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We demonstrate a memory device with bias electric field-manipulated multilevel resistance states based on ultra-thin and small area Fe70Ga30 (FeGa) films grown on BaZr0.2Ti0.8O3-0.5Ba0.7Ca0.3TiO3(BZT-0.5BCT) ferroelectric films. Studies have shown that BZT-0.5BCT ferroelectric films exhibit good ferroelectric properties with saturated polarization of 11.3 µC/cm2 and excellent piezoelectric properties with displacement up to 70 Å. A coercive field of 91 Oe is derived from the magnetic hysteresis loop of BZT-0.5BCT/FeGa composite films. Local ferroelectric domain and ferromagnetic domain structures have been probed, which confirm the multiferroicity of the composite films. By applying the bias electric field along the thickness of the films, current–voltage (I–V) behaviors of the FeGa films on the BZT–BCT films can be modulated, and multiple resistance states are generated. Based on the analysis of polarization switching behavior and the electrical transport characteristics, we ascribe this bias voltage modulation of the resistance state to strain-mediated converse magnetoelectric effect, interface bonding effect, and interface charge-co-mediated behaviors. This work suggests a promising approach for exploring multilevel and multifunctional data storage in multiferroic materials. [ABSTRACT FROM AUTHOR]

The electrical properties and dielectric response in NaYCuTiO ceramic prepared by conventional solid-state reaction method and sintered at 1,090 °C for 5 h were investigated as functions of frequency and temperature. Main phase of NaYCuTiO with CaCuTiO-like crystallographic structure and CuO secondary phase were observed in the X-ray diffraction pattern. Abnormal grain growth was observed just as observed in CaCuTiO ceramics. The NaYCuTiO ceramic exhibits a high ε′ of ~2.04 × 10 at 20 °C and 1 kHz and low tan δ (with the minimum 0.080 at 5 kHz). Impedance spectroscopy analysis reveals that NaYCuTiO ceramic is electrically heterogeneous, consisting of semiconducting grains and insulating grain boundaries. Giant ε′ response in NaYCuTiO ceramic is therefore attributed to an internal barrier layer capacitor effect. [ABSTRACT FROM AUTHOR]

A new lead-free perovskite Ba(BiTa)O was prepared by conventional ceramic fabrication technique at 1,200 °C/4 h in air atmosphere. The crystal symmetry, space group and unit cell dimensions were determined from the experimental results using FullProf software. The crystallite size and lattice strain were estimated from Williamson-Hall approach. XRD analysis of the compound indicated the formation of a single-phase cubic structure with the space group Pm3 m. EDAX and SEM studies were carried out in order to evaluate the quality and purity of the compound. Permittivity data showed a low temperature coefficient of capacitance ( T < 4%) up to +125 °C. Complex impedance analyses suggested the dielectric relaxation to be of non-Debye type. Electric modulus studies supported the hopping type of conduction in Ba(BiTa)O. [ABSTRACT FROM AUTHOR]

BaGdFeNbTaO was synthesized by a standard solid-state technique, which adopts a tetragonal filled tungsten bronze structure and exhibits paraelectric nature at room temperature. The dielectric temperature coefficient of BaGdFeNbTaO at 1 MHz is 147 ppm °C AC impedance plots were used as tools to analyze the electrical behavior of the sample as a function of frequency at different temperatures. The conduction is a thermally activated process with activation energy ~1.30 eV. The frequency-dependent maxima in the imaginary part of impedance are found to obey an Arrhenius law with activation energy ~1.34 eV. Such a value of activation energy suggests the existence of a relaxation mechanism (a conductive process), which may be interpreted by an ion hopping between neighboring sites within the crystalline lattice. [ABSTRACT FROM AUTHOR]

In this paper, the composition and structure of homogeneous silicon carbide layers produced by multiple implantation of 40-, 20-, 10-, 5- and 3-keV carbon ions into silicon were studied by transmission electron microscopy, X-ray diffraction, Auger spectroscopy, IR spectroscopy and Atomic force microscopy. After high temperature annealing the homogeneous, fine-grained, polycrystalline SiC0.95 and SiC1.4 films consists of globular or plate-like grains are obtained. The intensive translations of atoms during annealing at 800–1400 °C are taken place causing the deformation of the layer surface and the formation of grains with sizes ∼30–100 nm. The grains consist of chaotically oriented SiC crystallites with average sizes ∼5 nm. The temperature dependences of IR spectra parameters are evidence of similarity of carbon and silicon-carbon clusters types in SiC0.95 and SiC1.4 layers. An influence of carbon- and silicon-carbon clusters prevailed in as-implanted layer on the crystallization processes in silicon layers with high carbon concentration, are considered. [ABSTRACT FROM AUTHOR]

BiREWO6[RE=La, Nd, Pr, Sm, Gd, Dy, Tb, Yb, Y] ceramics have been prepared by the conventional solid-state ceramic route. The sintered samples are characterized by X-ray diffraction and SEM methods. The ceramics have high dielectric constants in the range 25–55 depending on the rare earth element. The dielectric losses of these ceramics increase with increase in the frequency and with increase in the rare earth crystal radii. [ABSTRACT FROM AUTHOR]