Pure and Co-doped NiTiO3 nanocrystalline powders were prepared by the sol-gel method. The effect of Co2+ doping on structural, optical and magnetic properties of NiTiO3 was investigated by X-ray diffraction, UV-vis absorption, Raman spectroscopy and vibration samples magnetometer. | Vietnam Journal of Science and Technology 56 (1A) (2018) 119-126 EFFECTS OF Co DOPING ON PROPERTIES OF ILMENITE NiTiO3 CERAMICS Tran Tat Dat1, Pham Phi Hung1, Dang Ngoc Toan2, Dang Duc Dung1, Cao Xuan Quan3, Luong Huu Bac1, * 1 School of Engineering Physics, HUST, 1 Dai Co Viet, Ha Noi, Viet Nam 2 Institute of Research and Development, , K7/25 Quang Trung, Da Nang, Viet Nam 3 Vietnam Metrology Institute, 8 Hoang Quoc Viet, Ha noi, Viet Nam * Email: Received: 15 August 2017; Accepted for publication: 15 February 2018 ABSTRACT Pure and Co-doped NiTiO3 nanocrystalline powders were prepared by the sol-gel method. The effect of Co2+ doping on structural, optical and magnetic properties of NiTiO3 was investigated by X-ray diffraction, UV-vis absorption, Raman spectroscopy and vibration samples magnetometer. It was found that all fabricated samples were in single phase with rhombohedral structure. The presence of Co modifies the optical properties of the NiTiO 3 nanocrystalline powders. Co doping in NiTiO3 resulted in decreasing of optical bandgap from to eV. The undoped and Co-doped samples showed weak ferromagnetism at room temperature. Keywords: NiTiO3, Co-doped NiTiO3, ilmenite, sol-gel, optical. 1. INTRODUCTION NiTiO3 (NTO) is an important and interesting member of the ATiO3 family which holds tremendous potential for a wide range of applications such as visible-light photocatalyst [1], solid oxide fuel cells [2], gas or glucose sensor [3, 4], and spin electronic devices with magnetoelectric effect [5]. NiTiO3 belongs to the ilmenite type structure with both Ni and Ti processing octahedral coordination and the alternating cation layers occupied by Ni2+ and Ti4+ alone [6]. The bulk NiTiO3 are antiferromagnetic materials with a Neel temperature of 22 K [7]. The Ti ions in 3d0 state of NiTiO3 dominate the ferroelectric polarization, whereas Ni ions (having partially filled orbitals) are considered to contribute to the .
