Pressure-induced phase transition in the cubic ScF<Subscript>3</Subscript> crystal

Pressure-induced phase transitions in the ScF₃ crystal were studied using synchrotron radiation diffraction, polarization microscopy, and Raman spectroscopy. The phase existing in the range 0.6–3.0 GPa is optically anisotropic; its structure is described by space group R ₃ c (Z = 2), and the transition is due to rotation of ScF₆ octahedra around a threefold axis. The pressure dependence of the structural parameters and angle of rotation are determined. The number of Raman spectral lines corresponds to that expected for this structure; above the phase transition point, a recovery of soft modes takes place. At a pressure of 3.0 GPa, a transition occurs to a new phase, which remains metastable as the pressure decreases. The results are interpreted using an ab initio method based on the Gordon-Kim approach.     

Analysis of the phase composition of human kidney stones in model objects with the use of synchrotron radiation diffraction

The possibility of using synchrotron radiation for X-ray diffraction analysis of kidney stones directly in a human has been investigated. Experiments using a special phantom object imitating a human body have been performed. The experimental results obtained show that the significant thickness of the objects studied and the presence of liquids and biological polymers do not impose fundamental limitations on the possibility of in vivo synchrotron radiation diffraction analysis of human kidney stones.     

Structural features of hydrate forms of iron(III) oxalate

The existence of hydrate forms of iron(III) oxalate, which noticeably differ from each other in the Mössbauer spectral parameters (isomer shift and quadrupole splitting), is detected. In the assumption of the formation of phases with different structural characteristics, the samples of compound under study are examined by the powder X-ray diffraction analysis (including the application of synchrotron radiation), Mössbauer and IR spectroscopy. It is shown that the phase characterized by new values of the Mössbauer parameters has its own IR spectrum and it is X-ray amorphous and metastable.     

Structural and Phase Transfromations in Superlocalization Band in Ni3Ge Single Crystal

Russian Physics Journal - The paper studies the high-temperature plastic deformation in Ni3Ge alloy single crystals localizing in a band a few tens of microns wide that reaches the shear strain of...     

Interaction between solid nickel and a tin–indium eutectic melt,and the nature of eutectic alloys

Structural transformations during reactions between nickel and an indium–tin eutectic melt are studied via the diffraction of high-energy synchrotron radiation. It is shown that InNi intermetallic compound is the first to form after melting. No phases belonging to a Ni–Sn system are observed. A hypothesis concerning the nanocluster structure of the eutectic melt is proposed: Structural formations with forbidden five-fold, seven-fold, and higher-order rotational axes of symmetry lie at the heart of nanosized clusters.     

Synchrotron radiation diffraction study of structural changes in the interaction of liquid and solid metals

Changes of the structure and phase composition occurring during the interaction of copper and its alloys in the solid-state phase with the liquid melts of indium, gallium and tin are considered. It is shown that the phase and morphological composition of interaction products depends on the relations between the rates of diffusion and the rates of reagent dissolution. Structural transformations that take place during contact melting and eutectic crystallization in the zones of indium–tin and indium–bismuth contacts are also considered. A hypothesis concerning the nature and microstructure of eutectics is proposed. All experiments are performed on the VEPP-3/VEPP-4 storage ring.     

How the tin concentration affects the interactions of intermetallic compounds of the Cu-Sn system with liquid gallium and a gallium-tin eutectic

Interactions in the copper-gallium-tin ternary system are studied. New phase formation involves the step of dissolution of solid copper alloys in a liquid phase. The induction period of tin segregation in an autonomous phase depends on tin concentration in the feed. The formation of solid solution of gallium in tin is suggested.