The size effect on atomic structure of a Cu64Zr36 amorphous system, including zero-dimensional small-size amorphous particles (SSAPs) and two-dimensional small-size amorphous films (SSAFs) together with bulk sample was investigated by molecular dynamics simulations. We revealed that sample size strongly affects local atomic structure in both Cu64Zr36 SSAPs and SSAFs, which are composed of core and shell (surface) components. Compared with core component, the shell component of SSAPs has lower average coordination number and average bond length, higher degree of ordering, and lower packing density due to the segregation of Cu atoms on the shell of Cu64Zr36 SSAPs. These atomic structure differences in SSAPs with various sizes result in different glass transition temperatures, in which the glass transition temperature for the shell component is found to be 577 K, which is much lower than 910 K for the core component. We further extended the size effect on the structure and glasses transition temperature to Cu64Zr36 SSAFs, and revealed that the T g decreases when SSAFs becomes thinner due to the following factors: different dynamic motion (mean square displacement), different density of core and surface and Cu segregation on the surface of SSAFs. The obtained results here are different from the results for the size effect on atomic structure of nanometer-sized crystalline metallic alloys.

Ab initio molecular dynamics simulations are performed to investigate the atomic structures and dynamics of NiZr and NiHf metallic liquids in a temperature range of 1400-2500 K. Calculated results are in good agreement with recently reported high temperature experimental data. Local atomic structures are analyzed and compared for NiZr and NiHf metallic liquids in terms of average bond length, coordination number, Honey-Andersen index, Bond-orientation order, spatial correlation and Voronoi tessellation methods. It is found that Zr-Zr bonds have larger average length of 3.32 Å than 3.22 Å for Hf-Hf bonds, causing sluggish diffusion in NiHf liquids. Zr and Hf atom-centered clusters with higher coordination numbers are inclined to aggregate with high-coordinated clusters, while Ni atom-centered clusters with lower coordination numbers prefer to avoiding to be the nearest neighbor with each other. Temperature dependent diffusion coefficients reveal the decoupled diffusion in both liquids, which are related with different spatial correlations for Ni- and Zr- (or Hf-) centered clusters.

LiGa 0.5 In 0.5 Se 2 is a new quaternary nonlinear optical crystal for the mid-IR application grown as a mixed crystal of the LiGaSe 2 −LiInSe 2 solid−solution system. It is transparent in the 0.47− 14 μm range and has an appropriate bandgap and a lower melting point than LiGaSe 2 and LiInSe 2 . It is more technological about the growth process since its homogeneity range is broader in the phase diagram. In this work, we have synthesized the LiGa 0.5 In 0.5 Se 2 polycrystal by the two-zone temperature method. LiGa 0.5 In 0.5 Se 2 single crystals (Φ26 mm × 50 mm) were grown through the modified Bridgman method with the c-axis seed crystal which has the smallest thermal expansion coefficient of the three main axes in 293−773 K. The crystal structure was studied by X-ray diffraction and the Rietveld refinement method. Due to the low transmittance of the as-grown crystals, a systematic thermal treatment experiment was carried out. In the annealing experiment, the crystal surface is seriously enriched with selenium due to the thermal diffusion of selenium, resulting in the crystal opacity and cracking, while after vacuum quenching at 873 K, the transmittance of the LiGa 0.5 In 0.5 Se 2 crystal wafer was greatly improved, the bandgap shows a large increase from 2.13 to 2.51 eV, and the quenched crystal shows strong SHG response (×1.91 LiGaSe 2 ). The chemical states and vibration modes of surface elements for both conditions were characterized by X-ray photoelectron and Raman spectra. Density functional theory calculations were carried out to simulate the phonon spectrum and phonon density of states, which can help to study the phonon vibration modes in the lattice.