Luminescence characterization of a sodium-rich feldspar

We, herein, report on the radioluminescence and thermoluminescence properties of a sodium-rich feldspar ((Na,K)[AlSi3O8]) with a mean molecular composition of orthoclase (Or) and Albite (Ab) of Or1Ab99. Despite the complexity of the luminescence emissions of the sample, it is possible to determine six different emission bands at about 300, 380, 420, 460, 550 and 680nm. The 300nm emission can be associated to structural defects related to the recombination process in which the diffusion of Na ions is involved. The UV-blue emission bands have the following features: (i) the 380nm, typical of mineral phases containing SiO4 groups, is related to intrinsic defects in the lattice; (ii) the 420nm band is associated with the presence of Cu(II) ions close to the hole traps or the recombination on a centre formed from a hole-oxygen atom adjacent to two Aluminum atoms (Al-O-Al) and (iii) the 460nm waveband is due to the presence of Ti4+. The green and red emissions are, respectively, associated with the presence of Mn2+ and Fe3+ ions. The ratio between the relative intensities, peaked at 290 (the more intense waveband) and 550nm is about 10 for both TL and RL, which implies that the efficiency of recombination centres does not change regardless of the type of the process.