Gadolinium doping affecting on structural, magnetic and dielectric properties of ZnO nanoparticles
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Gadolinium doping affecting on structural, magnetic and dielectric properties of ZnO nanoparticles M. Mazhdi1 · M. J. Tafreshi1 Received: 24 July 2019 / Accepted: 9 March 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract This work presents an investigation on the structural, magnetic and dielectric properties of the pure and gadolinium-doped ZnO nanoparticles synthesized by co-precipitation method. Three methods including Debye–Scherrer, Williamson–Hall and Rietveld were used to determine the phase and structural parameters of nanoparticles with more accuracy. FESEM images were used to show the morphology of nanoparticles and their size distribution. Structural defects and their concentration, caused by gadolinium doping, were confirmed by Raman spectroscopy measurement. The magnetic behavior of pure and Gd-doped ZnO nanoparticles was studied by measuring the magnetization for all the samples. The dielectric constant and dielectric loss of both pure and Gd-doped ZnO nanoparticles were measured in the frequency range of 102–107 Hz. Keywords Zinc oxide · DMS · Gd-doped ZnO NPs · Magnetic properties · Dielectric properties
1 Introduction In the last decade, the study of diluted magnetic semiconductors (DMSs) has attracted interest due to their potential applications in spintronic and optoelectronic devices [1, 2]. Using spin-polarized charge carriers has a wide application in semiconductor spintronic devices due to combination of ferromagnetism and semiconductivity in materials [3, 4]. Zinc oxide (ZnO) is a semiconductor material with a direct and wide band gap (3.2–3.37 eV), large exciton binding energy, high carrier mobility and high degree of tunability of charge carriers. ZnO crystallizes in hexagonal wurtzite structure (space group P 63mc) with lattice parameters of a = 3.2495 Å and c = 5.2069 Å [5–7]. The unique crystal structure and optical properties of ZnO have made it to become a good candidate for a wide range of applications in optoelectronic, transparent conductors, light-emitting displays, luminescence materials, photocatalytic and spintronic fields [2, 8–13]. In nanoscale, high quantum confinement affects on electronic structure. From other side, the structural, electrical and magnetic properties of nanostructures
* M. J. Tafreshi [email protected] 1
Faculty of physics, Semnan University, P.O. Box 35195‑363, Semnan, Iran
depend on parameters such as doping, defects and crystallinity [7, 14]. Transition metals or rare earth elements (REEs) induce unpaired electrons in host lattice of doped ZnO nanostructures which lead to room temperature ferromagnetism (RTFM). The indirect exchange interaction between 4f electrons and 5d or 6s electrons in REEs leads to magnetic moment. Many researchers have reported RTFM in REEsdoped ZnO [2, 6, 15, 16]. The structural defects such as oxygen vacancies (VO) and zinc interstitials ( Zni) induce ferromagnetism in REEs-doped ZnO [3, 6]. Gadolinium (Gd) is one of the REEs which causes a good magnetic behavior in ZnO [4]. Previously
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