Oxygen vacancy induced ferromagnetism in ball milled Zn 0.97 Ni 0.03 O: Conﬁrmation through electron spin resonance Shreenu Pattanaik a , Bijaylaxmi Biswal a , Urmishree Routray a , Jyoshnarani Mohapatra b , V.V. Srinivasu c , D.K. Mishra a,⇑ a Department of Physics, Faculty of Engineering and Technology (ITER), Siksha ‘O’ Anusandhan Deemed to be University, Khandagiri Square, Bhubaneswar 751030, Odisha, India b Department of Physics, College of Basic Science and Humanities, Orissa University of Agriculture and Technology, Bhubaneswar 751003, Odisha, India c Department of Physics, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1710, South Africa article info Article history: Received 16 February 2020 Received in revised form 16 March 2020 Accepted 19 March 2020 Available online xxxx Keywords: ZnO Nanoparticles Diluted magnetic semiconductor Electron spin resonance Defects Ferromagnetism abstract Among the semiconducting materials, ZnO is a versatile multifunctional candidate with a direct band gap of 3.37 eV at 300 K and large excitonic binding energy of 60 meV which can be useful for spintronics device applications. ZnO has high solubility for transition metals. The transition metals which have been used for DMS, Ni is the most efﬁcient doping element to improve the electrical, magnetic properties of ZnO. Ni doped ZnO would be a good candidate to achieve ferromagnetic property with a high curie tem- perature i.e. above the room temperature. In this study, Zn 1x Ni x O (x = 0.03) powder sample was success- fully synthesized by a ball milling technique. The X-ray diffraction analysis conﬁrms the polycrystalline, hexagonal wurzite structure for 3% Ni doped ZnO nanoparticles. The substitution of Ni in the ZnO matrix has been conﬁrmed by micro-Raman analysis with the observation of E 2 (High) vibrational mode at 437 cm 1 which refers to the strongest mode of vibration in wurtzite crystal structure. A broadened peak observed at 570 cm 1 informs about the presence of clusters of oxygen vacancies. VSM measurement of the sample shows the ferromagnetic hysteresis loop at room temperature with saturation moment of 9  10 5 emu/g. The calculated ‘g’ value of 1.95 from electron spin resonance spectrum suggests that the observed ferromagnetism is due to the oxygen vacancy. Ó 2020 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientiﬁc committee of the International Confer- ence on Nanomaterials for Energy, Environment and Sustainability. 1. Introduction Nanomaterials are cornerstones of nanoscience and nanotech- nology. It has the potential for revolutionizing the ways in which materials are synthesized and the range and nature of functional- ities that can be accessed. They have possessed unique physical, mechanical, optical, electrical and magnetic properties due to its increased surface to volume ratio and quantum conﬁnement effect [1]. Recently, Diluted magnetic semiconducting materials draw an immense interest among the researcher due to its spin transport and magnetic properties as these materials are used in various ﬁelds like optoelectronics, spintronics devices. Diluted magnetic semiconductors obtained by introducing a dilute amount of mag- netic impurities, i.e. transition metals ions at the cation sites of the host semiconductor and coupled with free carriers to yield fer- romagnetism via indirect interaction. Transition metal doped diluted magnetic semiconductors are potential candidates for the attainment of room temperature ferromagnetic properties with a high Curie temperature [2–4]. Among the semiconducting materials ZnO is a versatile multi- functional candidate with a direct band gap of 3.37 eV at 300 K, large excitonic binding energy of 60 MeV which can be useful for spintronics device applications. ZnO has high solubility for transi- tion metals. Various transition metals are used for the enhance- ment of the properties of ZnO. Among them, Ni is the most efﬁcient doping element to improve the electrical, magnetic prop- erties of ZnO [5,6]. The Ni 2+ has good chemical stability when it occupies the Zn 2+ sites and strengthens the optical, electrical and magnetic properties of the ZnO. Ni-doped ZnO would be a good candidate to achieve ferromagnetic property with a high Curie temperature i.e. above the room temperature [7–9]. The origin of ferromagnetism is due to the exchange interaction between the localized magnetic moment of transition metal ions https://doi.org/10.1016/j.matpr.2020.03.547 2214-7853/Ó 2020 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientiﬁc committee of the International Conference on Nanomaterials for Energy, Environment and Sustainability. ⇑ Corresponding author. E-mail addresses: dilipiuac@gmail.com, dilipmishra@soa.ac.in (D.K. Mishra). Materials Today: Proceedings xxx (xxxx) xxx Contents lists available at ScienceDirect Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr Please cite this article as: S. Pattanaik, B. Biswal, U. Routray et al., Oxygen vacancy induced ferromagnetism in ball milled Zn 0.97 Ni 0.03 O: Conﬁrmation through electron spin resonance, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2020.03.547