M. N. Smirnova

Crystallization of Mg(Fe 0.8 Ga 0.2 ) 2 O 4 - δ Films on Silicon with SiO 2 and TiO 2 Buffer Layers

The results of analysis of conceivable interactions between film and substrate materials during crystallization of Mg(Fe0.8Ga0.2)2O4-δ films with SiO2 and TiO2 buffer layers on silicon are reported. The calculated data are compared with the physicochemical parameters of Mg(Fe0.8Ga0.2)2O4-δ/Si, Mg(Fe0.8Ga0.2)2O4-δ/TiO2/Si, and Mg(Fe0.8Ga0.2)2O4-δ/SiO2/Si film heterostructures.

Effect of cobalt layer thickness on the magnetoelectric properties of Co/PbZr0.45Ti0.55O3/Co heterostructures

We have studied the magnetic properties and determined the optimal range of thicknesses of cobalt films grown on PbZr0.45Ti0.55O3 (PZT) ceramic substrates with smoothed surfaces. Using an ion-beam deposition-sputtering process, we have produced Co/PZT/Co heterostructures with smooth, thermally stable PZT/Co interfaces. The structures exhibit a reproducible magnetoelectric effect comparable in magnitude to that in known layered structures fabricated by splicing ferromagnetic and ferroelectric layers. A ferromagnetic layer of optimal thickness makes the largest contribution to the magnetoelectric effect. The structures can be used as elements of more complex, multilayer structures. The use of the ion-beam deposition-sputtering process allows one to scale up such heterostructures by microelectronic means in producing magnetoelectric devices.

Garnet Solid Solution (Y 1 – x Bi x ) 3 Fe 2.5 Ga 2.5 O 12

Samples of composition (Y1–xBix)3Fe2.5Ga2.5O12 (0 ≤ х ≤1), synthesized by the polyvinyl alcohol gel combustion method, have been studied by X-ray diffraction. It has been shown that the homogeneity range of the solid solution persists up to the composition Y1.5Bi1.5Fe2.5Ga2.5O12. This allows to consider gallium- substituted bismuth yttrium ferrites with an equimolar Fe: Ga ratio as stable materials for possible use in magnetooptics.

Features of Mg(Fe0.8Ga0.2)2O4 synthesis by glycine-nitrate method

A finely dispersed powder of composition Mg(Fe0.8Ga0.2)2O4 was prepared by glycine-nitrate method. The use of glycine as a reducing agent allows preparation of the product without carbon-containing admixtures with unimodal particle size distribution and lower crystallization temperature (as compared with nitrate-citrate method of Mg(Fe0.8Ga0.2)2O4 synthesis) immediately after reaction completion.

Gel decomposition and formation of MgFe1.6Ga0.4О4 powders

The thermal behavior of the gels that are formed in the synthesis of MgFe1.6Ga0.4О4 powders was studied by differential scanning calorimetry and thermogravimetry (DSC–TG). The combustion temperatures of the gels in flowing air and flowing argon were determined from experimental data and thermodynamic calculations. The calculations of combustion temperatures from the heat flow of reaction versus time are shown to be a reliable tool to determine the parameters of gel combustion.

Gel formation specifics in the synthesis of Mg(Fe0.8Ga0.2)2O4 by the glycine–nitrate method

The gel formed in the synthesis of Mg(Fe0.8Ga0.2)2O4 powder from corresponding metal nitrates and glycine was studied by thermal and IR spectral analyses. Being a bidentate ligand, glycine was established to initiate the gel combustion reaction resulting in the oxide of the above composition. Based on the data on ΔH298° and Cp of the reagents and reaction products, the thermodynamic parameters of this process were calculated.

Influence of the state of interfaces on the magnitude of the magnetoelectric effect in Co (Ni) films on PbZr0.45Ti0.55O3 and GaAs substrates

Co (Ni) films on ceramic lead zirconate titanate (PbZr0.45Ti0.55O3) ferroelectric substrates and single-crystal GaAs piezoelectric substrates are shown to exhibit a giant magnetoelectric response, which reaches 200 V/A at room temperature and mechanical Q of at least 1000. These findings are interpreted in terms of the formation of stable interfaces in thin-film heterostructures owing to good adhesion of dissimilar materials to substrate surfaces after ion beam sputtering/deposition processing. This will allow one to extend the applicability of the magnetoelectric effect at room temperature to commercially available microelectronic materials and integrate related hybrid structures into single-chip signal generation/processing devices.

Decomposition of aluminum oxynitride compounds in an air-vapor medium at 950°C

Aluminum oxynitride hydrolysis in wet air at a temperature of 950°C has been shown to lead to the formation of a phase whose composition lies beyond the Al2O3-AlN join in the Al-O-N system.

Synthesis of MgFe 1.6 Ga 0.4 O 4 by Gel Combustion Using Glycine and Hexamethylenetetramine

A powderlike material of composition MgFe1.6Ga0.4O4 was synthesized by gel combustion using a glycine–hexamethylenetetramine mixture. The gel produced by the synthesis was studied by thermal analysis (TGA/DSC) and IR spectroscopy. This mixture was shown to be efficient for obtaining homogeneous nanosized MgFe1.6Ga0.4O4. The morphology of the powders was characterized by scanning electron microscopy and X-ray powder diffraction analysis.

(Y 1– x Bi x )3(Fe 1– y Ga y ) 5 O 12 Solid Solution Region in the Ieneke Diagram

Garnet ferrites with the overall composition (Y1–xBix)3(Fe1–yGay)5O12 (0 ≤ х ≤1, 0 ≤ y ≤1) have been synthesized and characterized by X-ray diffraction. A relationship has been demonstrated between an increase in the concentration of Ga3+ cations and an increase in Bi2O3 solubility in ss-Y3(Fe,Ga)5O12.