1. School of Materials Science and Engineering, Jimma Institute Technology, Jimma University, P.O. Box 378, Jimma, Ethiopia
2. Department of Physics, Tezpur University, Napaam, Sonitpur, Assam 784028, India
3. Emerging Technology Centre, Materials Science Directorate, Ethiopian Biotechnology Institute, P.O. Box 5954, Addis Ababa, Ethiopia
4. School of Chemical Engineering, Jimma Institute Technology, Jimma University, P.O. Box 378, Jimma, Ethiopia