Hydrothermal Synthesis, Structural Investigation, Photoluminescence Features, and Emission Quantum Yield of Eu and Eu−Gd Silicates with Apatite-Type Structure

Abstract

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Photoluminescence of Eu3+-doped nanosized microporous titanosilicate—A structural analogue of the mineral pharmacosiderite

“…The increase of the relative intensity of the 5 D 0 → 7 F 4 transition was recently related with the distortion of the Eu 3+ local symmetry group towards a pure inversion centre environment [12]. A similar effect was also observed in silicate materials with hexagonal structure [10,13]. Such emission dependence on the excitation wavelength and the abnormal FWHM of the 5 D 0 → 7 F 0 transition (≈45 cm −1 ) are compatible with the presence of at least two distinct Eu 3+ local coordination sites.…”

A bona fide two-dimensional percolation model: an insight into the optimum photoactivator concentration in La2/3-xEuxTa2O7nanosheets

“…The wavelengths of these host excitation peaks are much longer than those of their absorption edges around 250 nm. Considering this result and the photoluminescence properties of many of the previously reported Eu 3+ -photoactivated oxides, the origin of these peaks is attributed to the O 2− -Eu 3+ charge-transfer transition rather than the band gap excitation [46][47][48][49][50]. The excitation maxima of the nanosheets shift to a shorter wavelength as their Eu 3+ contents decrease.…”

Phase transition and abnormal compressibility of lanthanide silicate with the apatite structure

“…Recently, lanthanide silicates with the apatite structure have been widely investigated due to their potential use as catalysts 5 , fast oxygen ion conductors, luminescent materials 6,7 and as actinide waste forms 4 As a new class of oxygen ion conductors, lanthanide silicate apatite has a "super" oxygen conductivity (2.42×10 -4 S cm -1 at 300 °C) at moderate temperatures, which is even higher than that of stabilized zirconia 8 (3.75×10 -6 S cm -1 at 300 °C). Most of the lanthanide silicate apatites are isostructural with calcium phosphate (P6 3 /m).…”