Phase dependent room-temperature ferromagnetism of Fe-doped TiO2 nanorods

S K S Patel,S Kurian,N S Gajbhiye

doi:10.1063/1.3679071

Abstract

Fe-doped TiO2(B) and anatase phases were synthesized at different thermal treatment conditions using Fe-doped hydrogen titanate nanorods as a precursor. X-ray diffraction, Raman and Mössbauer studies ruled out the formation of secondary phase of either metallic Fe or iron oxide cluster in the samples and confirmed the ferromagnetism have originated from the defects. Mössbauer spectroscopy studies show a doublet and measured isomer shifts support the high spin Fe3+ charge state occupying the Ti4+ sites with associated changes in local lattice environment. The magnetization at room-temperature of the TiO2(B) sample is 0.020 emu/g whereas that of anatase sample is 0.015 emu/g. The decrease of magnetization with the structural phase transformation from TiO2(B) to anatase is attributed to the reduction in number of defects (oxygen vacancy) during the transformation process. Existence of these defects was further supported by the photoluminescence measurements.

Highlights

Oxide based diluted magnetic semiconductors (DMSs) have attracted extensive scientific interest for fundamental research and development of spintronic and optoelectronic devices.[1,2,3,4,5] for their realizable applications, these DMSs systems must exhibit ferromagnetic behavior with the Curie temperature above room-temperature (RT)
The Fe-doped TiO2(B) and anatase nanorods were characterized by vibrating sample magnetometer (DMS ADE-EV7 model), field-emission scanning electron microscopy (Quanta 200, Netherland), transmission electron microscopy (TEM: Tecnai G2, operated at 200 kV), photoluminescence (Perkin Elmer LS 55 spectrophotometer)
The TiO2(B) nanorods were gradually transformed into anatase phase after heating treatment at 600 ◦C

Summary

INTRODUCTION

Oxide based diluted magnetic semiconductors (DMSs) have attracted extensive scientific interest for fundamental research and development of spintronic and optoelectronic devices.[1,2,3,4,5] for their realizable applications, these DMSs systems must exhibit ferromagnetic behavior with the Curie temperature above room-temperature (RT). These materials are based on the diamagnetic semiconductors but are doped with transition metals (TM) with unpaired d electrons at low concentrations.

EXPERIMENTAL SECTIONS

RESULTS AND DISCUSSION

CONCLUSIONS