Fe-doped In2O3 Research Articles

Effects of carbothermal annealing on structure defects, electrical and magnetic properties in Fe-doped In 2O 3

Fe-doped In2O3 powders were treated by the carbothermal annealing method, and phase transition from a paramagnetic insulator to a ferromagnetic metallic state was observed. No trace of any other impurity phase was detected in the carbothermally annealed samples with Fe content up to 16%. Rietveld refinements of X-ray diffraction and X-ray photoelectron spectra revealed that a large amount of interstitial indiums and oxygen vacancies were introduced with carbothermal annealing. These defects play an important role in inducing the ferromagnetism and metallic conductivity.

Structural, optical, and magnetic properties of Fe-doped In2O3 nanocubes

Fe-doped In2O3 nanocubes were synthesized by a solvothermal method. The lattice constant a decreases linearly as Fe doping concentration increases, and Raman scattering measurement proves the incorporation of Fe ions into the In2O3 crystal lattice. Mössbauer spectra show the presence of mixed valence of Fe ions instead of Fe3O4, while the sample is superparamagnetic. The products with an average diameter of 80 nm have a single-crystalline phase and appear as a square shape. Magnetic measurements confirm the superparamagnetic properties of the nanocubes, and electron paramagnetic resonance studies indicate Fe ions occupy different sites in the In2O3 matrix.

Synthesis and magnetic properties of Fe-doped (In 1− xHo x) 2O 3 solid solution

We synthesized Fe-doped In2O3–Ho2O3 solid solution Fe0.16 @ (In1−xHox)2O3 with x = 0, 0.027 and 0.054. Nanoparticles of Fe3O4 with diameter of ∼150 nm dispersed in the (In1−xHox)2O3 matrix. Magnetization of the x = 0, 0.027 and 0.054 samples was 2.1, 3.1 and 2.7 emu g−1, respectively, at a temperature of 300 K and in a magnetic field of 1 T. Enlargement of magnetization was observed as expected as the matrix effect for the x = 0.027 and 0.054 samples.

Giant positive magnetoresistance in Fe doped In2O3 and InREO3 (RE=Eu,Nd) composites

Synthesis and characterization of Fe and rare earth (RE) (RE=Eu,Nd) codoped bulk In2O3 oxide are reported. Composites consisting of Fe-doped In2O3 and InREO3 phases were formed, as determined by x-ray diffraction and transmission electron microscopy, with particle sizes of 50–120nm. The composites exhibit superparamagnetic and semiconducting behavior. A giant positive magnetoresistance is observed at low temperatures, reaching 81% and 50% at 5K in Eu–Fe and Nd–Fe codoped samples, respectively.

High temperature ferromagnetism and perpendicular magnetic anisotropy in Fe-doped In2O3 films

High temperature ferromagnetism and perpendicular magnetic anisotropy were observed in Fe-doped In2O3 magnetic semiconductor films deposited on R-cut sapphire by pulse laser deposition. The films show a Curie temperature as high as 927K. Strong perpendicular magnetic anisotropy with a remnant magnetization ratio of 0.77 and a coercivity of 680Oe is demonstrated. Extensive microstructure, composition, and magnetic studies indicate that Fe element incorporates into the indium oxide lattice by substituting the position of indium atoms, which suggests the observed ferromagnetism is intrinsic rather than from Fe clusters or any other magnetic impurity phases.

Synthesis and Characterization on Fe-doped In2O3 Nanoparticles

ABSTRACTPure and Fe-doped In2O3 nanocrystalline powder was synthesized using a solution chemistry route based on the Sol-Gel process, which is a simple and inexpensive technique and produces long-time stable stock solutions. The X-ray diffraction patterns revealed the formation of nanocrystalline particle size with well-crystallized cubic bixbyte structure. The average crystal size was calculated from XRD patterns using Debye-Scherrer's equation for the (222) peak and found to be 8 nm. This observation agrees well with the particle size estimated from transmission electron microscopy (TEM). The observed Raman peaks in the doped materials are shifted towards the lower frequency up to 15 cm−1 and we did not observed any additional new Raman modes with Fe doping. This clearly indicates that Fe ions are indeed occupying interstitial/substitutional sites in the host In2O3, in agreement with XPS measurements. Magnetic properties were studied using superconducting quantum interface device magnetometer (Quantum design MPMS XL-7). Preliminary magnetic measurement results suggest the incorporation of the dopants in the diamagnetic In2O3-host structure.

Electronic structure of Fe-doped In2O3 magnetic semiconductor with oxygen vacancies: Evidence for F-center mediated exchange interaction

Based on the first-principles calculations, the electronic structure and magnetic properties of Fe-doped In2O3 were theoretically investigated. The presence of the predominating defects in oxide, i.e., oxygen vacancies, can lead to strong ferromagnetic coupling between the nearest neighboring Fe cations. Spin density and band-projected charge distribution in the vicinity of the oxygen vacancies reveal that the ferromagnetic exchange is mediated by the donor impurity state, which mainly consists of Fe:3d and Fe:4s electrons trapped in oxygen vacancies. Such results provide direct evidence for the F-center mediated exchange interaction in oxide-based magnetic semiconductors.