proposed for the description of the excited state dynamics of the Bi{sup 3+}-related localized exciton in LiLaP{sub 4}O{sub 12}:Bi and the parameters of the triplet localized exciton state are determined. Keywords: Photoluminescence; Time-resolved spectroscopy; Excited states; Bi{sup 3+} centers; LiLaP{sub 4}O{sub 12}:Bi powders.

Topological phase, electronic, magnetic and optical properties of ScPdBi compound with Gd, Np and Cm impurities

Energy Technology Data Exchange (ETDEWEB)

Narimani, Mitra; Nourbakhsh, Zahra, E-mail: z.nourbakhsh@sci.ui.ac.ir

2017-07-15

Highlights: • Gd, Np and Cm impurities induce the magnetic moment in ScPdBi compound. • ScPdBi compound with Gd, Np and Cm impurities has normal band order. • The ε(0) and R(0) increase by increasing the atomic number of X atom. - Abstract: The electronic, magnetic and optical properties of X-doped ScPdBi (X = Gd, Np, Cm) are investigated in the framework of density functional theory. The exchange-correlation potential is treated using generalized gradient approximation with Coulomb interaction parameter. The band order and energy band gap of X-doped ScPdBi are investigated by calculation of band structure. The effect of doping impurity on magnetic properties of ScPdBi compound is studied by calculation of total and partial magnetic moments of X-doped ScPdBi compound. Furthermore, the optical properties of X-doped ScPdBi are calculated and compared in the energy range of 0–25 eV.

Study of Paramagnetic Species in γ-irradiated Lithium Borate Glasses Doped With Cu2+ Ions

International Nuclear Information System (INIS)

Mansour, A.; Abd-Allah, W.M.; El-Alaily, N.A.; Ezz-Eldin, F.M.

2013-01-01

Mixed alkali borate glasses doped with different concentration of Cu O ranging from (0.1-10) wt% have been prepared by the melt quenching technique. The prepared samples were studied by means of density, molar volume, infrared spectroscopy and electron paramagnetic resonance (EPR) measurements before and after successive gamma irradiation (50-200 kGy). The results showed that the density increase while molar volume decrease with the increase of CuO %. The infrared absorption studies revealed that structure of the glass network consists of BO 3 , BO 4 and B-O-Cu linkages. Gamma irradiation causes minor changes in the IR spectral bands which are related to the bond break of the B-O bond and formation non-bridging oxygen. Gamma irradiation causes irregular change in the intensities of the EPR spectra for samples doped with 0.1, 0.2 and 10 wt % of Cu O, however, no change in the EPR spectra of 2 and 5 wt % of Cu O for all absorbed doses (50-200 kGy). It is expected that the Cu-doped lithium borate glass 2 and 5 wt % of Cu O may be used for radiation shielding.

Effect of sulphur-doping on the formation of deep centers in n-type InP under irradiation

International Nuclear Information System (INIS)

Kol'chenko, T.I.; Lomako, V.M.; Moroz, S.E.

1988-01-01

Effect of sulfur-doping on the efficiency of electron trap formation in InP under irradiation was studied using deep level capacity nonstationary spectroscopy method (DLCNS). Structures with Schottky barrier based on epitaxial InP films with ∼10μm thickness (n 0 =8x10 14 -6x10 17 cm -3 ) were irradiated with 60 Co γ-quanta at 40 deg C; the particle flux intensity made up ∼10 12 cm -2 xs -1 . Experimental results presented allow one to conclude that InP doping with sulfur up to n 0 =6x10 17 cm -3 in contrast to the case of silicon doping does not produce a notable effect on the electron trap formation efficiency under irradiation. The observed reduction of configuration-bistable M-center introduction rate in samples with n 0 >10 16 cm -3 is explained by the change of filling of E c -0.12 eV level belonging to unknown X defect

Growth and properties of oxygen doped Bi2Sr2CaCu2O8+δ single crystals

International Nuclear Information System (INIS)

Kapitulnik, A.; Mitzi, D.B.

1990-01-01

This paper reports results on oxygen doped single crystals in the Bi 2 Sr 2 CaCu 2 O 8+δ system grown by a directional solidification method. Annealing of as made crystals in increasing partial pressure of oxygen reversibly depresses the superconducting transition temperature from 90K (as made) to 77K (oxygen pressure annealed). Magnetic and photoemission properties of these crystals will be discussed

One step synthesis of Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon spheres with enhanced photocatalytic performance

Energy Technology Data Exchange (ETDEWEB)

Qu, Lingling [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Luo, Zhijun, E-mail: lzj@ujs.edu.cn [School of the Environment, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093 (China); Tang, Chao [Maple Leaf International High School, Zhenjiang 212013 (China)

2013-11-15

Graphical abstract: Functional groups of sodium gluconate play synergetic roles in the formation of Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon core–shell nanosturctures (Bi@Bi{sub 2}O{sub 3}@CRCSs). Bi@Bi{sub 2}O{sub 3}@CRCSs exhibits significant enhanced photocatalytic activity under visible light irradiation. - Highlights: • One step synthesis of Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon spheres. • Functional groups of sodium gluconate play synergetic roles in the formation of Bi@Bi{sub 2}O{sub 3}@CRCSs. • Bi@Bi{sub 2}O{sub 3}@CRCSs exhibits enhanced photocatalytic activity under visible light irradiation. - Abstract: Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon core-shell nanosturctures (Bi@Bi{sub 2}O{sub 3}@CRCSs) have been synthesized via a one-step method. The core–shell nanosturctures of the as-prepared samples were confirmed by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and Raman spectroscopy. The formation of Bi@Bi{sub 2}O{sub 3}@CRCSs core–shell nanosturctures should attribute to the synergetic roles of different functional groups of sodium gluconate. Bi@Bi{sub 2}O{sub 3}@CRCSs exhibits significant enhanced photocatalytic activity under visible light irradiation (λ > 420 nm) and shows an O{sub 2}-dependent feature. According to trapping experiments of radicals and holes, hydroxyl radicals were not the main active oxidative species in the photocatalytic degradation of MB, but O{sub 2}·{sup −} are the main active oxidative species.

Orthorhombic polar Nd-doped BiFeO{sub 3} thin film on MgO substrate

Energy Technology Data Exchange (ETDEWEB)

Leontyev, I N; Janolin, P-E; Dkhil, B [Laboratoire Structures, Proprietes et Modelisation des Solides, UMR CNRS-Ecole Centrale Paris, 92295 Chatenay-Malabry Cedex (France); Yuzyuk, Yu I [Faculty of Physics, Southern Federal University, Zorge 5, Rostov-on-Don 344090 (Russian Federation); El-Marssi, M [Laboratoire de Physique de la Matiere Condensee, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens (France); Chernyshov, D; Dmitriev, V [Swiss-Norwegian Beam Lines at ESRF, Boite Postale 220, F-38043 Grenoble (France); Golovko, Yu I; Mukhortov, V M, E-mail: i.leontiev@rambler.ru [Southern Scientific Center RAS, Rostov-on-Don, 344006 (Russian Federation)

2011-08-24

A Nd-doped BiFeO{sub 3} thin film deposited on MgO substrate was studied by synchrotron diffraction. The ferroelectric nature of the film is proven by in-plane remanent polarization measurement. The highest possible symmetry of the film is determined to be orthorhombic, within the Fm2m space group. Such a structure is rotated by 45{sup 0} with respect to the substrate and is consistent with tilts of oxygen octahedra doubling the unit cell. This polar structure presents a rather unusual strain-accommodation mechanism. (fast track communication)

Intensive up-conversion photoluminescence of Er3+-doped Bi7Ti4NbO21 ferroelectric ceramics and its temperature sensing

Directory of Open Access Journals (Sweden)

Hua Zou

2014-10-01

Full Text Available The intensive up-conversion (UC photoluminescence and temperature sensing behavior of Er3+-doped Bi7Ti4NbO21(BTN ferroelectric ceramics prepared by a conventional solid-state reaction technique have been investigated. The X-ray diffraction and field emission scanning electron microscope analyses demonstrated that the Er3+-doped BTN ceramics are single phase and uniform flake-like structure. With the Er3+ ions doping, the intensive UC emission was observed without obviously changing the properties of ferroelectric. The optimal emission intensity was obtained when Er doping level was 15 mol.%. The temperature sensing behavior was studied by fluorescence intensity ratio (FIR technique of two green UC emission bands, and the experimental data fitted very well with the function of temperature in a range of 133–573 K. It suggested that the Er3+-doped BTN ferroelectric ceramics are very good candidates for applications such as optical thermometry, electro-optical devices and bio-imaging ceramics.

Influence of anisotropy and pinning centers on critical current properties in Bi-2212 superconductors

International Nuclear Information System (INIS)

Haraguchi, T.; Takayama, S.; Kiuchi, M.; Otabe, E.S.; Matsushita, T.; Yasuda, T.; Okayasu, S.; Uchida, S.; Shimoyama, J.; Kishio, K.

2006-01-01

The critical current density in Bi-2212 superconductors with various anisotropies irradiated by heavy ions was investigated in the medium temperature region to understand the effects of defect size and the anisotropy of the superconductor. It was found that the critical current density and the irreversibility field were larger for the specimen with larger defect and/or with smaller anisotropy. Introduction of stronger pinning centers and the optimization of the doping condition to improve the dimensionality are desired for further improvement of the critical current properties

Rapid Surface Oxidation as a Source of Surface Degradation Factor for Bi 2 Se 3

KAUST Repository

Kong, Desheng

2011-06-28

Bismuth selenide (Bi2Se3) is a topological insulator with metallic surface states (SS) residing in a large bulk bandgap. In experiments, synthesized Bi2Se3 is often heavily n-type doped due to selenium vacancies. Furthermore, it is discovered from experiments on bulk single crystals that Bi2Se3 gets additional n-type doping after exposure to the atmosphere, thereby reducing the relative contribution of SS in total conductivity. In this article, transport measurements on Bi2Se3 nanoribbons provide additional evidence of such environmental doping process. Systematic surface composition analyses by X-ray photoelectron spectroscopy reveal fast formation and continuous growth of native oxide on Bi2Se3 under ambient conditions. In addition to n-type doping at the surface, such surface oxidation is likely the material origin of the degradation of topological SS. Appropriate surface passivation or encapsulation may be required to probe topological SS of Bi2Se3 by transport measurements. © 2011 American Chemical Society.

Gd-substituted Bi-2223 superconductor

Indian Academy of Sciences (India)

The effects of gadolinium doping at calcium site on the normal and super- conducting properties of Bi-2223 system were ... quantities of the metal oxides and the carbonates were taken and thoroughly mixed. The calcination of the mixture after .... Therefore, Gd has higher solubility in (BiPb)-2223 as compared to Pr, and is, ...

Ferroelectric relaxor behaviour and impedance spectroscopy of Bi2O3-doped barium zirconium titanate ceramics

Science.gov (United States)

Mahajan, Sandeep; Thakur, O P; Bhattacharya, D K; Sreenivas, K

2009-03-01

Bi2O3-doped barium zirconate titanate ceramics, Ba1-xBix(Zr0.05Ti0.95)O3, have been prepared by the conventional solid-state reaction method. The ferroelectric relaxor behaviour and dielectric properties have been investigated in detail. By XRD analysis, it is suggested that up to x = 0.04, Bi3+ substitutes A-site ion, and thereafter with higher Bi3+ content, it enters the B-site sub lattice. Substitution of Bi3+ ions induces ferroelectric relaxor behaviour and the degree of relaxation behaviour increases with bismuth concentration. The remanent polarization and strain behaviour show a slight increase with the substitution level. The degree of hysteresis (strain versus electric field) also reduces from 21.4% to 4.6% with bismuth substitution. Impedance measurements were made on the prepared sample over a wide range of temperatures (300-723 K) and frequencies (40 Hz-1 MHz), which show the presence of both bulk and grain boundary effects in the material. The bulk and grain boundary conductivities determined from impedance study indicate the Arrhenius-type thermally activated process. Impedance spectroscopy is shown to be an efficient method capable of detecting the contributions of the resistances of grains and grain boundaries to the complex impedance of a ceramic system, accurately estimating its electrical conductivity as well as its corresponding activation energies and drawing conclusions on its structural properties.

Probing Photocatalytic Characteristics of Sb-Doped TiO2 under Visible Light Irradiation

Directory of Open Access Journals (Sweden)

Lingjing Luo

2014-01-01

Full Text Available Sb-doped TiO2 nanoparticle with varied dopant concentrations was synthesized using titanium tetrachloride (TiCl4 and antimony chloride (SbCl3 as the precursors. The properties of Sb-doped TiO2 nanoparticles were characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, fluorescence spectrophotometer, and Uv-vis spectrophotometer. The absorption edge of TiO2 nanoparticles could be extended to visible region after doping with antimony, in contrast to the UV absorption of pure TiO2. The results showed that the photocatalytic activity of Sb-doped TiO2 nanoparticles was much more active than pure TiO2. The 0.1% Sb-doped TiO2 nanoparticles demonstrated the best photocatalytic activity which was better than that of the Degussa P25 under visible light irradiation using terephthalic acid as fluorescent probe. The effects of Sb dopant on the photocatalytic activity and the involved mechanism were extensively investigated in this work as well.

Gd2O3 doped 0.82Bi0.5Na0.5TiO3–0.18Bi0.5K0.5TiO3 lead-free piezoelectric ceramics

International Nuclear Information System (INIS)

Fu, Peng; Xu, Zhijun; Chu, Ruiqing; Li, Wei; Wang, Wei; Liu, Yong

2012-01-01

Highlights: ► Gd 2 O 3 doped BNKT18 piezoelectric ceramics were designed and prepared. ► The electrical properties of the BNKT18 ceramics are improved with the addition of Gd 2 O 3 . ► The BNKT18 ceramics doped with 0.4 wt.% Gd 2 O 3 has better electrical properties. -- Abstract: Gd 2 O 3 (0–0.8 wt.%)-doped 0.82Bi 0.5 Na 0.5 TiO 3 –0.18Bi 0.5 K 0.5 TiO 3 (BNKT18) lead-free piezoelectric ceramics were synthesized by a conventional solid-state process. The effects of Gd 2 O 3 on the microstructure, the dielectric, ferroelectric and piezoelectric properties were investigated. X-ray diffraction (XRD) data shows that Gd 2 O 3 in an amount of 0.2–0.8 wt.% can diffuse into the lattice of BNKT18 ceramics and form a pure perovskite phase. Scanning electron microscope (SEM) images indicate that the grain size of BNKT18 ceramics decreases with the increase of Gd 2 O 3 content; in addition, all the modified ceramics have a clear grain boundary and a uniformly distributed grain size. At room temperature, the ferroelectric and piezoelectric properties of the BNKT18 ceramics have been improved with the addition of Gd 2 O 3 , and the BNKT18 ceramics doped with 0.4 wt.% Gd 2 O 3 have the highest piezoelectric constant (d 33 = 137 pC/N), highest relative dielectric constant (ε r = 1023) and lower dissipation factor (tan δ = 0.044) at a frequency of 10 kHz. The BNKT18 ceramics doped with 0.2 wt.% Gd 2 O 3 have the highest planar coupling factor (k p = 0.2463).

