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Nanocrystalline NiZnFeCrO (0 ≤ x ≤ 0.5) ferrite was prepared using a citrate method. The influence of Zn ion substitution on structure, magnetic, and electric properties of the NiZnFeCrO ferrite has been investigated. The X-ray diffraction results confirmed the formation of a single phase with a spinel cubic structure for NiZnFeCrO samples. The magnetization was found to be influenced by the surface spin canting angles, the porosity percentage, and the cation distributions. The variation of dielectric constant with temperature indicated that the investigated materials can be recommended to be used as good insulating ceramic materials at room temperature and as a semiconductor at higher temperatures. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI)-Ni0.5Zn0.5Fe1.5Cr0.5O4 (NZFCO) nanocomposites are conducting polymer–ferrite, which belongs to magneto-polymeric materials. They have very useful electromagnetic properties with new functions. The nanocomposites were synthesized in situ by polymerization of PANI in the presence of NZFCO nanoparticles. The results of XRD, FTIR spectra and TEM showed the presence of the two intended phases. The crystallite sizes measured were found to be in the nanorange (5–11nm) which are almost in agreement with XRD data. The selected area electron diffraction (SAED) pattern of the nanocomposite, showed the superposition of both PANI ring and the single spot of the ferrite nano-crystallite {111} reflections, which confirms that PANI is covering the ferrite nanocrystallites. The DTA analysis indicated the high temperature stability of the nano-composite phase (347°C) compared with PANI (270°C). The highest magnetic saturation (M s) was found for the nano-composite sample which have PANI concentration of (40% and 60%). The crystallite sizes, strains and change in lattice parameters were found to increase by increasing the percentage of PANI. The ac conductivity, dielectric constant and dielectric loss of all sample composition are much higher than that of PANI, the highest is for the sample which has has (60%) PANI concentration. The loss tangent were found to have very high values in the microwave range for certain concentrations and to have very low values for some other concentration with no definite systematic correlation. The temperature dependence of dielectric constant revealed a diffused phase transition (DPT) at higher temperature with higher dielectric constant of many order of magnitudes. The properties of magneto-polymeric nanocomposite are greatly influenced by the percentage of its component phases and the degree of mixing between the two phases. In general the different variety of the results obtained by just changing the relative percentage of PANI–NZFCO, made the present studied samples to be useful in many technological applications. [ABSTRACT FROM AUTHOR]

Abstract: InTe compound doped by 10% of Fe or Co respectively was synthesized. X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), energy dispersive X-ray (EDX), vibrating sample magnetometer (VSM) and Kiethley electrometer were used for characterizing the prepared samples. XRD show the presence of InTe0.9Fe0.1 or InTe0.9Co0.1 together with minor In4Te3 phase. InTe0.9Fe0.1 is ferromagnetic with high Curie and high blocking temperature, while InTe0.9Co0.1 is antiferromagnetic with two high Neels temperatures. σRT of InTe0.9Fe0.1 and InTe0.9Co0.1 are greater than those of InTe. The higher conductivity is due to the higher carrier's density obtained from the interaction of the sp-d orbitals, of the electric and magnetic system. The presence of In4Te3 minor phase and different kinds of defects are taking major roles in the formation of high Tc ferromagnetism and antiferromagnetism. [Copyright &y& Elsevier]

Abstract: xBaTiO 3 +(1− x)Ni0.5Zn0.5Fe1.5Cr0.5O4 (x =0.35, 0.5, 0.65) nanocomposites were synthesized by the sol–gel method. The two corresponding intended nanocomposites phases were confirmed by X-ray diffraction, no other foreign phases were present. The microstrain of the nanocomposite was found to depend on the ratio amount of BaTiO3 (BTO) in the nanocomposites. The tetragonality ratio c/a of BTO approximates its values to be (a = c) at concentration of 65% BTO. Magnetic properties showed superparamgnetic behavior at room temperature. The temperature dependent of dielectric constant measurements showed that the Curie temperature (T c) of the ferroelectric phase transition varies with different composites ratio. The dielectric properties of the composite increased with increase of ferrite content. The compressed stress generated by the lattice mismatch of the in planes at the interface of the ferroelectric and magnetic phases cause large strain. The mediation of this strain causes strong electromagnetic coupling creating new materials with good quality. [Copyright &y& Elsevier]

Abstract: The structural, magnetic and electric properties of Fe or Co doped InSe system has been studied. The X-ray diffraction patterns of the doped samples indicate the presence of InSe0.9Fe0.1 or InSe0.9Co0.1, together with a non-magnetic minor phase of In4Se3. The InSe0.9Fe0.1 system is ferromagnetic with high Curie temperature of 870K. In contrast, the InSe0.9Co0.1 system is antiferromagnetic with different Neel temperatures. Crystallite sizes of the different phases show anisotropy along different crystallographic directions, they vary from 9 to 40nm. The largest size is along the [00 l] direction normal to the staking layers planes. The random model was applied to explain the origin of ferromagnetic properties of Fe doped sample. The non-magnetic phase In4Se3 played a major role in the high temperature ferromagnetic properties of InSe0.9Fe0.1 and the polarization of magnetic spins. The electrical conductivity increased by an order of magnitude of 2 and 1.5 in the case of Fe and Co doped samples, respectively, suggesting that the incorporation of Fe or Co creates new band configuration and hence a modification of electronic density of states of the samples studied. The anomaly in the electrical properties after doping with Fe or Co may suggest that these doped samples may be used as spintronics materials. [Copyright &y& Elsevier]

The structural problem of oxygen diffusion into the ZnSe lattice annealed in air at different temperatures was studied. Different possible sites were tried for oxygen accommodation. It is found that oxygen atoms diffuse into the vacant sites of the Se atoms formed due to Se evaporation. The relative occupancy of the diffused oxygen was determined as a function of annealing temperature. ZnSe03 and ZnO phases start to develop at a temperature of 623 K and a period of 30 hours annealing time. [ABSTRACT FROM AUTHOR]

Structural and thermal expansion studies of Li[sub 2]ZrO[sub 3] were carried out by recording X-ray powder diffraction patterns at five temperatures, 82, 198, 300, 423 and 573 K. The Rietveld refinement method was used for the analysis. There were large anisotropic changes in the lattice parameters as a function of temperature, slight changes in the fractional coordinates of the different atoms, and anisotropic changes in the interatomic distances between the different cations. The correlation of these anisotropies with the structure is considered. [ABSTRACT FROM AUTHOR]