*Corresponding author: Myroslava Omelchenko Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland ISSN: 0976-3031 Research Article FERROMAGNETIC STATE OF UNDOPED AND Co, Mn DOPED ZnO NANOPARTICLES Myroslava Omelchenko Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland DOI: http://dx.doi.org/10.24327/ijrsr.2019.1002.3195 ARTICLE INFO ABSTRACT For the first time room temperature ferromagnetism (RTFM) is registered and analyzed in these materials. The detail description of the measured magnetization of the material, namely pure and doped ZnO nanoparticles, obtained by microwave solvothermal synthesis, is presented from the experimental and analytical point of view. Comparing announcements of room temperature ferromagnetic state reported by many authors and own experimental results one can claim that ferromagnetic state in pure and doped ZnO exist. But there are questions with lacking answers, like the stability of the room temperature ferromagnetic state, the nature of RTFM. This paper is focused on experimental registration using SQUID and description of ferromagnetic state. The Brillouin function fitting was applied to analyze the paramagnetic contribution of transitional metal (TM) dopands in the material. The magnetization of zinc oxide nanoparticles (NPs) doped with TM ions was obtained for the samples with nominal concentration 1% and 15% Co2+ and Mn2+ +each. The most unusual magnetic properties perform co-doped NPs - Zn(1-x-y)MnxCoyO. The nominal content of Co2+ and Mn2+ in the zinc oxide co-doped NPs was x = y = 1, 5, 10 and 15 mol%. INTRODUCTION New functional material – diluted magnetic semiconductor (DMS) with the ferromagnetic transition temperature (Curie temperature: T C ) around 300K is the very desirable result for modern spintronics, optoelectronic and high-power electronics devices. It is important to understand the origin and nature of the ferromagnetism in DMS for successful synthesis of high-T C ferromagnetic DMSs. K.Sato et. al. [1] discuss zink oxide, as a promising material for semiconductors, doped with transitional metal (TM), which have high-T C and whose magnetic properties are controllable by changing carrier density. Ferromagnetic state of ZnO-based DMS might be described as (Zn 1−x , TM x up ) O, in which the magnetic moments of all TM atoms are parallel and the system has a finite magnetization, where x is concentration of TM. The authors experimentally confirmed that high-T C are released in ZnO-based DMSs doped with V, Cr, Fe, Co or Ni. The stability of ferromagnetic state varies with the concentration of magnetic ion. So it is very important to investigate the magnetic properties with different concentrations of TM. According to the M. Mustaqima [2] Mn- and Co-doping ions in the ZnO matrix are usually the most promising systems for the fabrication of spintronic devices mainly because of their rich electron states and large substitutability of Zn in the lattice. Magnetic behavior of DMS strongly depends on concentration of dopand, spatial distribution of transitional metal in a crystal lattice and surface defects [2]. Many reports of ferromagnetism in the nano- structures of zinc oxide and thin films can be found in review articles [1, 2]. This paper is focused on nanoparticles because additional effects related to the high surface-to-volume ratio appear, making the ferromagnetic effects more complex but more interesting in nanoscale dimensions. Even pure zinc oxide has ferromagnetic state caused by deformations.There are some announcements about ferromagnetic state even in pure ZnO which are correlated with the experimental results presented in this paper. M. Mustaqima et.al [2] connects this ferromagnetic behavior to the surface defects. A few authors discussed ferromagnetism of un-doped ZnO in their papers [3-6]. Xu Zuo et al., using ab initio calculation based on density functional theory, showed that ferromagnetism in undoped ZnO is caused by oxygen interstitial and zinc vacancy. Acording to Ning Shuai [8] et al. room temperature ferromagnetism (RTF) in pure ZnO originates from the intrinsic point defects such as oxygen vacancy (V O ), oxygen interstitial (O i ), zinc vacancy (V Zn ), and zinc interstitial (Z ni ). Experimental conformation of RTFM in ZnO nanoparticles was reported by A. Sundaresan et.al [3]. Due to the large number of publications, it’s impossible to provide a full overview of this topic. This paper is focused on description of experimental obtaining of magnetization of pure, Available Online at http://www.recentscientific.com International Journal of Recent Scientific Research International Journal of Recent Scientific Research Vol. 10, Issue, 02(G), pp. 31124-31128, February, 2019 Copyright © Myroslava Omelchenko, 2019, this is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited. DOI: 10.24327/IJRSR CODEN: IJRSFP (USA) Article History: Received 4 th November, 2019 Received in revised form 25 th December, 2018 Accepted 23 rd January, 2019 Published online 28 th February, 2019 Key Words: ZnO nanoparticles; magnetization; paramagnetism; ferromagnetism; Brillouin function