Microstructure and electrical properties of (1−x)[0.8Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.2Bi{sub 0.5}K{sub 0.5}TiO{sub 3}]-xBiCoO{sub 3} lead-free ceramics

Energy Technology Data Exchange (ETDEWEB)

Wang, Ting [School of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710119 (China); Chen, Xiao-ming, E-mail: xmchen@snnu.edu.cn [School of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710119 (China); Qiu, Yan-zi [School of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710119 (China); Lian, Han-li [School of Science, Xi’an University of Posts and Telecommunications, Xi’an, 710121 (China); Chen, Wei-ting [Department of Electrical Engineering, National Cheng Kung University, Tainan City, 701, Taiwan (China)

2017-01-15

The (1−x)[0.8Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.2Bi{sub 0.5}K{sub 0.5}TiO{sub 3}]-xBiCoO{sub 3} (x = 0, 0.02, 0.05, abbreviated as BNKT, BNKT-002Co, BNKT-005Co, respectively) lead-free ferroelectric ceramics were prepared via the solid state reaction method. The phase structure, microstructure, dielectric, ferroelectric, pyroelectric, and piezoelectric properties of the ceramics were investigated comparatively by using a combination of characterization techniques. All the samples exhibit typical X-ray diffraction peaks of ABO{sub 3} perovskite structure. The doping of BiCoO{sub 3} causes a decrease in lattice parameters and an increase in grain size of the ceramics. The Raman spectroscopy results suggest a lattice distortion due to the doping. It is found that BNKT-002Co and BNKT-005Co have higher depolarization temperatures compared with BNKT. The Curie-Weiss law and modified Curie-Weiss law explored a diffuse phase transition character for all the samples. The results of ultraviolet–visible diffuse reflectance suggests that BiCoO{sub 3}-doped ceramics possess higher defect concentration. The impedance analysis shows a temperature dependent relaxation behavior, and the activation energy for the electrical responses varies with the change of BiCoO{sub 3} amount. The ferroelectric and piezoelectric properties of the ceramics decrease due to the doping of BiCoO{sub 3}. Based on the results of the Rayleigh analysis, it was suggested that the differences in the electrical properties among the ceramics are closely related to the change in oxygen vacancy concentration. - Highlights: • BNKT-xCo ceramics were prepared by solid-state reaction method. • Electrical properties of BNKT ceramics are changed by the doping of BiCoO{sub 3}. • The doping causes a decrease in lattice parameters and an increase in grain size. • T{sub d} of the ceramics increases with increasing x. • Oxygen vacancies play key role in determining electrical properties of the ceramics.

Gamma ray irradiation induced optical band gap variations in silica sol-gel doped sucrose

International Nuclear Information System (INIS)

Marzouki, F.; Farah, K.; Hamzaoui, A.H; Ben Ouada, H

2015-01-01

The silica xerogels doped sucrose was prepared via sol-gel process and exposed at room temperature to different doses of high energy ("6"0Co) gamma irradiation. Changes in the UV-visible and FTIR spectra of pristine and irradiated xerogels with varying of gamma doses rays show variation in the gap energy. It was found that energy gap of the investigated silica xerogels decreases with increasing the gamma irradiation doses. Thereby the irradiated samples reveal behaviour changes, from an insulator (Eg ∼5,8 eV) towards a semiconductor with (Eg ∼ 3.5 eV).

Electron irradiation response on Ge and Al-doped SiO{sub 2} optical fibres

Energy Technology Data Exchange (ETDEWEB)

Yaakob, N.H.; Wagiran, H. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Hossain, I., E-mail: imamhossain@utm.m [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Ramli, A.T. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Bradley, D.A [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Hashim, S. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Ali, H. [Department of Radiotherapy and Oncology, Hospital Sultan Ismail, Johor Darul Takzim (Malaysia)

2011-05-01

This paper describes the thermoluminescence response, sensitivity, stability and reproducibility of SiO{sub 2} optical fibres with various electron energies and doses. The TL materials that comprise Al- and Ge-doped silica fibres were used in this experiment. The TL results are compared with those of the commercially available TLD-100. The doped SiO{sub 2} optical fibres and TLD-100 are placed in a solid phantom and irradiated with 6, 9 and 12 MeV electron beams at doses ranging from 0.2 to 4.0 Gy using the LINAC at Hospital Sultan Ismail, Johor Bahru, Malaysia. It was found that the commercially available Al- and Ge-doped optical fibres have a linear dose-TL signal relationship. The intensity of TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre.

Calcium-doping effects on photovoltaic response and structure in multiferroic BiFeO{sub 3} ceramics

Energy Technology Data Exchange (ETDEWEB)

Tu, C. S. [Graduate Institute of Applied Science and Engineering, Fu Jen Catholic University, New Taipei City 24205, Taiwan (China); Department of Physics, Fu Jen Catholic University, New Taipei City 24205, Taiwan (China); Hung, C.-M.; Anthoninappen, J. [Graduate Institute of Applied Science and Engineering, Fu Jen Catholic University, New Taipei City 24205, Taiwan (China); Xu, Z.-R.; Ting, Y.; Peng, Y.-T. [Department of Physics, Fu Jen Catholic University, New Taipei City 24205, Taiwan (China); Schmidt, V. H.; Chien, R. R. [Department of Physics, Montana State University, Bozeman, Montana 59717 (United States)

2013-09-28

Photovoltaic (PV) effects, power-conversion efficiencies, and structures have been systematically measured in (Bi{sub 1−x}Ca{sub x})FeO{sub 3−δ} ceramics for x = 0.05, 0.10, and 0.15. The heterostructures of indium tin oxide (ITO) film/(Bi{sub 1−x}Ca{sub x})FeO{sub 3−δ} ceramics/Au film exhibit significant PV effects under illumination of λ = 405 nm. The maximum power-conversion efficiency in the ITO/(Bi{sub 0.90}Ca{sub 0.10})FeO{sub 2.95} (BFO10C)/Au can reach 0.0072%, which is larger than 0.0025% observed in the graphene/polycrystalline BFO/Pt films [Zang et al., Appl. Phys. Lett. 99, 132904 (2011)]. A theoretical model based on optically excited current in the depletion region between ITO film and Ca-doped BFO ceramics is used to describe the I-V characteristic, open-circuit voltage, and short-circuit current density as a function of illumination intensity. This work suggests that the Ca-substitution can reduce the rhombohedral distortion and stabilize the single-phase structure.

Study Free Radical Of Irradiated Pulasari (Alexyia reinwadrtii BI) By Using Electron Spin Resonance (ESR)

International Nuclear Information System (INIS)

Erizal; Chosdu, Rahayu

2000-01-01

In the effort to develop the application of gamma irradiation for medicinal plant preservation especially for seeds i.e. pulasari (Alyxia reinwardtii Bi), the characteristic of free radical of irradiated pulasari (water content 4-6%) at doses of 10; 20; 30 kGy after storage time ranged 0-70 days were studied by using electron spin resonance. It was found that with increasing irradiation dose, the yield of free radicals formation increase. The yield of free radical of pulasari powder more lower than in a chips state. With increasing storage time up 5 days, the yield of free radical decrease up to 60-70 %. At storage time up to 70 days, the free radical remained ranged 10-20%, relatively

Quantitative Raman Measurement of the Evolution of the Cooper-pair Density with Doping in Bi2Sr2CaCu2O8+δ Superconductors

International Nuclear Information System (INIS)

Blanc, S.; Gu, G.; Gallais, Y.; Sacuto, A.; Cazayous, M.; Measson, M.A.; Wen, J.S.; Xu, Z.J.

2009-01-01

We report Raman measurements on Bi 2 Sr 2 CaCu 2 O 8+δ single crystals that allow us to quantitatively evaluate the doping dependence of the density of Cooper pairs in the superconducting state. We show that the drastic loss of Cooper pairs in the antinodal region as the doping level is reduced is concomitant with a deep alteration of the quasiparticles dynamic above T c and consistent with a pseudogap that competes with superconductivity. Our data also reveal that the overall density of Cooper pairs evolves with doping, distinctly from the superfluid density above the doping level p c = 0.2.

X-ray diffraction topography observations of the core in Bi12SiO20 crystals doped with Mn

International Nuclear Information System (INIS)

Milenov, T.I.; Botev, P.A.; Rafailov, P.M.; Gospodinov, M.M.

2004-01-01

The core region in a bismuth silicate--Bi 12 SiO 20 (BSO) crystal doped with Mn was examined by X-ray double-crystal diffraction topography. Specific features were observed in the topographies as lines and contrast differences that point to defects occupying the central part of the crystal. We discuss the nature of these defects and propose an explanation in terms of stacking faults arranged in different structures

Preparation and properties of visible light responsive Y3+ doped Bi5Nb3O15 photocatalysts for Ornidazole decomposition

International Nuclear Information System (INIS)

Zhao, Jie; Yao, Binghua; He, Qiang; Zhang, Ting

2012-01-01

Highlights: ► A novel Y 3+ -Bi 5 Nb 3 O 15 material was prepared. ► Y 3+ -Bi 5 Nb 3 O 15 is firstly used for the photocatalytic degradation of Ornidazole. ► Possible pathway of Ornidazole degradation in aqueous solution is proposed. - Abstract: Nanoparticle of Bi 5 Nb 3 O 15 doped with Y 3+ was prepared for the first time by the sol–gel method combined with impregnation. The degradation of Ornidazole reacting with Y 3+ -Bi 5 Nb 3 O 15 was investigated to explore the feasibility of using Y 3+ -Bi 5 Nb 3 O 15 to treat antibiotics in wastewater. The products were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, UV–vis diffuse reflectance spectrum and X-ray photoelectron spectroscopy. The results showed that the Y 3+ -Bi 5 Nb 3 O 15 exhibited single-crystalline orthorhombic structure with small particle size (20–100 nm); additionally, its UV–vis absorbance edges significantly shift to the visible-light region. The as-prepared nanoparticles exhibited a high photocatalytic activity in the decomposition of Ornidazole and several possible pathways of degradation of Ornidazole were proposed according to the results of ultra-performance liquid chromatography tandem mass spectrometry.

Enhancment of ferromagnetism in Ba and Er co-doped BiFeO{sub 3} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Naeimi, A.S., E-mail: naeimi.a.s@gmail.com [Department of Physics, Aliabad Katoul Branch, Islamic Azad University, Aliabad Katoul (Iran, Islamic Republic of); Dehghan, E.; Sanavi Khoshnoud, D. [Department of Physics, Semnan University, Semnan 35195-363 (Iran, Islamic Republic of); Gholizadeh, A. [School of Physics, Damghan University (DU), Damghan (Iran, Islamic Republic of)

2015-11-01

Bi{sub 1−y−x}Ba{sub y}Er{sub x}FeO{sub 3} [BB{sub y}E{sub x}FO, (0.13≤y≤0.17, 0≤x≤0.2)] nanoparticles were successfully synthesized by a sol–gel method. The structural, microstructural and magnetic properties have been investigated, using X-ray diffraction, Raman scattering, field emission scanning electron microscopy (FE-SEM) and magnetometry measurements at room temperature. The refinement of X-ray diffraction pattern of BB{sub 0.15}E{sub 0}FO indicates a phase transition from rhombohedral (R3c) to tetragonal (P4mm) with increasing Ba content and a transition from the coexistence of rhombohedral–tetragonal phase to orthorhombic (Pbnm) in BB{sub 0.15}E{sub x}FO samples with increasing Er concentration. The Raman analysis confirms crystal phase transition in BB{sub 0.15}E{sub x}FO compounds. The FE-SEM and TEM analysis show that the average nanoparticle size is about 50–100 nm and it decreases with Er concentration. The remnant magnetisation of BB{sub 0.15}E{sub 0.1}FO sample (M{sub r}=0.98 emu/g) is approximately two times greater than compared to BB{sub 0.15}E{sub 0}FO (M{sub r}=0.51 emu/g) that may be attributed to the collapse of spin structure and modifying exchange interactions because of Er{sup +3} doping. This enhancement in magnetic properties at room temperature can play an important role for the practical applications. - Highlights: • Bi{sub 1−y−x}Ba{sub y}Er{sub x}FeO{sub 3} nanoparticles were successfully synthesized by a sol–gel route. • X-ray diffraction and Raman spectroscopy measurements confirmed a phase transition from rhombohedral–orthorhombic. • Considerable enhancement in magnetisation of BiFeO{sub 3} is obtained with Ba and Er co-doping.

Preparation and Faraday rotation of Bi-YIG/PMMA nanocomposite

Science.gov (United States)

Fu, H. P.; Hong, R. Y.; Wu, Y. J.; Di, G. Q.; Xu, B.; Zheng, Y.; Wei, D. G.

Bismuth-substituted yttrium iron garnet (Bi-YIG) nanoparticles (NPs) were prepared by coprecipitation and subsequent heating treatment. Thermal gravity-differential thermal analysis was performed to investigate the thermal behavior of the Bi-YIG precursors and to decide the best annealing temperature. Phase formation of garnet NPs was investigated by X-ray powder diffraction. The size of Bi-YIG NPs was investigated by transmission electron microscopy, and the magnetic properties of Bi-YIG NPs were measured using a vibrating sample magnetometer. The results show that the temperature needed for the transformation of Bi-YIG from the amorphous phase to the garnet phase decreases with increasing Bi content, and Bi-YIG NPs with sizes of 28-78 nm are obtained after heating treatment at 650-1000 °C. The saturation magnetization of Bi-YIG NPs increases as the Bi content increases. Moreover, the Faraday rotation of polymethyl methacrylate (PMMA) slices doped with Bi-YIG NPs was investigated. The results indicate that the angle of Faraday rotation increases with increasing Bi content in PMMA composites, and the maximum value of the figure of merit is 1.46°, which is comparable to the value of a sputtered film. The Bi-YIG NPs-doped PMMA slices are new promising materials for magneto-optical devices.

Photocatalytic activity of attapulgite–BiOCl–TiO2 toward degradation of methyl orange under UV and visible light irradiation

International Nuclear Information System (INIS)

Zhang, Lili; Zhang, Jiahui; Zhang, Weiguang; Liu, Jianquan; Zhong, Hui; Zhao, Yijiang

2015-01-01

Highlights: • Excellent photocatalyst was obtained by introducing BiOCl–TiO 2 onto attapulgite. • 100 mg L −1 methyl orange (MO) was totally decomposed under UV light within 70 min. • 92.6% of 10 mg L −1 MO was decomposed within 120 min under visible light. • ATT–BiOCl–TiO 2 show better activity than P 25 especially under visible light. • Mechanism of photocatalytic activity enhancement was identified. - Abstract: An environmental friendly composite photocatalyst with efficient UV and visible light activity has been synthesized by introducing BiOCl–TiO 2 hybrid oxide onto the surface of attapulgite (ATT) (denoted as ATT–BiOCl–TiO 2 ), using a simple in situ depositing technique. The obtained products were characterized by XRD, TEM, BET and UV–vis diffuse reflectance spectra measurements. Results showed that BiOCl–TiO 2 composite particles were successfully loaded onto attapulgite fibers' surface without obvious aggregation. The photocatalytic activity of ATT–BiOCl–TiO 2 was investigated by degradation of methyl orange under UV and visible light irradiation. It was found that 100 mg L −1 methyl orange was totally decomposed under UV light within 70 min and 92.57% of 10 mg L −1 methyl orange was decomposed under visible light within 120 min using ATT–BiOCl–TiO 2 as photocatalyst. These results were quite better than that of P 25 , especially under visible light irradiation. Possible mechanism for the enhancement was proposed

Ultrafast microwave hydrothermal synthesis and characterization of Bi1−xLaxFeO3 micronized particles

International Nuclear Information System (INIS)

Ponzoni, C.; Cannio, M.; Boccaccini, D.N.; Bahl, C.R.H.; Agersted, K.; Leonelli, C.

