I. Kaban

Structural properties of liquid Fe-Si alloys

Abstract The atomic structure of liquid Fe–Si alloys within the whole concentration range (including pure components) was investigated at the temperature of 1550 °C by means of X-ray diffraction. Analysis of the reported data on physical properties of Fe–Si melts has been carried out. Interrelation between liquid-state structure and solid-state properties was considered. Fe–Si alloys in the liquid state are shown to be micro-inhomogeneous and they contain atomic micro-formations (clusters) that differ by atomic composition and packing. There are five types of clusters: two of them consist of atoms of one kind (Fe or Al); the composition of the other clusters depends on the stoichiometry of solid Fe 3 Si, FeSi and Fe 2 Si 5 phases. The entire concentration range of the Fe–Si system consists of four concentration intervals. Within each interval melts are constituted of the clusters of two kinds. The variation of the component concentrations in Fe–Si alloys results in changing of volume fraction of each type clusters, whereas the atomic composition and arrangement inside the clusters remains constant.

Structure of liquid Fe-Al alloys

Abstract The atomic structure of liquid Fe–Al alloys within the whole concentration range (including pure components) has been studied at 1820 K by X-ray diffraction technique. Experimental data were compared with micro-heterogeneous model calculations. Reported physical properties of liquid Fe–Al alloys have been also considered. It is shown that all investigated melts of the Fe–Al system are micro-inhomogeneous and contain atomic micro-formations (clusters), which are distinguished by composition and atomic packing. There are four types of cluster, two of them contain atoms of one sort (Fe or Al); composition of two other types of cluster respects to the stoichiometry of solid Fe2Al5 and Fe3Al phases. The variation of the component concentrations in Fe–Al alloys results in changing of volume fraction of each cluster type whereas the atomic composition and arrangement inside the clusters remains constant.

Surface tension and density of binary lead and lead-free Sn-based solders

The surface tension and density of the liquid Sn60Pb40, Sn90Pb10, Sn96.5Ag3.5 and Sn97Cu3 solder alloys (wt%) have been determined experimentally over a wide temperature interval. It is established that the surface tension of liquid Sn90Pb10 is about 7% higher than that of a traditional Sn60Pb40 solder and that the surface tension of Sn96.5Ag3.5 and Sn97Cu3 alloys is about 12% higher than that of Sn60Pb40. The analytical expressions for the temperature dependences of the surface tension and density are given.

Structure of molten copper-germanium alloys

Abstract Copper–germanium alloys in liquid state at 1373 K have been investigated. Non-linear behaviour of the structure-sensitive parameters and electrical resistivity of the alloys versus concentration have been observed. Close relation between the crystal structure and the local ordering in molten Cu–Ge alloys has been found. The inhomogeneous structure of the liquid Cu–Ge alloys at a microscopic level was established. Melts are shown to contain clusters from pure components and clusters with composition corresponding to that of the intermetallic compound Cu 3 Ge existing in the solid phase.

Short-range order in amorphous germanium-tellurium alloys

Abstract The atomic structure of Te-rich amorphous germanium tellurides has been investigated experimentally with high-energy synchrotron radiation and modeled by means of the reverse Monte Carlo technique. Total and partial structure factors and pair correlation functions were simulated. It is shown that the structure of Ge20Te80 and Ge15Te85 glasses can be described by GeTe4 tetrahedra as structural units which are bridged by Te–Te bonds.

Structure of GeSe4-In and GeSe5-In glasses.

(Ge(0.2)Se(0.8))(100-x)In(x) and (Ge(0.17)Se(0.83))(100-x)In(x) (x = 0, 5, 10, 15 at.%) chalcogenide glasses have been studied with high-energy x-ray diffraction, neutron diffraction and extended x-ray absorption spectroscopy at Ge, Se and In K-edges. The experimental data were modelled simultaneously with the reverse Monte Carlo simulation method. GeSe(4/2) tetrahedra are shown to be the main structural units in the binary and ternary glasses investigated. Indium bonds to the excess Se atoms in the ternary Ge-Se-In glasses. While the majority of In atoms have three Se neighbours, some In atoms may be tetrahedrally coordinated by Se.

Local atomic environment in amorphous Ge15Te85

The structure of amorphous Ge15Te85 has been studied by neutron and x-ray diffraction. Experimental data have been modelled simultaneously with the reverse Monte Carlo simulation method. The contrast between structure factors together with the application of some plausible physical constraints allowed the separation of the three partial pair correlation functions and determination of Ge and Te local environment.

Structural studies on Te-rich Ge-Te melts

The structure of liquid Ge15Te85, Ge25Te75 and Ge33Te67 alloys has been studied by neutron and x-ray diffraction. Datasets obtained by the two techniques have been modelled simultaneously with the reverse Monte Carlo simulation method. As a result, the first coordination numbers and nearest neighbour distances for the studied alloys were estimated. On the basis of the experimental data, Ge–Ge bonding appears to be present in liquid Ge25Te75 and Ge33Te67. It has been found that temperature dependences of the physico-chemical properties correlate with the structural changes in liquid Ge15Te85.

Radiation-modified structure of Ge25Sb15S60 and Ge35Sb5S60 glasses.

Atomic structures of Ge(25)Sb(15)S(60) and Ge(35)Sb(5)S(60) glasses are investigated in the gamma-irradiated and annealed after gamma-irradiation states by means of high-energy synchrotron x-ray diffraction technique. The first sharp diffraction peak (FSDP) is detected at around 1.1 A(-1) in the structure factors of both alloys studied. The FSDP position is found to be stable for radiation/annealing treatment of the samples, while the FSDP intensity shows some changes between gamma-irradiated and annealed states. The peaks in the pair distribution functions observed between 2 and 4 A are related to the Ge-S, Ge-Sb, and Sb-Sb first neighbor correlations and Ge-Ge second neighbor correlations in the edge-shared GeS(42) tetrahedra, and S-S and/or Ge-Ge second neighbor correlations in the corner-shared GeS(42) tetrahedra. Three mechanisms of the radiation-/annealing-induced changes are discussed in the framework of coordination topological defect formation and bond-free solid angle concepts.

Structural investigations of Ge 5 As x Se 95-x and Ge 15 As x Se 85-x glasses using x-ray diffraction and extended x-ray fine structure spectroscopy

The structure of Ge(5)As(x)Se(95-x) (x = 10, 20, 30, 38 at.%) and Ge(15)As(x)Se(85-x) (x = 10, 25, 34 at.%) glasses has been investigated by high-energy x-ray diffraction and extended x-ray absorption fine structure measurements. The experimental datasets have been modelled using the reverse Monte Carlo simulation technique. The model atomic configurations have been analysed in detail. It has been found that the homonuclear Ge-Ge, As-As, Se-Se and heteronuclear Ge-As bonds play an important role in the structure formation of the Ge-As-Se glasses. The total number of these bonds decreases quite slowly with the mean coordination number similarly to the nonlinear refractive index.