Magnetic and electric properties of Bi(La)Sr(Ca)Mn2O6

Bi1-xLaxSrMn2O6 and BiSr1-xCaxMn2O6 are prepared by solid state reaction. They are n-type semiconductors with ferromagnetism at room temperture. When Bi is substituted partly by rare earth, a negative magnetoresistance effect is observed in the pellet of Bi1-xLaxSrMn2O6. There are semiconductor-metal transitions at 820 K in BiSrMn2O6. The transitions are attributed to the magnetic transition at high temperature. The substitution of Ca for Sr makes the transition temperature increase. However, when Bi is partly substituted by La, the solid solution does not change into metal. (C) 1996 Academic Press, Inc.

The effect of some factors on the electric properties of rare earth complex oxide

The rare earth complex oxides with different types have been synthesized. Their structures and electric properties have been investigated. According to our experimental results, the effects of the outest shell electronic configuration, electron spin state, electron transport path and formation of cluster on the electric properties of rare earth complex oxides have been summarized. When the electrons in the outest shell of the central metallic ion are unpair, and the outest shell is not half-filled, the electric conductibilities of these compounds are better, If there is a -M-X-M-X- or -M-M-M- (the distances between two atoms <0.31 nm) continuous electron transport path, and the electron configurations of the central metallic ion conform to the above condition, then the electric conductibilities are good, The isolate cluster can not become the continuous electron transport path, therefore, the formation of the isolate cluster will reduce the conductibility.

Reduced-size polarized basis sets for calculations of molecular electric properties. III. Second-row atoms

Reduced-size polarized (ZmPolX) basis sets are developed for the second-row atoms X = Si, P, S, and Cl. The generation of these basis sets follows from a simple physical model of the polarization effect of the external electric field which leads to highly compact polarization functions to be added to the chosen initial basis set. The performance of the ZmPolX sets has been investigated in calculations of molecular dipole moments and polarizabilities. Only a small deterioration of the quality of the calculated molecular electric properties has been found. Simultaneously the size of the present reduced-size ZmPolX basis sets is about one-third smaller than that of the usual polarized (PolX) sets. This reduction considerably widens the range of applications of the ZmPolX sets in calculations of molecular dipole moments, dipole polarizabilities, and related properties.

Magnetic and transport properties of (Ba1-xKx)Fe2As2

Single crystals of (Bal - xKx)Fe2As2 were prepared using the Sn flux method. Two heating methods were used to prepare the single crystals: the slow heating and rapid heating methods. It was found that the single crystals grown using the slow heating method were not superconducting due to a significant loss of potassium. When the rapid heating method was used, the single crystals were observed to be superconducting with the desired potassium concentration. The energy dispersive X-ray spectroscopy analysis indicated the presence of multiple phases in the single crystals. Using single crystal X-ray diffraction, the crystal structure of the single crystals was found to be 14/mmm tetragonal at room temperature. The magnetic measurements on the single crystals indicated the presence of multiple phases and magnetic impurities.

Large Changes of Static Electric Properties Induced by Hydrogen Bonding: An ab Initio Study of Linear HCN Oligomers

We report the partitioning of the interaction-induced static electronic dipole (hyper)polarizabilities for linear hydrogen cyanide complexes into contributions arising from various interaction energy terms. We analyzed the nonadditivities of the studied properties and used these data to predict the electric properties of an infinite chain. The interaction-induced static electric dipole properties and their nonadditivities were analyzed using an approach based on numerical differentiation of the interaction energy components estimated in an external electric field. These were obtained using the hybrid variational-perturbational interaction energy decomposition scheme, augmented with coupled-cluster calculations, with singles, doubles, and noniterative triples. Our results indicate that the interaction-induced dipole moments and polarizabilities are primarily electrostatic in nature; however, the composition of the interaction hyperpolarizabilities is much more complex. The overlap effects substantially quench the contributions due to electrostatic interactions, and therefore, the major components are due to the induction and exchange induction terms, as well as the intramolecular electron-correlation corrections. A particularly intriguing observation is that the interaction first hyperpolarizability in the studied systems not only is much larger than the corresponding sum of monomer properties, but also has the opposite sign. We show that this effect can be viewed as a direct consequence of hydrogen-bonding interactions that lead to a decrease of the hyperpolarizability of the proton acceptor and an increase of the hyperpolarizability of the proton donor. In the case of the first hyperpolarizability, we also observed the largest nonadditivity of interaction properties (nearly 17%) which further enhances the effects of pairwise interactions.