2015-01-01

In this work a microwave assisted hydrothermal method is applied to successfully synthesize lanthanum doped bismuth ferrites (BLFO, Bi 1−x La x FeO 3 where x = 0, 0.15, 0.30 and 0.45). The growth mechanism of the Bi 1−x La x FeO 3 crystallites is discussed in detail. The existence of the single-phase perovskite structure for all the doped samples is confirmed by the X-ray powder diffraction patterns. A peak shift, observed at lower angle with increasing La doping concentration, indicates that the BiFeO 3 lattice is doped. The results of TG/DTA show a shift in the transition temperature from 805 °C to 815 °C as function of the La-doping for all the doped powders. At higher levels of La doping, i.e. x = 0.30 and 0.45, significant weight losses occur above 860 °C suggesting a change in the physical and chemical properties. Finally, magnetic measurements are carried out at room temperature for pure BiFeO 3 and Bi 0.85 La 0.15 FeO 3 . The results indicate that the materials are both weakly ferromagnetic, with no significant hysteresis in the curves. - Graphical abstract: Display Omitted - Highlights: • MW hydrothermal method applied to synthesize Bi 1−x La x FeO 3 , x = 0, 0.15, 0.30, 0.45. • A single-phase perovskite structure for all the samples was confirmed by XRD. • A T c shift in La doped BiFeO 3 DTA was observed as function of the La-doping. • Magnetic measurements indicate that the materials are weakly ferromagnetic

Performance analysis of bi-directional broadband passive optical network using erbium-doped fiber amplifier

Science.gov (United States)

Almalaq, Yasser; Matin, Mohammad A.

2014-09-01

The broadband passive optical network (BPON) has the ability to support high-speed data, voice, and video services to home and small businesses customers. In this work, the performance of bi-directional BPON is analyzed for both down and up streams traffic cases by the help of erbium doped fiber amplifier (EDFA). The importance of BPON is reduced cost. Because PBON uses a splitter the cost of the maintenance between the providers and the customers side is suitable. In the proposed research, BPON has been tested by the use of bit error rate (BER) analyzer. BER analyzer realizes maximum Q factor, minimum bit error rate, and eye height.

[sup 205]Bi/[sup 206]Bi cyclotron production from Pb-isotopes for absorption studies in humans

Energy Technology Data Exchange (ETDEWEB)

Fischer, R.; Dresow, B.; Heinrich, H.C. (Universitaetskrankenhaus Eppendorf, Hamburg (Germany). Abt. Medizinische Biochemie); Wendel, J.; Bechtold, V. (Kernforschungszentrum Karlsruhe GmbH (Germany). Inst. fuer Kernphysik)

1993-12-01

Pb(p,xn) thick target excitation functions were measured in the energy range 10-38 MeV in order to optimize the production of isotopically pure radiobismuth from [sup nat]Pb, [sup 206]Pb, and [sup 207]Pb. Additionally, the decay of Po-isotopes from deuteron irradiation of natural bismuth ([sup 209]Bi) was exploited for radiobismuth production. [sup 205]Bi was produced from [sup 206]Pb at 20 MeV with only 2% of [sup 206]Bi at 4 weeks post irradiation. Bismuth compounds as used in the treatment of peptic ulcer were labeled with [sup 205]Bi for absorption studies in animals and subjects. (Author).

A Green Desulfurization Technique: Utilization of Flue Gas SO2 to Produce H2 via a Photoelectrochemical Process Based on Mo-Doped BiVO4

Directory of Open Access Journals (Sweden)

Jin Han

2017-12-01

Full Text Available A green photoelectrochemical (PEC process with simultaneous SO2 removal and H2 production has attracted an increasing attention. The proposed process uses flue gas SO2 to improve H2 production. The improvement of the efficiency of this process is necessary before it can become industrial viable. Herein, we reported a Mo modified BiVO4 photocatalysts for a simultaneous SO2 removal and H2 production. And the PEC performance could be significantly improved with doping and flue gas removal. The evolution rate of H2 and removal of SO2 could be enhanced by almost three times after Mo doping as compared with pristine BiVO4. The enhanced H2 production and SO2 removal is attributed to the improved bulk charge carrier transportation after Mo doping, and greatly enhanced oxidation reaction kinetics on the photoanode due to the formation of SO32− after SO2 absorption by the electrolyte. Due to the utilization of SO2 to improve the production of H2, the proposed PEC process may become a profitable desulfurization technique.

A green desulfurization technique: utilization of flue gas SO2 to produce H2 via a photoelectrochemical process based on Mo-doped BiVO4

Science.gov (United States)

Han, Jin; Li, Kejian; Cheng, Hanyun; Zhang, Liwu

2017-12-01

A green photoelectrochemical (PEC) process with simultaneous SO2 removal and H2 production has attracted an increasing attention. The proposed process uses flue gas SO2 to improve H2 production. The improvement of the efficiency of this process is necessary before it can become industrial viable. Herein, we reported a Mo modified BiVO4 photocatalysts for a simultaneous SO2 removal and H2 production. And the PEC performance could be significantly improved with doping and flue gas removal. The evolution rate of H2 and removal of SO2 could be enhanced by almost 3 times after Mo doping as compared with pristine BiVO4. The enhanced H2 production and SO2 removal is attributed to the improved bulk charge carrier transportation after Mo doping, and greatly enhanced oxidation reaction kinetics on the photoanode due to the formation of SO32- after SO2 absorption by the electrolyte. Due to the utilization of SO2 to improve the production of H2, the proposed PEC process may become a profitable desulfurization technique.

Photocatalytic removal of tetrabromobisphenol A by magnetically separable flower-like BiOBr/BiOI/Fe{sub 3}O{sub 4} hybrid nanocomposites under visible-light irradiation

Energy Technology Data Exchange (ETDEWEB)

Gao, Shengwang [Department of Chemistry, College of Science, North University of China, Taiyuan 030051 (China); State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Guo, Changsheng; Hou, Song; Wan, Li [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Wang, Qiang [Heilongjiang Research Academy of Environmental Sciences, Harbin 150056 (China); Lv, Jiapei; Zhang, Yuan [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Gao, Jianfeng [Department of Chemistry, College of Science, North University of China, Taiyuan 030051 (China); Meng, Wei [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Xu, Jian, E-mail: xujian@craes.org.cn [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China)

2017-06-05

Highlights: • A novel BiOBr/BiOI/Fe{sub 3}O{sub 4} hybrid nanocomposites was prepared for the first time. • BiOBr-BiOI-Fe{sub 3}O{sub 4} (2:2:0.5) displays superior photocatalytic activity for TBBPA. • Good magnetic property makes it easy for the material’s recovery from solution. • The photocatalytic reaction mechanism of BiOBr/BiOI/Fe{sub 3}O{sub 4} was proposed. • Superoxide radical is the dominant ROS in TBBPA degradation. - Abstract: A novel flower-like three-dimensional BiOBr/BiOI/Fe{sub 3}O{sub 4} heterojunction photocatalyst was synthesized using a simple in situ co-precipitation method at room temperature. The hybrid composites were characterized by a couple of techniques including X-ray powder diffraction, scanning electron microscope, transmission electron microscopy, ultraviolet-visible diffuse reflection spectroscopy, Brunauer-Emmett-Teller, X-ray photo-electron spectroscopy, photoluminescence technique, and vibrating sample magnetometer. Fe{sub 3}O{sub 4} nanoparticles were perfectly loaded on the surface of BiOBr/BiOI microspheres. The recyclable magnetic BiOBr/BiOI/Fe{sub 3}O{sub 4} was employed to degrade TBBPA under visible light irradiation. The optimal removal efficiency of the ternary BiOBr/BiOI/Fe{sub 3}O{sub 4} (2:2:0.5) nanocomposite reached up to 98.5% for TBBPA in aqueous solution. The superior photocatalytic activity of BiOBr/BiOI/Fe{sub 3}O{sub 4} was mainly ascribed to large surface area and appropriate energy gaps, resulting in the effective adsorption and separation of electrons-hole pairs. The photogenerated reactive species determined by free radicals trapping experiments revealed that the excellent catalytic activity was primarily driven by ·O{sub 2}{sup −} radical. The photocatalytic degradation kinetics and a detailed mechanism were also proposed. Result demonstrated that the BiOBr/BiOI/Fe{sub 3}O{sub 4} can be magnetically recycled, and maintain high photocatalytic activity after reuse over five cycles. It

Y{sub 3}Fe{sub 5}O{sub 12}/Na,Bi,Sr-doped PZT particulate magnetoelectric composites

Energy Technology Data Exchange (ETDEWEB)

Lisnevskaya, I.V., E-mail: liv@sfedu.ru; Bobrova, I.A.; Lupeiko, T.G.; Agamirzoeva, M.R.; Myagkaya, K.V.

2016-05-01

Magnetoelectric (ME) composites of Na, Bi, Sr substituted lead zirconate titanate (PZT) and yttrium iron garnet having representative formula (100−x) wt% Na,Bi,Sr-doped PZT (PZTNB-1)+x wt% Y{sub 3}Fe{sub 5}O{sub 12} (YIG) with x=10–90 were manufactured using powdered components obtained through sol–gel processes. It is shown that the decrease in sintering temperature provided by the use of finely dispersed PZTNB-1 and YIG powders allows to significantly reduce content of fluorite-like foreign phase based on zirconium oxide, which forms due to the interfacial interaction during heat treatment and becomes stabilized by yttrium oxide. Connectivity has considerable effect on the value of ME coefficient of composite ceramics. With the same x value, ΔE/ΔH characteristic decreases when changing from 0–3-type structured composites (PZT grains embedded in ferrite matrix) to 3-3-(interpenetrating network of two phases) and especially 3-0-type samples (YIG grains embedded in PZT matrix); in the last case this can be attributed to the substrate clamping effect when ferrite grains are clamped with piezoelectric matrix. ΔE/ΔH value of 0–3 composites with x=40–60 wt% was found to be ∼1.6 mV/(cm Oe). - Highlights: • Y{sub 3}Fe{sub 5}O{sub 12}/Na,Bi,Sr-doped PZT particulate magnetoelectric composites were prepared. • The decrease in sintering temperature reduces the content of foreign phase of ZrO{sub 2}. • Connectivity pattern is important factor for magnetoelectric response. • The value of ME coefficient reaches ~1,6 mV/(cm Oe) in 0–3 composites.

Thermoluminescence and recovery processes in pure and doped NaCl after 20 K irradiation

International Nuclear Information System (INIS)

Lopez, F.J.; Aguilar, M.; Jaque, F.; Agullo-Lopez, F.

1980-01-01

The thermoluminescence (TL) spectra after X-ray irradiation at 20 K have been investigated for pure as well as divalent cation doped NaCl. The F-centre decay has also been determined in pure and Ca and Mg doped NaCl for comparison purposes. A clear decrease in F-centre concentration appears to correlate with glow peaks at 44 and 50 K for pure and Ca-doped samples. Main glow peak appearing at 69 K is not associated to any appreciable F-centre decay step. Below liquid nitrogen temperature (LNT) all peaks show both σ and π exciton emission bands. Above LNT, the glow peaks for doped samples show the σ emission together with another band at 410 nm, whereas pure samples still present the intrinsic emission bands. (author)

Absorption, fluorescence and second harmonic generation in Cr3+-doped BiB3O6 glasses

Science.gov (United States)

Kuznik, W.; Fuks-Janczarek, I.; Wojciechowski, A.; Kityk, I. V.; Kiisk, V.; Majchrowski, A.; Jaroszewicz, L. R.; Brik, M. G.; Nagy, G. U. L.

2015-06-01

Synthesis, spectral properties and photoinduced nonlinear optical effects of chromium-doped BiB3O6 glass are studied in the present paper. Absorption, excitation and time resolved luminescence spectra are presented and luminescence decay behavior is discussed. Detailed analysis of the obtained spectra (assignment of the most prominent spectral features in terms of the corresponding Cr3+ energy levels, crystal field strength Dq, Racah parameters B and C) was performed. A weak photostimulated second harmonic generation signal was found to increase drastically due to poling by proton implantation in the investigated sample.

Single crystal growth of high-temperature superconductor Bi2.1Sr1.9Ca1.0Cu2.0AlyOx

International Nuclear Information System (INIS)

Gu, G.D.; Lin, Z.W.

2000-01-01

The effect of Al doping on the crystal growth of Bi-2212 was studied by a floating zone method. The results show that the planar solid-liquid interface breaks down into a cellular growth front while increasing Al doping in the rods of Bi 2.1 Sr 1.9 Ca 1.0 Cu 2.0 Al y O x . The size of the single crystals decreases with the increase in Al doping. The solubility limit for Al or the maximum Cu-site substitution by Al in the Bi-2212 crystals is less than y = 0.01. The majority of nominal Al doping in the rods forms an Al-rich phase in the grain boundaries of the single crystals. The superconductivity of as-grown Al-doped crystals decreases progressively with increasing Al doping in the rods, however, the T c for annealed Al-doped crystals does not change with increasing Al doping in the rods. The unchanged T c for annealed Al-doped Bi-2212 crystals either suggests that a small amount of Al substitution in the Cu site does not cause T c to drop significantly, or indicates that Al only enters the Bi-2212 crystals as an impurity, but does not substitute at the Cu site in the Bi-2212 crystals. (author)

Microstructural changes of Y-doped V-4Cr-4Ti alloys after ion and neutron irradiation

Directory of Open Access Journals (Sweden)

H. Watanabe

2016-12-01

Full Text Available High-purity Y-doped V-4Cr-4Ti alloys (0.1–0.2wt. % Y, manufactured by the National Institute for Fusion Science (NIFS, were used for this study. Heavy-ion and fission-neutron irradiation was carried out at temperatures 673–873K. During the ion irradiation at 873K, the microstructure was controlled by the formation of Ti(C,O,N precipitates lying on the (100 plane. Y addition effectively suppressed the growth of Ti(C,O,N precipitates, especially at lower dose irradiation to up to 4 dpa. However, at higher dose levels (12.0 dpa, the number density was almost at the same levels irrespective of the presence of Y. After neutron irradiation at 873K, fine titanium oxides were also observed in all V alloys. However, smaller oxide sizes were observed in the Y-doped samples under the same irradiation conditions. The detailed analysis of EDS showed that the center of the Ti(C,O,N precipitates was mainly enriched by nitrogen. The results showed that the contribution of not only oxygen atoms picked up from the irradiation environment but also nitrogen atoms is essential to understand the microstructural evolution of V-4Cr-4Ti-Y alloys.

