An assessment of the entire Al-Fe system including D03 ordering

The thermal expansion of hexagonal GaN bulk crystals was studied in an extended temperature range from $12\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}1025\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The lattice parameters $a$ and $c$ were measured by high-resolution x-ray diffraction. The temperature dependence of the derived thermal expansion coefficients along the $a$ and $c$ directions could be well described over the entire temperature range within both the Debye model and the Einstein model. Debye temperatures of $(868\ifmmode\pm\else\textpm\fi{}20)\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and $(898\ifmmode\pm\else\textpm\fi{}24)\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and Einstein temperatures of $(636\ifmmode\pm\else\textpm\fi{}13)\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and $(662\ifmmode\pm\else\textpm\fi{}18)\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ were derived along the $a$ and $c$ axes, respectively, and compared to available literature values.

Temperature dependence of the thermal expansion of GaN

Optoelectrical and microelectronic devices involving gallium nitride have become a challenge but their development is limited because of a lack of suitable substrates. This paper deals with the crystal growth of gallium nitride, the processes leading to GaN bulk crystals being significantly expanded during the last decade (the ones involving GaN thin films or nanocrystallites are not studied in this review). The main reviewed routes are: (i) the high pressure nitrogen solution growth (H.P.N.S.G.), (ii) the Na flux method, and (iii) the ammonothermal crystal growth.

Gallium nitride bulk crystal growth processes : a review

Intermetallic compounds of Ni and Ga as catalysts for the synthesis of methanol

We present a computational screening of experimental structural repositories for fast Li-ion conductors, with the goal of finding new candidate materials for application as solid-state electrolytes in next-generation batteries. We start from ∼1400 unique Li-containing materials, of which ∼900 are insulators at the level of density-functional theory. For those, we calculate the diffusion coefficient in a highly automated fashion, using extensive molecular dynamics simulations on a potential energy surface (the recently published pinball model) fitted on first-principles forces. The ∼130 most promising candidates are studied with full first-principles molecular dynamics, including an estimate of the activation barrier for the most diffusive structures. The results of the first-principles simulations of the candidate solid-state electrolytes found are discussed in detail.

High-throughput computational screening for solid-state Li-ion conductors

Phase diagram and thermodynamic properties of the Ni-Ga system are assessed based on the CALPHAD approach, using all available experimental data and applying appropriate thermodynamic models. The liquid phase and the Ni-based solid solution (Ni) are treated as disordered solutions. The thermodynamic behavior of the ordered intermetallic compounds with appreciable ranges of homogeneity, Ni3Ga and NiGa, are described by a two-sublattice model, and the order-disorder transformation between Ni3Ga and fcc-(Ni) is also explicitly considered in this work. The other five intermetallic compounds are treated as stoichiometric line compounds. The phase diagram and the thermodynamic properties calculated from the optimized model parameters are in good agreement with most of the experimental data.

Thermodynamic assessment of the Ni-Ga system

Transition metal chalcogenides (TMChs) have recently attracted a great deal of interest in the chemical and physical research fields. These compounds have a common crystal structure: they usually consist of two-dimensional or quasi-two-dimensional layers stacked along the direction perpendicular to the layers. The combination between layers is generally by van der Waals interaction or weak chemical bonding, making the layered chalcogenides potential hosts for intercalation. Alkali metals, alkaline earths, rare earths, and organic groups or compounds can be intercalated into the structure as spacing layers, resulting in a variety of new compounds and exhibiting interesting physical and chemical properties. In this review, we introduce and summarize the latest advances in chemical intercalation and the role of these spacing layers in TMChs, and their relation to relevant properties. Especially, we focus on the developments of chemical intercalation in Fe chalcogenide superconductors to understand the effect...

Chemical Intercalations in Layered Transition Metal Chalcogenides: Syntheses, Structures, and Related Properties

Assessment of Li–Ga–N ternary system and GaN single crystal growth

Preparation and characterizations of bulk GaN crystals

Colorless transparent hexagonal GaN platelet crystals with a size of 1–4 mm have been grown under more moderate conditions (800 °C, 1∼2 atm) using Li3N and Ga. Growth mechanism of this method was revealed by a series of experiment results. The morphologies of GaN single crystals were observed with an optical microscope and a scanning electron microscope. The crystal was characterized by X-ray powder diffraction and Raman scattering spectrum.

Wenxia Yuan

Papers

Thermodynamic assessment of the Ni-Ga system

Chemical Intercalations in Layered Transition Metal Chalcogenides: Syntheses, Structures, and Related Properties

Assessment of Li–Ga–N ternary system and GaN single crystal growth

Preparation and characterizations of bulk GaN crystals

Bulk GaN single crystals: growth mechanism by using Li3N and Ga