1. Applied Inorganic Chemistry Laboratory, Department of Inorganic Chemistry, Faculty of Sciences, University of Yaoundé I, P.O. Box: 812, 3.315 Rue de l’université, 00000 Yaoundé, Cameroon
2. Research Institute on Ceramics, University of Limoges, CEC, 12 Rue Atlantis, 87068 Limoges, France