Weakly Ordered Nanostructured Silver Disilicate and Its Colloidal Solutions: Preparation and Properties

Technical Physics - It was shown that the interaction of silver cations in alkaline aqueous solutions with various kinds of silicates, regardless of their chemical and aggregation state, leads to...     

Preparation of Nanosized α-Fe2O3 Using Mechanical Activation

The processes occurring during the mechanical activation of a-Fe₂O₃ (hematite) in the presence of oleic acid in a centrifugal-planetary mill have been investigated. Mechanical activation for 10 h afforded hematite powder with particles size of 10–40 nm, as shown by means of X-ray diffraction analysis, FTIR spectroscopy, high-resolution transmission electron microscopy, and specific surface area measurements. Longer milling has led to mechanochemical transformation of hematite into Fe₃O₄ (magnetite).

     

Solid-phase synthesis of nanocrystalline lanthanum zirconate using mechanical activation

Nanocrystalline lanthanum zirconate La₂Zr₂O₇ was synthesized by the solid-phase method using preliminary mechanical activation of a La₂O₃ and ZrO₂ mixture. Processes occurring during heating the mixture of mechanoactivated lanthanum and zirconium oxides were studied using the X-ray phase analysis, IR spectroscopy, and complex thermal analysis. Synthesized lanthanum zirconate was characterized by the X-ray phase analysis and transmission electron microscopy methods.     

Studying the Optical and Structural Properties of Three-Dimensional InGaP(As) Islands Formed by Substitution of Elements of the Fifth Group

Technical Physics - A new method for the formation of three-dimensional quantum-dimensional InGaP(As) islands is proposed, which consists in replacing phosphorus with arsenic in an InGaP layer...     

Examination of the Capabilities of Metalorganic Vapor-Phase Epitaxy in Fabrication of Thin InAs/GaSb Layers

Technical Physics - The capabilities of metalorganic vapor-phase epitaxy (MOVPE) in fabrication of structures with thin (1–2 nm) alternating InAs/GaSb layers on a GaSb substrate are studied....     

Formation of silver nanoparticles in photothermorefractive glasses during electron irradiation

The formation of silver nanoparticles in photothermorefractive glasses during electron irradiation and subsequent heat treatment is experimentally studied. The optical density spectra of samples at various stages of heat treatment are compared. The formation of metallic nanoparticles is shown to occur during both electron irradiation and subsequent heat treatment. Nanoparticles are localized in layers parallel to the surface. At the initial stage of nanoparticle formation, the key role is played by the appearance of a negative bulk charge in the near-surface layer in glass, which results in the field-assisted migration of positive metal ions and a characteristic layered distribution of metallic nanoparticles in the glass volume.     

Solid-state synthesis of nanocrystalline strontium zirconate assisted by mechanical activation

Nanocrystalline SrZrO₃ has been synthesized by a solid-state procedure using mechanical preactivation of a strontium carbonate–zirconia mixture in an AGO-2 centrifugal planetary mill. The effect of mechanical activation of the reactant mixture on the processes occurring during its subsequent heating has been studied by thermal analysis. The resulting strontium zirconate has been characterized by X-ray diffraction and by scanning and transmission electron microscopy.     

Synthesis of La<Subscript>2</Subscript>Zr<Subscript>2</Subscript>O<Subscript>7</Subscript> by thermal treatment of mechanically activated salt mixture

A lanthanum zirconate La₂Zr₂O₇ was synthesized by soft mechanochemical method using zirconium oxynitrate ZrO(NO₃)₂·6H₂O and lanthanum carbonate La₂(CO₃)₃·8H₂O as reagents. Mechanical activation of the reagents was carried out in a centrifugal planetary ball mill. The processes occurring during calcination of the jointly and the separately mechanically activated salt mixture were studied using DSC, TG coupled with mass spectrometry, XRD analysis, and FTIR spectroscopy. It was shown that in the course of joint mechanical activation in the mill alongside with intimate mixing of the reagents and their amorphization exchange reaction occurred, producing lanthanum nitrate, basic lanthanum nitrate, basic zirconium carbonate, and hydrated zirconium oxide. The DSC curve of the jointly mechanically activated salt mixture showed a strong exothermic peak at 878 °C which was not associated with mass loss. This peak was attributed to La₂Zr₂O₇ crystallization in agreement with XRD data. Nanocrystalline lanthanum zirconate synthesized by annealing of the jointly mechanically activated salt mixture was characterized using XRD analysis, scanning, and transmission electron microscopy.