Synthesis and crystal chemistry of microporous titanates K sub(x)(Ti,M) sub(8)O sub(16) where M=Sc-Ni

• Published in: Journal of solid state chemistry Vol. 220; pp. 45 - 53
• Main Authors: Moetakef, Pouya, Larson, Amber M, Hodges, Brenna C, Zavalij, Peter, Gaskell, Karen J, Piccoli, Philip M, Rodriguez, Efrain E
• Format: Journal Article
• Language: English
• Published: 01.12.2014
• Subjects: Channels; Chemical composition; Crystals; Diffraction; Magnetization; Single crystals; Titanates; X-rays
• ISSN: 0022-4596
• DOI: 10.1016/j.jssc.2014.08.012

Through salt-flux methods, single crystals of eight novel hollandite-type titanates have been grown with the stoichiometry K sub(x)(Ti sub(8-y)M sub(y)) sub(8)O sub(16) for x=y approximately 1.5 where M super(3+)=Sc, Ti, V, Cr, Mn, and Fe, and for x/2=y approximately 0.75 where M super(2+)=Co and Ni. Single crystal and powder X-ray diffraction reveals phase pure crystals with tetragonal space group I4/m. These titanates are microporous oxides with 1-dimensional channels where the non-framework cation, K, resides. In addition to diffraction, spectroscopic methods were used to characterize the chemical composition of both the bulk and surface. X-ray photoelectron spectroscopy affords the oxidation states of the substituted transition metals M on the surface and energy dispersive X-ray spectroscopy the metal ratios, including that of potassium, for an overall accurate description of the chemical composition of both the bulk and surface. Magnetization versus temperature measurements indicate that all phases are Curie paramagnets with effective magnetic moments consistent with the d-electron count given by combined X-ray diffraction and elemental analysis techniques.