Optical characterisation of rare earths in natural fluorapatite

Fluorapatite coming from Jumilla (Spain) has been investigated by means of optical absorption, photoluminescence and lifetimes. The absorption spectra at room and low temperature in the range 450-850 nm showed mainly the pres ence of Nd3+ ions. The emission and excitation spectra in the UV region rev eal also the presence of Ce3+ ions, which cannot be detected by absorption due to the tail of the matrix absorption edge. In addition to the infrared emission at 0.89, 1.06 and 1.33 mum coming from the Nd3+ ions and the UV em ission around 380 nm due to the presence of Ce3+ ions, an intense red emiss ion (lambda = 600 nm) is observed after blue-green excitation. Following th e characteristics of the red band as well as its lifetime (tau = 132 mus) t his emission has been attributed to the presence of Pr3+ ions. (C) 2001 Pub lished by Elsevier Science B.V.