Experimental and theoretical studies of the ferroelastic domain structure of the (NH 4) 3 H(SeO 4) 2 crystal in phases III and IV are performed. Using the refined structural data the orientations of Wand W 0-type domain walls, as well as the temperature evolution of the domain structure are investigated. It is shown that in spite of the fact that the room temperature phase III has a triclinic s...

The asymmetric units of the title compounds, C10H8N6O4, (I), and C14H16N6O4, (II), each contain half of the respective mol-ecule which is completed by inversion symmetry. The two molecules differ in the ester moiety (acetate versus butyrate) and the crystal symmetry is different, i.e. triclinic for (I) and monoclinic for (II). The di-azido-phenyl-ene moieties are essentially planar [maximum dev...

The EPR spectrum of single crystals scandium orthosilicate doped with chromium was studied in the X-band. In crystallographic and local coordinate systems, parameters spin Hamiltonians two Cr 3+ centers that have replaced nonequivalent triclinic positions demonstrate orthorhombic symmetry principal axes are determined. Gd center localized one position discovered studied, fine structure its grou...

The hydration of Mg-stabilized triclinic and monoclinic tricalcium silicate samples were studied using quasielastic neutron scattering to follow the fixation of hydrogen into the reaction products and by applying hydration models to the data. The quantity of Ca(OH)2 produced during hydration was also determined using inelastic neutron scattering. The monoclinic form was found to be intrinsicall...

A coordinate-invariant generalization of the Lyddane-Sachs-Teller relation is presented for polar vibrations in materials with monoclinic and triclinic crystal systems. The generalization is derived from an eigendielectric displacement vector summation approach, which is equivalent to the microscopic Born-Huang description of polar lattice vibrations in the harmonic approximation. An expression...

The title compound, [SnCl₂(C₅H₄NS)₂], is the product of reaction of 2,2'-dipyridyl disulfide with tin tetra-chloride. The Sn(IV) atom adopts a distorted octa-hedral geometry, with the two bidentate pyridine-2-thiol-ate ligands forming two planar four-membered chelate rings. The two Sn-Cl, two Sn-N and two Sn-S bonds are in cis, cis and trans configurations, respectively. The crystal grown from ...

The earlier suggested energy-level model based on an orbital singlet ground state for 3d 6 and 3d 4 ions at trigonal sites with large triclinic distortion is adopted to develop the single-ion theory of magnetic anisotropy. The Hamiltonian consisting of eight spin Hamiltonian terms and the molecular field is solved by perturbat ion theory. The resulting energies E M s with M s = 0. ± 1, ± 2 are ...

A series of thio-phenes substituted in positions 2 and 5 by imine groups have been synthesized using a solvent-free approach, and their crystal structures determined. The substituents are chiral groups, and the expected absolute configuration for each mol-ecule was confirmed by refinement of the Flack parameter. The compounds are 2,5-bis-[(S)-(+)-(1,2,3,4-tetra-hydro-naphthalen-1-yl)imino]-thio...

Finite strain and vorticity analyses were carried out in the deformed conglomerate and micro-conglomerate of Goushti shear zone in the Sanandaj-Sirjan metamorphic belt (Zagros Mountains Iran). These deformed rocks are bounded between two NE and SW major thrust faults. Finite strain measurements on three principal planes of strain ellipsoid show the higher amounts of strain ratios near the major...