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(Pb1-xSrx)TiO3系铁电陶瓷介电特性的测试分析  [PDF]
王茂祥,孙平
材料工程 , 2007,
Abstract: 采用常规陶瓷工艺掺杂不同含量的分析纯SiO2和La2O3,在不同烧结温度下,制备了系列(Pb1-xSrx)TiO3(简称PST)铁电陶瓷。对所制备的PST铁电陶瓷的介电特性进行了测试分析。1250℃烧结温度较1200℃烧结温度下样品在居里点处的温度系数α有所提高,介电常数ε略高(均在103量级),介电损耗D略有降低。随着工作频率的增加,样品介电常数有较明显的下降,介电损耗D略有增加。
Optical and electro-optical characteristics of hot-pressing (Pb1-xLax)TiO3 ferroelectric ceramics  [cached]
Londono, F. A.,Eiras, J. A.,Garcia, D.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2012, DOI: 10.3989/cyv.482012
Abstract: La-modified PbTiO3-based ceramics (PLT) are the subject of many studies in term of piezoelectric and pyroelectric applications, but the processing of PLT to optimize their transparency and electro-optical properties has not been studied in detail. Ferroelectric (Pb1-xLax)TiO3 (PLT) ceramics, with 0.18 ≤ x ≤ 0.23, were produced by a solid state reaction and uniaxially hot pressing for 3h at a temperature of 1220 oC, and a pressure of ~6,0 MPa. High density, translucent reddish color and high dc conductivity were observed for all compositions. Nevertheless appropriate thermal treatments in an O2 atmosphere, after hot pressing, led to ceramics with good properties for dielectric, optical and electro-optical studies. The heat-treated samples revealed a homogeneous microstructure, absence of second phases, increased of the transmittance in the visible and infrared range and reduced dc conductivity. These features allowed the electro-optical coefficient of the (Pb,La)TiO3 system to be calculated. Las cerámicas basadas en PbTiO3 con adición de La, (PLT) han sido ampliamente estudiadas debido a sus aplicaciones piro y piezoeléctricas. Por otra parte, el procesamiento de PLT para optimizar su transparencia y sus propiedades electro-ópticas no ha sido estudiado com el mismo detalle. En el presente trabajo, se han preparado cerámicas ferroeléctricas de (Pb1-xLax) TiO3 (PLT) con 0.18 ≤ x ≤ 0.23, mediante síntesis en estado sólido y prensado uniaxial en caliente por 3 h a una temperatura de 1220 oC, y una presión de ~6,0 MPa. En todas l s composiciones se han observado una alta densidad, baja transparencia y conducción eléctrica elevada. Mediante adecuados tratamientos posteriores en atmósfera de O2 se há mejorado la calidad eléctrica y óptica de dichas cerámicas. La microestructura es homogénea, la transmitancia en las regiones visible e infrarroja crece y la conductividad DC disminuye. Estas características han permitido medir el coeficiente electro-óptico en muestras del sistema (Pb,La)TiO3.
ESTUDIO DE LA TRANSICIóN DE FASE ESTRUCTURAL EN EL SISTEMA PB1?X LA X TIO3
RINCóN JOYA,MIRYAM; BARBA ORTEGA,JOSé JOSé;
DYNA , 2011,
Abstract: the samples of pb1?xlaxtio3 (plt) were prepared using the conventional mixed oxide of high purity sintered at a temperature of 1200°c, with compositions x = 0.0, 2.5, 5, 10.15 and 20%. the samples were analyzed using micro raman spectroscopy to observe the structural phase transition from tetragonal to cubic, by applying high temperature and hydrostatic pressure. we used the molecular dynamics simulation to describe the structural phase transition of the plt-induced temperature variation. x-ray diffraction (xrd) and scanning electron microscopy (sem) were used to study the synthesis of the samples obtained.
Structure effects on the optical properties of thin (PbLa)TiO3 films
Carre?o,N. L. V.; Rangel,J. H. G.; Pinheiro,C. D.; Longo,E.; Leite,E. R.; Varela,J. A.; Campos,C. E. M.; Pisani,P. S.;
Latin American applied research , 2007,
Abstract: amorphous thin films of pb1-xlaxtio3 (with x=0, 13 and 27 mol %) were prepared by the polymeric precursor method and deposited by spin coating on glass substrates. the films were characterized by x-ray diffraction (xdr) and scanning electron microscopy (sem) and the band gap energy of the amorphous plt films was calculated from the uv-vis spectra. the obtained values were compared to that theoretically calculated. the observed decrease of the band gap was attributed to increased density of defects in the amorphous structure. futhermore photoluminescence (pl) at room temperature was observed for thin (pbla)tio3 films.
Structure effects on the optical properties of thin (PbLa)TiO3 films
N. L. V. Carre?o,J. H. G. Rangel,C. D. Pinheiro,E. Longo
Latin American applied research , 2007,
Abstract: Amorphous thin films of Pb1-xLaxTiO3 (with x=0, 13 and 27 mol %) were prepared by the polymeric precursor method and deposited by spin coating on glass substrates. The films were characterized by X-ray diffraction (XDR) and scanning electron microscopy (SEM) and the band gap energy of the amorphous PLT films was calculated from the UV-VIS spectra. The obtained values were compared to that theoretically calculated. The observed decrease of the band gap was attributed to increased density of defects in the amorphous structure. Futhermore photoluminescence (PL) at room temperature was observed for thin (PbLa)TiO3 films.
Structural and electronic properties of Pb1-xCdxTe and Pb1-xMnxTe ternary alloys  [PDF]
Malgorzata Bukala,Piotr Sankowski,Ryszard Buczko,Perla Kacman
Physics , 2012, DOI: 10.1103/PhysRevB.86.085205
Abstract: A systematic theoretical study of two PbTe-based ternary alloys, Pb1-xCdxTe and Pb1-xMnxTe, is reported. First, using ab initio methods we study the stability of the crystal structure of CdTe - PbTe solid solutions, to predict the composition for which rock-salt structure of PbTe changes into zinc-blende structure of CdTe. The dependence of the lattice parameter on Cd (Mn) content x in the mixed crystals is studied by the same methods. The obtained decrease of the lattice constant with x agrees with what is observed in both alloys. The band structures of PbTe-based ternary compounds are calculated within a tight-binding approach. To describe correctly the constituent materials new tight-binding parameterizations for PbTe and MnTe bulk crystals as well as a tight-binding description of rock-salt CdTe are proposed. For both studied ternary alloys, the calculated band gap in the L point increases with x, in qualitative agreement with photoluminescence measurements in the infrared. The results show also that in p-type Pb1-xCdxTe and Pb1-xMnxTe mixed crystals an enhancement of thermoelectrical power can be expected.
Functional Analysis of Conserved Motifs in Influenza Virus PB1 Protein  [PDF]
Caroline Chu, Shufang Fan, Chengjun Li, Catherine Macken, Jin Hyun Kim, Masato Hatta, Gabriele Neumann, Yoshihiro Kawaoka
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0036113
Abstract: The influenza virus RNA polymerase complex is a heterotrimer composed of the PB1, PB2, and PA subunits. PB1, the catalytic core and structural backbone of the polymerase, possesses four highly conserved amino acid motifs that are present among all viral RNA-dependent RNA polymerases. A previous study demonstrated the importance of several of these conserved amino acids in PB1 for influenza polymerase activity through mutational analysis. However, a small number of viruses isolated in nature possesses non-consensus amino acids in one of the four motifs, most of which have not been tested for their replicative ability. Here, we assessed the transcription/replication activities of 25 selected PB1 mutations found in natural isolates by using minireplicon assays in human and avian cells. Most of the mutations tested significantly reduced polymerase activity. One exception was mutation K480R, observed in several pandemic (H1N1) 2009 viruses, which slightly increased polymerase activity relative to wild-type. However, in the background of the pandemic A/California/04/2009 (H1N1) virus, this mutation did not affect virus titers in cell culture. Our results further demonstrate the functional importance of the four conserved PB1 motifs in influenza virus transcription/replication. The finding of natural isolates with non-consensus PB1 motifs that are nonfunctional in minireplicon assays suggests compensatory mutations and/or mixed infections which may have ‘rescued’ the inactive PB1 protein.
Optical properties of Pb1-xMnxSe thin films
Pb1-xMnxSe薄膜的光学特性

