Crystal structure, vibrational properties and luminescence of NaMg3Al(MoO4)(5) crystal doped with Cr3+ ions

摘要

Crystals of NaMg3Al(MoO4)(5) doped with 0.5% Cr3+ ions have been synthesized and characterized by a single-crystal X-ray structure analysis and IR, Raman, electron absorption and luminescence spectroscopic studies. It has been shown that NaMg3Al(MoO4)(5) crystallizes in the P (1) over bar structure, with a = 6.8744(8) angstrom, b = 6.9342(7) angstrom, c = 17.605(2) angstrom, alpha = 87.788(8)degrees, beta = 87.727(9)degrees, gamma = 78.501(9)degrees, Z = 2. The characteristic feature of the structure is its enormously large thermal displacement parameter for sodium, even at 105 K. The IR and Raman spectra indicate significant interactions between the MoO42- ions in the structure. The electron absorption, excitation and luminescence studies have shown that there are at least two different sites of incorporated Cr3+ ions in the NaMg3Al(MoO4)(5) crystal structure. They differ themselves by strength of crystalline field. One of them is characterized by Cr3+ in low ligand field and T-4(2) --> (4)A(2) emission whereas the second is characterized by higher strength of the crystal field and dominant E-2 --> (4)A(2) emission. Temperature-dependent studies show that the compound does not exhibit any phase transition. (C) 2005 Elsevier Inc. All rights reserved.