Bio synthesis of rare earth and transition metal ions doped oxide nano structured materials for multifunctional applications

Abstract

Rare earth (RE) activated nanosized oxide phosphors were of interest because of their drastic improvement in luminescence output and radiation stability, which ultimately result in the introduction of display phosphor. For effective coating and optimum brightness, phosphors should be narrow particle size distribution and homogeneously doped activator. Traditionally multi component ceramics have been prepared by solid state method, which involve physical mixing of hydroxide, oxide, carbonate, nitrate or sulphate raw materials followed by high temperature treatment, 1500 0C several calcination temperatures to enable the formation of target material. This method results in powders with coarse grained, agglomerated structure with very low surface. High temperature was needed for solid-state material formation, give rise to poor sintering behavior, inhomogeneous microstructure, possibly abnormal grain growth and lack of control of cation stoichiometry, formation of large particles with low surface area introduces impurity and defects, which were harmful to luminescence. Further, high temperature sintering results in dense and hard phosphors which were difficult to be crushed or grained. newline