Strain behavior of lanthanum modified BiFeO3 thin films prepared via soft chemical method

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Lithium-lanthanum double chromates

Synthesis and crystallographic data are reported for low and high temperature forms of LiLa(CrO4)2. The compounds are closely related to lamellar rare earth phosphates and arsenates of sodium and to RbLu(CrO4)2. Lattice parameters of the orthorhombic (low temperature) and monoclinic (high temperature) forms are given. The low temperature form is moisture sensitive and Li+ ions are easily displaced by protons. Thermal decomposition takes place at 250 °C and results in the formation of LiCrO2, LaCrO4, LaCrO3 and Cr2O3. © 1993.

Synthesis, characterization and spectroscopy of the europium doped lanthanum trimetaphosphate

Orthorhombic modification of europium doped lanthanum trimetaphosphate has been prepared. The compound was obtained by precipitation of rare earth chloride solution with trimetaphosphoric acid. The characterizations were made using X-ray diffractometry, chemical analysis and infrared spectroscopy. Excitation and emission spectra were recorded at liquid nitrogen and room temperatures. Assignments of the 5D0→7FJ (J=0, 1, 2, 3, 4, 5) transitions were made and an unusual high 5D0→7F4 transition intensity with six split lines has been observed. Structural distortion of the crystal lattice may be caused by the Eu3+ ion inclusion. The simple overlap model was applied for the calculation of the total splitting of the 5D0→7F1 transition, the 5D0→7F0/5D 0→7F2 transition intensity ratio and the Ωλ (λ=2.4) intensity parameters. Theoretical predictions showed to be in good accordance with the experimental data. © 1988 Elsevier Science S.A.

Solid-state compounds of 4-chlorobenzylidenepyruvate with lanthanides preparation and thermal studies

Solid-state compounds Ln-4Cl-BP, where Ln represents lighter trivalent lanthanides and 4Cl-BP is 4-chlorobenzylidenepyruvate, were prepared. Thermogravimetry, derivative thermogravimetry (TG and DTG), differential scanning calorimetry (DSC) and other methods of analysis were used to characterize and to study the thermal behaviour of these compounds.

Nanoparticles of La1-xSrxMnO3 compounds

A nanoparticles of La1-xSrxMnO3 were synthesized using homogenous coprecipitation method. The precipate was washed with water and dried at 80 °C. The samples were characterized by X-ray powder diffraction, transmission electron microscopy (TEM) and electrical resistivity as a function of temperature. The TEM results show that the particle size is in the nanometer scale.

Sintering of cobalt and strontium doped lanthanum chromite obtained by combustion synthesis

Lanthanum chromite (LaCrO3) is one of the most adequate materials for use as interconnector in solid oxide fuel cell (SOFC) applications, due to its intrinsic properties, namely its good electrical conductivity and resistance to environment conditions in fuel cell operations. Due to difficulties in sintering, additives are usually added to help in the densification process. In this work, the influence of added cobalt and strontium, in the sintering of LaCrO3 obtained by combustion synthesis was studied. The starting materials were respectively nitrates of chromium, lanthanum, cobalt and strontium, and urea was used as fuel. The results show that by increasing the strontium and cobalt concentrations it is possible to reduce the temperature of sintering. Using both additives, the sintering processes took place in lesser times than normally used for this material, as well as greater values of density were attained.

Melt textured Y123 bulk and thick film

YBa2Cu3O7-δ - 25mol%Y2BaCuO5 bars and thick films have been melt textured using a stationary furnace with a temperature gradient of 3 or 6°C/cm. Samples are heated above the peritectic reaction temperature and quenched to just above the solidification temperature and then slowly cooled below the solidification temperature. All bar shaped samples consist of 2-5 mm grains though the grain orientations strongly depend on the heat treatment conditions. The bar shows the maximum Jc of above 3,000 A/cm2, whereas the maximum Jc of 200 A/cm2 and Tczero of 88K are obtained for the thick film on (100) LaAlO3 single crystal.

Cubic silsesquioxanes for use in solution processable organic light emitting diodes (OLED)

Commercial products using organic light emitting diode (OLED) display technology have begun to appear in cell phones, mp3 players and even televisions. One key area that has allowed and will allow for this technology to continue its ascension into the flat panel display and lighting markets is materials R and D. From this perspective, recent progress in cubic silsesquioxane (SSQ) based materials may provide some new advantageous properties well suited for OLEDs. In this feature article we provide an overview of recent progress in the synthesis, characterization and implementation of SSQ-based materials with properties well suited for application in solution processable organic/polymer electronics, specifically OLEDs.

