Nanophosphors have been extensively investigated during the last decade due to their application potential for various high-performance displays and devices. Currently the preparation of nanophosphor materials is considered to be an art rather than science and is based on finding luminescence properties, crystalline nature, morphology, particle size and different types of transitions that can take place in different types of nanophosphors. For this study, the review of the rare earth doped nanophosphors (from La to Lt) by the most simple and cost-effective sol - gel method is reported and discussed. The results from the reviewed papers give the analysed data of particle size of rare-earth doped nanophosphors which varies from 5 to 50 nm. The particles show emission peaks from 450 to 650 nm at 5D0 --> 7Fj where j varies from 1-6. Crystal size of the particles has been investigated by X-Ray technique. The average crystalline size was estimated from the full width at half maximum of diffraction peak by Debye - Scherrer formula [Dhkl =kλ/ β(2θ) (cosθ)]. Morphology has been studied by Scanning Electron Microscope (SEM). The wavelengths of the emission peaks are widely influenced by pre-heating temperature. The phosphor annealed at below 1200 C show the optimal persistent luminescence and nano-particle size. Review shows that most of the nanophosphors show the morphology which is spherical, uniform and monoclinic.

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