(Ga,Ge)-Analogue of Tourmaline: Crystal Structure and Composition

Crystallography Reports - Crystals of a (Ga,Ge)-analogue of tourmaline have been synthesized by hydrothermal method in the temperature range of 600–650°C under a pressure of 100 MPa. The...     

On generalized Poisson–Nernst–Planck equations with inhomogeneous boundary conditions: a‐priori estimates and stability

In this paper, we consider the strongly nonlinear Nernst–Planck equations coupled with the quasi‐linear Poisson equation under inhomogeneous, moreover, nonlinear boundary conditions. This system describes joint multi‐component electrokinetics in a pore phase. The system is supplemented by the force balance and by the volume and positivity constraints. We establish well‐posedness of the problem in the variational setting. Namely, we prove the existence theorem supported by the energy and the entropy a‐priori estimates, and we provide the Lyapunov stability of the solution as well as its uniqueness in special cases. Copyright © 2016 John Wiley & Sons, Ltd.     

Magnetophoresis of Microparticles in a Magnetic Fluid

Russian Physics Journal - An experimental setup is developed for studying magnetophoresis in a layer of a magnetic fluid several millimeters thick by the method of light transmission and...     

Crystal structure of holtite I

The crystal structure of As-containing holtite I is refined (Ital Structures diffractometer, 939 crystallographically independent reflections, anisotropic approximation, R = 0.047). The parameters of the orthorhombic unit cell are a = 4.695(1) Å, b = 11.906(3) Å, c = 20.38(3) Å, sp. gr. Pnma, Z = 4. On the whole, the structural formula obtained, (Si_2.43Sb_0.36As_0.21)BO₃[(Al_0.62Ta_0.26□)Al₂(Al_0.98□)₂(Al_0.94□)₂O₁₂](O,OH,□)_2.65, corresponds to the electron-probe analysis data. The statistical replacement of (Si,As)O₄ tetrahedra by pyramidal [SbO₃] groups is confirmed. The X-ray diffraction spectra of holtite I are compared with those of holtite II.     

Crystal structure of zirconium-rich seidozerite

The crystal structure of seidozerite was refined (a Siemens P4 diffractometer, MoK _α radiation, 1180 independent reflections, anisotropic refinement, R = 0.053). The monoclinic unit-cell parameters are a = 5.627(1) Å, b = 7.134(1) Å, c = 18.590(4) Å, β = 102.68(1)°, sp. gr. P2/c, Z = 4. The structural formula, Na_1.6Ca_0.275Mn_0.425Ti_0.575Zr_0.925[Si₂O₇]OF, agrees well with the results of the electron probe analysis. Seidozerite is demonstrated to belong to the meroplesiotype polysomatic series including the structures of more than 30 titano-and zirconosilicates.