Browsing by Author "Ravikumar, Patta"

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    Preparation and characterization of nanocrystalline Nickel-oxide powders and thin films
    (2017) Ravikumar, Patta
    More, faster, better, cheaper are the modern mantras and demands of our device-happy and data-centered world. To achieve these, one requires technologies for processing and storing information. With thin connection, the new field of research, termed as spintronics, is focused in multidisciplinary level and intensified by a strong synergy between breakthroughs in basic science and industrial applications. The key elements of semiconductor spintronics are injection, manipulation, transfer and detection of spin-polarized carriers across a semiconductor device. Therefore, the topic of diluted magnetic semiconductor has received extensive interest for spintronics.Thus, in this thesis work, we first prepared nanocrystalline NiO by using high-energy planetary mill process under dry mill conditions in a ball mill filled with high purity argon gas. Systematic studies of evolution of nanocrystalline structure, vibrational, electronic, magnetic and resonance properties of NiO powders were carried out as a function of milling speed to tune the properties of NiO powders. The ball mill process produced single phase face centered cubic (fcc) nanocrystalline NiO powders with the average crystal size of nanometer range (~ 11 nm) without any impurities within the detection limit of the techniques utilized. The milled NiO powders were subsequently heat treated at elevated temperatures under air atmosphere and the changes occurring in the structure and physical properties were evaluated to study the origin of ferromagnetism in these nanocrystalline NiO powders