Forgotten and Resurrected Chernovite-(Y): YAsO₄ Doped with Eu³⁺ Ions as a Potential Nanosized Luminophore

Abstract

In the present work, a precipitation method was employed to prepare nanosized YAsO doped with Eu ions. The raw nanomaterials have been thermally treated in a temperature range between 500 and 900 °C for 3 h. The XRD analysis demonstrated that the powders were single-phase nanopowders with high crystallite dispersion. Our studies were focused on relating the luminescence properties of the Eu dopant to the nanocrystallite (NC) size. The average NC size varied accordingly between 15 and 45 nm. We have found that the size effect is manifested mainly in the expansion of the cell volume and broadening of XRD peaks, as indicated by Rietveld analysis. Moreover, the emission and excitation spectra, although typical for Eu ions, demonstrated some degree of variability with calcination temperatures and doping concentration. To explain these differences, a detailed analysis of luminescence spectra by the Judd-Ofelt theory has been performed.

Eu3+/2+ co-doping system induced by adjusting Al/Y ratio in Eu doped CaYAlO4: preparation, bond energy, site preference and 5D0–7F4 transition intensity

“…The dominated 5 D 0 / 7 F 4 ($703 nm) transition emission is infrequent. Only some numerable phosphors show that they have stronger intensity of 5 28 Similarly, this phenomenon has been found in CaYAlO 4 with Eu doped. But, the stronger emission of 5 D 0 -7 F 4 disappeared when Eu 3+ and Tb 3+ were codoped into CaYAlO 4 .…”

“…Only some numerable phosphors show that they have stronger intensity of 5 D 0 – 7 F 4 than 5 D 0 – 7 F 1 , such as Sr 0.99 [La (1− x ) Eu x ] 1.01 Zn 0.99 O 3.495 , 23 LaBO 3 :Eu 3+ , 24 Na 9 [EuW 10 O 36 ]·14H 2 O, 25 Na 2 CaSiO 4 :Eu 3+ , 26 Ca 2 Ga 2 SiO 7 :Eu 3+ , 27 YAsO 4 :Eu. 28 Similarly, this phenomenon has been found in CaYAlO 4 with Eu doped. But, the stronger emission of 5 D 0 – 7 F 4 disappeared when Eu 3+ and Tb 3+ were co-doped into CaYAlO 4 .…”

“…To gain some insight into the nature of the luminescence behavior of Al 3+ ions in crystal CaYAlO 4 :2%Eu powders, the Judd–Ofelt model was applied to the determination of spontaneous emission coefficients. The intensity parameters Ω 2 and Ω 4 were determined from luminescence spectra using the method proposed by Kodaira et al 28,35 …”

“…To gain some insight into the nature of the luminescence behavior of Al 3+ ions in crystal CaYAlO 4 :2%Eu powders, the Judd-Ofelt model was applied to the determination of spontaneous emission coefficients. The intensity parameters U 2 and U 4 were determined from luminescence spectra using the method proposed by Kodaira et al 28,35 The emission intensity, I ¼ ħuAN, is expressed in terms of the surface under the emission curve, where ħu is the transition energy, N is the population of the emitting level ( 5 D 0 ) and the Einstein's coefficient of spontaneous emission can be given by 25…”

Structural and Luminescence Behavior of Nanocrystalline Orthophosphate KMeY(PO4)2: Eu3+ (Me = Ca, Sr) Synthesized by Hydrothermal Method

“…The decay curves of samples annealed at 500 °C have biexponential characteristics, which confirmed the localization of europium ions on the nanograins surface and inside the bulk. The calculated values of decay time were typical for Eu 3+ ions [ 35 , 41 , 42 , 43 ]; for example, the decay time of the Eu 3+ ions in the Y 2 O 3 compound equaled 2 ms, while for YAsO 4 :Eu 3+ it was around 4 ms. Increasing the annealing temperature caused a decrease in decay time, which was in good agreement with the observed behavior of emission intensity. The enhancement of non-radiative processes with annealing temperatures confirmed registered decay curves.…”