The host structure and the synchrotron radiation VUV-UV luminescence properties of samples BaMg2Si2O7 (BMSO):Ln (Ce3+, Eu2+) at different doping levels and different temperatures were investigated in detail. Three important aspects are studied to elucidate the luminescence properties of samples: (1) the vacuum referred binding energy (VRBE) scheme is constructed with the electron binding in the BMSO host bands and in the Ce3+ and Eu2+ impurity levels with the aim to explain the different thermal stabilities of Ce3+ and Eu2+ emissions; (2) the electron-vibrational interaction analysis on the narrow Eu2+ emission indicates a weak electron-phonon interaction in the current case; (3) by using three models (Inokuti-Hirayama, Yokota-Tanimoto, and Burshteǐn models) at different conditions, the energy transfer dynamics between Ce3+ and Eu2+ was analyzed. It reveals that the energy transfer from Ce3+ to Eu2+ via electric dipole-dipole (EDD) interaction is dominant while energy migration between Ce3+ is negligible. Finally, the X-ray excited luminescence spectra of samples BMSO:Ce3+/Eu2+ are collected to evaluate their possible scintillator applications.@en

A series of Ln-doped KSrPO4 (Ln = Ce3+, Eu3+, Eu2+, Pr3+) phosphors are prepared through a high-temperature solid-state method. The KSrPO4 compound is confirmed to possess a β-K2SO4 structure with the Pnma group by Rietveld refinement, and the temperature-dependent lattice parameters are investigated with the powder X-ray diffraction results at different temperatures. Ce3+ and Eu3+ ions are introduced to probe the crystal field strength (CFS) and the lanthanide site symmetry by using VUV-UV-vis spectroscopy. The temperature-dependent luminescence properties of KSrPO4: Ce3+/Eu2+ exhibit an excellent thermal stability of Ce3+/Eu2+ luminescence. Based on the VUV-UV-vis spectra of Ce3+ and Eu3+ doped KSrPO4, the vacuum referred binding energy (VRBE) scheme is constructed to understand the redox properties of Eu, the 5d energy levels of Pr3+ and the thermal quenching characteristics of Ce3+ and Eu2+ luminescence.@en

In this work, we demonstrate a potential thermometric material after systematic studies on the concentration/temperature-dependent spectroscopic properties of Pr3+ excited multiplets and of the Pr3+-Ti4+ intervalence charge transfer (IVCT) state in (La1-xPrx)2MgTiO6. The experimental results indicate that the electron population efficiency between the involved Pr3+ 4f multiplets is directly governed by multi-phonon relaxation (MPR) and cross relaxation (CR), and the IVCT state provides an additional contribution to the 1D2 luminescence. A schematic energy level diagram is proposed to illustrate the electron population pathway in Pr3+ doped La2MgTiO6. The observations clarify that the dramatic thermal-quenching of 3P0 luminescence is mainly induced by the electronic configuration crossover between the 3P0 multiplet and the IVCT state. On the other hand, the 1D2 luminescence possesses an excellent thermal stability in a large temperature region. These temperature sensing features of the Pr3+ doped La2MgTiO6 material indicate its potential application in optical thermometric techniques.@en

A series of Ce3+-doped (Ca,Sr)2Al2SiO7 phosphors with different Ce3+ and Ca2+/Sr2+ concentrations were prepared by a high temperature solid-state reaction technique. To get insight into the structure-luminescence relationship, the impact of incorporation of Sr2+ on structure of (Ca,Sr)2Al2SiO7 was first investigated via Rietveld refinement of high quality X-ray diffraction (XRD) data, and then the VUV-UV excitation and UV-vis emission spectra of (Ca,Sr)2Al2SiO7:Ce3+ were collected at low temperature. The results reveal that the crystal structure evolution of (Ca,Sr)2Al2SiO7:Ce3+ has influences on band gaps and Ce3+ luminescence properties including 4f-5di (i = 1-5) transition energies, radiative lifetime, emission intensity, quantum efficiency, and thermal stability. Moreover, the influence of Sr2+ content on the energy of Eu3+-O2- charge-transfer states (CTS) in (Ca,Sr)2Al2SiO7:Eu3+ was studied in order to construct vacuum referred binding energy (VRBE) schemes with the aim to further understand the luminescence properties of (Ca,Sr)2Al2SiO7:Ce3+. Finally, X-ray excited luminescence (XEL) spectra were measured to evaluate the possibility of (Ca,Sr)2Al2SiO7:Ce3+ as a scintillation material.@en