The Influence of Mechanical Activation of Quartz and Quartz/γ-Al2O3 Mixtures on the Sodium A Zeolite Formation

It could be shown that the preparation of sodium A zeolite is possible by the reaction of quartz and γ-Al₂O₃ with NaOH-solution. The zeolite formation is dependent on the mechanical preliminary treatment of quartz. Only the partially crystalline part of quartz dissolves and reacts with Al₂O₃ to form zeolite. The grinding of quartz/γ-Al₂O₃ mixtures can in certain limits raise the zeolite formation but essentially only influences the kinetics of the zeolite formation.     

Mechanical Damping of YBa2Cu3O7 –x at Temperatures above 300 K

Damping of ultrasonic waves with frequencies in the 100 kHz region was measured in the temperature region 300 … 1000 K. Two peaks could be observed (near 400 K or near 700 K, respectively). Occurrence of these peaks depends on oxygen content of the sample. The higher temperature peak is attributed to phase transition Pmmm 〈– – –〉 P 4/mmm of YBa₂Cu₃O_{7 – x}.     

Oxide-free etching of (100) InP surfaces

We report several combinations of chemical preparation procedures for selective cleaning of InP (100) surfaces in connection with storage procedures. A complex of analytical methods was used to get information about the surface state, the morphology, and the perfection of the surface. Using a standard etch procedure developed by KURTH et al. a post-deoxidation by small concentrated HF or HNO₃ is sufficient to get oxide-free, clean InP (100) surfaces even after a storage in methanol for some hours.     

Crystal and molecular structure of 2.2′-dihydroxyazobenzene

C₁₂H₁₀N₂O₂; monoclinic, space group P1 2₁/c 1 (Z = 2), 826 observed independent reflexions, R = 0.043; lattice dimensions at 25 °C, a = 975.8(3) pm, b = 466.8(1) pm, c = 1186.8(2) pm, β = 108.51(1)°.     

Chemistry of organic eutectics: Phenanthrene — benzoic acid and phenanthrene — cinnamic acid systems

Solid-liquid equilibrium data for binary systems of phenanthrene with benzoic acid and cinnamic acid, expressed in the form of temperature-composition curves, show the formation of a simple eutectic in each case. Linear velocity of crystallisation (v), studied by capillary method at different undercoolings (ΔT), suggests the applicability of Hillig-Turnbull equation, v = u(ΔT) ⁿ, where u and n are constants depending on the nature of solidification. Data on heats of fusion of pure components and eutectics, determined by the DTA method, infer appreciable interaction among the components in the eutectic melts. To highlight the nature of interactions among the components forming the eutectic melt, the excess thermodynamic functions such as h^E, s^E, and g^E were computed. Microscopic studies reveal that the structure of eutectic is different from those of the parent components. Infrared spectra, recorded in the region, 4000 —625 cm⁻¹, indicate weak interactions among the components in the eutectic.     

Dynamics of loop soliton solutions of $${\pmb {\mathcal {PT}}}$$PT-symmetric nonlocal short pulse equation

Nonlinear Dynamics - In this article, we present a system of coupled short pulse equations as integrability condition of associated generalized linear eigenvalue problem. We obtain system of...     

Charge Properties of Thorium Implanted in Silicon Oxide

Physics of Atomic Nuclei - A study of thorium atoms implanted in silicon oxide was carried out within the density functional theory method. The charge properties of Th in the ThO2:nSiO2 and...