Bi-Cheng Zhou

Adsorption-controlled growth of La-doped BaSnO3 by molecular-beam epitaxy

Epitaxial La doped BaSnO3 films were grown in an adsorption controlled regime by molecular beam epitaxy, where the excess volatile SnOx desorbs from the film surface. A film grown on a (001) DyScO3 substrate exhibited a mobility of 183 cm^2 V^-1 s^-1 at room temperature and 400 cm^2 V^-1 s^-1 at 10 K, despite the high concentration (1.2x10^11 cm^-2) of threading dislocations present. In comparison to other reports, we observe a much lower concentration of (BaO)2 Ruddlesden Popper crystallographic shear faults. This suggests that in addition to threading dislocations that other defects possibly (BaO)2 crystallographic shear defects or point defects significantly reduce the electron mobility.

Data set for diffusion coefficients of alloying elements in dilute Mg alloys from first-principles

Diffusion coefficients of alloying elements in Mg are critical for the development of new Mg alloys for lightweight applications. Here we present the data set of the temperature-dependent dilute tracer diffusion coefficients for 47 substitutional alloying elements in hexagonal closed packed (hcp) Mg calculated from first-principles calculations based on density functional theory (DFT) by combining transition state theory and an 8-frequency model. Benchmark for the DFT calculations and systematic comparison with experimental diffusion data are also presented. The data set refers to “Diffusion coefficients of alloying elements in dilute Mg alloys: A comprehensive first-principles study” by Zhou et al. [1].

First-principles Study of Diffusion Coefficients of Alloy Elements in Dilute Mg Alloys

The equilibrium thermodynamic properties of Mg alloys are reasonably well understood, but the kinetics of these alloys is explored to a far lesser extent, especially diffusion coefficients of alloying elements in Mg. In the present work, first-principles calculations based on the Density Functional Theory (DFT) were used to calculate the dilute tracer diffusion coefficients in Mg for 61 elements, including rare earths, as a function of temperature using an 8-frequency model. An improved generalized gradient approximation of PBEsol was used in the present work, which is able to well describe both vacancy formation energies and vibrational properties. Systematic trends of diffusion activation energies of various solutes were analyzed. Remarkable agreements of the calculated results compared with available experimental data were obtained.