Reinvestigation of phase equilibria up to the solidus line and properties of the phases from the V2O5–Sm2O3 system

Abstract The discrepancies in knowledge about the number and type of compounds formed in the binary oxide system V 2 O 5 –Sm 2 O 3 , were the inspiration to undertake verification studies. Therefore, the main goal of these studies was to determine finally what compounds are forming in this system and what properties they exhibit. Such information is necessary to find their potential applications, e.g. as luminophores or electrode materials. As part of this work, using the method of high-temperature reactions occurring in the solid state between V 2 O 5 and Sm 2 O 3 oxides, the formation of three samarium(III) vanadates(V) with the formulas: SmVO 4 , Sm 8 V 2 O 17 and Sm 5 VO 10 was demonstrated. It was found that all of the obtained compounds are thermally stable up to at least 1350°C and that they belong to the group of electrical semiconductors. Based on the obtained results, a new composition of the eutectic mixture formed between SmVO 4 and V 2 O 5 , was also determined, and a new version of the diagram of phase equilibria established in the binary system of V 2 O 5 –Sm 2 O 3 oxides in the air atmosphere up to 1600°C was constructed. The following methods were used in the study: differential thermal analysis combined with simultaneous thermogravimetric analysis (DTA–TG), optical pyrometry, X-ray diffraction (XRD), ultraviolet and visible spectroscopy with diffuse reflectance spectroscopy (UV–VIS–DRS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM–EDX) and gas ultrapycnometry.