Study of coexisting phases in Bi doped La{sub 0.67}Sr{sub 0.33}MnO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Kambhala, Nagaiah [Centre for Nano and Soft Matter Sciences, Jalahalli, Bangalore 560013 (India); Chen, Miaoxiang [Advanced Nanofabrication, Imaging and Characterization Core Lab, King Abdullah University of Science and Technology, Thuwal 239955 (Saudi Arabia); Li, Peng; Zhang, Xi-xiang [Materials Science and Engineering, King Abdullah University of Science and Technology, Thuwal 239955 (Saudi Arabia); Rajesh, Desapogu [School of Physics, University of Hyderabad, Hyderabad 500046 (India); Bhagyashree, K.S.; Goveas, Lora Rita; Bhat, S.V. [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Kumar, P. Anil; Mathieu, Roland [Department of Engineering Sciences, Uppsala University, SE-751 21 Uppsala (Sweden); Angappane, S., E-mail: angappane@cens.res.in [Centre for Nano and Soft Matter Sciences, Jalahalli, Bangalore 560013 (India)

2016-05-15

We report the remarkable phase separation behavior in La{sub 0.67}Sr{sub 0.33}MnO{sub 3} doped with Bi{sup 3+} ion at La site. The temperature dependent resistivity and magnetization of La{sub 0.67−x}Bi{sub x}Sr{sub 0.33}MnO{sub 3} (x>0) show the presence of phase separation of ferromagnetic metallic and charge ordered antiferromagnetic insulating phases. Markedly, the field dependant magnetization studies of La{sub 0.67−x}Bi{sub x}Sr{sub 0.33}MnO{sub 3} (x=0.3) show the metamagnetic nature of ferromagnetic metallic state implying the competition of coexisting ferromagnetic metallic and charge ordered antiferromagnetic phases. The electron spin resonance and exchange bias studies of La{sub 0.67−x}Bi{sub x}Sr{sub 0.33}MnO{sub 3} (x=0.4 and 0.5) substantiate the coexistence of ferromagnetic clusters in antiferromagnetic matrix. - Highlights: • La{sub 0.67−x}Bi{sub x}Sr{sub 0.33}MnO{sub 3} show the transition from rhombohedral to orthorhombic structure. • Resistivity and magnetization for x>0 show phase separation of FMM and AFI phases. • La{sub 0.37}Bi{sub 0.3}Sr{sub 0.33}MnO{sub 3} exhibits a competition of FMM and AFI phases. • Magnetization and ESR illustrate coexisting FM clusters in AFM matrix for x=0.4, 0.5.

The layered double hydroxide route to Bi-Zn co-doped TiO₂ with high photocatalytic activity under visible light.

Science.gov (United States)

Benalioua, Bahia; Mansour, Meriem; Bentouami, Abdelhadi; Boury, Bruno; Elandaloussi, El Hadj

2015-05-15

In this work, a co-doped Bi-Zn-TiO₂ photocatalist is synthesized by an original synthesis route of layered double hydroxide followed by heat treatment at 670 °C. After characterization the photocatalyst efficiency is estimated by the photo-discoloration of an anionic dye (indigo carmine) under visible light and compare to TiO₂-P25 as reference material. In this new photocatalyst, anatase and ZnO wurtzite are the only identified crystalline phase, rutile and Bi₂O₃ being undetected. Moreover, the binding energy of Bi determined (XPS analysis) is different from the one of Bi in Bi₂O₃. Compared to TiO₂-P25, the absorption is red shifted (UV-vis DRS) and the Bi-Zn-TiO₂ photocatalyst showed sorption capacity toward indigo carmine higher than that TiO₂-P25. The kinetics of the photo-discoloration is faster with Bi-Zn-TiO₂ than with TiO₂-P25. Indeed, a complete discoloration is obtained after 70 min and 120 min in the presence of Bi-Zn-TiO₂ and TiO₂-P25 respectively. The identification of the responsible species on photo-discoloration was carried out in the presence of different scavengers. The study showed that the first responsible is h(+) specie with a moderate contribution of superoxide anion radical and a minor contribution of the hydroxyl radical. The material showed high stability after five uses with the same rate of photo-discoloration. Copyright © 2015 Elsevier B.V. All rights reserved.

Posterior magnetic effect on the pure and doped Fe-Ni alloy under neutron irradiation

International Nuclear Information System (INIS)

Ferreira, Iris

1974-01-01

Polycrystalline specimens of unirradiated and neutron irradiated Fe-Ni alloys have been studied in the temperature range RT - 500 deg C. The study was carried out in pure (50-50) as well as in Si, A1, Cr and Mo doped samples. Initial magnetic permeability was measured in unirradiated (virgin)and in neutron irradiated samples, during isochronal and linear thermal treatments. The main results are: a magnetic After Effect (MAE) is detected in the temperature range 370 deg C - Tc, where Tc is the Curie Temperature. In this range an activation energy of 3.2 ± 0.2 eV was determined for the Cr doped Fe-Ni alloy (impurity content: 0.1%); measurements made in the irradiated samples, during a linear temperature treatment, show the existence of several MAE zones in the temperature range RT - Tc. The isochronal annealing experiments show that these MAE zones are accompanied by a decrease in the room temperature value of the magnetic permeability, for zones between RT and a certain temperature T 1 . Above this range there is a steep increase in the room temperature permeability. Activation energies were determined for pure and Mo-doped (0.1%) samples for the first MAE zone (50 deg C - 120 deg C). The values obtained 1.25 - 0.08 eV and 1.42 ± 0.09 eV, respectively; the impurity - doped samples show a different behaviour relative to the pure ones: samples with low impurity content (0.1% and 0.5% of Si, Al or Mo) present an enhancement in the amplitude and also an overlapping of the diffusion stages. On the other hand, samples with higher impurity content (2 and 4% of Mo) show a decrease in these amplitudes. (author)

Effect of 14N ion irradiation on Bi2Sr2CaCu2Oy superconductors

International Nuclear Information System (INIS)

Sharma, M.L.; Ashwini Kumar, P.K.; Sarkar, S.K.; Virdi, G.S.; Rup, R.

1993-01-01

The effect of 14 N ion irradiation on a bulk Bi 2 Sr 2 CaCu 2 O y high-T c superconducting system has been studied. The incident energy was kept at 150 keV and the irradiation dose varied between 1 x 10 11 cm -2 and 1 x 10 16 cm -2 . It has been observed that the resistive transition occurs at lower temperatures for the irradiated specimens and the width (10-90% transition) of the superconducting transition decreases. Scanning transmission electron microscopy and x-ray diffraction (XRD) studies were carried out to evaluate the change in surface microstructure and XRD peak intensities due to irradiation. The results are discussed in the light of the similarity of atomic sizes of N and O atoms. (author)

Role of valence changes and nanoscale atomic displacements in BiS2-based superconductors.

Science.gov (United States)

Cheng, Jie; Zhai, Huifei; Wang, Yu; Xu, Wei; Liu, Shengli; Cao, Guanghan

2016-11-22

Superconductivity within layered crystal structures has attracted sustained interest among condensed matter community, primarily due to their exotic superconducting properties. EuBiS 2 F is a newly discovered member in the BiS 2 -based superconducting family, which shows superconductivity at 0.3 K without extrinsic doping. With 50 at.% Ce substitution for Eu, superconductivity is enhanced with Tc increased up to 2.2 K. However, the mechanisms for the T c enhancement have not yet been elucidated. In this study, the Ce-doping effect on the self-electron-doped superconductor EuBiS 2 F was investigated by X-ray absorption spectroscopy (XAS). We have established a relationship between Ce-doping and the T c enhancement in terms of Eu valence changes and nanoscale atomic displacements. The new finding sheds light on the interplay among superconductivity, charge and local structure in BiS 2 -based superconductors.

Influence of gamma-ray irradiation on Faraday effect of Cu-doped germano-silicate optical fiber

Energy Technology Data Exchange (ETDEWEB)

Kim, Youngwoong; Ju, Seongmin; Jeong, Seongmook; Jang, Myoung-Jin [Department of Physics and Photon Science, School of Information and Communications, Gwangju Institute of Science and Technology, 261 Cheomdan-gwagiro, Buk-Gu, Gwangju 500-712 (Korea, Republic of); Kim, Jong-Yeol; Lee, Nam-Ho; Jung, Hyun-Kyu [Nuclear Convergence Technology Development Department, Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong-gu, Daejeon (Korea, Republic of); Han, Won-Taek, E-mail: wthan@gist.ac.kr [Department of Physics and Photon Science, School of Information and Communications, Gwangju Institute of Science and Technology, 261 Cheomdan-gwagiro, Buk-Gu, Gwangju 500-712 (Korea, Republic of)

2015-02-01

Influence of gamma-ray irradiation on the Faraday effect of the Cu-doped germano-silicate optical fiber was investigated. The Verdet constant of the gamma-ray irradiated optical fiber at 660 nm was measured to be 3.07 rad T{sup −1} m{sup −1}, 1.46 times larger than that of before the irradiation at total dose of 1200 Gy. Cu-related radiation-induced defect centers and Cu metal particles which were reduced from Cu{sup 2+} ions by the irradiation are thought to be responsible for the increase in the Verdet constant of the optical fiber.

Integrated Bi2O3 nanostructure modified with Au nanoparticles for enhanced photocatalytic activity under visible light irradiation

Directory of Open Access Journals (Sweden)

Hankwon Lim

2017-06-01

Full Text Available An integrated Bi2O3 (i-Bi2O3 nanostructure with a particle size 10 nm inducing agglomerated structure were synthesized by dissolving bismuth nitrate pentahydrate in diethylene glycol at 180 °C with post heat treatment. The prepared i-Bi2O3 nanostructures were employed for the construction of Au/i-Bi2O3 composite system and characterized by X-ray diffraction pattern, UV–visible diffuse reflectance spectroscopy (DRS, and transmission electron microscopy, X-ray photoemission spectroscopy (XPS and Energy dispersive X-ray spectroscopy (EDS. The i-Bi2O3 nanostructure and Au/i-Bi2O3 composite system were found to exhibit high photocatalytic activity than commercial Bi2O3 in decomposing salicylic acid under visible light irradiation. The high catalytic activity of i-Bi2O3 nanostructure was deduced to be caused by charge separation facilitated by electron hopping between the particles within the integrated structure and space-charge separation between i-Bi2O3 and Au. The charge separation behavior in i-Bi2O3 nanostructure was further bolstered by comparing the measured. OH radical produced in the solution with i-Bi2O3 nanostructure, commercial Bi2O3 and Au/i-Bi2O3 composite which readily react with 1,4-terephthalic acid (TA inducing 2-hydroxy terephthalic acid (TAOH that shows unique fluorescence peak at 426 nm. The space-charge separation between i-Bi2O3 and Au was confirmed by measuring the electron spin resonance (ESR spectra.

Enhanced photocatalytic degradation of norfloxacin in aqueous Bi2WO6 dispersions containing nonionic surfactant under visible light irradiation

International Nuclear Information System (INIS)

Tang, Lin; Wang, Jiajia; Zeng, Guangming; Liu, Yani; Deng, Yaocheng; Zhou, Yaoyu; Tang, Jing; Wang, Jingjing; Guo, Zhi

2016-01-01

Highlights: • TX100 strongly enhanced the adsorption and photodegradation of NOF in Bi 2 WO 6 dispersions under visible light irradiation (400–750 nm). • Cu 2+ (10 mM) significantly suppressed the photocatalytic degradation of NOF. • FT-IR demonstrated that the NOF adsorbed on Bi 2 WO 6 was completely degraded. • Three possible photocatalytic degradation pathways of NOF were proposed, according to the HPLC/MS/MS analysis. - Abstract: Photocatalytic degradation is an alternative method to remove pharmaceutical compounds in water, however it is hard to achieve efficient rate because of the poor solubility of pharmaceutical compounds in water. This study investigated the photodegradation of norfloxacin in a nonionic surfactant Triton-X100 (TX100)/Bi 2 WO 6 dispersion under visible light irradiation (400–750 nm). It was found that the degradation of poorly soluble NOF can be strongly enhanced with the addition of TX100. TX100 was adsorbed strongly on Bi 2 WO 6 surface and accelerated NOF photodegradation at the critical micelle concentration (CMC = 0.25 mM). Higher TX100 concentration (>0.25 mM) lowered the degradation rate. In the presence of TX100, the degradation rate reached the maximum value when the pH value was 8.06. FTIR analyses demonstrated that the adsorbed NOF on the catalyst was completely degraded after 2 h irradiation. According to the intermediates identified by HPLC/MS/MS, three possible degradation pathways were proposed to include addition of hydroxyl radical to quinolone ring, elimination of piperazynilic ring in fluoroquinolone molecules, and replacement of F atoms on the aromatic ring by hydroxyl radicals.

First-principles calculation of the structure and electronic properties of Fe-substituted Bi2Ti2O7

Science.gov (United States)

Huang, Jin-Dou; Zhang, Zhenyi; Lin, Feng; Dong, Bin

2017-12-01

We performed first-principles calculations to investigate the formation energy, geometry structure, and electronic property of Fe-doped Bi2Ti2O7 systems with different Fe doping content. The calculated formation energies indicate that the substitutional configurations of Fe-doping Bi2Ti2O7 are easy to obtain under O-rich growth condition, but their thermodynamic stability decreases with the increase of Fe content. The calculated spin-resolved density of states and band structures indicate that the introduction of Fe into Bi2Ti2O7 brings high spin polarization. The spin-down impurity levels in Fe x Bi2-x Ti2O7 and spin-up impurity levels in Fe x Bi2Ti2-x O7 systems locate in the bottom of conduction band and narrow the band gap significantly, thus leading to the absorption of visible light. Interestingly, the impurity states in Fe x Bi2-x Ti2O7 are the efficient separation center of photogenerated electron and hole, and less affected by Fe doping content, in comparison, the levels of impurity band in Fe x Bi2Ti2-x O7 systems are largely effected by the Fe doping content, and high Fe doping content is the key factor to improve the separating rate of photogenerated electron and hole.

Bi-layer non-doped small-molecular white organic light-emitting diodes with high colour stability

International Nuclear Information System (INIS)

Chen Shuming; Kwok, Hoi-Sing; Zhao Zujin; Tang Benzhong; Wang Zhiming; Lu Ping; Gao Zhao; Ma Yuguang

2011-01-01

Bi-layer non-doped white organic light-emitting diodes (WOLEDs) with hole-transporting layer 4-(4-(1,2,2-triphenylvinyl)phenyl)-7-(5-(4-(1,2,2-triphenylvinyl)phenyl) thiophen-2yl)benzo[c][1,2,5]thiadiazole (BTPETTD) as a red emitter and electron-transporting layer 4,4'-bis(1-phenyl-1H-phenanthro[9,10-d]imidazol-2-yl)biphenyl (DDPi) as a blue emitter are demonstrated. The blue emission is due to direct recombination of excitons in DPPi, while the red emission originates not only from the direct recombination of excitons in BTPETTD but also from a colour down-conversion process by absorbing blue emission and re-emitting red photons. The combination of blue emission and red emission yields an efficient and extremely stable white colour, regardless of driving voltages. In our demonstration, a bi-layer WOLED with an efficiency of 4.2 cd A -1 at 1000 cd m -2 , 1931 Commision International de L'Eclairage coordinates of (0.31, 0.31) and a high colour rendering index of 92 over a wide range of driving voltages is obtained.

Dosimetric properties of dysprosium doped lithium borate glass irradiated by 6 MV photons

Science.gov (United States)

Ab Rasid, A.; Wagiran, H.; Hashim, S.; Ibrahim, Z.; Ali, H.

