Influence of high pressure on the luminescence transitions of Mn⁴⁺-doped gadolinium gallium garnet

Abstract

We present results of a high-pressure photoluminescence study of Mn-and Ca-doped gadolinium gallium garnet (GGG) crystals. Since the Mn 4+ ion has the same electronic structure of the open 3d 3 shell as Cr 3+ , its spectroscopic properties are expected to be similar to those of the Cr-doped GGG. We observed the luminescence R-lines of various Mn 4+ centres in GGG. In the 0-118 kbar pressure range those R-lines shift linearly to lower energies. The pressure coefficients are of the order of 2 cm −1 kbar −1 , about three times larger than that for Cr 3+ ions. This fact can be explained by different strength of coupling of isoelectronic Cr 3+ and Mn 4+ ions with GGG host. The changes of the radiative decay times of the Mn 4+ centres as a function of pressure are fitted with a theoretical model.

Pressure dependence of spectral positions and widths of emission lines related to 5DJ→7FJ electronic transitions in Sm2+ ions doped into SrFCl single crystal

“…[12]) and in Mn 4+ -doped gadolinium gallium garnet [13] with decrease of the interelectronic repulsion (Racah parameters B and C) and of the crystal-field parameters [14,15]. The pressureinduced line shifts for the 5 D J -7 F J electronic transitions in the system under study, SrFCl:Sm 2+ , were interpreted [16,17] in the molecular orbital approximation, taking into account the contributions from the point charge, charge penetration, exchange, overlap and covalency effects responsible for changes in the crystal-field parameters under pressure.…”

Pressure-induced changes in the energetic structure of the 3d3 ions in solid matrices

“…The properties of this dopand have been studied in Gd 3 Ga 5 O 12 (GGG) crystals [22] and respective data are listed in Tables 1 and 2. At ambient pressure, Mn 4+ impurity in GGG experiences a strong crystal field as opposite to Cr 3+ , which undergoes much weaker electrostatic interaction with ligands.…”

“…The successful application of Cr 3+ -doped materials stimulated our interests in research of other ions with 3d 3 electronic configuration such as Mn 4+ [22,23].…”

Enhanced luminous efficiency in Pr3+ activated Ca0.5La(MoO4)2 red phosphor with blue excitation for WLED applications

“…1 D 2 caused by the multiphonon relaxation process is very weak; nearly negligible might also be affected by Pr 3? concentration quenching [32,33]. Upon 449 nm excitation, the emission from 1 D 2 level is an absence in the case of Ca 0.5 La(MoO 4 ) 2 :Pr 3?…”

“…Upon 449 nm excitation, the emission from 1 D 2 level is an absence in the case of Ca 0.5 La(MoO 4 ) 2 :Pr 3? and can be only recorded under resonant conditions [32,33]. Also the energy of 4f 1 5d 1 band in Ca 0.5 La(MoO 4 ) 2 :Pr 3?…”