1. Doctoral Program of Mathematics and Natural Sciences, Faculty of Mathematics and Natural Sciences, Universitas Sriwijaya, Ogan Ilir 30662, Indonesia
2. Research Group on Magnetic Materials, Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Sriwijaya, Ogan Ilir 30662, Indonesia
3. Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Sriwijaya, Ogan Ilir 30662, Indonesia