Probing the oxidation state and coordination geometry of uranium ion in SrZrO3 perovskite

• First report on speciation of uranium in strontium zirconate.
• CV and absorption spectra confirms the presence of U(VI).
• PL shows presence of uranium as uranate (UO6)6−.
• Life time data shows (UO6)6− is getting stabilized in two different environments.

SrZrO3:U was synthesized using gel-combustion method and characterized using powder X-ray diffraction. In view of the fact that zirconate based perovskite material can be a probable candidate for immobilization of nuclear waste, 1.0 mol% of uranium was doped in strontium zirconate and its valence state and coordination behavior was investigated using voltammetry and photoluminescence (PL) studies. Cyclic voltammetry, differential pulse voltammetry and UV–Visible spectroscopy have shown the existence of uranium in +6 oxidation state in strontium zirconate. Linearity of the current vs. scan rate plot showed that on doping, uranium is adsorbed in strontium zirconate matrix. The PL spectrum of the sample showed green emission band at 537 nm without any vibronic structure along with excitation peaks at 326, 362,392, 412, 424, 445 and 487 nm. This indicated the presence of uranium as uranate (UO6)6− in the strontium zirconate. These results were further corroborated with lifetime measurement.

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