Contents lists available at ScienceDirect Materials Science & Engineering B journal homepage: www.elsevier.com/locate/mseb Multiferroicity in Mg-doped ZnO nanoparticles Anindita Samanta a , M.N. Goswami b, ⁎ , P.K. Mahapatra c a Department of Physics & Techno-Physics, Vidyasagar University, Midnapore 721102, West Bengal, India b Department of Physics, Midnapore College, Midnapore 721101, West Bengal, India c Department of Physics, ITER, Siksha ‘O’ Anusandhan, Bhubaneswar 751030, Odisha, India ARTICLE INFO Keywords: Mg doped ZnO nanopowder UV–VIS spectroscopy Dielectric properties Ferroelectric nature Magneto-electric coupling ABSTRACT Zn 1-x Mg x O (x = 0.0, 0.03, 0.06, 0.09, 0.12, 0.15) nanoparticles have been synthesized using hydroxyoxalate type precursor by simple chemical precipitation method. X-Ray diffraction (XRD) study reveals that the nanoparticles crystallize in the hexagonal wurtzite structure in the space group P6 3 mc with (1 0 0) being the preferred growth plane. The average crystallite size of the compounds acquired from XRD and TEM analyses are nearly identical with values around 30 ± 5 nm. The doped samples, with reported ferromagnetic properties, are found to have ferroelectric properties. The magneto-electric (ME) voltage coefficient of the multiferroic samples is found to have appreciable values and increases with increase in doping concentration. 1. Introduction ZnO, a n-type II-VI semiconducting multifunctional material, under ambient conditions, crystallizes in the hexagonal wurtzite structure with the space group P6 3 mc [1]. The n-type semiconducting properties in ZnO are mainly due to the occurrence of oxygen vacancies and zinc interstitials in the sample during fabrication. The other attributes of ZnO being wide direct band gap (3.37 eV), high exciton binding energy of 60 meV [2], good transparency, high electron mobility, strong room temperature luminescence and very high chemical stability. The wide band gap of the compound makes it suitable for high temperature and high power operations with low electronic noise and provides the sample the ability to sustain very large electric fields. It exhibits a strong UV emission peak at 380 nm mainly due to the recombination of free excitons. These properties make the compound suitable for appli- cations as transparent electrodes in liquid crystal displays, energy saving and heat protecting windows, thin film transistors, gas sensors etc. Being an attracting luminescent material, ZnO is used in optoe- lectronic devices, such as ultraviolet light emitting diodes (LEDs) and laser diodes (LD’s) [3,4]. The success in nanometer ZnO lasers cata- pulted the research on ZnO and its doped material again to the fore- front. The polar Zn-O bonds and non-centro symmetric crystal structure results in the ferro [5,6], piezo and pyro electricity in the wurtzite ZnO. Room temperature ferromagnetism has also been observed in pristine ZnO. The ferromagnetic property in the ZnO is assigned to the occur- rence of oxygen vacancy, zinc interstitials and zinc vacancies in the sample [7]. The multiferroic character of ZnO is expected to find potential applications in spintronics and multiple-state memory de- vices. Doping is considered to be the effective means of controlling the electrical conductivity, dielectric, magnetic and other physical proper- ties of a semiconductor. It has been suggested that while the doping of transition metal elements in ZnO can lead to improved ferromagnetic properties, the addition of rare earth elements lead to improved optical properties. Recently, the ferromagnetic properties have been reported in non-magnetic element like Li and Mg doped ZnO [8–10]. Magnesium doping in ZnO results in band gap tuning, since the band gap of MgO is 7.4 eV and for a 15% doping the band gap can be raised to around 3.9 eV. However, factors like oxygen vacancies are likely to play a role in the band gap formation of the samples. The doping is expected to change the conductivity by over 10 orders of magnitude. The Mg incorporation in the ZnO matrix is not expected to produce extra strain as the ionic radius of Mg 2+ (0.66 Å) is slightly smaller than that of Zn 2+ (0.74 Å) and is reported to have solubility limit as high as 20 mol percentage. Although there are some reports on the ferromag- netic properties of Mg doped ZnO, there are very few reports on di- electric property of Mg doped ZnO [11]. Literature on multiferroic property and magneto-electric coupling of ZnO is very rare. The tuning of optical, magnetic and ferroelectric properties of ZnO also depends on its preparation method. We thus motivated to study the optical, elec- tromagnetic and ME coupling properties of ZnO nanoparticles synthe- sized by simple chemical precipitation method using hydroxyoxalate type precursor. https://doi.org/10.1016/j.mseb.2019.05.008 Received 15 March 2018; Received in revised form 1 February 2019; Accepted 6 May 2019 ⁎ Corresponding author. E-mail address: makhanlal@gmail.com (M.N. Goswami). Materials Science & Engineering B 245 (2019) 1–8 0921-5107/ © 2019 Elsevier B.V. All rights reserved. T