Probing Site Symmetry Around Eu3+ in Nanocrystalline ThO2 Using Time Resolved Emission Spectroscopy |
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Authors: | Santosh K. Gupta Madhusudan Krishnadas Bhide Shrikant Vasant Godbole Venkataraman Natarajan |
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Affiliation: | Radio Chemistry Division, Bhabha Atomic Research Centre, , Mumbai, 400085 India |
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Abstract: | ThO2:Eu3+ nanoparticles were synthesized at 300°C by combustion route using urea as a fuel and characterized by thermogravimetric/differential thermal analysis, X‐ray diffraction, transmission electron microscopy, and photoluminescence techniques. To investigate the effect of annealing temperature, as synthesized powder were heated further at 500°C, 700°C, and 900°C. It was observed that extent of asymmetry around Eu3+ at 700°C/900°C is very high as compared to as‐prepared or 500°C annealed sample. Based on the time resolved emission spectroscopic investigations, it was inferred that two different types of Eu3+ ions were present in the ThO2 nanoparticles. In ThO2 structure, Eu3+ ions occupy two sites; cubic (Oh) and noncubic (2v) as can be confirmed from our emission studies. Short‐lived species T1 (~1.3–3.4 ms) predominates at higher annealing temperature arises because of Eu3+ ions occupying noncubic (2v) sites without inversion symmetry, whereas long‐lived species T2 (~4.6–6.6 ms) can be ascribed to Eu3+ ions occupying cubic sites (Oh) with inversion symmetry. |
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