Research & Reviews: Journal of Material Sciences
MenuISSN:2321-6212
ISSN:2321-6212
Ramya Nair, Sandeep Nigam and V Sudarsan
Bhabha Atomic Research Centre, India
Posters & Accepted Abstracts: Res. Rev. J Mat. Sci
Rare-earth borates are excellent candidates for solid state lightening application due to its robust nature and brilliant optical properties. GdBO3: Eu3+ is one of the finest phosphors existing amongst borate phosphors for primary red color. In this work we investigate the nature of structure-composition-optical relationships in both nano and bulk forms of GdBO3:Eu3+. Nanophosphors have unique physical and chemical properties as compared to their bulk counterpart and so their emission efficiencies vary which can finely be tuned and considerably improved. GdBO3 exists in both monoclinic and triclinic phase. GdBO3 containing 1 at.% Eu3+ were prepared in nano-crystalline, monoclinic and triclinic forms by hydrothermal and polyol route. Techniques like XRD, FTIR, TEM, luminescence and lifetime measurements were used to characterize the samples. SAED pattern illustrate phase formation while presence of nano rods with 200 nm length and width less than 10 nm are confirmed from TEM images. Boron was found in both trigonal and tetrahedral coordination in nanorods and triclinic phase, whereas only BO4 structural unit exists in monoclinic GdBO3. Based on bond angle and bond length values obtained from Rietveld refinement of the XRD patterns it is inferred that local environment around Eu3+ in the triclinic form is more distorted compared to monoclinic form. This explains increase in the relative intensity of electric dipole allowed transition of Eu3+ in triclinic form compared to monoclinic form. Red to orange ratio of Eu3+ in triclinic and nanorods is found to be higher than the monoclinic phase. From the results it is inferred that the nanorods have improved red color characteristics compared to the other two forms. By size tuning we improvised optical parameters of the phosphor to develop materials with optimum luminescence characteristics.
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