Phase transition, radio- and photoluminescence of K3Lu(PO4)2 doped with Pr3+ ions

Luminescent characteristics of K3Lu(PO4)2:Pr3+ (1 and 5 mol.%) microcrystalline powders, a promising optical material for scintillation applications, were investigated using various experimental techniques. The material shows emission features connected with both high intensity interconfigurational 4f15d→4f2 transitions (broad UV emission bands) and intraconfigurational 4f2→4f2 transitions (weak emission lines in the visible range). The output of X-ray excited 4f15d→4f2 emission of Pr3+ increases with a temperature rise from 90 K to room tem- perature and higher depending on the Pr3+ ions concentration. The high 5% concentration of Pr3+ ions is found to be favourable for the stabilization of a monoclinic phase (P21/m space group) over a trigonal one (P3 space group) while emission properties of the material reveal that a phase transition occurs at higher temperatures. Decay kinetics of Pr3+ 4f15d→4f2 emission are recorded upon excitation with high repetition rate X-ray syn- chrotron excitation and pulse cathode ray excitation. Issues related to a non-exponential decay of luminescence and presence of slow decay components are discussed in terms of energy transfer dynamics. The presence of defects was revealed with thermoluminescence measurements and these are suggested to be the mainly responsible for delayed recombination of charge carriers on the Pr3+ 4f15d states. Some peculiarities of host-to- impurity energy transfer are discusse

Unraveling Pr3+ 5d-4f emission in LiLa9(SiO4)6O2 crystals doped with Pr3+ ions

LiLa9(SiO4)(6)O-2 (LLSO) crystals doped with Pr3+ ions were grown using the slow cooling flux method. The crystals were characterized by means of luminescence and optical spectroscopy and luminescence decay measurements upon excitation in UV, VUV and X-ray range including using synchrotron radiation sources. The spectroscopic data revealed the presence Pr3+ 5d <-> 4f emission and excitation bands related to Pr3+ ions replacing La3+ i n two nonequivalent positions, and features related Pr3+ 4f -> 4f emission. The photon cascade emission is not observed in LLSO:Pr3+, since Pr3+ S-1(0) state is above the bottom of 4f(n-1)5d mixed-states band. Apart from the emission features related to Pr3+, a defect-related emission was observed upon UV, VUV, and ionizing radiation excitation. Presence of the defects was shown with thermoluminescence measurements and suggested to be the main reason for suppression the 5d -> 4f emission. Peculiarities of host-to-impurity energy transfer are analyzed and discussed

Fast UV Luminescence of Pr

The double phosphate Ca9Lu(PO4)7 doped with 1 mol% of Pr3+ was prepared by solid-state reaction. The obtained material was characterized by powder X-ray diffraction (XRD). The luminescence spectroscopy and the excited state dynamics of this material were studied upon VUV excitation using synchrotron radiation. The sample has shown efficient 5d-4f emission upon direct VUV excitation of 5d levels. It was observed that energy transfer from host to Pr3+ 5d states is inefficient. The decay kinetic of the Pr3+ 5d-4f emission in this host lattice upon direct VUV excitation of 5d levels is characterized by a decay time of 17 ns with no significant rise after the excitation pulse. No significant temperature dependence of the decay time was observed within the range 8-300 K

Energy conversion in LiSrPO4 doped with Pr3+ ions

We report on the time-resolved luminescence spectroscopic characterization of LiSrPO4 doped with Pr3+-ions, that we found potentially attractive for scintillation applications. The spectroscopic study included measurements of photoluminescence, X-ray excited luminescence, thermally stimulated luminescence and time-resolved pulse cathodoluminescence spectra. In addition, luminescence decay kinetics were studied upon high-frequency X-ray and pulse cathode beam excitation. LiSrPO4:Pr3+ showed Pr3+ emission connected with intraconfigurational 4f(2)-> 4f(2) and interconfigurational 4f(1)5d -> 4f(2) transitions. The presence of defects was shown with thermoluminescence measurements and suggested to be the main reason for delayed recombination of charge carriers on Pr3+ 4f(1)5d states. Some peculiarities of host-to-impurity energy transfer are discussed

Impurity and defect-related luminescence of Ce3+ doped LiLa9(SiO4)6O2 crystals upon UV-VUV, X-ray and cathode ray excitation

We report on the synthesis and comprehensive characterization of Ce3+ doped LiLa9(SiO4)(6)O-2 (LLSO) crystals, grown using the slow cooling flux method. The luminescence and optical spectroscopic properties and luminescence decay kinetics were studied upon excitation with UV, VUV, X-ray photons and cathode rays. Two impurity Ce3+ centres substituting for La3+ - ions in two nonequivalent crystal positions are observed in LLSO:Ce3+. They are well distinguished spectroscopically in the UV range both in emission and excitation spectra. Apart from emission associated with Ce3+ 5d -> 4f interconfigurational transitions, a low-temperature defect-related emission has been observed upon UV-VUV and higher energy X-ray excitation. Processes lying behind the temperature quenching and host-to-impurity energy transfer are analyzed and discussed

YAG:Pr3+ transparent ceramics for applications in photonics: Synthesis and characterization

Y3Al5O12 (YAG) transparent ceramics doped with Pr3+ have been obtained by vacuum sintering of spray dried commercial powders and characterized by XRD and SEM techniques. A comprehensive spectroscopic investigation has then been carried out including: absorption spectra and decay time measurements in the visible-IR spectral region and x-ray and VUV excitation and emission properties studied with synchrotron radiation. The main processes responsible for the excited states dynamics have been identified and characterized. Comparison with the properties of the single crystal reveals that the investigated material has interesting perspectives for applications in optics and photonics

Vacuum ultraviolet synchrotron measurements of excitons in NaMgF3:Yb2+NaMgF_3:Yb^{2+}

Results of a vacuum ultraviolet spectroscopic characterization of NaMgF$_{3}$:Yb$^{2+}$ are presented. The material demonstrates emission features associated with self-trapped excitons and impurity-trapped excitons. The emission features noticeably overlap giving rise to a broad emission band from 17 000 to 35 000 cm$^{−1}$ at a sample temperature of 8 K. To identify the true profiles of the emission features we have used a deconvolution procedure. The deconvolution was possible due to the thermal quenching of self-trapped excitons at room temperature that allowed for direct observations of the impurity trapped exciton emission band. Energy transfer between host electronic excitations (excitons and e–h pairs) and Yb$^{2+}$ ions leading to the formation of impurity-trapped excitons is evident from excitation spectra

YAG:Pr3+ transparent ceramics for applications in photonics: Synthesis and characterization

Y3Al5O12 (YAG) transparent ceramics doped with Pr3+ have been obtained by vacuum sintering of spray dried commercial powders and characterized by XRD and SEM techniques. A comprehensive spectroscopic investigation has then been carried out including: absorption spectra and decay time measurements in the visible-IR spectral region and x-ray and VUV excitation and emission properties studied with synchrotron radiation. The main processes responsible for the excited states dynamics have been identified and characterized. Comparison with the properties of the single crystal reveals that the investigated material has interesting perspectives for applications in optics and photonic