Near-infrared photoluminescence in phosphate minerals and related glass–ceramics

Fertilizing glass–ceramics were prepared and characterized by photoluminescence (PL) spectroscopy. These materials, and some of the related phosphorites, unexpectedly exhibited intense PL emission in the near-infrared region. In the 1100–1250 nm range a very intense doublet at 1161 and 1149 nm and a less intense band at 1214 nm were assigned to emission from the uncommon ionic species MnV. Therefore, one of the d2 ions such as CrIV and MnV which are of growing interest in the field of solid-state lasers, was found in minerals for the first time. In order to obtain further information about these materials, structural and spectroscopic properties of the raw materials were recorded separately. As far as the coordination of MnV is concerned, the hypothesis of partial substitution of PV by MnV in the phosphate lattice appears to be quite reliable. Typical PL emission of neodymium was also observed both in glass–ceramics and in raw materials.