1. Department of Materials Science and Engineering, Jimma Institute of Technology, Jimma University, P.O. Box 378, Jimma, Ethiopia
2. Department of Physics, University of the Free State (QwaQwa Campus), P.O. Box 339, Bloemfontein, South Africa
3. Department of Chemical and Physical Sciences, Walter Sisulu University (Mthatha Campus), Private Bag XI UNITRA 5117, Mthatha, South Africa
4. Department of Materials Science and Engineering, Adama Science and Technology University, P.O. Box 1888, Adama, Ethiopia
5. Center of Advanced Materials Science and Engineering, Adama Science and Technology University, P.O. Box 1888, Adama, Ethiopia