Crystal growth and luminescence properties of Ti-doped LiAlO2 for neutron scintillator

Modifications of micro-pulling-down method for the growth of selected Li-containing crystals for neutron scintillator and VUV scintillation crystals

“…The original intention was to exploit its broadband d-d 2 E-2 T 2 transition. However, it has been found that Ti has been incorporated into the host matrix in the form of Ti 4 þ , which was confirmed by the occurrence of the Ti 4 þ charge transfer (CT) emission with a decay time of about 2.5 ms [5]. This is reasonably fast response for neutron imaging applications.…”

“…The Ti 3 þ d-d 2 E-2 T 2 broad-band luminescence transition usually occurs at longer wavelengths around 600 nm, which well matches the region of contemporary avalanche photodiode sensitivity. Influence of the impurities on the luminescence properties of Ti-doped LiAlO 2 was found to be an important point [5]. Parasitic luminescence of unclear origin located at 740 nm was found in all the crystals.…”

“…The XRD results demonstrated that the remained solidified substance contained Al-rich LiAl 5 O 8 phase [5]. Without the Li excess, the growth was not stable and the crystal quality was soon degraded due to enhanced LiAl 5 O 8 phase formation due to the mentioned incongruent Li 2 O evaporation.…”

“…Crystal growth and luminescence study of the Ti-doped LiAlO 2 has been performed recently [5], and Ti 3 þ was considered as a luminescence center in the LiAlO 2 host matrix. The original intention was to exploit its broadband d-d 2 E-2 T 2 transition.…”

“…For the low Ti concentrations (around 0.1 mol%) number of such defects is negligible from the point of view of crystal growth. However, increasing the Ti concentration to 1% leads to slight degradation of the crystal quality and the scintillation properties [5]. Therefore, charge compensation by aliovalent ions, such as Mg 2 þ , should be considered especially for higher Ti concentrations.…”