Photon cascade luminescence from Pr³⁺ ions in LiPrP₄O₁₂ polyphosphate

Abstract

The spectral-kinetic properties of luminescence from LiY1−x Pr x P4O12 (x = 1, 0.1) phosphors are studied in the 10–300 K temperature range upon excitation within the UV–VUV spectral range. The luminescence observed for LiPrP4O12 at low temperatures is attributed to both intra-configurational 4f2 → 4f2 and inter-configurational 4f5d → 4f2 radiative transitions of Pr3+. The temperature dependence of emission and the decay kinetics of Pr3+ luminescence from LiY1−x Pr x P4O12 (x = 1, 0.1) phosphors are explained by temperature stimulated transitions from the 1S0 to the Pr3+ 4f5d state. At low temperatures, the energy potential barrier between the 1S0 and 4f5d states is 0.014 eV for LiPrP4O12. The spectral overlap of the 1S0 and 4f5d states of Pr3+ in LiY0.9Pr0.1P4O12 determines the luminescence properties in the entire temperature range studied.

Structural and optical investigation of nanocrystalline lithium lanthanum praseodymium tetraphosphate powders

“…The intensity of these absorption bands increased with the Pr 3þ concentration. The additional band (at around 220 nm (~45,500 cm À1 )) seen for the samples with higher praseodymium concentration (>20%) at the edge of a broad 4f 2 / 4f5d band could be assigned to the 3 H 4 / 1 S 0 line because, the location of the 1 S 0 level for LiPrP 4 O 12 was estimated to be around 216 nm (46,300 cm À1 ) [2,13].…”

“…It was shown that this effect takes place also in some tetraphosphates [13]. To determine this process in the investigated samples, emission spectra in the UVeVis range were registered under 212 nm excitation.…”

“…Until now, the microcrystalline samples of LiPr(PO 3 ) 4 , LiLa 0.999 Pr 0.001 (PO 3 ) 4 , and LiY 0.9 Pr 0.1 (PO 3 ) 4 were investigated [13,14]. In this work, we report the structural and optical properties of the LiLa 1Àx Pr x (PO 3 ) 4 nanocrystalline powders with the Pr 3þ concentration in the wide range of 1e100 mol%.…”

Spectroscopy and energy level location of the trivalent lanthanides in LiYP4O12

“…The excitations to 5d 2 , 5d 3 , and 5d 4 build the broad structure between 6.45 eV and 7.75 eV. The emission bands at 5.48 eV, 5 [5,17]. Because the ionic radius of Pr 3+ and La 3+ is larger than that of Y 3+ , the crystal field interaction with the 5d electron is somewhat smaller; just enough to locate the lowest 5d state above the 1 S 0 state and PCE can occur.…”

“…Srivastava et al studied the photon cascade emission (PCE) of Pr 3+ in LiLaP 4 O 12 [5]. PCE emission is also observed in stoichiometric LiPrP 4 O 12 [17]. Tb 3+ in NaGdP 4 O 12 was studied by Zhong et al [6], and stoichiometric KTbP 4 O 12 by Kim et al [7].…”