engleski

Magnetic Behaviour of Rutile-type CrMO4 (M = Nb, Ta) Materials Prepared from Single-molecular Precursors

Mixed-metal oxides are an important class of advanced materials, due to their stability, low cost, low toxicity, useful photophysical properties and wide range of technological applications, whereby the effect of structure and morphology of these materials correlates their magnetic behaviour.1 Up to now, solid- state, sol–gel or hydrothermal preparation protocols have been explored for controlling structural and microstructural characteristics of targeted mixed-metal oxides. However, more traditional preparation routes of obtaining highly crystalline materials usually use high temperature treatment, which can often increase the particle size and decrease the surface area. The possibility of using heterometallic oxalate- based compounds as single-source molecular precursors through thermal decomposition process in reproducible synthesis of nanomaterials, that provides excellent control of the stoichiometry and crystallite size in the nanoregime, has been considered only recently.1 Herein we show a potential of [Cr2(bpy)4(μ- O)4Nb2(C2O4)4]·3H2O (1) and [Cr(bpy)2(H2O)(μ- O)Ta(C2O4)3]2·3.5H2O (2), well-defined and structurally characterized compounds, 2, 3 to act as single-molecular precursors for the preparation of the phase-pure highly-crystalline CrNbO4 and CrTaO4 nanosize powders. Detailed evolution of crystalline phase composition as a function of heat-treatment during the decomposition of 1 and 2 was carried out by the means of powder X-ray diffraction (PXRD). The crystallite size and lattice strain were calculated from the PXRD line-broadening analysis performed during the Rietveld structure refinement. A low temperature magnetic transition was observed in both samples, for CrNbO4 at 9.3 K and for CrTaO4 at 3.5 K, whereas a spin-glass like behaviour was observed for the CrTaO4 as suggested from the ZF and ZFC curves. [1] J. Popović, et al. Inorg. Chem. 56, 2017, 3983–3989 (2017) [2] M. Jurić, et al. Inorg. Chem. 56, 2017, 6879-6889 (2017) [3] L. Androš Dubraja, New J. Chem. DOI: 10.1039/c8nj01493k (2018)

mixed-metal oxides ; magnetization ; PXRD

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