A spectroscopic study of Ce³⁺ ion in calcium metaphosphate glass

Absorption, excitation, emission spectra and lifetime measurements of cerium doped calcium metaphosphate glass in the concentration range 3·83×10¹⁸–6·34×10²⁰ ions cm⁻³ are investigated. The ultraviolet absorption spectra reflects the 4f→5d transitions where the 5d state is split into five levels due to the cubic crystal field in the glass matrix. The visible absorption is probably due to interconfigurational 4f→5d transition of Ce³⁺ ion where two Ce³⁺ ions are bound via O²⁻ ions making a complex of the type Ce³⁺–O²⁻–Ce³⁺. The infrared absorption spectra reflects the intraconfigurational ²F_5/2→²F_7/2 transitions of Ce³⁺ ion. It is shown that two kinds of fluorescent centres are present. Emission in the ultraviolet region arises from the lowest 5d states of Ce³⁺ and that at the long wavelength red region and in the infrared are probably from the interconfigurational 4f→5d states of Ce³⁺–O²⁻–Ce³⁺ complex. The 5d electronic states of the complex in turn can be generated through electronic transitions into the 4f¹ 5d band of Ce³⁺. The quantum efficiency for the emission in the ultraviolet region is almost unity and concentration independent.