基于PLZT的电光偏转器的特性研究

采用具有高二次电光效应的掺镧锆钛酸铅陶瓷材料（PLZT），设计和制备了一种基于折射率随外加电压发生变化的电光偏转器。构建了测试系统，测得PLZT的电光系数是R33=2.1

沉积温度对LaF3薄膜性能的影响

abstract {LaF₃ single-layer coatings were prepared by thermal boat evaporation at the deposition temperatures of 189, 255, 277 and 321°C respectively. The crystal structures of the coatings were characterized by X-ray diffraction (XRD). A spectrophotometer was employed to measure its transmittance. Moreover, refractive index, extinction coefficient and cut-off wavelength were obtained from the measured transmittance spectral curve. The residual stress was evaluated by the Stoney's equation and optical interferometer. Laser induce damage threshold (LIDT) was performed by a tripled Nd:YAG laser system. The results show that the crystallization status becomes better with the deposition temperature increasing. Correspondingly, the grain size also gets larger. Meanwhile, the coatings become more compact and the refractive index increases. However, the absorption of coatings seriously rises and the cut-off wavelength drifts to the long wave. In addition, the residual stress also increases and the intrinsic stress plays a determinant role in the coating. The LIDT of the coating also enhances at high temperature.}

Study of colossal magnetoresistance and pressure effects in La2/3Ca1/3MnO2 thin films /

The main purpose of this thesis is to study properties of La2/3Cai/3Mn03, both polycrystalline ceramics and thin films. This material has striking related electrical and magnetic properties. Thin films show colossal negative magnetoresistance (CMR) near transition from an insulating to a metallic state accompanied closely by transition from a paramagnetic to a ferromagnetic state. The double exchange mechanism (DE) and the Jahn-Teller deformations play an important role in CMR effect. Applied pressure has a very similar effect as does an applied magnetic field, except, at low temperatures (T

Systematic studies of the effect of pressure on magnetic and electronic properties of La2/3Ca1/3MnO3 thin films with various thicknesses /

Interest in mixed-valent perovskite manganese oxides of La\-xAxMnO^ (v4-divalent alkaline earth Ca, Sr or Ba), whose unusual properties were discovered nearly a half century ago, has recently been revived. The discovery of the colossal magnetoresistance and pressure effects introduced new questions concerning the complex interplay between lattice structure, magnetism and transport in doped perovskite manganites. In this study, we report our experimental investigations of pressure and magnetic field dependencies of La-i/sCai/sMnOs (LCMO) epitaxial films with various thickness on SrTiO$ substrate. An analysis of film thickness dependency of the resistivity of LCMO epitaxial films under pressure and magnetic field has been performed by taking into account substrate contributions. This verifies the correlation of lattice distortion with magnetic and transport properties. Strong dependencies of Mn — O — Mn bond bending and Mn — O bond stretching with pressure as well as Mn spin alignment with magnetic field, and the lattice distortion induced by the substrate are discussed.

Electronic and magnetic properties of LaV1-xO3 /

A series of LaVi^xOs compounds (x=0.00, 0.02, 0.04, 0.06, 0.08) were prepeired using the standard solid reaction. The samples were chareicterized by X-ray diffraction (XRD), fourprobe resistivity, smd magnetic susceptibility studies. Powder X-ray diffraction analysis indicated the formation of a single-phase sample with a orthorhombic structure which was first found in GdFeOs (space group Pnma) . The Unit Cell program was used for calculating lattice peirameters from XFID data. The XRD spectnim could be indexed on a cubic lattice with Og = 2ap ~ (7.8578 to 7.9414 A). The lattice parameter was observed to increase as the Vanadium vacancy increased. Four-probe resistivity measurements exhibited semiconductor behavior for all sajnples from room temperature down to 19K. The resistivity of samples increased with increasing Vanadium vacancy. The resistivity of samples demonstrated activated conduction with an activation energy of approximately 0.2 eV. The activation energy increased with increasing lattice parameter. Field cool magnetic susceptibility measurements were performed with field of 500 G from 300 K to 5 K. These measurements indicated the presence of an antiferromagnetic transition at about 140 K. The data was fitted above Neel temperature to Ciurie-Weiss law yielding a negative parameignetic Curie temperature. This implies that antiferromagnetic ordering is present.