NASICON-type Na3.6Lu1.8- x(PO4)3: x Eu3+ phosphors: structure and luminescence

Nataliya Krutyak; Dmitry Spassky; Dina V Deyneko; Andrey Antropov; Vladimir A Morozov; Bogdan I Lazoryak; Vitali Nagirnyi

doi:10.1039/d2dt01741e

NASICON-type Na_3.6Lu_{1.8- x}(PO₄)₃: x Eu³⁺ phosphors: structure and luminescence

Dalton Trans. 2022 Aug 9;51(31):11840-11850. doi: 10.1039/d2dt01741e.

Authors

Nataliya Krutyak^{1

2}, Dmitry Spassky^{2

3}, Dina V Deyneko⁴, Andrey Antropov⁴, Vladimir A Morozov⁴, Bogdan I Lazoryak⁴, Vitali Nagirnyi²

Affiliations

¹ Physics Department, Lomonosov Moscow State University, Leninskie Gory 1, 119991, Moscow, Russia. krutyak@ut.ee.
² Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411, Tartu, Estonia.
³ Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Leninskie Gory 1, 119991, Moscow, Russia.
⁴ Chemistry Department, Lomonosov Moscow State University, Leninskie Gory 1, 119991, Moscow, Russia.

PMID: 35866538
DOI: 10.1039/d2dt01741e

Abstract

Na_3.6Lu_1.8-x(PO₄)₃:xEu³⁺ phosphors were synthesized by a high-temperature solid-state reaction. A powder X-ray diffraction study revealed that homogeneous solid solutions with a NASICON-type structure were formed at 0 ≤ x ≤ 0.7. The Na_3.6Lu_1.8(PO₄)₃ structure was refined from the powder X-ray diffraction data and the cation distribution in the lattice sites of the NASICON-type structure was revealed. The refinement indicates structural disorder caused by the displacement of a part of Lu cations along the c axis inside the (Lu/Na)O₆ octahedra that is confirmed by the broadened emission lines of Eu³⁺, which substitutes Lu cations. The highest Eu³⁺ luminescence intensity is found in Na_3.6Lu_1.8-x(PO₄)₃:xEu³⁺ for x = 0.5, whereas a further increase of the Eu³⁺ content leads to concentration quenching that is shown to occur due to the dipole-dipole interaction. An enhanced temperature stability of the Eu³⁺ emission was observed at the excitation energy of 3.23 eV. At this excitation energy, thermal quenching of the emission caused by the ⁷F₀ → ⁵L₇ transitions is compensated by the intensity increase of the emission related to the ⁷F₁ → ⁵G_J transitions, which occurs due to the increase of the ⁷F₁ level population, induced by a temperature rise.