Synthesis structural and luminescence studies of rare earth and transition metal ions doped silicates

Abstract

Nanostructured materials are the entities that appear between molecular/isolated atom newlineand extended solids. Recent research on luminescent nanomaterials provide challenges newlineto both sensing in biomedical engineering, environmental control, etc. Nanophosphors newlinemay have a number of potential advantages over traditional micron-sized phosphors. newlineSuch Nano sized phosphor particles are reported to be somewhat different in their newlineelectrical, optical and structural characteristics. Further, the differences in electrical and newlineoptical characteristics of lt15nm sized particles may cause quantum confinement due to newlinehigh surface to volume ratio, which results in enhancement of their luminescence newlineefficiency. Therefore, synthesis routes play an important role in synthesizing the newlinenanomaterials and evaluating various properties. Traditionally multi component ceramics have been prepared by solid-state method, which involve physical mixing of hydroxide, oxide, carbonate, nitrate or newlinesulphate raw materials followed by high temperature treatment, (1500 oC) with several newlinecalcinations temperature to enable the formation of target material. This method results newlinein powders with coarse grained, agglomerated structure with very low surface. High newlinetemperature is required for solid-state material formation, which give rise to poor newlinesintering behaviour, inhomogeneous microstructure, possibly abnormal grain growth newlineand lack of control of cation stoichiometry, formation of large particles with low surface newlinearea introduces impurity and defects, which are harmful to luminescence. Further, high newlinetemperature sintering results in dense and hard phosphors which are difficult to be newlinecrushed or grained. newline newline