2015-07-01

Undoped and dysprosium doped lithium borate glass system with empirical formula (70-x) B2O3-30 Li2O-(x) Dy2O3 (x=0.1, 0.3, 0.5, 0.7, 1.0 mol%) were prepared using the melt-quenching technique. The dosimetric measurements were performed by irradiating the samples to 6 MV photon beam using linear accelerator (LINAC) over a dose range of 0.5-5.0 Gy. The glass series of dysprosium doped lithium borate glass produced the best thermoluminescence (TL) glow curve with the highest intensity peak from sample with 1.0 mol% Dy2O3 concentration. Minimum detectable dose was detected at 2.24 mGy, good linearity of regression coefficient, high reproducibility and high sensitivity compared to the undoped glass are from 1.0 mol% dysprosium doped lithium borate glass. The results indicated that the series of dysprosium doped lithium glasses have a great potential to be considered as a thermoluminescence dosimetry (TLD).

Ferroelectric relaxor behaviour and impedance spectroscopy of Bi{sub 2}O{sub 3}-doped barium zirconium titanate ceramics

Energy Technology Data Exchange (ETDEWEB)

Mahajan, Sandeep; Thakur, O P; Bhattacharya, D K [Electroceramics Group, Solid State Physics Laboratory, Lucknow Road, Delhi-110054 (India); Sreenivas, K, E-mail: omprakasht@hotmail.co [Department of Physics and Astrophysics, University of Delhi- 110007 (India)

2009-03-21

Bi{sub 2}O{sub 3}-doped barium zirconate titanate ceramics, Ba{sub 1-x}Bi{sub x}(Zr{sub 0.05}Ti{sub 0.95})O{sub 3}, have been prepared by the conventional solid-state reaction method. The ferroelectric relaxor behaviour and dielectric properties have been investigated in detail. By XRD analysis, it is suggested that up to x = 0.04, Bi{sup 3+} substitutes A-site ion, and thereafter with higher Bi{sup 3+} content, it enters the B-site sub lattice. Substitution of Bi{sup 3+} ions induces ferroelectric relaxor behaviour and the degree of relaxation behaviour increases with bismuth concentration. The remanent polarization and strain behaviour show a slight increase with the substitution level. The degree of hysteresis (strain versus electric field) also reduces from 21.4% to 4.6% with bismuth substitution. Impedance measurements were made on the prepared sample over a wide range of temperatures (300-723 K) and frequencies (40 Hz-1 MHz), which show the presence of both bulk and grain boundary effects in the material. The bulk and grain boundary conductivities determined from impedance study indicate the Arrhenius-type thermally activated process. Impedance spectroscopy is shown to be an efficient method capable of detecting the contributions of the resistances of grains and grain boundaries to the complex impedance of a ceramic system, accurately estimating its electrical conductivity as well as its corresponding activation energies and drawing conclusions on its structural properties.

Effect of P on Microstructure and Mechanical Properties of Sn-Bi Solder

Directory of Open Access Journals (Sweden)

WANG Xiao-jing

2016-07-01

Full Text Available Micro alloy metals P or P/Cu/Zn were added into Sn-Bi alloy to investigate the doping effects on microstructure, mechanical property, deformation fracture from the function of P in pure tin. The results show that doping 1%( mass fraction, same as below P to pure tin can improve the strength and stiffness, decrease the plasticity. Only 0.1%P additive degenerates the mechanical property of Sn-Bi alloy, this is related to the existing form of element P in the base metal and the microstructure of the base metal. In Sn base alloy, P is distributed in phase or grain boundaries in the form of Sn-P intermetallic compounds (IMC, restricting the diffusion and shifting of deformation. Therefore, Sn-1P alloy, IMC distributed in beta-tin base plays a role of strengthening in pure tin doped situation, in Sn-Bi alloy instead, enhancing the deformation mismatch under loading becoming the weak spots where cracks may initiate and propagate, and leading to brittle fracture . Finally, addition of P/Zn/Cu simultaneously to Sn-Bi alloy, the doping can optimize the microstructure, improve the strength and enhance the ultimate tensile strength (UTS of Sn-Bi alloys.

Enhancement in electrical and magnetic properties with Ti-doping in Bi0.5La0.5Fe0.5Mn0.5O3

Science.gov (United States)

Singh, Rahul; Gupta, Prince Kumar; Kumar, Shiv; Joshi, Amish G.; Ghosh, A. K.; Patil, S.; Chatterjee, Sandip

2017-04-01

In this investigation, we have synthesized Bi0.5La0.5Fe0.5Mn0.5-xTixO3 (where x = 0 and 0.05) samples. The Rietveld refinement of X-ray diffraction (XRD) patterns shows that the systems crystallize in the orthorhombic phase with the Pnma space group. The observed Raman modes support the XRD results. The appearance of prominent A1-3 and weak E-2 modes in Bi0.5La0.5Fe0.5Mn0.45Ti0.05O3 indicates the presence of chemically more active Bi-O covalent bonds. Ferromagnetism of Bi0.5La0.5Fe0.5Mn0.5O3 is enhanced by Ti doping at the Mn-site, indicating that these particular samples might be interesting for device applications.

Synthesis of TiO2/Bi2S3 heterojunction with a nuclear-shell structure and its high photocatalytic activity

International Nuclear Information System (INIS)

Lu, Juan; Han, Qiaofeng; Wang, Zuoshan

2012-01-01

Highlights: ► Bi 2 S 3 was doped into TiO 2 and it was clearly proved by the expander of the crystalline lattice in XRD result. ► As-prepared TiO 2 /Bi 2 S 3 heterojunctions have a nuclear-shell structure which has not been reported. ► As-prepared TiO 2 /Bi 2 S 3 heterojunctions have the excellent photocatalytic activity. -- Abstract: TiO 2 /Bi 2 S 3 heterojunctions with a nuclear-shell structure were prepared by the coprecipitation method. The products were characterized by X-ray diffraction analysis, Raman spectra, transmission electron microscope images and energy dispersion X-ray spectra. Results showed that as-prepared Bi 2 S 3 was urchin-like, made from many nanorods, and TiO 2 /Bi 2 S 3 heterojunctions have a similar nuclear-shell structure, with Bi 2 S 3 as the shell and TiO 2 as the nuclear. The photocatalytic experiments performed under UV irradiation using methyl orange as the pollutant revealed that the photocatalytic activity of TiO 2 could be improved by introduction of an appropriate amount of Bi 2 S 3 . However, excessive amount of Bi 2 S 3 would result in the decrease of photocatalytic activity of TiO 2 . The relative mechanism was proposed.

Photocatalytic properties of BiVO4 prepared by the co-precipitation method: Degradation of rhodamine B and possible reaction mechanisms under visible irradiation

International Nuclear Information System (INIS)

Martinez-de la Cruz, A.; Perez, U.M. Garcia

2010-01-01

Bismuth vanadate (BiVO 4 ) was synthesized by the co-precipitation method at 200 o C. The photocatalytic activity of the oxide was tested for the photodegradation of rhodamine B under visible light irradiation. The analysis of the total organic carbon showed that the mineralization of rhodamine B over a BiVO 4 photocatalyst (∼40% after 100 h of irradiation) is feasible. In the same way, a gas chromatography analysis coupled with mass spectroscopy revealed the existence of organic intermediates during the photodegradation process such as ethylbenzene, o-xylene, m-xylene, and phthalic anhydride. The modification of variables such as dispersion pH, amount of dissolved O 2 , and irradiation source was studied in order to know the details about the photodegradation mechanism.

Microstructural and electrical characteristics of rare earth oxides doped ZnO varistor films

Science.gov (United States)

Jiao, Lei; Mei, Yunzhu; Xu, Dong; Zhong, Sujuan; Ma, Jia; Zhang, Lei; Bao, Li

2018-02-01

ZnO-Bi2O3 varistor films doped with two kinds of rare earth element oxides (Lu2O3 and Yb2O3) were prepared by the sol-gel method. The effects of Lu2O3/Yb2O3 doping on the microstructure and electrical characteristics of ZnO-Bi2O3 varistor films were investigated. All samples show a homogenized morphology and an improved nonlinear relationship between the electric field (E) and current density (I). Both Yb2O3 and Lu2O3 doping can decrease the grain size of ZnO-Bi2O3 varistor films and improve the electrical properties, which have a positive effect on the development of ZnO varistor ceramics. Yb2O3 doping significantly increases the dielectric constant at low frequency. 0.2 mol. % Yb2O3 doped ZnO-Bi2O3 varistor films exhibit the highest nonlinear coefficient (2.5) and the lowest leakage current (328 μA) among Lu2O3/Yb2O3 doped ZnO-Bi2O3 varistor films. Similarly, 0.1 mol. % Lu2O3 doping increases the nonlinear coefficient to 1.9 and decrease the leakage current to 462 μA.

Carrier doping into a superconducting BaPb0.7Bi0.3O3‑δ epitaxial film using an electric double-layer transistor structure

Science.gov (United States)

Komori, S.; Kakeya, I.

2018-06-01

Doping evolution of the unconventional superconducting properties in BaBiO3-based compounds has yet to be clarified in detail due to the significant change of the oxygen concentration accompanied by the chemical substitution. We suggest that the carrier concentration of an unconventional superconductor, BaPb0.7Bi0.3O3‑δ , is controllable without inducing chemical or structural changes using an electric double-layer transistor structure. The critical temperature is found to decrease systematically with increasing carrier concentration.

Crystal structure and magnetic properties of the Cr-doped spiral antiferromagnet BiMnFe{sub 2}O{sub 6}

Energy Technology Data Exchange (ETDEWEB)

Batuk, Dmitry, E-mail: Dmitry.batuk@ua.ac.be [Electron Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp (Belgium); De Dobbelaere, Christopher [Inorganic and Physical Chemistry Group, Hasselt University, Institute for Materials Research, Agoralaan Building D, B-3590, Diepenbeek (Belgium); Tsirlin, Alexander A. [National Institute of Chemical Physics and Biophysics, 12618, Tallinn (Estonia); Abakumov, Artem M. [Electron Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp (Belgium); Hardy, An; Van Bael, Marlies K. [Inorganic and Physical Chemistry Group, Hasselt University, Institute for Materials Research, Agoralaan Building D, B-3590, Diepenbeek (Belgium); IMEC vzw, Division IMOMEC, Agoralaan Building D, B-3590, Diepenbeek (Belgium); Greenblatt, Martha [Department of Chemistry and Chemical Biology, Rutgers, State University of New Jersey, 610 Taylor Road, Piscataway, New Jersey, 08854-8087 (United States); Hadermann, Joke [Electron Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp (Belgium)

2013-09-01

Graphical abstract: - Highlights: • The substitution of Cr for Mn in BiMnFe{sub 2}O{sub 6} is possible by the solution–gel method. • The BiCr{sub x}Mn{sub 1−x}Fe{sub 2}O{sub 6} solid solution is obtained for the x values up to 0.3. • Increasing Cr content lowers the temperature of the antiferromagnetic ordering. - Abstract: We report the Cr{sup 3+} for Mn{sup 3+} substitution in the BiMnFe{sub 2}O{sub 6} structure. The BiCr{sub x}Mn{sub 1−x}Fe{sub 2}O{sub 6} solid solution is obtained by the solution–gel synthesis technique for the x values up to 0.3. The crystal structure investigation using a combination of X-ray powder diffraction and transmission electron microscopy demonstrates that the compounds retain the parent BiMnFe{sub 2}O{sub 6} structure (for x = 0.3, a = 5.02010(6)Å, b = 7.06594(7)Å, c = 12.6174(1)Å, S.G. Pbcm, R{sub I} = 0.036, R{sub P} = 0.011) with only a slight decrease in the cell parameters associated with the Cr{sup 3+} for Mn{sup 3+} substitution. Magnetic susceptibility measurements suggest strong similarities in the magnetic behavior of BiCr{sub x}Mn{sub 1−x}Fe{sub 2}O{sub 6} (x = 0.2; 0.3) and parent BiMnFe{sub 2}O{sub 6}. Only T{sub N} slightly decreases upon Cr doping that indicates a very subtle influence of Cr{sup 3+} cations on the magnetic properties at the available substitution rates.

Modifications in the rhombohedral degree of distortion and magnetic properties of Ba-doped BiFeO3 as a function of synthesis methodology

International Nuclear Information System (INIS)

Rojas-George, G.; Silva, J.; Castañeda, R.; Lardizábal, D.; Graeve, O.A.; Fuentes, L.; Reyes-Rojas, A.

2014-01-01

We present an analysis of crystallographic symmetry and the origin of the pseudo-cubic character of doped BiFeO 3 . Specifically, barium-doped bismuth ferrite, Bi 1−x Ba x FeO 3 (x = 0.05, 0.075, 0.1, 0.125), perovskite-type nanoparticles have been synthesized by implementing five modifications to the sol–gel technique (citric acid-assisted sol–gel method, ethylene glycol method, tartaric acid-assisted sol–gel method, polyvinyl alcohol–ethylene glycol method, and EDTA complexing sol–gel method) and their final pseudo-cubic character is discussed. The effect of the carboxylic groups and hydroxyl groups during synthesis is critical to obtain single phase BBFO. Fourier transform infrared spectroscopy and thermogravimetric analysis is used to study the decomposition and thermal behavior of the precursors and their relation to the final nanoparticle characteristics. X-ray diffraction analysis shows a single phase with symmetry changes for four of the five synthesis methodologies employed. Only the EDTA complexing sol–gel method, where EDTA is used as dissolver and chelating agent, is not satisfactory in all concentration ranges. Rietveld results suggest that the degree of distortion of the rhombohedral symmetry in the crystallized BiFeO 3 powders decreases 12% as a result of progressive substitution of Bi 3+ by Ba 2+ and that there is no shift from rhombohedral to tetragonal symmetry. Magnetization properties of samples with a low-distortion rhombohedral structure show higher magnetic saturation and remanent magnetization than samples with high-distortion rhombohedral structure. - Highlights: • Ba–BiFeO 3 : rhombohedral distortion degree is highly affected by the chemical method. • Rietveld results show no shift in BBFO from rhombohedral to tetragonal symmetry. • The low-distortion rhombohedral structure show higher magnetic saturation. • To stabilize a metal complex is necessary a balance between COOH − and OH − groups

Spin-rotation symmetry breaking and triplet superconducting state in doped topological insulator CuxBi2Se3

Science.gov (United States)

Zheng, Guo-Qing

Spontaneous symmetry breaking is an important concept for understanding physics ranging from the elementary particles to states of matter. For example, the superconducting state breaks global gauge symmetry, and unconventional superconductors can break additional symmetries. In particular, spin rotational symmetry is expected to be broken in spin-triplet superconductors. However, experimental evidence for such symmetry breaking has not been obtained so far in any candidate compounds. We report 77Se nuclear magnetic resonance measurements which showed that spin rotation symmetry is spontaneously broken in the hexagonal plane of the electron-doped topological insulator Cu0.3Bi2Se3 below the superconducting transition temperature Tc =3.4 K. Our results not only establish spin-triplet (odd parity) superconductivity in this compound, but also serve to lay a foundation for the research of topological superconductivity (Ref.). We will also report the doping mechanism and superconductivity in Sn1-xInxTe.

