Concentration dependence study of VUV–UV–visible luminescence of Nd3+ and Gd3+ in LuLiF4

Abstract

An overview of absorption and luminescence characteristics of Nd 3+ and Gd 3+ centers in a LiLuF 4 single crystal host is provided. Single crystals doped with the above rare earth ions were prepared by micro-pulling-down technique in the form of rods a few cm long with a diameter of about 2 mm. Excitation and emission spectra and fast decay kinetics in VUV and UV spectral regions were measured at room temperature. The observed absorption and emission peaks are due to the 5d-4f and 4f-4f optical transitions of Nd 3+ and Gd 3+ centers. Concentration dependence of the decay kinetics is also discussed.

Luminescence mechanism in doubly Gd, Nd-codoped fluoride crystals for VUV scintillators

“…This idea is also supported by the fact that the intensities of the Gd 3+ 4f-4f lines almost do not increase in the BaLuYF:Gd20%Nd5% with respect to the Gd5%Nd5% sample. The decrease of the Nd 3+ 5d-4f emission intensity in the presence of large amount of Gd can be also explained by an increased probability of an energy back-transfer from the Nd 3+ 5d-levels to the Gd 3+ 4f ones, which was also concluded in [18].…”

“…This is an apparent proof that Gd 3+ codoping improves the scintillation efficiency for higher dopant concentration. It will be shown later that there is an energy transfer mechanism from the Gd 3+ 4f levels to the Nd 3+ 5d ones, as was suggested in [18].…”

“…As stated for the BaLuYF:Gd20%Nd5% above and in [18], there can be an energy back-transfer from the Nd 3+ levels to the Gd 3+ ones, which can consist in overlapping of the other Nd 3+ 5d or 4f levels with the Gd 3+ 4f ones. The comparison of the Nd 3+ 5d-4f photoluminescence emission spectrum under 147 nm excitation for the BaLuYF:Nd1% sample with the transmittance spectrum for the BaLuYF:Gd20% crystal is displayed in the figure 6.…”

“…Recently, improvement of scintillation properties by Gd 3+ codoping was observed for the LiLuF4:Nd VUV scintillator [18]. However, no detailed explanation about this phenomenon was given and and it was only noted that there the energy transfer the highest Nd 3+ 5d state is improved in the presence of Gd 3+ .…”

Luminescence properties of Nd3+ doped LiLuF4 single crystals with different dopant concentrations

“…1. Some absorption bands corresponding to 4f-4f transitions of Nd 3+ were observed [11,12], except for LuLiF 4 :Nd1% due to the instrumental detection limit.…”