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The Co[Fe.sub.2][O.sub.4]-BaTi[O.sub.3] core-shell structure composite has been successfully synthesized by wet chemical method. X-ray characterization showed that the composite consisted of two single phases: Co[Fe.sub.2][O.sub.4] and BaTi[O.sub.3]. The saturation magnetization of the Co[Fe.sub.2][O.sub.4] component in composite was found to be similar to those of the bulk sample. It was observed that the longitudinal and transverse magnetoelectric coefficients of the core-shell structure are 18 times higher than those of the mixed structure. Index Terms--Barium titanate, cobalt ferrite, magnetoelectric effect, multiferroics.

Abstract: A new method using a magnetic pulse field in order to measure the ME effect of CoFe2O4–BaTiO3 core-shell structure composite has been developed. This new method combines advantages of both quasi-static and dynamic ones and allows quantifying the whole ME response of the materials. The maximum ME coefficient of this composite is 5.5 and 4.2mV/cmOe for longitudinal and transverse measurements, respectively. These values are bigger than those measured by the lock-in technique and can be attributed to the fact that the pulse field method determines the full magnetoelectric coefficient whereas the AC method determines only the part that corresponds to the amplitude of the AC field. Both pulse duration and field sweep rate dH/dt are found to affect the ME response of the composite. [Copyright &y& Elsevier]

Abstract: Barium ferrite nanoparticles were synthesized by hydrothermal method. The grain size of BaFe12O19 produced chemically at temperatures between 150 and 200°C with a reaction time of 12h varies from 9 to 15nm. At 4.2K a grain size independent coercive field of about 1.2kOe was found. However, at 300K, the coercivity changes from 230Oe up to 590Oe. The magnetization at 4.2 and 300K increases linearly with grain size. In TEM images it can be seen, that the materials are composed of plate-like and stick-like particles. The amount of the stick-like particles increases with synthesis temperature. The low values of the coercivity at 300K are discussed in terms of demagnetising field and the nearness of the blocking temperature. The increase of the magnetization with reaction temperature may be attributed to the increase of grain size. [Copyright &y& Elsevier]

Abstract: Co1−x Zn x Fe2O4 (x =0, 0.2 and 0.4) fine powders with particles size of 3nm were prepared by hydrolysis method. The powders were annealed at 500°C for 3h. With heat treatment, the average particles size increased to 12nm with corresponding increase in blocking temperature, saturation magnetization and reduced remanence. A significant increase in coercive field was found only for the pure CoFe2O4. [Copyright &y& Elsevier]

The CoFe2O4-BaTiO3 core-shell structure composite has been successfully synthesized by wet chemical method. X-ray characterization showed that the composite consisted of two single phases: CoFe2O4 and BaTiO3. The saturation magnetization of the CoFe2O4 component in composite was found to be similar to those of the bulk sample. It was observed that the longitudinal and transverse magnetoelectric coefficients of the core-shell structure are 18 times higher than those of the mixed structure. [ABSTRACT FROM AUTHOR]

Scandium perovskite (Sc0.94Mn0.06)Mn0.65Ni0.35O3, synthesized at high pressure and high temperature, has a triclinic structure (space group ) at room temperature and ambient pressure with a √2apx√2apx2ap structure with α≈90°, β≈89°, γ≈90°. Magnetic measurements show that the material displays Curie-Weiss behaviour above 50 K with C=2.11 emu K mol-1 (μeff=4.11 μB per formula unit) and θ=−95.27 K. Bond valence sum analysis of the crystal structure shows that manganese is present in three different oxidation states (+2, +3, +4), with the +2 oxidation state on the A site resulting in a highly tilted perovskite structure (average tilt 21.2° compared with 15.7° calculated for LaCaMnNbO6), giving the formula. [ABSTRACT FROM AUTHOR]

Abstract: Nanocrystalline CoFe2O4 with an average grain size of about 40nm was successfully prepared by a modified citrate-gel method. At temperatures of 3 and 300K, the measured coercive fields are 0.43 and 0.07T and the magnetizations at 7T are 89 and 83emu/g, respectively. At room temperature, the longitudinal and transversal magnetostriction values are −130 and 70ppm, respectively. The contribution of a disordered magnetic phase was detected by the occurrence of a peak in the ac-susceptibilities curves at around 250K. The temperature dependence of the field-cooled and zero field-cooled low-field magnetization showed a larger irreversibility below this temperature. This disordered phase behaves like a spin-glass, which is coexisting with the ferrimagnetically ordered main phase [Copyright &y& Elsevier]

Abstract: The preparation conditions affect the microstructure of the samples and influence the coupling between the magnetostrictive and piezoelectric phases in magnetoelectric composites. In this work, the optimum conditions for preparing CoFe2O4–BaTiO3 core–shell structure magnetoelectric composites were investigated. For pressing the composite powders, an optimum pressure of 6tons/cm2 was found. For the sintering process, to sinter the sample at 1250°C for 4h was best suited. By changing the preparation conditions, the magnetoelectric effect (ME) coefficients of the studied samples may change 20 times, from 0.18 to 3.53 and 0.1 to 2.23mV/cmOe for longitudinal and transverse measurements, respectively. This shows the preparation conditions, which mean that the microstructure plays an important role for the magnetoelectric effect in CoFe2O4–BaTiO3 magnetoelectric composites. [Copyright &y& Elsevier]

Scandium perovskite (Sc0.94Mn0.06)Mn0.65Ni0.35O3, synthesized at high pressure and high temperature, has a triclinic structure (space group ) at room temperature and ambient pressure with a √2ap×√2ap×2ap structure with α≈90(°),β≈89(°),γ≈90(°). Magnetic measurements show that the material displays Curie-Weiss behaviour above 50 K with C=2.11 emu K mol(-1) (μeff=4.11 μB per formula unit) and θ=-95.27 K. Bond valence sum analysis of the crystal structure shows that manganese is present in three different oxidation states (+2, +3, +4), with the +2 oxidation state on the A site resulting in a highly tilted perovskite structure (average tilt 21.2(°) compared with 15.7(°) calculated for LaCaMnNbO6), giving the formula (Sc3+(0.94)Mn2+(0.06))(Mn4+(0.41)Mn3+(0.09))(Mn3+(0.15)Ni2+(0.35))O3.