Study of morphology effects on magnetic interactions and band gap variations for 3d late transition metal bi-doped ZnO nanostructures by hybrid DFT calculations

Energy Technology Data Exchange (ETDEWEB)

Datta, Soumendu, E-mail: soumendu@bose.res.in; Baral, Sayan; Mookerjee, Abhijit [Department of Condensed Matter Physics and Material Sciences, S.N. Bose National Centre for Basic Sciences, JD Block, Sector-III, Salt Lake City, Kolkata 700 098 (India); Kaphle, Gopi Chandra [Central Department of Physics, Tribhuvan University, Kathmandu (Nepal)

2015-08-28

Using density functional theory (DFT) based electronic structure calculations, the effects of morphology of semiconducting nanostructures on the magnetic interaction between two magnetic dopant atoms as well as a possibility of tuning band gaps have been studied in the case of the bi-doped (ZnO){sub 24} nanostructures with the impurity dopant atoms of the 3d late transition metals—Mn, Fe, Co, Ni, and Cu. To explore the morphology effect, three different structures of the host (ZnO){sub 24} nano-system, having different degrees of spatial confinement, have been considered: a two dimensional nanosheet, a one dimensional nanotube, and a finite cage-shaped nanocluster. The present study employs hybrid density functional theory to accurately describe the electronic structure of all the systems. It is shown here that the magnetic coupling between the two dopant atoms remains mostly anti-ferromagnetic in the course of changing the morphology from the sheet geometry to the cage-shaped geometry of the host systems, except for the case of energetically most stable bi-Mn doping, which shows a transition from ferromagnetic to anti-ferromagnetic coupling with decreasing aspect ratio of the host system. The effect of the shape change, however, has a significant effect on the overall band gap variations of both the pristine as well as all the bi-doped systems, irrespective of the nature of the dopant atoms and provides a means for easy tunability of their optoelectronic properties.

Effects of 60 MeV C5+ ion irradiation on PmT-PVC and p-TSA doped PoT-PVC blends

International Nuclear Information System (INIS)

Lakshmi, G.B.V.S.; Siddiqui, Azher M.; Ali, Vazid; Kulriya, Pawan K.; Zulfequar, M.

2008-01-01

Poly(m-toluidine) (PmT) and Poly(o-toluidine) (PoT) have been synthesized from derivatives of aniline (m-toluidine), (o-toluidine) monomers by chemical oxidative polymerization method. After polymerization, PoT powder was doped with p-toluene sulphonic acid (p-TSA) and the polymer powders were blended with poly vinyl chloride (PVC) to achieve PmT and p-TSA doped PoT dispersed films. XRD, FTIR and UV-visible studies were carried out to get their structural changes and optical information. These blends were irradiated by 60 MeV C 5+ ions with different fluences. Post Irradiation XRD, FTIR and UV-visible spectroscopy were also performed on all films. On p-TSA doped PoT-PVC blends dc-conductivity measurements are also carried out before and after irradiation. The results show structural modifications which lead to changes in optical and electrical properties

Doping of semiconductors using radiation defects produced by irradiation with protons and alpha particles

International Nuclear Information System (INIS)

Kozlov, V.A.; Kozlovski, V.V.

2001-01-01

One of the modern methods for modifying semiconductors using beams of protons and alpha particles is analyzed; this modification is accomplished by the controlled introduction of radiation defects into the semiconductor. It is shown that doping semiconductors with radiation defects produced by irradiation with light ions opens up fresh opportunities for controlling the properties of semiconducting materials and for the development of new devices designed for optoelectronics, microelectronics, and nanoelectronics based on these materials; these devices differ favorably from those obtained by conventional doping methods, i.e., by diffusion, epitaxy, and ion implantation

BiCuSeO Thermoelectrics: An Update on Recent Progress and Perspective

Directory of Open Access Journals (Sweden)

Xiaoxuan Zhang

2017-02-01

Full Text Available A BiCuSeO system has been reported as a promising thermoelectric material and has attracted great attention in the thermoelectric community since 2010. Recently, several remarkable studies have been reported and the ZT of BiCuSeO was pushed to a higher level. It motivates us to systematically summarize the recent reports on the BiCuSeO system. In this short review, we start with several attempts to optimize thermoelectric properties of BiCuSeO. Then, we introduce several opinions to explore the origins of low thermal conductivity for BiCuSeO. Several approaches to enhance thermoelectric performance are also summarized, including modulation doping, introducing dual-vacancies, and dual-doping, etc. At last, we propose some possible strategies for enhancing thermoelectric performance of BiCuSeO in future research.

Luminescent properties of (Y,Gd)BO3:Bi3+,RE3+ (RE=Eu, Tb) phosphor under VUV/UV excitation

International Nuclear Information System (INIS)

Zeng Xiaoqing; Im, Seoung-Jae; Jang, Sang-Hun; Kim, Young-Mo; Park, Hyoung-Bin; Son, Seung-Hyun; Hatanaka, Hidekazu; Kim, Gi-Young; Kim, Seul-Gi

2006-01-01

Bi 3+ - and RE 3+ -co-doped (Y,Gd)BO 3 phosphors were prepared and their luminescent properties under vacuum ultraviolet (VUV)/UV excitation were investigated. Strong red emission for (Y,Gd)BO 3 :Bi 3+ ,Eu 3+ and strong green emission for (Y,Gd)BO 3 :Bi 3+ ,Tb 3+ are observed under VUV excitation from 147 to 200 nm with a much broader excitation region than that of single Eu 3+ -doped or Tb 3+ -doped (Y,Gd)BO 3 phosphor. Strong emissions are also observed under UV excitation around 265 nm where as nearly no luminescence is observed for single Eu 3+ -doped or Tb 3+ -doped (Y,Gd)BO 3 . The luminescence enhancement of Bi 3+ - and RE 3+ -co-doped (Y,Gd)BO 3 phosphors is due to energy transfer from Bi 3+ ion to Eu 3+ or Tb 3+ ion not only in the VUV region but also in the UV region. Besides, host sensitization competition between Bi 3+ and Eu 3+ or Tb 3+ is also observed. The investigated phosphors may be preferable for devices with a VUV light 147-200 nm as an excitation source such as PDP or mercury-free fluorescent lamp

Visible-light-driven N-(BiO)2CO3/Graphene oxide composites with improved photocatalytic activity and selectivity for NOx removal

Science.gov (United States)

Chen, Meijuan; Huang, Yu; Yao, Jie; Cao, Jun-ji; Liu, Yuan

2018-02-01

N-doped (BiO)2CO3 (NBOC)/graphene oxide (GO) composite obtained from three-dimensional hierarchical microspheres is successfully synthesized by one-pot hydrothermal method for the first time. In this synthesis, citrate ion plays a critical role in N doping. The obtained samples are used to degrade gaseous nitrogen oxides (NOx) at parts-per-billion (ppb) level under visible-light irradiation. NBOC-GO composite with 1.0 wt% graphene oxide (GO) displays the highest photocatalytic NO removal efficiency, which is 4.3 times higher than that of pristine (BiO)2CO3. Moreover, NBOC-GO composite significantly inhibits toxic NO2 intermediate production, indicating its high selectivity for NO conversion. Compared with regular GO, N doping considerably improves the catalytic performance of NBOC-GO composite, which increases NO removal by 74.6% and fully inhibits NO2 generation. The improved photocatalytic activity is mainly ascribed to extended optical absorption ability and enhanced separation efficiency of photogenerated charge carriers over NBOC-GO composite. Both results of electron spin resonance and theoretical analysis of band structure indicate that NO removal is dominated by oxidation with rad OH and rad O2- radicals. The photocatalytic activity improvement mechanism over the NBOC-GO composite is proposed accordingly based on systematic characterizations. This study demonstrates a feasible route to fabricating Bi-containing composites with high selectivity and stability for air pollution control and provides a new insight into the associated photocatalytic mechanisms.

Enhanced infrared-to-visible up-conversion emission and temperature sensitivity in (Er3+,Yb3+, and W6+) tri-doped Bi4Ti3O12 ferroelectric oxide

Science.gov (United States)

Bokolia, Renuka; Mondal, Manisha; Rai, V. K.; Sreenivas, K.

2017-02-01

Strong up conversion (UC) luminescence at 527, 550, and 662 nm is compared under an excitation of 980 nm in single doped (Er3+), co-doped (Er3+/Yb3+), and (Er3+/Yb3+/W6+) tri-doped bismuth titanate (Bi4Ti3O12). For the co-doped system, the frequency (UC) emission intensity due to Er3+ ions is enhanced significantly in the green bands due to the efficient energy transfer from Yb3+ to Er3+ ions. Further increase in the emission intensity is seen with non-luminescent W6+ ions in the tri-doped system due to the modification in the local crystal field around the Er3+ ions, and is evidenced through a gradual change in the crystal structure of the host lattice with increasing W6+ content. The observed changes in the fluorescence lifetime and the associated energy transfer mechanisms are discussed. A progressive reduction of the lifetime of the 4S3/2 levels of Er3+ ions from 72 to 58.7 μs with the introduction of Yb3+ and W6+ dopant increases the transition probability and enhances the UC emission intensity. The efficiency of the energy transfer process ( η ) in the co-doped and tri-doped systems is found to be 9.4% and 18.6%, respectively, in comparison to the single doped system. Temperature sensing based on the fluorescence intensity ratio (FR) technique shows high sensitivity (0.0123 K-1) in the high temperature range (293 to 523 K) for an optimum content of Er3+, Yb3+, and W6+ with x = 0.03, y = 0.18, and z = 0.06 at. % in the tri-doped Bi4-x-yErxYbyTi3-zWzO12 ferroelectric composition, and is found useful for potential applications in optical thermometry.

Optimization of excess Bi doping to enhance ferroic orders of spin casted BiFeO3 thin film

International Nuclear Information System (INIS)

Gupta, Surbhi; Gupta, Vinay; Tomar, Monika; James, A. R.; Pal, Madhuparna; Guo, Ruyan; Bhalla, Amar

2014-01-01

Multiferroic Bismuth Ferrite (BiFeO 3 ) thin films with varying excess bismuth (Bi) concentration were grown by chemical solution deposition technique. Room temperature multiferroic properties (ferromagnetism, ferroelectricity, and piezoelectricity) of the deposited BiFeO 3 thin films have been studied. High resolution X-ray diffraction and Raman spectroscopy studies reveal that the dominant phases formed in the prepared samples change continuously from a mixture of BiFeO 3 and Fe 2 O 3 to pure BiFeO 3 phase and, subsequently, to a mixture of BiFeO 3 and Bi 2 O 3 with increase in the concentration of excess Bi from 0% to 15%. BiFeO 3 thin films having low content (0% and 2%) of excess Bi showed the traces of ferromagnetic phase (γ-Fe 2 O 3 ). Deterioration in ferroic properties of BiFeO 3 thin films is also observed when prepared with higher content (15%) of excess Bi. Single-phased BiFeO 3 thin film prepared with 5% excess Bi concentration exhibited the soft ferromagnetic hysteresis loops and ferroelectric characteristics with remnant polarization 4.2 μC/cm 2 and saturation magnetization 11.66 emu/g. The switching of fine spontaneous domains with applied dc bias has been observed using piezoresponse force microscopy in BiFeO 3 thin films having 5% excess Bi. The results are important to identify optimum excess Bi concentration needed for the formation of single phase BiFeO 3 thin films exhibiting the improved multiferroic properties.

Efficient degradation of tetrabromobisphenol A by heterostructured Ag/Bi5Nb3O15 material under the simulated sunlight irradiation

International Nuclear Information System (INIS)

Guo, Yingna; Chen, Ling; Ma, Fengyan; Zhang, Shengqu; Yang, Yuxin; Yuan, Xing; Guo, Yihang

2011-01-01

Heterostructured metallic silver-layered bismuth niobate two-component system (Ag/Bi 5 Nb 3 O 15 ) was developed for the first time by a mild hydrothermal method combined with photodeposition. The Ag/Bi 5 Nb 3 O 15 exhibited single-crystalline orthorhombic structure with small particle size (50-200 nm) and octahedral as well as sheet-like shape; additionally, it possessed photoresponse in both UV and visible region. As a novel alternative photocatalysts to TiO 2 , the photocatalytic activity of the Ag/Bi 5 Nb 3 O 15 was evaluated by the degradation of tetrabromobisphenol A, a member from the family of the brominated flame retardant, under solar simulating Xe lamp irradiation, and enhanced photocatalytic activity in compared to Bi 5 Nb 3 O 15 itself and Degussa P25 was obtained.

Gamma irradiation effects of 51Cr(III) isotope exchange in doped magnesium chromate - zinc chromate mixtures

International Nuclear Information System (INIS)

Mahfouz, R.M.

1984-01-01

Gamma irradiation effects of 51 Cr(III) isotope exchange in magnesium chromate - zinc chromate mixtures doped with 51 Cr(III) were investigated. It was found that γ irradiation has an oxidation effect and the percentage of exchanged 51 Cr(VI) increases with the increasing γ-ray dose. The data are explained in terms of mechanistic model involving metal and ligand vacancies exchange and substitution reactions. (author)

Facile synthesis of BiOF/Bi{sub 2}O{sub 3}/reduced graphene oxide photocatalyst with highly efficient and stable natural sunlight photocatalytic performance

Energy Technology Data Exchange (ETDEWEB)

Hu, Limin; Dong, Shuying; Li, Qilu; Feng, Jinglan; Pi, Yunqing; Liu, Menglin [School of Environment, Henan Normal University, Key Laboratory for Yellow River and Huai River Water Environmental and Pollution Control, Ministry of Education, Henan Key Laboratory for Environmental Pollution Control, Xinxiang, Henan 453007 (China); Sun, Jingyu, E-mail: sunjy-cnc@pku.edu.cn [Center for Nanochemistry (CNC), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Sun, Jianhui, E-mail: sunjh@htu.cn [School of Environment, Henan Normal University, Key Laboratory for Yellow River and Huai River Water Environmental and Pollution Control, Ministry of Education, Henan Key Laboratory for Environmental Pollution Control, Xinxiang, Henan 453007 (China)

2015-06-05

Highlights: • A dual Bi-based ball-shaped material BiOF/Bi{sub 2}O{sub 3} were facilely synthesized. • The composition effect of BiOF/Bi{sub 2}O{sub 3}/RGO hybrid were probed for the first time. • The photocatalytic performances were evaluated upon natural sunlight irradiation. • The composites showed a twofold augmentation in the degradation efficiency. • The hybrid photocatalyst can be easily recycled for three times. - Abstract: A facile and efficient route for the controllable synthesis of BiOF/Bi{sub 2}O{sub 3} nanostructures by hydrolysis method was reported, where the as-prepared BiOF/Bi{sub 2}O{sub 3} was subsequently incorporated with reduced graphene oxide (RGO) sheets to form BiOF/Bi{sub 2}O{sub 3}/RGO composites. The obtained BiOF/Bi{sub 2}O{sub 3} and BiOF/Bi{sub 2}O{sub 3}/RGO composites were well characterized with the aid of various techniques to probe their crystallographic, morphological, chemical and optical properties. Photocatalytic capacities of the pure BiOF/Bi{sub 2}O{sub 3} and BiOF/Bi{sub 2}O{sub 3}/RGO composites have been investigated by the degradation of Rhodamine B (RhB)-contained wastewater under natural sunlight irradiation. A twofold augmentation of degradation efficiency was in turn observed for BiOF/Bi{sub 2}O{sub 3}/RGO composites compared with that of pure BiOF/Bi{sub 2}O{sub 3} under the natural sunlight irradiation. The optimum conditions, the effects of the active species and stabilities in photocatalytic performances of the BiOF/Bi{sub 2}O{sub 3}/RGO composites have also been probed.