Wang Qing-Lei,Wu Hui-Zhen,Si Jian-Xiao,Xu Tian-Ning,Xia Ming-Long,Xie Zheng-Sheng,Lao Yan-Feng,
王擎雷
,吴惠桢,斯剑霄,徐天宁,夏明龙,谢正生,劳燕锋

物理学报 , 2007,
Abstract: 采用分子束外延的方法在BaF2(111)衬底上制备出了高质量的Pb1-xMnxSe(0≤x≤0.0681)薄膜.X射线衍射结果表明,Pb1-xMnxSe薄膜为立方相NaCl型结构,没有观察到MnSe相分离现象,薄膜的取向为平行于衬底(111)晶面.晶格常数随着Mn含量的增加逐渐减小,Mn含量由Vegard公式得到.通
The abnormal sensitivity and its mechanism of (Ba, Pb)TiO3 semiconductor ceramics
The abnormal sensitivity and its mechanism of (Ba, Pb)TiO3 semiconductor ceramics

Tian Yuming,Xu Mingxia,Huang Ping,E Lei,Hao Huzai,Cui Cai’e,
TIANYuming
,XUMingxia,HUANGPing,ELei,HAOHuzai,CUICai'e

科学通报(英文版) , 2005,
Abstract: The resistance-temperature properties of porous (Ba, Pb)TiO3 semiconductor ceramic were systematically studied. It was found that the resistance of (Ba, Pb)TiO3 ceramic having been placed in the air for a long time was abnormally increased with the increase of the temperature from the room temperature to 70°C prior to the Curie point. Further research showed that this abnormal resistance-temperature property was linked to its humidity sensitivity. When the relative humidity changed from 11% to 93%, the resistance of (Ba, Pb)TiO3 ceramic decreased three orders of magnitude. Furthermore, the humidity-resistance was approximately linear in single logarithm coordinate. According to the surface adsorption, grain-boundary potential barrier and ferroelectric-paraelectric phase transformation, the specific sensitive mechanism of (Ba, Pb)TiO3 ceramic was analyzed qualitatively.
MAGNETISM OF THE SUN  [PDF]
CHANDRAKANT L. TUMBADE
Indian Streams Research Journal , 2013,
Abstract: The Sun is a magnetically active star. It supports a strong, changing magnetic field that varies year-to-year and reverses direction about every eleven years around solar maximum. The Sun's magnetic field leads to many effects that are collectively called solar activity, including sunspots on the surface of the Sun, solar flares, and variations in solar wind that carry material through the Solar System. For study of magnetism of the Sun i.e. Solar Magnetism. Magnetic fields are present almost everywhere on the Sun. Without these fields the Sun would have been a rather dull object.
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