YAlO₃:Mn nanocrystals obtained in sol‐gel and their properties

Abstract

Manganese-doped yttrium aluminum perovskite (YAP) nanocrystalline samples of 0.05 at%, 0.2 at% and the reference single crystal of predicted 0.02 at% Mn, 0.02% Si concentration in YAP were investigated by the following methods: X-ray powder diffraction, scanning electron microscopy, EPR, SQUID and XPS. These examinations revealed that the obtained material was not single phase and the trace of Y 3 Al 5 O 12 (YAG) appeared. As is evident from EPR studies, the manganese in all investigated samples is occupying an yttrium site and the valence of manganese remains as Mn 2+. The EPR spectra of both powder YAP:Mn samples are the same, an expected difference in the intensity well reflects the nominal concentration of manganese. The single crystal perovskite YAlO 3 doped with manganese showed very complex and strongly anisotropic EPR spectrum. The EPR data showed the presence of Mn 2+ ions substituting yttrium site and Cr 3+ and Fe 3+undesirable impurities which occupied aluminum site. The magnetic moments of manganese calculated for the nanopowders confirmed Mn 2+ state. The SEM/EDS and XPS analyses showed the chemical composition of nanopowders as very consistent for both methods. For both samples the lower content of aluminum in relation to the nominal value was found. The SEM images show that the sample 0.2 at% Mn has more agglomerated structure.

Fundamental luminescence properties of Mn4+ activated Ca14Al10Zn6O35 phosphor

“…However, it should be noticed that Mn 4+ and Mn 2+ have almost the same EPR signal characterization, and the constant A depends greatly on the covalency between Mn and its ligands. 41,52 Therefore, it is difficult to identify Mn 4+ and Mn 2+ (and their ratio) accurately only from the EPR spectrum. 42 On the other hand, it is known that both Mn 4+ and Mn 2+ ions are efficient activators in various hosts.…”

Influence of Homogenization and Micro/Nano Source of Starting Powders on Format Ion of the Single YAP Phase

“…Thus, because of high costs of YAPmonocrystals manufacturing and the expected different behaviour of polycrystalline ceramics under the relevant excitation, manufacturing of RE-doped YAP powders or polycrystalline ceramics is a challenging task in nowadays research community. The results on preparation of YAP powders/nanopowders are scarce and they show complexity of that phase formation [7][8][9][10][11][12][13][14]. The topic of this work is to check the possibility of manufacturing the monophase YAP powder or polycrystalline ceramics by the solid-state reaction method using different particle size of starting powders and methods of homogenization.…”