Photon Irradiation Response on Ge and Al-Doped SiO2 Optical Fibres

Science.gov (United States)

Yaakob, Nor Haliza; Wagiran, Husin; Ramli, Ahmad Termizi; Ali, Hassan; Asni, Hazila

2010-07-01

Recently, research groups have reported a number of radiation effects on the applications of SiO2 optical fibres with possible use as dosimeter material because these optical fibre provide a good basis for medical radiation dosimetry. The objective of this study is to investigate the thermoluminescence response and fading characteristic for germanium and aluminium doped SiO2 optical fibres with photon irradiation. These optical fibres are placed in solid phantom and irradiated to 6 and 10 MV photon beam at dose ranging from 0.06 Gy to 0.24 Gy using Primus MLC 3339 linear accelerator at Hospital Sultan Ismail, Johor Bahru. In fading studies, the TL measurements were continued up to 14 days period. The optical fibres will produce glow curves whereby the information is then analyzed. Al and Ge-doped optical fibres have a linear dose-TL signal relationship that is proportionality between the TL signal and the doses. Comparison for TL response between different linear accelerator showed a good agreement because these optical fibres also have a linear dose-TL signal relationship even using different equipments.

Growth and properties of oxygen- and ion-doped Bi2Sr2CaCu2O8+δ single crystals

International Nuclear Information System (INIS)

Mitzi, D.B.; Lombardo, L.W.; Kapitulnik, A.; Laderman, S.S.; Jacowitz, R.D.

1990-01-01

A directional solidification method for growing large single crystals in the Bi 2 Sr 2 CaCu 2 O 8+δ system is reported. Ion doping, with replacement of La for Sr and Y for Ca, as well as oxygen doping in these crystals has been explored. Doped and undoped crystals have been characterized using microprobe analysis, x-ray diffraction, thermogravimetric analysis, and magnetic and Hall measurements. Ion doping results in little change of the superconducting transition for substitution levels below 20--25%, while beyond this level the Meissner signal broadens and the low-temperature Meissner signal decreases. Microprobe analysis and x-ray diffraction performed on these more highly substituted single crystals provide evidence for inhomogeneity and phase segregation into regions of distinct composition. Annealing unsubstituted crystals in increasing partial pressures of oxygen reversibly depresses the superconducting transition temperature from 90 (as made) to 77 K (oxygen pressure annealed), while the carrier concentrations, as determined from Hall effect measurements, increase from n=3.1(3)x10 21 cm -3 (0.34 holes per Cu site) to 4.6(3)x10 21 cm -3 (0.50 holes per Cu site)

Y3Fe5O12/Na,Bi,Sr-doped PZT particulate magnetoelectric composites

Science.gov (United States)

Lisnevskaya, I. V.; Bobrova, I. A.; Lupeiko, T. G.; Agamirzoeva, M. R.; Myagkaya, K. V.

2016-05-01

Magnetoelectric (ME) composites of Na, Bi, Sr substituted lead zirconate titanate (PZT) and yttrium iron garnet having representative formula (100-x) wt% Na,Bi,Sr-doped PZT (PZTNB-1)+x wt% Y3Fe5O12 (YIG) with x=10-90 were manufactured using powdered components obtained through sol-gel processes. It is shown that the decrease in sintering temperature provided by the use of finely dispersed PZTNB-1 and YIG powders allows to significantly reduce content of fluorite-like foreign phase based on zirconium oxide, which forms due to the interfacial interaction during heat treatment and becomes stabilized by yttrium oxide. Connectivity has considerable effect on the value of ME coefficient of composite ceramics. With the same x value, ΔE/ΔH characteristic decreases when changing from 0-3-type structured composites (PZT grains embedded in ferrite matrix) to 3-3-(interpenetrating network of two phases) and especially 3-0-type samples (YIG grains embedded in PZT matrix); in the last case this can be attributed to the substrate clamping effect when ferrite grains are clamped with piezoelectric matrix. ΔE/ΔH value of 0-3 composites with x=40-60 wt% was found to be ∼1.6 mV/(cm Oe).

Thermal spike model interpretation of sputtering yield data for Bi thin films irradiated by MeV {sup 84}Kr{sup 15+} ions

Energy Technology Data Exchange (ETDEWEB)

Mammeri, S. [Centre de Recherche Nucléaire d’Alger, B.P. 399, 02 Bd. Frantz Fanon, Alger-gare, Algiers (Algeria); Ouichaoui, S., E-mail: souichaoui@gmail.com [Université des Sciences et de la Technologie H. Boumediene (USTHB), Faculté de Physique, Laboratoire SNIRM, B.P. 32, El-Alia, 16111 Bab Ezzouar, Algiers (Algeria); Ammi, H. [Centre de Recherche Nucléaire d’Alger, B.P. 399, 02 Bd. Frantz Fanon, Alger-gare, Algiers (Algeria); Pineda-Vargas, C.A. [iThemba LABS, National Research Foundation, P.O. Box 722, Somerset West 7129 (South Africa); Faculty of Health and Wellness Sciences, CPUT, P.O. Box 1906, Bellville 7535 (South Africa); Dib, A. [Centre de Recherche Nucléaire d’Alger, B.P. 399, 02 Bd. Frantz Fanon, Alger-gare, Algiers (Algeria); Msimanga, M. [iThemba LABS, National Research Foundation, P. Bag 11, Wits 2050, Johannesburg (South Africa); Department of Physics, Tshwane University of Technology, P. Bag X680, Pretoria 001 (South Africa)

2015-07-01

A modified thermal spike model initially proposed to account for defect formation in metals within the high heavy ion energy regime is adapted for describing the sputtering of Bi thin films under MeV Kr ions. Surface temperature profiles for both the electronic and atomic subsystems have been carefully evaluated versus the radial distance and time with introducing appropriate values of the Bi target electronic stopping power for multi-charged Kr{sup 15+} heavy ions as well as different target physical proprieties like specific heats and thermal conductivities. Then, the total sputtering yields of the irradiated Bi thin films have been determined from a spatiotemporal integration of the local atomic evaporation rate. Besides, an expected non negligible contribution of elastic nuclear collisions to the Bi target sputtering yields and ion-induced surface effects has also been considered in our calculation. Finally, the latter thermal spike model allowed us to derive numerical sputtering yields in satisfactorily agreement with existing experimental data both over the low and high heavy ion energy regions, respectively, dominated by elastic nuclear collisions and inelastic electronic collisions, in particular with our data taken recently for Bi thin films irradiated by 27.5 MeV Kr{sup 15+} heavy ions. An overall consistency of our model calculation with the predictions of sputtering yield theoretical models within the target nuclear stopping power regime was also pointed out.

Synthesis and characterization of multiferroic Sm-doped BiFeO{sub 3} nanopowders and their bulk dielectric properties

Energy Technology Data Exchange (ETDEWEB)

Yotburut, Benjaporn [School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Thongbai, Prasit [Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Yamwong, Teerapon [National Metals and Materials Technology Center (MTEC), Thailand Science Park, Pathumthani 12120 (Thailand); Maensiri, Santi, E-mail: santimaensiri@g.sut.ac.th [School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); SUT Center of Excellence on Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand)

2017-09-01

Highlights: • Bi{sub 1−x}Sm{sub x}FeO{sub 3} nanopowders were prepared by a simple co-precipitation method. • The prepared samples were well characterized by XRD, TEM, SEM, and XAS. • The XANES spectra identified the valence state of Fe ion in all nanopowders as 3+. • Increasing in applied dc bias voltage from 0 to 20 V causes a decrease in the dielectric constant. • The relaxation activation energy of a LFR is larger than that of a HFR. - Abstract: Multiferroic Bi{sub 1−x}Sm{sub x}FeO{sub 3} (x = 0, 0.05, 0.1, 0.2, and 0.3) nanopowders with particle sizes of 69–22.6 nm were prepared by a simple co-precipitation method. The structure and morphology of the samples were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD patterns confirmed the phase transition from rhombohedral to orthorhombic phases. The results of X-ray absorption spectroscopy (XAS) data indicate that the oxidation state of Fe in the sample was Fe{sup 3+}. The results of magnetic properties revealed the enhancement of weak ferromagnetic property with increasing Sm doping in BFO nanopowders. SEM images revealed that the average grain size decreased with an increase in Sm concentration. Undoped BFO ceramics exhibited a high dielectric constant ε′ ∼1.1 × 10{sup 4} and a low loss tangent of tan δ ∼0.5 at room temperature for 1 kHz. The room temperature dielectric constant decreased with increasing concentration of Sm doping and the dielectric relaxation peaks were observed at x ≤ 0.1. The dielectric relaxation peaks which were observed at all frequency ranges were x ≤ 0.1 samples which were attributed to Maxwell-Wagner relaxation. As the temperature increased, great increases in dielectric permittivity were observed in all the Bi{sub 1−x}Sm{sub x}FeO{sub 3} samples. The effects of grain boundaries on the dielectric properties of Sm-doped BFO ceramics were investigated by measuring the dielectric responds in the frequencies of 100 Hz–1

Swift heavy ion irradiation induced phase transformation in undoped and niobium doped titanium dioxide composite thin films

Energy Technology Data Exchange (ETDEWEB)

Gautam, Subodh K., E-mail: subodhkgtm@gmail.com [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Chettah, Abdelhak [LGMM Laboratory, Université 20 Août 1955-Skikda, BP 26, 21000 Skikda (Algeria); Singh, R.G. [Department of Physics, Bhagini Nivedita College, Delhi University, Delhi 110043 (India); Ojha, Sunil; Singh, Fouran [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India)

2016-07-15

Study reports the effect of swift heavy ion (SHI) irradiation induced phase transformation in undoped and Niobium doped anatase TiO{sub 2} composite thin films. Investigations were carried out at different densities of electronic excitations (EEs) using 120 MeV Ag and 130 MeV Ni ions irradiations. Films were initially annealed at 900 °C and results revealed that undoped films were highly stable in anatase phase, while the Nb doped films showed the composite nature with the weak presence of Niobium penta-oxide (Nb{sub 2}O{sub 5}) phase. The effect at low density of EEs in undoped film show partial anatase to rutile phase transformation; however doped film shows only further growth of Nb{sub 2}O{sub 5} phase beside the anatase to rutile phase transformation. At higher density of EEs induced by Ag ions, registered continuous ion track of ∼3 nm in lattice which leads to nano-crystallization followed by decomposition/amorphization of rutile TiO{sub 2} and Nb{sub 2}O{sub 5} phases in undoped and doped films, respectively. However, Ni ions are only induced discontinuous sequence of ion tracks with creation of damage and disorder and do not show amorphization in the lattice. The in-elastic thermal spike calculations were carried out for anatase TiO{sub 2} phase to understand the effect of EEs on anatase to rutile phase transformation followed by amorphization in NTO films in terms of continuous and discontinuous track formation by SHI irradiation.

Critical current densities and flux creep rate in Co-doped BaFe2As2 with columnar defects introduced by heavy-Ion irradiation

International Nuclear Information System (INIS)

Nakajima, Y.; Tsuchiya, Y.; Taen, T.; Yagyuda, H.; Tamegai, T.; Okayasu, S.; Sasase, M.; Kitamura, H.; Murakami, T.

2010-01-01

We report the formation of columnar defects in Co-doped BaFe 2 As 2 single crystals with different heavy-ion irradiations. The formation of columnar defects by 200 MeV Au ion irradiation is confirmed by transmission electron microscopy and their density is about 40% of the irradiation dose. Magneto-optical imaging and bulk magnetization measurements reveal that the critical current density J c is enhanced in the 200 MeV Au and 800 MeV Xe ion irradiated samples while J c is unchanged in the 200 MeV Ni ion irradiated sample. We also find that vortex creep rates are strongly suppressed by the columnar defects. We compare the effect of heavy-ion irradiation into Co-doped BaFe 2 As 2 and cuprate superconductors.

The phase diagram and magnetic properties of Co and Ti co-doped (1−x)BiFeO_3–xLaFeO_3 solid solutions

International Nuclear Information System (INIS)

Wu, Jiangtao; Xu, Jun; Li, Nan; Jiang, Yaqi; Xie, Zhaoxiong

2015-01-01

Single phase Co and Ti co-doped Bi_1_−_xFeO_3−La_xFeO_3 (x = 0–1) solid solutions were prepared by the sol–gel method. Room temperature x-ray powder diffraction (XRD) patterns showed that the structures of as-prepared Bi_1_−_xLa_xFe_0_._9_0Co_0_._0_5Ti_0_._0_5O_3 solid solutions transformed from rhombohedral R3c to tetragonal P4mm and then to orthorhombic Pnma, with increasing La concentration from 0 to 1. In situ high-temperature XRD (HTXRD) analysis further revealed that rhombohedral structure R3c (x ≤ 0.16) and tetragonal structure P4mm (0.17 ≤ x ≤ 0.40) changed to orthorhombic Pnma along with increasing temperature, and the phase transition temperature decreased with the increase of La doping concentration. However, the orthorhombic structure Pnma (x ≥ 0.41) kept stable even when the temperature reached 850 °C. The phase diagram of as-prepared binary solid solutions of Bi_1_−_xLa_xFe_0_._9_0Co_0_._0_5Ti_0_._0_5O_3(x = 0–1) was drawn on the basis of XRD and HTXRD analysis. Magnetic measurement revealed that the magnetic properties are greatly enhanced with the increase of La content. - Highlights: • Single phase Co and Ti co-doped (1−x)BiFeO_3–xLaFeO_3 (x = 0–1) solid solutions were synthesized. • The phase transitions were investigated by tuning composition and temperature. • Phase diagram was constructed according to the results of XRD for the first time. • The magnetization of solid solution can be enhanced when increasing La content.

Protons in neutron-irradiated and thermochemically reduced MgO crystals doped with lithium impurities

International Nuclear Information System (INIS)

Gonzalez, R.; Pareja, R.; Chen, Y.

1992-01-01

H - (hydride) ions have been observed in lithium-doped MgO crystals which have been neutron irradiated or thermochemically reduced (TCR). Infrared-absorption measurements have been used to identify the local modes of the H - ions in these crystals. The concentration of the H - ions in the neutron-irradiated crystals is found to be far less than that found in the TCR crystals. The thermal stability of H - and oxygen vacancies in both oxidizing and reducing atmospheres are investigated. The emergence of sharp structures due to OH - ions is attributed to the displacements of substitutional Li + ions, leaving behind unperturbed OH - ions, via a mechanism of rapid radiation-induced diffusion during irradiation in a reactor. Results of neutron-irradiated MgO:Li, which had previously been oxidized at high temperature, are also presented

Modeling of helium bubble nucleation and growth in neutron irradiated boron doped RAFM steels

International Nuclear Information System (INIS)

Dethloff, Christian; Gaganidze, Ermile; Svetukhin, Vyacheslav V.; Aktaa, Jarir

2012-01-01

Reduced activation ferritic/martensitic (RAFM) steels are promising candidates for structural materials in future fusion technology. In addition to other irradiation defects, the transmuted helium is believed to strongly influence material hardening and embrittlement behavior. A phenomenological model based on kinetic rate equations is developed to describe homogeneous nucleation and growth of helium bubbles in neutron irradiated RAFM steels. The model is adapted to different 10 B doped EUROFER97 based heats, which already had been studied in past irradiation experiments. Simulations yield bubble size distributions, whereby effects of helium generation rate, surface energy, helium sinks and helium density are investigated. Peak bubble diameters under different conditions are compared to preliminary microstructural results on irradiated specimens. Helium induced hardening was calculated by applying the Dispersed Barrier Hardening model to simulated cluster size distributions. Quantitative microstructural investigations of unirradiated and irradiated specimens will be used to support and verify the model.

