title: Revisiting the crystal structure and thermal properties of NaMgAl(oxalate)3 x 9 H2O/Cr(III): an extraordinary spectral hole-burning material.
abstract: We have reinvestigated the crystal structure and thermal properties of NaMgAl(oxalate)(3) x 9 H(2)O. In the thermal gravimetric analysis the steps of dehydration and decomposition/oxidation yield a mass change that is commensurate with 9 water molecules of hydration. Dehydration steps occur at 127, 171, and 201 degrees C whereas the oxalate ligand decomposes in steps at 403 and 424 degrees C with a final oxidation step at 692 degrees C. A refinement of the single crystal X-ray diffraction data taken at 200 K affirms the P3c1 space group with nine water molecules of hydration and unit cell parameters a = b = 16.7349(2) A and c = 12.6338(1) A with Z = 6. The structures can be described in terms of modulations of an idealised Z = 1 structure in P3lm. T-Cycle experiments of spectral holes in the R(1)-line yield a single Gaussian barrier with T(0) +/- sigma(T) of 46 +/- 21 K and three barriers with 40 +/- 12, 70 +/- 10, 107 +/- 5 K for perprotonated and partially deuterated (46%) NaMgAl(oxalate)(3) x 9 H(2)O/Cr(III) 0.5%, respectively.
authors: School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, ADFA, Canberra, ACT 2600, Australia. h.riesen@adfa.edu.au
authors: Hans
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authors: Riesen
authors: A David
authors: AD
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