Structural development and magnetic phenomenon in Zn–Cr–Fe multi oxide nano-crystals

The Cr³⁺ ions doped multi-oxide ZnFe_2−xCr_xO₄ ferrite nanoparticles have been synthesized by chemical co-precipitation method. Site occupancies of Zn²⁺, Cr³⁺ and Fe³⁺ ions were analyzed using X-ray diffraction data and Buerger's method. The effect of the constituent phase variation on the magnetic hysteresis behavior was examined by saturation magnetization which decreases with the increase in Cr³⁺ content in place of Fe³⁺ ions at octahedral B-site. Typical blocking temperature (T_B) around 90 K was observed by zero field cooling and field cooling magnetization study. Room temperature Mössbauer spectra show two paramagnetic doublets (tetrahedral and octahedral sites). The isomer shifts of both doublets decrease whereas quadrupole splitting and relative area of tetrahedral A-site increases with increasing Cr³⁺ substitution. The dielectric constant (measured on compositions x=0, 0.4, 0.8 and 1.0) increases when the temperature increases as in the semiconductor. This behavior is attributed to the hopping of electrons between Fe²⁺ and Fe³⁺ ions with a thermal activation.     

Room temperature ferromagnetism in Ni doped In2O3 nanoparticles

In the present work, Ni doped In₂O₃ nanoparticles were prepared using simple co-precipitation method. From the x-ray diffraction analysis it is observed that all samples exhibit single phase polycrystalline nature. All the diffraction lines correspond to the bixbyite type cubic structure. A UV visible analysis reveals that optical band gap decreases from 4.63 to 3.84 eV with Ni doping. DC magnetization measurements reveal that Ni doped In₂O₃ nanoparticles exhibit room temperature ferromagnetism.     

First-Principles Investigation of Electronic Properties of GaAsxSb1 –x Ternary Alloys

Semiconductors - Compositional variations in GaAs based ternary alloys have exhibited wide range alterations in electronic properties. In the present paper, first-principles study of...     

Structural and magnetic properties of Zn1-xcoxO nanorods prepared by microwave irradiation technique

We have successfully synthesized large-scale aggregative flowerlike Zn1-xCo(x)O (0.0 < or = x < or = 0.07) nanostructures, consisting of many branches of nanorods at different orientations with diameter within 100-150 nm (tip diameter approximately 50 nm) and length of approximately 1 microm. The rods were prepared using Zinc nitrate, cobalt nitrate and KOH in 180 Watt microwave radiation for short time interval. The synthesized nanorods were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM) and DC magnetization measurements. XRD and TEM results indicate that the novel flowerlike nanostructures are hexagonal with wurtzite structure and Co ions were successfully incorporated into the lattice position of Zn ions in ZnO matrix. The selected area electron diffraction (SAED) pattern reveals that the nanorods are single crystal in nature and preferentially grow along [0 0 1] direction. Magnetic studies show that Zn1-xCo(x)O nanorods exhibit room temperature ferromagnetism. This novel nanostructure could be a promising candidate for a variety of future spintronic applications.     

Study of magnetic entropy change in La0.65Sr0.35Cu0.1Mn0.9O3 complex perovskite

The magnetocaloric properties of new complex magnetic material La_0.65Sr_0.35Cu_0.1Mn_0.9O₃, suitable for the Ericsson cycle, have been investigated. For this material, the effect of Cu doping can be attributed to a combination of doping disorder, Cu-Mn super exchange interactions and a site-percolation mechanism, which suppress the metallic conduction and Curie temperature. The Curie temperature decreases to 355 K. The magnetocaloric study exposes a comparable value of the magnetic entropy change for La_0.65Sr_0.35Cu_0.1Mn_0.9O₃ sample, the value of the maximum entropy change, increases from 1.132 J/kgK to 3.11 J/kgK as magnetic field increases from 1 T to 4 T. A large relative cooling power (RCP) has been observed for La_0.65Sr_0.35Cu_0.1Mn_0.9O_3. As a result, the studied sample can be considered as potential material for magnetic refrigeration.     

Irradiation induced texturing in the Mg0.95Mn0.05Fe2O4 ferrite thin film

We present a study on the effect of swift heavy ions irradiation on the structural and magnetic properties of Mg_0.95Mn_0.05Fe₂O₄ ferrite thin film grown by pulsed laser deposition technique. X-ray diffraction (XRD) pattern of the as-deposited film reveals a cubic spinel structure with an intermediate phase of α-Fe₂O₃. This impurity phase completely dissolves upon irradiation with 200 MeV Ag¹⁵⁺-ions and it exhibits a strong crystallographic texture along the (440) plane. The magnetization values start increasing systematically with irradiation at lower fluence values, whereas decrease for higher one. This decrease in magnetic signal can be attributed to partial amorphization caused by irradiation in agreement with XRD and atomic/magnetic force microscopic images.     

Erratum to: First-Principles Investigation of Electronic Properties of GaAsxSb1 – x Ternary Alloys

Semiconductors - erratum     

Effect of Cu seed on the synthesis and characterization of FeCo alloy nano-particles by using polyol method

Fine metal particles with uniform shape, narrow size distribution and high purity are increasingly needed for specific uses in high tech industrial application. We report the direct chemical synthesis of FeCo alloy particles using the mixture of FeCl2·4H2O, Co (Ac)2·4H2O (Ac: acetate) and NaOH in ethylene glycol, and then obtained FeCo alloy particles better dispersed by adding the polyvinylpyrrolidone (PVP) and also the size could be controlled by adding copper. The prepared nano-particles were characterized using FESEM, XRD and VSM. The mean diameter of these particles was varied in the range of sub- mi- crometer to nanometer with metal-ion concentration. FeCo particles showed the typical soft magnetic properties.     

Synthesis and ageing effect in FeO nanoparticles: Transformation to core-shell FeO/Fe3O4 and their magnetic characterization

This paper reports the magnetic properties of partially oxidized FeO nanoparticles (NPs) prepared using thermal decomposition of iron acetylacetonate at high temperature. X-ray diffraction (XRD) analysis confirmed that the resulting NPs comprise a mixture of wüstite and magnetite phases, which are subsequently confirmed using high resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED) pattern. Magnetic properties were investigated using vibrating sample magnetometer (VSM), which exhibit superparamagnetic (SPM) behavior at room temperature. Alternatively, below 200 K, a large exchange bias field has been observed in field cooled mode whose magnitude increases with the decrease in measuring temperature attaining a maximum value of ∼2.3 kOe at 2 K accompanied by coercivity enhancement (∼3.4 kOe) and high field of irreversibility (>50 kOe). The results are discussed taking into account the role of interface exchange coupling on the macroscopic magnetic properties of the nanoparticles.