bluuebunny/crossref_metadata_2025_split huggingface dataset:
Method of X‐ray spectral microanalysis of PbTe and SnTe obtained by the iodide method
Authors: Assenov R. , Moshnikov V. A. , Patarov B. , Yaskov D. A. 
Published: January 2007

AbstractThis an examination of the characteristics of the X‐ray spectral microanalysis of the tellurides of lead and thin, obtained by the iodide method. It was demonstrated that applying the method of calculating the composition in relation to the relative intensity of the characteristic X‐ray radiations of the analytical lines TeLα and ILα secures the possibility of analyzing relief surfaces. Besides that, the method makes it possible to make calculations without using numerous traditional semi‐empirical expressions under conditions of changes in the values of the accelerating voltage.
A simple optical method of measuring the tilt bias angle of liquid crystals
Authors: Jain S. C. , Singh H. K. , Balakrishnan K. S. , Chandra S. 
Published: January 2007

AbstractA simple optical method based on refractive indices measurement for determining the tilt bias angle of liquid crystals is described. The required refractive indices no, ne and nθ are measured by (i) Abbe's refractometer and by (ii) optical wedge method. The tilt bias angle by this technique can be determined to accuracy of ± 0.2° in the high tilt angle range (20° to 40°). This method is rather simple and quick and does not require any external magnetic field and/or knowledge of other physical constant of liquid crystals, as are necessary in some of the earlier reported methods.
Induced SA phases in binary systems with EDA complexing
Authors: Pelzl G. , Böttger U. , Diele S. , Demus D. 
Published: January 2007

AbstractThe phase diagrams of 13 binary systems are presented in which electron donor‐acceptor (EDA) complexing is clearly detectable. In all binary systems studied the same electron donor compound was used whereas the electron acceptor compounds were members of two homologous series. It was found that the induction of smectic A phases increases with increasing length of the alkyl chain of the acceptor compound and with increasing stability of the complexes.
New high precision lifetime measurements in pure copper and a 0.3 at.% AgSb alloy with a BaF2 lifetime spectrometer
Authors: Ederhof M. , Lühr‐Tanck W. , Sager A. , Kurschat Th. , Hehenkamp Th. 
Published: January 2007

AbstractThe temperature dependence of positron annihilation in copper and a 0.3 at.% AgSb alloy has been investigated by measuring the positron lifetime. In both cases the vacancy lifetime is nearly independent on temperature while the bulk lifetime shows a rapid increase after the onset of detectable vacancies. This increase can be explained by trapping during thermalization with an enhanced trapping rate.
Structural phase transitions in Cu2–xFeyS crystals
Authors: Ismailov D. I. , Asadov Yu. G. , Gasymov G. B. 
Published: January 2007

AbstractCrystals with Cu2−xFeyS compositions (x = 0.30, 0.25, 0.20, 0.15; y = 0.05) have been synthetized and obtained by the method of slow cooling. X‐ray diffractometric studies have shown that at room temperature the above crystals consist of an orthorhombic phase (anilite), a monoclinic phase (djurlite), and their metastable high‐temperature facecentered cubic phases (FCC)1 and (FCC)2, respectively. A crystallographic relation has been found between the lattices of the orthorhombic, monoclinic and (FCC)1 phase. It is shown that all these phases transform in the final analysis to a single high‐temperature fcc phase. All the transitions are reversible, i.e. in the course of inverse cooling to room temperature, the diffraction patterns are restored completely in reverse order.
Positron lifetime in inhomogeneous metallic materials
Authors: Gondzik J. , Stachowiak H. 
Published: January 2007

AbstractA positron is considered in an inhomogeneous jellium model according to a formalism following from the theory of liquids. This leads to a nonlocal treatment of the screening of this particle. Annihilation rates have been found inferior to the ones for a homogeneous electron gas, in agreement with positron lifetime measurements.
The interaction of Ni and Au with HCl during quenching
Authors: Beasley P. , Alam A. , West R. N. 
Published: January 2007

AbstractDuring annealing of Ni and Au, previously quenched into HCl at 203 K, annealing stages that cannot easily be explained in terns of the migration of open volume defects are observed. The contamination of the hot samples with hydrogen released from the quenching fluid is suggested as the origin of these additional annealing stages.
Study of clustering of vacancies in cold‐worked nickel by positron annihilation spectroscopy
Authors: Sundar C. S. , Bharathi A. , Gopinathan K. P. 
Published: January 2007

