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Effects of N concentration on electronic and optical properties of N-doped PbTiO_3

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Journal of Semiconductors 2015年第9期36卷 36-40页

作者：赵银女闫金良 Dean's Office Ludong University School of Physics and Optoelectronic Engineering Ludong University

The p-type N-doped PbTiO3 with different doping concentrations have been studied by first-principles calculations. The charge density differences, band structures, density of states and optical properties have been investigated. After an oxygen atom is substituted by a nitrogen atom in the crystals, the valance bands move to high energy levels and the Fermi energy level gets into the top of the valance bands. Results show that the values of the band gaps are decreased and the stability is weakened when the N concentration increases. The 2.5 at% N-doped PbTiO3 shows the best p-type conductivity and the visible-light absorption can be enhanced most at this doping concentration, which is necessary in semiconductors or photocatalysts.

关键词： semiconductor doping electric property optical property electronic structure

Structure and electric Properties of (1-x)(Bi_(1/2)Na_(1/2)) TiO_3-xBaTiO_3 Systems

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Journal of Wuhan University of Technology(Materials Science) 2007年第2期22卷 315-319页

作者：刘云飞吕忆农 College of Materials Science and Engineering Nanjing University of Technology

The structural, dielectric and piezoelectric properties of （1-x）（Bi1/2Na1/2） TiO3-xBaTiO3 ceramics were investigated for the compositional range, x=0.02, 0.04, 0.06, 0.08, 0.10. The samples were synthesized by a conventional solid-state reaction technique. All compositions show a single perovskite structure, and X-ray powder diffraction patterns can be indexed using a rhombohedral structure. Lattice constants and lattice distortion increase while the amount of BaTiO3 increases. The X-ray diffraction results show the morphotropic phase boundary （MPB） of （1-x）（Bi1/2Na12） TiO3-xBaTiO3 exists in near x=0.06-0.08. Temperature dependence of dielectric constant eT33/ε0 measurement reveals that all compositions experience one structural phase and two ferroelectric phases transition below 400℃： rhombohedral （or rhombohedral plus tetragonal） ferroelectric phase ←→ tetragonal antiferroelectric phase ←→ tetragonal paraelectric phase. Relaxor behaviors exist in the course of ferroelectric to antiferroelectric phase transition. Dielectric and piezoelectric properties are enhanced in the MPB range for （ 1-x）（Bi1/2Na1/2）TiO3-xBaTiO3.

关键词： bismuth sodium titanate morphotropic phase boundary relaxor electric property

Effects of filler loading and surface modification on electrical and thermal properties of epoxy/montmorillonite composite

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Chinese Physics B 2018年第11期27卷 332-339页

作者：贾梓睿高振国兰笛成永红吴广磊吴宏景 School of Science Northwestern Polytechnical University Xi'an 710072 China Center of Nanomaterials for Renewable Energy (CNRE) State Key Laboratory of Electrical Insulation and Power Equipment School of Electrical Engineering Xi'an Jiaotong University Xi'an 710049 China Institute of Materials for Energy and Environment State Key Laboratory Breeding Based of New Fiber Materials and Modern Textile College of Materials Science and Engineering Qingdao University Qingdao 266071 China

Epoxy-based composites containing montmorillonite（MMT） modified by silylation reaction with γ-aminopropyltriethoxysilane（γ-APTES） and 3-（glycidyloxypropyl） trimethoxysilane（GPTMS） are successfully prepared.The effects of filler loading and surface modification on the electrical and thermal properties of the epoxy/MMT composites are investigated. Compared with the pure epoxy resin, the epoxy/MMT composite, whether MMT is surface-treated or not, shows low dielectric permittivity, low dielectric loss, and enhanced dielectric strength. The MMT in the epoxy/MMT composite also influences the thermal properties of the composite by improving the thermal conductivity and stability.Surface functionalization of MMT not only conduces to the better dispersion of the nanoparticles, but also significantly affects the electric and thermal properties of the hybrid by influencing the interfaces between MMT and epoxy resin.Improved interfaces are good for enhancing the electric and thermal properties of nanocomposites. What is more, the MMT modified with GPTMS rather than γ-APTES is found to have greater influence on improving the interface between the MMT filler and polymer matrices, thus resulting in lower dielectric loss, lower electric conductivity, higher breakdown strength, lower thermal conductivity, and higher thermal stability.

关键词： modified epoxy resin surface modification electric property thermal property

Electronic structures and optical properties of Nb-doped SrTiO_3 from first principles

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Journal of Semiconductors 2016年第7期37卷 12-16页

作者：焦淑娟闫金良孙桂鹏赵银女 School of Physics and Optoelectronic Engineering Ludong University

The n-type Nb-doped SrTiO3 with different doping concentrations were studied by first principles cal- culations. The effects of Nb concentration on the formation enthalpy, electronic structure and optical property were investigated. Results show that Nb preferentially enters the Ti site in SrTiO3, which is in good agreement with the experimental observation. The Fermi level of Nb-doped SrTiO3 moves into the bottom of the conduction band, and the system becomes an n-type semiconductor. The effect of Nb-doping concentration on the conductivity was discussed from the microscopic point of view. Furthermore, the 1.11 at% Nb-doped SrTiO3 shows strong absorp- tion in the visible light and becomes a very useful material for photo-catalytic activity. The 1.67 at% and 2.5 at% Nb-doped models will be potential transparent conductive materials.

关键词： semiconductor doping electric property optical property electronic structure

Effects of K2Ti6O13 Whiskers on Structure and Properties of PBZT Ferroelectric Ceramics

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Effects of K2Ti6O13 Whiskers on Structure and Properties of ...