The ground-state crystal structures of the boron hydride series ABH4 (A = Li, Na, K, Rb, Cs) have been established from first principle projected-augmented plane-wave calculations by considering different possible structural arrangements and subjecting the test structures to structural relaxations. LiBH4 crystallizes with orthorhombic symmetry (KGaH4-type; Pnma), NaBH4, KBH4, and RbBH4 with tet...

We have studied the surfaces of zirconia (ZrO2) by first-principles calculations using density functional theory. We predict surface energies and relaxations for the principal surfaces of different bulk phases of zirconia. We find that the stoichiometric tetragonal~111! and monoclinic~1̄11! are the most stable surfaces. We find a strong linear correlation between surface energies before and afte...

Crystals of the RADIALIS protein from Antirrhinum majus were grown by vapour diffusion after limited proteolysis. Mass spectrometry indicated that an 8 kDa fragment had been crystallized corresponding to the predicted MYB DNA-binding domain. X-ray data collected at room temperature were consistent with tetragonal symmetry, whereas data collected at 100 K using crystals cryoprotected by suppleme...

Monoclinic raspite PbWO4 nanobelts were synthesized by a facile composite-salt-mediated method. By in situ heating to above 538 C inside the chamber of a transmission electron microscope, the raspite nanobelts transformed irreversibly to tetragonal scheelite phase. By analyzing the experimental data, three possible topotactic transformation relationships between raspite and scheelite phases hav...

The microscopic mechanism leading to stabilization of cubic and tetragonal forms of zirconia (ZrO2) is analyzed by means of a self-consistent tight-binding model. Using this model, energies and structures of zirconia containing different vacancy concentrations are calculated, equivalent in concentration to the charge compensating vacancies associated with dissolved yttria (Y2O3) in the tetragon...

NaFe2As2 is investigated experimentally using powder x-ray diffraction and Raman spectroscopy at pressures up to 23 GPa at room temperature and using ab-initio calculations. The results reveal a pressure-induced structural modification at 4 GPa from the starting tetragonal to a collapsed tetragonal phase. We determined the changes in interatomic distances under pressure that allowed us to conne...

Using high resolution x-ray diffraction (XRD) on high purity powders, we resolved the structure and ab symmetry of the intriguing compound Sr2VO4 from room temperature down to 20 K to an unprecedented level of accuracy. Upon cooling, this set of data unambiguously reveals a second-order phase transition lowering the symmetry from tetragonal to orthorhombic at a temperature Tc2 = 136 K. The obse...

Degradation of yttria-stabilized zirconia dental implants abutments due to the tetragonal to monoclinic phase transformation was studied in detail by microstructural characterization using Electron Back Scatter Diffraction (EBSD). The amount and distribution of the monoclinic phase, the grain-size distribution and crystallographic orientations between tetragonal and monoclinic crystals in 3 mol...

Recombinant pigeon-liver malic enzyme was expressed in Escherichia coli and purified to homogeneity. Two different crystal forms were grown by the hanging-drop vapour-diffusion method. Both types of crystals belong to the tetragonal space group P4(2)22, with unit-cell dimensions a = b = 163.8, c = 174.3 A for the octahedral crystals and a = b = 124.5, c = 179.2 A for the rod-like crystals. X-ra...

Tetragonal Li10GeP2S12 (LGPS) is the best solid Li ion conductor known to date. So far, the structure of the electrolyte was only determined from powder diffraction and Rietveld refinement. Here, we present the first single-crystal structure analysis of the tetragonal LGPS structure. The reported structure is largely verified. However, an additional Li position is clearly identified which might...