AbstractThe clustering of vacancies occurring during the isochronal and isothermal annealing treatments of a 40% cold‐worked nickel has been investigated through positron lifetime measurements. The observed variation in lifetime has been quantitatively understood by modelling the defect reactions amongst vacancies leading to the formation of vacancy clusters.
Studies on the relation between the magnetic properties and positron lifetime of ALNICO 8 permanent magnet alloys
Authors: Shan‐Yi Liu , Guan‐Qu Zhu , Shao‐Jie Wang 
Published: January 2007

AbstractAlloys ALNICO 8 have been wildly used in industries for their excellent magnetic properties and reliable temperature stability.The present paper has studies the relation between the maximum magnetic energy product (MMEP) of columnar crystallizated AlNiCo 8 permanent magnet alloys cooled continuously in magnetic fields and positron lifetime in this material. The experimental results show that the minimum decay constant τ1 reaches gradually its saturation as MMEP increase, this means the trapped effect obviously happens in the specimens with low MMEP. With the increase of MMEP, the τ2 component reflecting the crystal imperfection decreased, hence, the crystal perfection improved. Mössbauer spectroscopic results also show that with the increase of MMEP, the more parts of magnetic moments orientate to magnetizate direction. This work gives valuable data to improve the properties of materials.
Application of the positron annihilation method for investigations of the diffusion of helium in metals
Authors: Pajak J. , Pietrzak R. , Szatanik R. , Rozenfeld B. 
Published: January 2007

AbstractA method which permits to determine the diffusion coefficient of helium in metals from the measurements of the time dependence of the intensity of annihilation radiation has been outlined. The diffusion of helium cold‐rolled and cold‐rolled and annealed nickel has been investigated. It has been found that the value of the diffusion coefficient of helium along the grain boundaries and dislocations in nickel is of the order of 10−13 cm2 s−1.
On the possibility of polytypism in semistatistically defected wurtzite‐type crystals of CdS
Authors: Horodecki A. J. 
Published: January 2007

AbstractThe analysis of extraordinary reflections of X‐ray pattern of CdS thin films is presented which indicates the existence of 22 H polytype. For the conditions that are favourable for polytypism a new dependence of Madelung constant on the crystal structure is proposed. All of the results are consistent with the concept of semistatistically defected wurtzite crystal.
The possible influence of electric moments on the growth of thin films of pyroelectrics from vapour phase
Authors: Horodecki A. J. 
Published: January 2007

AbstractElectric moments of substrate surface interact with any polar species coming‐in from vapour phase. The re‐mapping of substrate electricity will be continued if both these species and crystals are of uniaxial polarity. Consequently, the additional field at the growing surface is the resultant of crystal “memory” and of pyroelectric charge and seems to be the main reason for the texture. Moreover, considering the microrelaxation of growth the numerous pairs of cation vacancy — anion vacancy are expected. The results indicate the way for understanding the peculiarities of X‐ray pattern of CdS thin films.
Epitaxy of AIBIIIC semiconductors
Authors: Schumann B. , Tempel A. , Kühn G. 
Published: January 2007

AbstractEpitaxial layers of AIBIIIC compounds were grown by the flash evaporation technique and investigated using reflection electron diffraction. Geometric‐structural considerations allow the prediction of epitaxial relationships and types of epitaxy (one‐ or three‐dimensional, multiple orientation). These properties of the epitaxial layers were confirmed experimentally. Furthermore, the epitaxial temperature ranges, non‐equilibrium phases, defects, and special features of the epitaxial growth are described. Especially, the influence of lattice misfit is discussed.
Heat capacity of Ag6Ge10p12 from 180 to 550 K
Authors: Nowak E. , Neumann H. , Omar M. S. 
Published: January 2007

AbstractThe molar heat capacity at constant pressure of Ag6Ge10P12 is measured in the temperature range from 180 to 550 K and the standard molar enthalpies and entropies relative to 298.15 K are calculated on the basis of these data. From a comparison of the temperature variation of the apparent Debye temperatures in CuGe2P3 and Ag6Ge10P12 it is concluded that lattice anharmonicity is more pronounced in Ag6Ge10P12 than in CuGe2P3.
Chemical etching and polishing of InP
Authors: Kurth E. , Reif A. , Gottschalch V. , Finster J. , Butter E. 
Published: January 2007