Modeling of helium bubble nucleation and growth in neutron irradiated boron doped RAFM steels

Energy Technology Data Exchange (ETDEWEB)

Dethloff, Christian, E-mail: christian.dethloff@kit.edu [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Gaganidze, Ermile [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Svetukhin, Vyacheslav V. [Ulyanovsk State University, Leo Tolstoy Str. 42, 432970 Ulyanovsk (Russian Federation); Aktaa, Jarir [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

2012-07-15

Reduced activation ferritic/martensitic (RAFM) steels are promising candidates for structural materials in future fusion technology. In addition to other irradiation defects, the transmuted helium is believed to strongly influence material hardening and embrittlement behavior. A phenomenological model based on kinetic rate equations is developed to describe homogeneous nucleation and growth of helium bubbles in neutron irradiated RAFM steels. The model is adapted to different {sup 10}B doped EUROFER97 based heats, which already had been studied in past irradiation experiments. Simulations yield bubble size distributions, whereby effects of helium generation rate, surface energy, helium sinks and helium density are investigated. Peak bubble diameters under different conditions are compared to preliminary microstructural results on irradiated specimens. Helium induced hardening was calculated by applying the Dispersed Barrier Hardening model to simulated cluster size distributions. Quantitative microstructural investigations of unirradiated and irradiated specimens will be used to support and verify the model.

Novel Bi/BiOBr/AgBr composite microspheres: Ion exchange synthesis and photocatalytic performance

Science.gov (United States)

Lyu, Jianchang; Li, Zhenlu; Ge, Ming

2018-06-01

Novel Bi/BiOBr/AgBr composite microspheres were prepared by a rational in situ ion exchange reaction between Bi/BiOBr microspheres and AgNO3. The characteristic of the as-obtained ternary microspheres was tested by X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDS), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and photoluminescence (PL). Under visible light irradiation, Bi/BiOBr/AgBr microspheres exhibited an excellent photocatalytic efficiency for rhodamine B (RhB) degradation, which was about 1.4 and 4.9 times as high as that of Bi/BiOBr and BiOBr/AgBr, demonstrating that the highest separation efficiency of charge carriers in the heterostructured Bi/BiOBr/AgBr. The photocatalytic activity of Bi/BiOBr/AgBr microspheres just exhibited a slight decrease after three consecutive cycles. The photocatalytic mechanism investigation confirmed that the superoxide radicals (O2•-) were the dominant reactive oxygen species for RhB degradation in Bi/BiOBr/AgBr suspension.

Specific features of nonlinear optical properties of Eu3+ doped BiFeO3 nanopowders near antiferromagnetic transition

Science.gov (United States)

El Bahraoui, T.; Sekkati, M.; Taibi, M.; Abd-Lefdil, M.; El-Naggar, A. M.; AlZayed, N. S.; Albassam, A. A.; Kityk, I. V.; Maciag, A.

2016-01-01

The monitoring of the Eu3+ doped BiFeO3 nanopowders was performed near the antiferromagnetic transformation by photoinduced optical second harmonic generation. As photoinduced laser beams we have used bicolor coherent excitations of the Er:glass laser emitting at 1540 nm with frequency repetition about 15 ns. The studies of the photoinduced SHG were performed versus temperature including the temperature range of ferromagnetic-ferroelectric transition (350 °C…390 °C). The optimal light polarization and intensity ratio were chosen; the sensitivity of the photoinduced SHG to the multiferroic phase transitions was explored.

Enhanced photocatalytic degradation of norfloxacin in aqueous Bi{sub 2}WO{sub 6} dispersions containing nonionic surfactant under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Tang, Lin, E-mail: tanglin@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Wang, Jiajia [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Zeng, Guangming, E-mail: zgming@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Liu, Yani; Deng, Yaocheng; Zhou, Yaoyu; Tang, Jing; Wang, Jingjing; Guo, Zhi [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China)

2016-04-05

Highlights: • TX100 strongly enhanced the adsorption and photodegradation of NOF in Bi{sub 2}WO{sub 6} dispersions under visible light irradiation (400–750 nm). • Cu{sup 2+} (10 mM) significantly suppressed the photocatalytic degradation of NOF. • FT-IR demonstrated that the NOF adsorbed on Bi{sub 2}WO{sub 6} was completely degraded. • Three possible photocatalytic degradation pathways of NOF were proposed, according to the HPLC/MS/MS analysis. - Abstract: Photocatalytic degradation is an alternative method to remove pharmaceutical compounds in water, however it is hard to achieve efficient rate because of the poor solubility of pharmaceutical compounds in water. This study investigated the photodegradation of norfloxacin in a nonionic surfactant Triton-X100 (TX100)/Bi{sub 2}WO{sub 6} dispersion under visible light irradiation (400–750 nm). It was found that the degradation of poorly soluble NOF can be strongly enhanced with the addition of TX100. TX100 was adsorbed strongly on Bi{sub 2}WO{sub 6} surface and accelerated NOF photodegradation at the critical micelle concentration (CMC = 0.25 mM). Higher TX100 concentration (>0.25 mM) lowered the degradation rate. In the presence of TX100, the degradation rate reached the maximum value when the pH value was 8.06. FTIR analyses demonstrated that the adsorbed NOF on the catalyst was completely degraded after 2 h irradiation. According to the intermediates identified by HPLC/MS/MS, three possible degradation pathways were proposed to include addition of hydroxyl radical to quinolone ring, elimination of piperazynilic ring in fluoroquinolone molecules, and replacement of F atoms on the aromatic ring by hydroxyl radicals.

Ultrafast microwave hydrothermal synthesis and characterization of Bi{sub 1−x}La{sub x}FeO{sub 3} micronized particles

Energy Technology Data Exchange (ETDEWEB)

Ponzoni, C. [Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Modena 42025 (Italy); Cannio, M., E-mail: maria.cannio@unimore.it [Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Modena 42025 (Italy); Boccaccini, D.N.; Bahl, C.R.H.; Agersted, K. [Department of Energy Conversion and Storage, Technical University of Denmark Frederiksborgvej, 4000 Roskilde (Denmark); Leonelli, C. [Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Modena 42025 (Italy)

2015-07-15

In this work a microwave assisted hydrothermal method is applied to successfully synthesize lanthanum doped bismuth ferrites (BLFO, Bi{sub 1−x}La{sub x}FeO{sub 3} where x = 0, 0.15, 0.30 and 0.45). The growth mechanism of the Bi{sub 1−x}La{sub x}FeO{sub 3} crystallites is discussed in detail. The existence of the single-phase perovskite structure for all the doped samples is confirmed by the X-ray powder diffraction patterns. A peak shift, observed at lower angle with increasing La doping concentration, indicates that the BiFeO{sub 3} lattice is doped. The results of TG/DTA show a shift in the transition temperature from 805 °C to 815 °C as function of the La-doping for all the doped powders. At higher levels of La doping, i.e. x = 0.30 and 0.45, significant weight losses occur above 860 °C suggesting a change in the physical and chemical properties. Finally, magnetic measurements are carried out at room temperature for pure BiFeO{sub 3} and Bi{sub 0.85}La{sub 0.15}FeO{sub 3}. The results indicate that the materials are both weakly ferromagnetic, with no significant hysteresis in the curves. - Graphical abstract: Display Omitted - Highlights: • MW hydrothermal method applied to synthesize Bi{sub 1−x}La{sub x}FeO{sub 3}, x = 0, 0.15, 0.30, 0.45. • A single-phase perovskite structure for all the samples was confirmed by XRD. • A T{sub c} shift in La doped BiFeO{sub 3} DTA was observed as function of the La-doping. • Magnetic measurements indicate that the materials are weakly ferromagnetic.

Photocatalytic properties of BiVO{sub 4} prepared by the co-precipitation method: Degradation of rhodamine B and possible reaction mechanisms under visible irradiation

Energy Technology Data Exchange (ETDEWEB)

Martinez-de la Cruz, A., E-mail: azael70@yahoo.com.mx [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Ciudad Universitaria, C.P. 66451, San Nicolas de los Garza, N.L. (Mexico); Perez, U.M. Garcia [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Ciudad Universitaria, C.P. 66451, San Nicolas de los Garza, N.L. (Mexico)

2010-02-15

Bismuth vanadate (BiVO{sub 4}) was synthesized by the co-precipitation method at 200 {sup o}C. The photocatalytic activity of the oxide was tested for the photodegradation of rhodamine B under visible light irradiation. The analysis of the total organic carbon showed that the mineralization of rhodamine B over a BiVO{sub 4} photocatalyst ({approx}40% after 100 h of irradiation) is feasible. In the same way, a gas chromatography analysis coupled with mass spectroscopy revealed the existence of organic intermediates during the photodegradation process such as ethylbenzene, o-xylene, m-xylene, and phthalic anhydride. The modification of variables such as dispersion pH, amount of dissolved O{sub 2}, and irradiation source was studied in order to know the details about the photodegradation mechanism.

Thermoelectric Properties in Fermi Level Tuned Topological Materials (Bi1-xSnx)2Te3

Science.gov (United States)

Lin, Chan-Chieh; Shon, Won Hyuk; Rathnam, Lydia; Rhyee, Jong-Soo

2018-03-01

We investigated the thermoelectric properties of Sn-doped (Bi1-xSnx)2Te3 (x = 0, 0.1, 0.3, 0.5, and 0.7%) compounds, which is known as topological insulators. Fermi level tuning by Sn-doping can be justified by the n- to p-type transition with increasing Sn-doping concentration, as confirmed by Seebeck coefficient and Hall coefficient. Near x = 0.3 and 0.5%, the Fermi level resides inside the bulk band gap, resulting in a low Seebeck coefficient and increase of electrical resistivity. The magnetoconductivity with applying magnetic field showed weak antilocalization (WAL) effect for pristine Bi2Te3 while Sn-doped compounds do not follow the WAL behavior of magneto-conductivity, implying that the topological surface Dirac band contribution in magneto-conductivity is suppressed with decreasing the Fermi level by Sn-doping. This research can be applied to the topological composite of p-type/n-type topological materials by Fermi level tuning via Sn-doping in Bi2Te3 compounds.

Doping influence by some transition elements on the irradiation effects in nuclear waste glasses; Influence du dopage par certains elements de transition sur les effets d'irradiation dans des verres d'interet nucleaire

Energy Technology Data Exchange (ETDEWEB)

Florent, Olivier

2006-06-15

High-level waste glasses are submitted to auto-irradiation. Modelling it using external irradiations on simple glasses revealed defects production and non negligible structural changes. This thesis aims at determining the impact of a more complex composition on these effects, especially the influence of adding polyvalent transition metals. Silicate, soda-lime and alumino-borosilicate glasses are doped with different iron, chromium and manganese concentrations then {beta} irradiated at different doses up to 10{sup 9} Gy. Non doped glasses show an increase of their density and polymerisation coupled with a molecular oxygen and point defects production. Adding 0.16 mol% Fe decreases the amount of defects by 85 % and all irradiation effects. A Fe{sup 3+} reduction is also observed by EPR, optical absorption and indirectly by Raman spectroscopy. A higher than 0.32 mol% Fe concentration causes complete blockage of the evolution of polymerisation, density and defect production. The same results are obtained on chromium or manganese doped glasses. An original in situ optical absorption device shows the quick decrease of Fe{sup 3+} amount to a 25 % lower level during irradiation. Stopping irradiation causes a lower decrease of 65 %, suggesting a dynamic (h{sup 0}/e-) consuming equilibrium. He{sup +} and Kr{sup 3+} ions and {gamma} irradiated glasses tend to confirm these phenomena for all kind of irradiation with electronic excitations. (author)

BiOI/TiO2-nanorod array heterojunction solar cell: Growth, charge transport kinetics and photoelectrochemical properties

International Nuclear Information System (INIS)

Wang, Lingyun; Daoud, Walid A.

2015-01-01

Highlights: • BiOI/TiO 2 photoanodes were fabricated by a simple solvothermal/hydrothermal method. • BiOI/TiO 2 (PVP) showed a 13-fold increase in photocurrent density compared to TiO 2 . • Charge transport kinetics within the BiOI/TiO 2 heterojunctions are discussed. - Abstract: A series of BiOI/TiO 2 -nanorod array photoanodes were grown on fluorine-doped tin oxide (FTO) glass using a simple two-step solvothermal/hydrothermal method. The effects of the hydrothermal process, such as TiO 2 nanorod growth time, BiOI concentration and the role of surfactant, polyvinylpyrrolidone (PVP), on the growth of BiOI, were investigated. The heterojunctions were characterized by X-ray diffraction, UV–vis absorbance spectroscopy and scanning electron microscopy. The photoelectrochemical properties of the as-grown junctions, such as linear sweep voltammetry (LSV) behavior, photocurrent response and incident photon-to-electron conversion efficiency (IPCE) under Xenon lamp illumination, are presented. The cell with BiOI/TiO 2 (PVP) as photoanode can reach a short current density (J sc ) of 0.13 mA/cm 2 and open circuit voltage (V oc ) of 0.46 V vs. Ag/AgCl under the irradiation of a 300 W Xenon lamp. Compared to bare TiO 2 , the IPCE of BiOI/TiO 2 (PVP) increased 4–5 times at 380 nm. Furthermore, the charge transport kinetics within the heterojunction is also discussed

The effect of Ag doping on superconducting properties of the Bi-Pb-Sr-Ca-Cu-O tape fabricated by an Ag sheath

International Nuclear Information System (INIS)

Oota, A.; Horio, T.; Ohba, K.; Iwasaki, K.

1992-01-01

The powder-in-tube method using an Ag sheath is applied to achieve high current capacity in the tapes of Bi-Pb-Sr-Ca-Cu-O (BPSCCO) with the high-T c phase (T c =110 K), by a combination process of cold working and sintering. Two kinds of the BPSCCO powder with and without Ag doping are used as the materials for tape fabrication. The morphology, structure, and critical current density J c are investigated on the tapes by x-ray diffraction, differential thermal analysis, scanning electron microscope, magnetic susceptibility, and I-V curves. The optimum sintering conditions to obtain a maximum in the value of J c at 77 K and 0 T are presented in the Ag-doped tapes and the nondoped ones. An improvement in the J c vs B properties up to 1 T at 77 K is presented in the BPSCCO tape by Ag doping. The Ag doping causes neither change in the value of T c (=110 K) nor decomposition of the high-T c phase

Bi2O2Se nanosheet: An excellent high-temperature n-type thermoelectric material

Science.gov (United States)