EFFECT OF CHROMIUM SUBSTITUTION ON STRUCTURAL,ELECTRICAL AND MAGNETIC PROPERTIES OF NANOCRYSTALLINE SUBSTITUTED STRONTIUM HEXAFERRITES

Abstract

Strontium M-Type hexaferrite have been of considerable interest for many years due to their appropriate magnetic properties which applied in many applications such as microwave devices, high density magnetic recording, electronic devices and medicine.Several cations such as Cr+3, Al+3, In+3 and etc substituted in order to improve the magnetic and electrical properties of strontiumhexaferrite. Nanosize Chromium substituted strontium hexaferrite SrCrxFe12-xO19 (x=0-8) synthesized by microwave assisted Solgel auto-combustion route using urea as a fuel/reductant and nitrates as oxidants.The structural and magnetic behaviourof these samples were studied using X-ray diffraction (XRD), vibrating sample magnetometer and Transmission Electron Microscope (TEM).(XRD)studies reveal that microwave-assisted combustion synthesis route yields materials with higher degree of compositional stability and phase purity.Both a and c lattice parameters calculated systematically decrease with increasing Cr content.The effects of Cr3+ ions on the Strontium Lanthanum ferrites were reported and discussed in detail.The site preference of Cr3+ and magnetic properties of the ferrites have been studied using hysteresis.The results show that the magnetic properties are closely related to the distributions of Cr3+ ions on the five crystallographic sites.The saturation magnetization systematically decreases, however, the coercivitydecreases with Cr concentration.The magnetization results indicate that the Cr3+ ions preferentially occupy the 2a, 12k, and 4fVI sites.