AbstractThis paper describes possibilities of several chemical preparations for the selective cleaning of InP surfaces. The investigations of the surface states after the chemical treatment were carried out by means of XPS measurements. A pre‐etching with (NH4)2S2O8:H2SO4:H2O and a polishing with 1% bromine in methanol produce optically smooth (100)‐ and (111) P surfaces free of oxides.
An estimation of fracture stress in a brittle solid
Authors: Majumdar B. , Dubey B. N. , Chandra B. P. 
Published: January 2007

AbstractThe present paper reports for the first time an exact analytic expression that can be used for obtaining fracture stress σF, when fracture occurs in the elastic limit and also when fracture occurs after general yield (σF > σY) in a brittle solid. The present paper may provide a new basis to fracture‐safe design of brittle materials.
Thermally stimulated depolarization currents in OH−‐doped NaCl and KCl crystals
Authors: Suszyńska M. , Capelletti R. 
Published: January 2007

AbstractThe main features of the high‐temperature ITC band are analyzed on the basis of experimental results obtained for NaCl and KCl crystals containing the hydroxyl ions. The unusual behaviour of this band has been compared with that described previously for alkali halides, AH, (LiF, NaCl, KCl) doped with some divalent cations, Me++, (Be, Eu, Ni, Pb).It has been shown that — similar to the case of the Me++‐doping‐most of the results obtained can be explained in frames of the Maxwell‐Wagner‐Sillars model of interfacial polarization induced by the impurities forming the charge clouds to the dislocation lines. An ITC band can be detected due to the fact that these regions exhibit electric conductivity and dielectric constants different from those characteristic of the bulk material. The role of the charge of dislocations in the induced polarization phenomenon is shortly discussed.
Low temperature investigations of e−‐irradiated GaAs
Authors: Mascher P. , Kerr D. , Dannefaer S. 
Published: January 2007

AbstractPositron lifetime measurements have been performed on electron irradiated chromium doped semi‐insulating GaAs as a function of annealing between 139 and 908 K. Trapping at negatively charged GaAs defects and by a vacancy mixture dominated by trivacancies took place in the as‐irradiated state. Upon annealing around 210 K divacancies were formed from the trivacancies as caused by migrating arsenic interstitials. Complete trapping prevailed up to 530 K but decreased then rapidly at higher temperatures due to the migration of divacancies which also remove the GaAs defects.
Dependence of positron capture rate on dislocation density in solid solutions of KCl—KBr
Authors: Dhanalakshmi S. R. , Nagarajan T. , Ramasamy S. 
Published: January 2007

AbstractGenerally well‐annealed alkali halide crystals exhibit three lifetime components. τ1 arises due to annihilation with anion and τ2 due to Bloch Ps. The origin of τ3 is not well understood. Positron lifetime and etching techniques have been performed on solid solutions of KCl100−xBrx with mole % of x = 0.0, 15, 30, 37, 50, 70, and 100. The positron lifetime spectra have been analysed to resolve into three components. The positron capture rate K3 for the longest lived component and the dislocation density shows a non‐linear variation with composition. The positron capture rate varies linearly with the dislocation density of the samples. The origin of τ3 is identified as due to positronium formation in the dislocations present in the samples. The trapping probability per dislocation has been estimated to be 2.2 × 10−12/s.
Positron lifetime studies of X‐irradiated N‐acetyl‐D,L‐alanine
Authors: Walker William W. 
Published: January 2007

AbstractPolycrystalline samples of N‐acetyl‐D,L‐alanine (AA) which had received an X‐ray dose of approximately 6 Mrad have been studied by the positron annihilation technique. Data were obtained as a function of time following the radiation treatment, and also as a function of subsequent annealing temperature. The large decrease of the intensity of the longest lifetime component (I3) was observed to be reversible when assisted by heat treatment.
Structural characterization of the ammonium trimolybdate hydrate (NH4)2Mo3O10 · H2O
Authors: Hodorowicz S. A. , Lasocha W. 
Published: January 2007

