PROCEEDINGS OF THE SHEVCHENKO SCIENTIFIC SOCIETY

Chemical Sciences

Archive / Том LVI 2019

Yaroslava LOMNYTSKA, Mariya DZEVENKO, Аnastasiya KUSHNIR

Ivan Franko National University of Lviv, Kyryla and Mefodiya Str. 6, UA-79005 Lviv, Ukraine

DOI: https://doi.org/10.37827/ntsh.chem.2019.56.056

THE INTERACTION OF TANTAL AND VANADIUM WITH HIGH CONTENT OF PHOSPHORUS

Interaction of the components in Ta–V–P system was investigated by X-ray methods and isothermal section of phase diagrams were constructed at 1070 K in the region up to 67 at. % P. The part of the system (50–67 at. % P) was additionally investigated at 870 K. Samples for the investigations were prepared from mixtures of tantalum, vanadium and phosphorus powders, each of purity greater than 99.9%. The mixtures were pressed into pellets and sintered at 1070 K. The samples were annealed at 1070 K during 800 hours. The new ternary phosphide was found in the region of high phosphorus content. The composition of compound can be described by the formula Ta0.95(3)V0.05(3)P2. The crystal structure has been determined from X-ray powder data: structure type OsGe2, space group C2/m, lattice parameters a=8.8602(4), b=3.2666(2), c=7.4867(4) Å, β=119.309(2)°; residual factors RI = 0.038, Rp = 0.140. The atoms of tantalum and vanadium form mixture in the structure of this compound, however, the content of V is rather small similar to the isotypical compounds Ta0.92(2)Cr0.08(2)P2 and Ta0.93(3)Ti0.07(3)P2. It looks like that such small addition of vanadium stabilizes the quasi binary phase TaP2. The ternary compounds with this structure type form in Ta-M'-P (M' - transition 3d metals and Zr and Mo) ternary systems as well. The additional investigation of existence of biphosphides ТаР2 and VP2, both with OsGe2-type, was performed. These binary phosphides were found in samples which have been annealed at 870 K, and not found in the samples annealed at 1070 K. The phase analyses of samples annealed at 1070 K show the presence of monophosphides ТаР and VP and P. Therefore, it can be argued that the biphosphides ТаР2 and VP2 exist up to ~900 K. The exact value of the temperature of ТаР2 VP2 compounds decomposition was not determinated. The character of component interaction in the ternary Ta–V–P system is rather similar to the other related ternary system Ti–M–P (M – 3d-metal). The common feature of all these systems is the existence of ternary compound with composition TiMP and the ternary phosphides Ta1-xM’xP2 with high phosphorus content.

Keywords: ternary phosphides, crystal structure, phase equilibria, X-ray methods of analysis.

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How to Cite

Lomnytska Y., Dzevenko M., Kushnir А. THE INTERACTION OF TANTAL AND VANADIUM WITH HIGH CONTENT OF PHOSPHORUS Proc. Shevchenko Sci. Soc. Chem. Sci. 2019 Vol. LVI. P. 56-63.

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