Multicomponent Diamond-Like Semiconductors Based on the InBV–CdS System: Bulk and Surface Properties

Semiconductors - According to developed methods, in the fields of the mutual solubility of initial binary compounds (InP, InSb, and CdS), solid solutions of the InP–CdS and InSb–CdS...     

Structure and composition of guanidine acrylate, guanidine methacrylate, their homopolymers, and copolymers with diallyldimethylammonium chloride

Structures and compositions of the monomers guanidine acrylate and guanidine methacrylate, their homopolymers, and copolymers with diallyldimethylammonium chloride enriched in acrylate comonomer units were determined. It was shown that ampholytic copolymers, owing to their ionic nature, contained comonomeric guanidine acrylate or methacrylate units and diallyldimethylammonium chloride units, as well as the acrylate comonomer with the diallyl counterion and polymeric acrylate and diallyl ion pairs. It follows from IR and ¹H NMR data that guanidine methacrylate has the same structure (with two hydrogen bonds) in the solid state and in solutions. Guanidine acrylate structures in the solid state and in dimethylsulfoxide are identical and analogous to guanidine methacrylate structure in this solvent. In water, the guanidine acrylate structure has another type of hydrogen bonding (with one hydrogen bond, where the proton is shifted toward the guanidine group). These features of hydrogen bonding of guanidine acrylate and guanidine methacrylate are also retained in their homopolymers and copolymers with diallyldimethylammonium chloride. It was shown that the thermal stability of the copolymers was higher than that of their homopolymers, confirming the formation of intramolecular ion pairs of oppositely charged units of ampholytic copolymers. Moreover, the thermal stability of guanidine methacrylate-diallyldimethylammonium chloride copolymers is higher than that of guanidine acrylate-diallyldimethylammonium chloride copolymers.     

Thermal Transformations of an Aluminoborophosphate Binder

Thermal transformations of a commercial aluminoborophosphate binder are studied in a broad temperature range by optical microscopy, x-ray diffraction, IR spectroscopy, and thermal analysis. The introduction of B₂O₃ reduces the temperature of phosphate polycondensation, enhances the stability of cyclometaphosphates in a broad temperature range (180–1100°C), and reduces the stability of hydrogen phosphates.     

Efferct of the μ-phase on the properties of superhigh-temperature derofmable nickel alloy KhN60KVYuMB

One of the requirements imposed on high-temperature nickel alloys for long-term operation under high temperatures and stresses is structural stability, which ensures constant properties during operation of parts. It is known that the main strengthening phase of nickel alloys is a -phase of the type (Ni, Cr)₃(Al, N) or (Ni, Cr)₃(Al, Ti, Nb), which may amount to 50% in deformable nickel alloys. In addition, these alloys contain a certain amount of carbides, borides, and carbonitrides (up to 3 wt. %). An increase in the content of alloying elements in high-temperature alloys may cause formation of undesirable TCP-phases in their structure. For example, at high contents of molybdenum and tungsten a thin lamellar p-phase (Ni, Co, Fe)₇(Mo, W)₆ is segregated. The authors investigated the effect of the -phase on the set of chemical properties of industrial alloy KhN60KVYuMB (pressed rods 105 mm in diameter).Translated from Metailovedenie i Termicheskaya Obrabotka Metallov, No. 9, pp. 15–19, September, 1995.     

Electrical properties of a SiC-Si multilayer structure

The charge properties of a multilayer structure, composed of silicon-carbide polytypes on a silicon substrate, are investigated. Knowledge of the properties of the space-charge region of silicon and the possibility of affecting the surface of a structure by the field effect [1] provides data on the charge processes at the interfaces between the polytypes. These data are urgent for improving the methods of synthesizing electronic structures based on SiC polytypes.     

Studying natural oxide on the surface of n-Si(111), n-Si(100), and p-Si(111) single crystal wafers by X-ray reflection spectroscopy

The state of the surface of standard phosphorus-doped n-Si(111) and n-Si(100) (KEF grade) and boron-doped p-Si(111) (KDB grade) single-crystal wafers treated in a 50% HF–70% HNO₃ (1: 3, v/v) polishing solution has been studied using soft X-ray reflection spectroscopy. The fine structure of the reflection spectra in the region of the Si L _2,3 ionization threshold has been analyzed. The dependence of the natural oxide thickness on the orientation of a silicon single crystal surface is established.     

Passivation of Chrome-Plated Sheet Iron in Electrolytes Based on Chromium(III) Salts

Passivation of chrome-plated sheet iron in electrolytes based on Cr(III) salts and capable of completely replacing highly toxic and aggressive electrolyte based on Cr(VI), is studied.     

Structural special features and infrared spectra of absorption of ultradisperse boron nitride

Conclusions The ultradisperse powders of boron nitride with the mean particle size of 5.3–66 nm showed marked anisotropic deformation of the crystal lattice as a result of the structural stresses which are caused by the dimensional factor and are distributed nonuniformly through the volume of the particle.The turbostratic strain leads mainly to weakening of the interlayer bonds and shifts the maximum of the band of the interplanar oscillations to lower frequency by 17 cm^–1 for the specimen with a dispersion of 5.3 nm. In addition to this, the turbostratic strain causes asymmetric widening of the band of the intraplanar oscillations in the short-wave wing of the curve and displaces the maximum of this band by 20 cm^–1 to the short-wave range (for the specimen with a dispersion of 5.3 nm).Examination by the IR spectral method showed that the interatomic bonds shorten on the average by 10^–4 nm within the limits of the flat lattices. The investigations revealed the regular nature of the removal of the strain of the crystal lattice from the ultradisperse boron nitride during vacuum heat treatment accompanied by sintering of the powder.Translated from Poroshkovaya Metallurgiya, No. 1(301), pp. 85–91, January, 1988.