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Synthesis, Characterization and Luminescence Properties of Pr³⁺-Doped C12A7 and C3A

E. Tõldsepp, E. Feldbach, M. Kirm

Journal of Ceramic Science and Technology, Vol. 4, No. 2 (2013), pp. 77-84

DOI: 10.4416/JCST2012-00039a

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Abstract

This paper presents comparative results of luminescence studies on complex wide-band-gap calcium aluminates 12CaO·7Al2O3 (C12A7, Eg∼7.0 eV) and 3CaO·Al2O3 (C3A, Eg∼6.5 eV) doped with Pr3+ ions. Doped C12A7 ceramics and C3A powders were prepared via self-propagating combustion synthesis followed by different thermal treatments. Time-resolved VUV spectroscopy of C3A:Pr3+ revealed fast interconfigurational 5d-4f emission of Pr3+ in the region of 3 eV – 4.5 eVwith lifetimes of ∼ 17 ns upon direct excitation of Pr3+ 5d levels, and ∼ 30 ns upon interband transitions. Acceleration of decay times (∼ 12 – 13 ns) were observed upon XUV excitation at 130 eV. In C3A, multiple non-equivalent lattice sites for Pr3+ ions were identified. The energy transfer from host to Pr3+ 5d states is inefficient, particularly in C12A7, where the separation of 5d-4f transitions from other competing luminescence channels is not straightforward owing to the complexity of the host crystal band structure. The slow intraconfigurational 4f-4f emission originating from the second stage of 4f cascade was observed for both compounds.

Keywords

Calcium aluminate, C12A7, C3A, praseodymium, VUV spectroscopy

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