Zirconia-based nanocrystals in the ZrO2-In2O3 system

Zirconia-based ZrO₂-In₂O₃ nanocrystals are prepared by hydrothermal treatment of coprecipitated zirconium oxyhydroxide and indium hydroxide. Indium oxide is shown to dissolve predominantly in cubic zirconia nanocrystals. Its solubility in nanocrystalline zirconia notably exceeds the equilibrium In₂O₃ solubility in ZrO₂ single crystals.     

Deposition of Al2O3 and SiO2 Films via Pyrolysis of Aluminum Acetylacetonate and Hexamethyldisiloxane in the Presence of Nitrogen Compounds

Kinetic measurements were used to assess the effects of N₂O, NO, and diethylamine on the chemical vapor deposition of SiO₂ films on Si from hexamethyldisiloxane and the effect of diethylamine on the deposition of Al₂O₃ films on Si, GaAs, and InP from aluminum acetylacetonate. The composition of the films was determined by electron probe x-ray microanalysis and Auger electron spectroscopy. The deposition kinetics and properties of the films are correlated with the nature of the gaseous admixture and process parameters.     

Thermal Oxidation of a Single-Crystal GaAs Surface Treated in Sulfur Vapor

Inorganic Materials - Surface modification of GaAs in sulfur vapor by different procedures and subsequent annealing and thermal oxidation have an advantageous effect on the properties of...     

Facile co-precipitated synthesis of NdFeO3 perovskite nanoparticles for lithium-ion battery anodes

In this report, NdFeO₃ perovskite nanoparticles were facilely prepared by co-precipitation of Nd³⁺ and Fe³⁺ cations in hot water, followed with the pyrolysis process in atmospheric conditions. Morphology and crystal structure of NdFeO₃ perovskite were determined with appropriate methods, revealing orthorhombic lattice with size distribution from 40 to 180 nm. Functioning as anode lithium-ion batteries (LIBs), NdFeO₃ exhibited great electrochemical performance such as high retention capacity, excellent cyclability, and high current rate. Such enhanced electrochemical efficiency was evidently ascribed to the perovskite structure of NdFeO₃ due to short lithium-ion diffusion pathway and volume expansion control of working material during lithiation/delithiation operation. By demonstrating a capacity value of 475 mAh g^?1 even through 450 cycles at 0.1 A g^?1, NdFeO₃ perovskite nanoparticles proved itself a competitive anode material for the coming generations of LIBs. In addition, this novel synthesis method is suitable for mass production of perovskite materials for long-life lithium-storage facilities.

     

Effect of high-temperature annealing on solid-state reactions in hydroxyapatite/TiO<Subscript>2</Subscript> films on titanium substrates

Hydroxyapatite (HA) films 0.5 and 1 μm thick with a 0.2-μm TiO₂ underlayer have been grown on titanium by rf magnetron sputtering. After annealing in an argon atmosphere at 900, 950, and 1000°C for 30 and 60 min, the phase composition, elemental composition, and surface morphology of the films have been determined by scanning electron microscopy, X-ray microanalysis, and X-ray diffraction. The surface microstructure of the films is shown to depend on annealing temperature. X-ray microanalysis results indicate that, at HA layer thicknesses of both 1 and 0.5 μm, the Ca/P ratio increases with annealing temperature. In addition, the Ca/P ratio in the films produced under identical conditions depends on the film thickness. X-ray diffraction data indicate the presence of reaction intermediates. A TiO₂ interlayer in the HA/Ti system inhibits titanium oxidation, and the reaction intermediates forming during heat treatment improve the adhesion between the titanium and HA.     

Influence of the physicochemical nature of chemical stimulators and the way they are introduced into a system on the mechanism of the thermal oxidation of GaAs and InP

Studies of the chemically stimulated thermal oxidation of GaAs and InP demonstrate that the physicochemical nature of the chemical stimulator determines the mechanism of the process and the possibility of introducing it into the system in different ways. It has been shown that, when a chemical stimulator is introduced through the gas phase or applied to a semiconductor surface by mild methods, the oxidation process follows an oxygen transfer mechanism. When harsh methods are used to apply chemical stimulators that ensure persistent cyclic behavior of the process, it follows a synchronous catalytic mechanism.     

Thermal oxidation of indium phosphide in the presence of lead, zirconium, and titanium oxides

A nonlinear effect of activation of InP thermal oxidation by lead, titanium, and zirconium oxides introduced during the process was discovered. The source of the activating admixtures was their solid solution. Under such conditions, mass transfer of metal cations towards the outer interface of the solid-phase source becomes the reaction-rate-limiting process. Oxide formation in an InP film is the governing process     

Growth of vanadium oxide films on InP under mild conditions and thermal oxidation of the resultant structures

Techniques have been developed for producing vanadium oxide films (10 nm to 1 μm thick) on indium phosphide using vanadium(V) oxide gels and sols through immersion and deposition from aerosol. Using scanning tunneling microscopy and X-ray diffraction, we have studied the influence of annealing temperature and time on the morphology and composition of the films and the influence of the films on the thermal oxidation of InP.     

Metalorganic Chemical Vapor Deposition of Antimony Oxide Films on Semiconductor Substrates

The growth kinetics of oxide films on silicon and gallium arsenide substrates were studied, using alkyl and alkoxide metalorganic precursors (triethylantimony, tripropylantimony, antimony butoxide, and antimony tri--aminoethoxide). The effect of thermal annealing on the microstructure and properties of the films was examined. Analysis of the deposition kinetics, composition, and properties of the films demonstrates that metalorganic chemical vapor deposition in an oxidizing atmosphere, using antimony butoxide or triethylantimony as a precursor, enables the growth of insulating layers on Si and GaAs at low temperatures (130–300°C).