AbstractWhen normal molybdate solutions are acidified, various isopolymolybdates of increasing degrees of condensation are formed according to different acidifications and other conditions (Sasaki, Sillen; Tsigdinos; Tytko, Glemser). Attempts to identify some complexes have not, however, led to definite conclusions about their existence. In particular, Lindquist — basing on an analytical and X‐ray powder study — suggested that ammonium trimolybdates (NH4)2O · 3 MoO3 · aq described by some authors (Mellor; Guiter; Chans et al.) may be double salts of hepta‐ and octamolybdate. Recently, fibrillar crystals of ammonium isopolymolybdate have been isolated (Lasocha, Hodorowicz). The results of physicochemical analyses correspond to the formula (NH4)2Mo3O10 · H2O. In this paper we focus our attention on the structural characterization of the compound obtained.
Growth mechanism in atomic layer epitaxy (III) reevaporation of Cd and Te from CdTe (111) surfaces and thick elemental deposits monitored by quadrupole‐mass spectrometry
Authors: Herman M. A. , Juza P. , Faschinger W. , Sitter H. 
Published: January 2007

AbstractQuadrupole‐mass spectroscopical (QMS) studies on isothermal reevaporation of Cd and Te species from the CdTe (111) surface have been performed in two extreme cases. The first concerns the reevaporation of thick, bulk‐like non‐crystalline Cd and Te films deposited in high vacuum at room temperature on the (111) surface, whereas in the second case evaporation of the constituent species from the bare single crystalline (111) surface has been investigated. The fluxes of the species desorbing in high vacuum (10−6 Pa) have been monitored with QMS and the desorption temperatures have been measured with a thermocouple mounted as near as possible to the sample surface. The following values Ea(Cd)bulk = 1.13 ± 0.12 eV, Ea(Te)bulk = 1.64 ± 0.18 eV and Ea(Cd)(111) = 1.13 ± 0.06 eV, Ea(Te)(111) = 1.92 ± 0.13 eV of the activation energies for these two cases have been determined from the slopes of the Arrhenius plots.Using these experimental values, the numbers of atomic bonds NCd and NTe occurring in the atomic aggregates of quasi‐gas molecules forming the near surface quasi‐gas transition layers have been estimated. For Cd quasi‐gas molecules 2 ≤ NCd ≤ 5, whereas for Te molecules 3 ≤ NTe ≤ 10. However, no prediction concerning the number of atoms creating the quasi‐gas molecules could be made on the basis of the QMS investigations.It has also been shown that Cd atoms evaporate from the bare single crystalline CdTe (111) surface with an activation energy that is equal (in the limits of the experimental error) to the activation energy for sublimation of Cd atoms from pure, non‐crystalline, bulk Cd pieces. The analogous activation energy measured for Te atoms is about 20% larger than that of the relevant sublimation process. This result confirms the fact that Te atoms are bound much stronger in the CdTe crystal lattice than Cd atoms.
Spectrometer for the study of three‐photon annihilation of three‐photon annihilation of positrons
Authors: Georgiev A. , Misheva M. , Mishev P. , Toumbev G. , Vinarov N. 
Published: January 2007

AbstractA three channel spectrometer for studying three‐photon annihilation is reported. It is based on a fast‐fast coincidence circuit and includes NaJ(Tl) scintillation detectors, constant fraction differential discriminators, a fast coincidence circuit with variable resolving time (6 ns—60 ns), a linear gate and a multichannel analyzer.The possibility of using positron source 64Cu in the spectrometer, its advantages and disadvantages are discussed. In this connection we describe the special units coupled to the spectrometer as well as a method which helps to avoid the influence of the short decay time of 64Cu of the accuracy of the experimental results.
Automatic system for the storage and search of annihilation data
Authors: Abdurasulev Z. , Zhuravleva G. , Malyan V. 
Published: January 2007

AbstractAn automatic information‐searching system AIPS‐Positronika has been developed and is successfully working for several years at the Institute of Electronics of the Uzbek Academy of Sciences. It is intended for collecting, storing, searching and output of information on positron annihilation (Abdurasulev et al.). At present this system has been further developed as an annihilation data bank including the array of experimental annihilation spectra and their individual descriptions (Arifov et al.; Malyan et al.).
On the mechanism of AlSi alloy structure modification by metal antimony
Authors: Yaneva S. , Stojanova L. , Stoichev N. , Kamenova Z. 
Published: January 2007

AbstractIn the process of AlSi alloys solidification in presence of Sb the intermetallic compound AlSb is taking obviously a significant part. An adsorptional incorporation mechanism of AlSb action is proposed. It depends strongly on the antimony concentration in the melt.The modifying effect is influenced also by a possibility of nucleation and growth of the AlSb phase itself.
Results of texture simulation in b.c.c. materials
Authors: Dörfel I. 
Published: January 2007

