The exchange-correlation functionals of the generalized gradient approximation (GGA) are still the most used for the calculations of the geometry and electronic structure of solids. The PBE functional [J. P. Perdew et al., Phys. Rev. Lett. 77, 3865 (1996)], the most common of them, provides excellent results in many cases. However, very recently other GGA functionals have been proposed and compete in accuracy with the PBE functional, in particular for the structure of solids. We have tested these GGA functionals, as well as the local-density approximation (LDA) and TPSS (meta-GGA approximation) functionals, on a large set of solids using an accurate implementation of the Kohn-Sham equations, namely, the full-potential linearized augmented plane-wave and local orbitals method. Often these recently proposed GGA functionals lead to improvement over LDA and PBE, but unfortunately none of them can be considered as good for all investigated solids.

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Calculation of the lattice constant of solids with semilocal functionals

Borates and silicate glasses containing boron oxide have been widely used for optical lenses with high refractive index and low dispersion characteristics. Alkali borate glasses are of great technological interest especially lithium borates as solid electrolytes because of their fast ionic conduction. In this study the optical properties including infrared and refractive index and density of lithium borate glass as a base glass were studied. The effect of the presence of either aluminum or lead oxide, or the presence of one of the following transition metal, Fe 2 O 3 , TiO 2 or V 2 O 5 was investigated. The effect of exposing the glass to either gamma, or fast neutron irradiation on the last properties was also studied. The results showed that three main bands appeared due to bending vibration or stretching of either, tetrahedral or triagonal borate units. The addition of alkalies causes only a shift of the bands either to higher or lower wavelength. Glass containing lead oxide had the highest refractive index and density, also the presence of any of the transition metal oxide lowering the average coordination number of oxygen which causes a compaction of the structure hence an increase in the values of density and refractive index. Since irradiation of glass causes compaction of B 2 O 3 by breaking the bonds between triagonal elements, the average ring size becomes smaller which leads to an increase in density and refractive index too.

Effect of irradiation on some optical properties and density of lithium borate glass

Study of microstructure and phase evolution of hot-dipped aluminide mild steel during high-temperature diffusion using electron backscatter diffraction

Vibrational analysis of the two non-equivalent, tetrahedral tungstate (WO4) units in Ce2(WO4)3 and La2(WO4)3

Lithium ion conductivity and thermal behaviour of glasses and crystallised glasses in the system Li2O–Al2O3–TiO2–P2O5

On presente les resultats preliminaires des investigations de l'action d'un nouveau laser a base de tungstate de lanthane dope au neodyme. Les mesures de fluorescence et d'absorption sont effectuees sur des echantillons a environ 2.4%. On trouve des proprietes qui permettent de bonnes applications pratiques

A New Laser Host Crystals - Lanthanum Tungstate La2 (WO4)3

Three series of glassy samples are prepared by means of rapid quenching in the systems Li2O-TiO2-P2O5, Li2O-TiO2-P2O5-SiO2, and Li2O-TiO2-P2O5-SiO2-V2O5. Their glass transition temperature, crystallization temperature, density, and electrical conductivity are measured by DTA, Archimedes method, and impedance spectroscopy method, respectively. The electrical conductivity measurements indicate that as more glass formers are added to the Li2O-P2O5 system, the room temperature conductivity increases, while the activation energy E(a) decreases.

The effects of mixed glass formers on the properties of non‐crystalline lithium ion conductors

Phase equilibria in the ternary Nd-Cs-Si system up to a Co:Nd atomic ratio of 2:1 and an Si:Nd atomic ratio of 3:5 were studied by means of X-ray powder diffraction. A total of seven ternary compounds were identified. Among the seven ternary compounds found in this system, the solid solubility of two compounds had not been reported previously: NdC0 t3 _ .. Si.. with 2.5~x ~ 4 and NdColl_x Six with 1.2~x ~ 1.8. Other new information includes the crysta! structure of NdCo 13 _ .. Si... It has a tetragonal structure, related to the NaZn13-type, with a = 7.811-7.763 A, c = 11.430-11.464 A, and the atomic ordering is similar to Ce 2Ni17Si9 • A limited solid solution range has also been found for Nd2Co17 _ x Si... This isothermal section consists of 26 three-phase and four two-phase regions.

Phase relations in the Nd-Co-Si system at 800°C

Effects of Mn and Cu doping in La(T,Al)13 (T=Fe,Co) on crystal structure and magnetic properties

The crystal structure of the B-rich phase Pr1+eFe4B4 in the PrFeB ternary system is studied by means of X-ray powder diffraction and electron diffraction methods. One-dimensional composition-incommensurate structure along c-direction is found in the compound Pr1+eFe4B4. In fact the structure of this compound is composed of FeB substructure and Pr substructure. Both substructures have the tetragonal symmetry with the same lattice parameter a, but there is no lowest common multiple relation between cFeB and cPr parameters. The lattice parameter at room temperature of Pr1+eFe4B4 is a = 0.7144, cFeB = 0.3900, cPr = 0.3485 nm and after quenching from 950 °C a = 0.7138 nm, cFeB = 0.3881 nm and cPr = 0.3618 nm. The space groups of substructures of FeB and Pr are P42/ncm and I4/mmm, respectively.



Mittels Rontgenpulverbeugung und Elektronenbeugung wird die Kristallstruktur der B-reichen Pr1+eFe4B4-Phase im ternaren PrFeB-System untersucht. In der Verbindung Pr1+eFe4B4 wird eine eindimensionale zusammensetzungsinkommensurable Struktur in c-Richtung gefunden. Tatsachlich ist die Struktur dieser Verbindung aus der FeB-Substruktur und der Pr-Substruktur zusammengesetzt. Beide Substrukturen haben tetragonale Symmetrie mit demselben Gitterparameter a, es gibt jedoch keine Beziehung des kleinsten gemeinsamen Vielfachen zwischen den cFeB- und cPr-Parametern. Der Gitterparameter bei Zimmertemperatur fur Pr1+eFe4B4 betragt a = 0,7144, cFeB = 0,3900, cPr = 0,3485 nm und nach Abschrecken von 950 °C a = 0,7138, cFeB = 0,3881 und cPr = 0,3618 nm. Die Raumgruppen der Substrukturen von FeB und Pr sind P42/ncm bzw. I4/mmm.

Jingkui Liang

Papers

A New Laser Host Crystals - Lanthanum Tungstate La2 (WO4)3

The effects of mixed glass formers on the properties of non‐crystalline lithium ion conductors

Phase relations in the Nd-Co-Si system at 800°C

Effects of Mn and Cu doping in La(T,Al)13 (T=Fe,Co) on crystal structure and magnetic properties

The study of the one‐dimensional composition‐incommensurate structure of Pr1+ϵFe4B4