Os doped YMnO 3 multiferroic: A study investigating the electrical properties through tuning the doping level O. Polat a, * , M. Coskun b , F.M. Coskun b , Z. Durmus c , M. Caglar d , A. Turut b a Faculty of Engineering, Department of Industrial Engineering, Istanbul Kultur University, 34156, Bakirkoy, Istanbul, Turkey b Faculty of Engineering and Natural Sciences, Department of Engineering Physics, Istanbul Medeniyet University, 34700, Uskudar, Istanbul, Turkey c Ba glar Mah., Gunesli Konutlar, No: 38, D-24, 34212, Bagcilar, Istanbul, Turkey d Faculty of Science, Department of Physics, Anadolu University, 26470, Eskisehir, Turkey article info Article history: Received 2 February 2018 Received in revised form 15 April 2018 Accepted 17 April 2018 Available online 18 April 2018 Keywords: YMnO 3 Os doping Relaxation Dielectric constant Conductivity abstract Previously, it has been demonstrated the electrical and magnetic properties of YMnO 3 (YMO) can be tuned with substitution of different elements into Y and/or Mn sites. In this study, the electrical prop- erties of YMO were explored via substituting osmium (Os) into Mn site with various mol %. The crys- talline morphology of synthesized YMnO 3 and YMn 1-x Os x O 3 (YMOO) (x ¼ 0.01, 0.05, 0.10) powders were characterized with X-ray diffractometer (XRD) and infrared spectroscopy (IR) measurements. The crys- talline morphology of synthesized powders was studied via scanning electron microscope (SEM). Oxidation states of constituent elements have been examined by X-ray photoelectron spectroscopy (XPS). Electrical properties of YMO and YMOO powders were investigated by dielectric/impedance spectrometer at various temperatures and frequencies. Electric modulus measurements unveiled that for each of x ¼ 0, 0.01 and 0.05 samples there are three relaxation peaks while x ¼ 0.10 sample shows four relaxation peaks. It has been shown that dielectric constant and conductivity properties of parent YMO can be enhanced via Os substitution, particularly, 10 mol % Os doped sample has the highest dielectric constant and conductivity at various temperatures and frequency regions. Moreover, the conduction mechanisms were also examined. It turned out that in order to explain conduction mechanism, multiple models need to be considered in the studied materials. © 2018 Published by Elsevier B.V. 1. Introduction Multiferroic materials that demonstrate a changed electric po- larization by a magnetic field or a changed magnetization by an electric field have recently initiated enormous interest for their potential applications in the next-generation novel multifunction devices such as spintronics, data storage, sensors and so on [1e 12]. The hexagonal manganites, with RMnO 3 chemical formula, are good examples of multiferroic materials. Among these hexagonal manganites, YMnO 3 (YMO) has attracted more attention owing to its high ferroelectric transition temperature (T C ~ 950 K) and anti- ferromagnetic transition temperature (T N ~ 75 K) [13, 14]. The crys- tal structure of YMO is formed by MnO 5 trigonal bipyramids in which three in-plane and two apical oxygen ions surround indi- vidual manganese (Mn) ion. In this structure, the ferroelectricity is related to the small tilting of MnO 5 and trigonal bipyramids buck- ling of Y layers. The origin of magnetism, on the other hand, is attributed to Mn 3þ spins, which align anti-ferromagnetically in the ab plane of YMO structure below 75 K [15]. YMO is considered as a good candidate for high temperature sensing and actuation appli- cations due to i) its high Curie temperature, ~950 K and ii) being lead-free component. Most of the multiferroics have transition ions such as Mn 3þ , Fe 3þ , which have partially filled d-orbitals, at their B- side atom [16, 17]. Thermal conductivity of these materials is related to the variation of the oxidation state of transition ions. Therefore, most of the multiferroics demonstrate low polarization, poor dielectric features and high leakage current [18]. To minimize or eliminate such losses, it is needed to understand the essence of electrical transport mechanism in multiferroic materials. Even though many works have been conducted to shed light on multi- ferroics properties of YMO, there have been fewer reports regarding the electrical conductivity and dielectric properties of YMO at wide range temperature and frequency regions [19e22]. Various research groups have tried to modify the electrical and magnetic * Corresponding author. E-mail address: o.polat@iku.edu.tr (O. Polat). Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: http://www.elsevier.com/locate/jalcom https://doi.org/10.1016/j.jallcom.2018.04.200 0925-8388/© 2018 Published by Elsevier B.V. Journal of Alloys and Compounds 752 (2018) 274e288