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Hitherto unreported vanadium oxyfluoride VO2F has been synthesized using a solid state reaction at a pressure of 4 GPa and 800 °C. This long awaited vanadium oxyfluoride fills the existing gap of ReO3-type MO2F compounds of Group 5 elements, from which only NbO2F and TaO2F have been known to exist to date. VO2F crystallizes with the VF3-type structure, space group Rc, with a = 5.1226(1) A and c = 13.0686(3) A as determined by powder X-ray diffraction. Highly structured diffuse streaking observed in electron diffraction patterns evidences local O/F ordering. VO2F exhibits two regions upon discharge in a lithium cell, an upper sloped region in the range of 3.9–2.2 V and a lower plateau at 2.15 V. Discharge of VO2F to 1 V provides a gravimetric capacity of 450 mA h g−1. VO2F can reversibly insert up to 1 Li+ per vanadium above 2.15 V without destruction of the host structure, delivering a gravimetric capacity as high as 250 mA h g−1 and pointing to VO2F as a promising intercalation electrode.

Several Fe–Ga mixed oxide samples denoted as Fe1 − xGax (x = 0, 0.10, 0.25, 0.50, 0.75, 0.90) have been synthesised by a conventional coprecipitation method at controlled pH, dried at 363 K for 24 hours and calcined at 673 K and 1073 K for 3 hours. All samples were characterised by X-ray diffraction, chemical analyses, thermogravimetry and differential thermal analysis (TG-DTA) and FT-IR and UV-VIS spectroscopies. It was found all materials formed a solid solution, α-(Fe,Ga)2O3, in the entire Fe/Ga compositional range until 673 K. Samples calcined at 1073 K gave rise to biphasic systems for x > 0.5 due to the different structure of β-Ga2O3 compared to α-Fe2O3. Surface acidity of samples was studied by pivalonitrile molecule adsorption on a pressed pellet of each material, and weak Lewis acidity was found in all cases, it not being possible to distinguish between both types of cation site on the surface, and Bronsted acidity that increased with increasing Ga content. Methanol molecules were also adsorbed, showing an increase of reactivity for those samples with very low Ga content.

Powders belonging to the Fe2O3–Al2O3 system prepared by a coprecipitation method have been characterized from the point of view of their solid-state and surface structure by X-ray diffraction (XRD), Fourier-transform (far) infrared (FTIR/FT-FIR), diffuse reflectance ultraviolet–visible (DR-UV–VIS) Spectroscopy, BET surface area and porosity and adsorption of probe molecules. In samples calcined at 673 K a disordered defective spinel-type phase, γ-FeAlO3, has been found, containing Fe3+ in octahedral sites and Al3+ in both octahedral and tetrahedral sites, both in the bulk and on the surface. Samples calcined at 1173 K are composed of mixtures of two saturated solid solutions with corundum–haematite-type structures. The surface of these biphasic materials is dominated by the higher reactivity of α-Fe2O3 with respect to α-Al2O3, although tetrahedral Al3+ is also found at the surface of the saturated solid solution of Fe2O3 in α-Al2O3. Al3+ added to Fe2O3 tends to stabilize the spinel-type phase and to hinder sintering, while Fe3+ added to Al2O3 accelerates the γ→α phase transition and sintering.

FT Raman and FTIR/FTFIR skeletal spectra of different TiO2 powders, of both synthetic and commercial origin, and of Sr, Ba, Co and Ni metatitanates are reported and discussed in relation to the predictions of factor group analyses. The ability of vibrational techniques to show the presence of brookite impurities in both anatase and rutile, and of rutile in anatase, as well as to give morphological and surface information is emphasized. The spectra of SrTiO3, BaTiO3, NiTiO3 and CoTiO3 are also discussed in relation to their different structures (pervoskite and ilmenite-type).