Microstructural and electric properties of bismuth-layered structured ceramics - SrBi2(Ta1-xNbx)O-9

Ceramic samples of SrBi2(Nb1-xTax)O-9 (0 less than or equal to x less than or equal to 1) were prepared by the solid state reaction method in order to investigate their structural and electrical features as well as obtain useful information to improve the properties of SrBi2(Nb1-xTax)O-9 as a thin film. The X-ray diffraction patterns and the scanning electronic microscopy photomicrographs show no secondary phases but the formation of a solid-state solution for all the composition. The ac conductivity of the samples, measured at 25 degreesC and 100 kHz frequency, decreases with the increase of Ta content. Such results were explained by intrinsic conductivity of pure components.

Microstructure and electric properties of a SnO2 based varistor

High non-linear J x E electrical characteristic (alpha=41) were obtained in the Nb2O5 and Cr2O3 doped CoO highly densified SnO2 ceramics. X-ray diffraction analysis showed that these ceramics are apparently single phase. Electrical properties and microstructure are highly dependent on the Cr2O3 concentration and on the sintering temperature. Excess of Cr2O3 leads to porous ceramics destroying the material's electrical characteristics probably due to precipitation of second phase of CoCr2O4 Dopant segregation and/or solid solution formation at the grain boundaries can be responsible for the formation of the electrical barriers which originate the varistor behaviour. (C) 1998 Elsevier B.V. Limited and Techna S.r.l. All rights reserved.

Effect of La2O3 addition and O-2 atmosphere on the electric properties of SnO2TiO2

The electric properties of (Sn, Ti)O-2 doped with 1.00 mol% CoO, 0.05 mol% Nb2O5 and xmol% La2O3 (0.25 less than or equal to x less than or equal to 1.00) have been studied. Sn0.25Ti0.75Co0.01Nb0.005 doped with 0.50 mol% La2O3 has a nonlinearity coefficient of 6. An increase in the concentration of La2O3 raised its resistivity, thereby altering the electric properties of the material. A thermal treatment in oxygen atmosphere increased the nonlinearity coefficient to a value of 9. (C) 2003 Elsevier B.V. All rights reserved.

Monofilamentary Ag/Bi:2212 tapes - Effects of silver powder addition

The Bi-Sr-Ca-Cu-O system has been one of the most studied superconducting ceramic materials for industry applications. The most of the studies with this aim are on silver/ceramic composites, due to the benefits and great compatibility of this metal with the oxide. Tapes made by the powder in tube (PIT) method have been successfully tested in pilot power plants in many countries but in Brazil. In this paper, 5, 10, and 20-wt% silver powders are introduced to compose the core of the tape along with the Bi:2212 ceramic powder. The results of electrical experiments are compared with those made with no silver addition Ag tapes. The best current density, at 60 K and no applied magnetic field, was found for the 10-wt% silver proportion, doubling the value obtained for the tape with no silver in the core.

Structural and magnetic properties of insulating Zn1-xCoxO thin films

Cobalt-doped ZnO (Zn1-xCoxO) thin films were fabricated by reactive magnetron cosputtering. The processing conditions were carefully designed to avoid the occurrence of Co precipitations. The films are c-axis oriented, and the solubility limit of Co in ZnO is less than 17%, determined by x-ray diffraction. X-ray photoemission spectroscopy measurements show Co ions have a chemical valance of 2+. In this paper, hysteresis loops were clearly observed for Zn1-xCoxO films at room temperature. The coercive field, as well as saturation magnetization per Co atom, decreases with increasing Co content, within the range of 0.07

Durability and photo-electric characteristics of a mille-feuille structured amorphous selenium (a-Se)-arsenic selenide (As2Se3) multi-layered thin film

A mille-feuille structured amorphous selenium (a-Se)-arsenic selenide (As2Se3) multi-layered thin film and a mixed amorphous Se-As2Se3 film is compared from a durability perspective and photo-electric perspective. The former is durable to incident laser induced degradation after numerous laser scans and does not crystallise till 105 of annealing, both of which are improved properties from the mixed evaporated film. In terms of photo-electric properties, the ratio between the photocurrent and the dark current improved whereas the increase of the dark current was higher than that of As2Se3 due to the unique current path developed within the mille-feuille structure. Implementing this structure into various amorphous semiconductors may open up a new possibility towards structure-sensitive amorphous photoconductors. © 2013 Elsevier B.V.