Evidence of Wolframite-Type Structure in Ultrasmall Nanocrystals with a Targeted Composition MnWO4

• Published in: Inorganic chemistry 2019-06, Vol.58 (12), p.7822-7827
• Main Authors: Patureau, Pascaline, Dessapt, Rémi, Petit, Pierre-Emmanuel, Landrot, Gautier, Payen, Christophe, Deniard, Philippe
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.9b00464

Here, we report a study of white-ochre powders with targeted composition MnWO4 prepared via a coprecipitation method. Through X-ray total scattering combined with pair distribution function analysis and Rietveld refinement of X-ray diffraction data, we find that their crystal structure is similar to that of bulk-MnWO4, despite a mean crystallite size of 1.0–1.6 nm and a significant deviation of the average chemical composition from MnWO4. The chemical formula derived from elemental and thermogravimetric analyses is Mn0.8­WO3.6­(OH)0.4·3H2O. X-ray absorption and magnetic susceptibility measurements show that Mn and W have the same oxidation states as in MnWO4. No magnetic ordering or spin glass or superparamagnetic behavior is observed above 2 K, unlike in the case of MnWO4 nanocrystals having a mean size higher than 10 nm.