Emission controlled dual emitting Eu-doped CaMgSi2O6 nanophosphors

Well-dispersed Eu-doped CaMgSi2O6 (CMS) nanophosphors of 4-16 nm size range were synthesized by a simple co-precipitation method followed by thermal annealing in controlled ambient. Emission behaviors of the nanophosphors have been studied to optimize and tune their emissions in desired spectral range (red, blue or both). Effects of temperature and calcination atmosphere on the inter-conversion (Eu3+↔Eu2+) ability of europium ions in CMS matrix have been studied thoroughly. It has been observed that by calcinating the nanophosphors in oxidizing atmosphere like O2, about 70% of the incorporated europium atoms can be transformed to their trivalent (Eu3+) state. On the other hand, calcinating the nanophosphors in reducing atmosphere like H2+N2 mixture, about 99% of Eu ions can be transformed to their divalent state (Eu2+). It has been demonstrated that by controlling the temperature and ambient of calcination, a dual emitting CMS:Eu nanophosphor could be converted either to blue or red emitting nanophosphor of high emission efficiency. The interchangeable emission characteristic of the size controlled nanophosphor is expected to have immense impact in the fabrication of highly efficient luminescent and display devices.