AbstractRolling textures of b.c.c. polycrystals are simulated by the „full constraint”︁ (FC)‐ and the „relaxed constraint”︁ (RC)‐Taylor model, by the FC‐model with glide asymmetry in {112}〈111〉slip systems included, by a combination of FC‐ and RC‐model, and by this combination with glide asymmetry included, respectively. Several cases of activated slip system families have been investigated. Simulation results are compared qualitatively with experimental ones.
Bulk modulus — volume relationship in alkali halides with rocksalt structure
Authors: Neumann H. 
Published: January 2007

AbstractIt is shown that the bulk modulus of the alkali halides with rocksalt structure follows the simple relation B = b0(1 — b1fc) V where V0 is the unit cell volume, fc the spectroscopically defined covalency of the chemical bond, and b0, b1, and n are constants having the same values for all compounds. This result is compared with the bulk modulus scaling law found for the tetrahedral semiconductors.
Photoelectrochemical solar cells based on TiS2/TiO2(TiOxSy) photoelectrodes
Authors: Chandra Babu K. S. , Srivastava O. N. 
Published: January 2007

AbstractA new photoelectrode of TiS2/TiO2 alloy with a possible new TiOxSy phase has been synthesized for the first time in the present investigation. This photoanode exhibits improved photoelectrochemical (PEC) response as compared to either TiS2 or TiO2 photoelectrode. With this new photoelectrode high PEC conversion efficiency is evidenced by large photovoltage (840 mv) and significantly high photocurrent density (40 mA/cm2). The photovoltage obtained in the present system is significantly high and the photocurrent density is the highest reported so far for the TiO2 based systems. It has been suggested that the enhancement in photoactivity in the present system is due to the reduced band gap of TiOxSy alloy material. Such a band gap reduction is thought to be facilitated by the downward movement of the valence band of titanium disulphide which is made up of chalcogen atoms through substitution of sulphur atoms by oxygen atoms.
Synthesis and characterization of ZSM‐8‐type zeolite crystals
Authors: Joshi M. S. , Mohan Prabhu K. 
Published: January 2007

AbstractProcedure for hydrothermal synthesis of ZSM‐8‐type zeolite crystals, using TEA—OH as a template, in the system having molar composition 16.2 (Na2O) — Al2O3 — 117 (SiO2) — 4.8 (TEA)2O — 3887 H2O at 170 °C is described. Results of characterization of these crystals by XRD, IR, EDAX, SEM, TGA, and adsorption studies are described and discussed. X‐ray diffraction studies establish that the crystals are ZSM‐8‐type with structure similar to that of ZSM‐5‐type crystals. Crystals have prismatic bipyramidal morphology with average size 18–25 microns. Degased calcined samples adsorb xylenes in the order p > m > 0. Pore length per unit cell, estimated from n‐hexane adsorption studies, is 46 Å.
Investigation on synthesis, characterization, and electronic behaviour of zinc oxide thin films in relation to fabrication of oxygen gas sensor
Authors: Arya S. P. S. , Srivastava O. N. 
Published: January 2007

AbstractThe zinc oxide thin films were prepared by spray pyrolysis method. The films were characterized by means of X‐ray diffraction and scanning electron microscopy techniques. The annealing treatment at 300 ± 30 °C for 15 and 30 hours improved the crystallinity of the film and also led to a homogeneous film surface. The O2 gas sensing properties of the zinc oxide thin film were studied by investigating the variation of the electrical resistance of the film as a function of O2 partial pressure at various temperatures. The gas sensing property was found to depend on the film characteristics in regard to its state of crystallinity and surface conditions. The gas sensing property was also dependent on the temperature at which the sensing was done. The optimum oxygen gas sensivity was obtained when the temperature of the zinc oxide sensor was maintained at 400 °C. The study reveals that sprayed zinc oxide thin films may be used as a low cost solid state oxygen gas sensor.
Characterization of plasma etching of molybdenum polycid conductor stacks in Cl2/CF4 and Cl2/CF4/O2
Authors: Handke R. , Lippert G. 
Published: January 2007

AbstractThe present paper is concerned with an extremly anisotropic two‐step patterning process for Mo2Si/poly‐Si double layers with an etch‐stop on thick P‐doped CVD‐SiO2. As etching gas Cl2/CF4/O2 and Cl2/CF4 are used. By means of etch rate dependencies, volatilities of possible reaction products and results, obtained from the literature it is attempted to develop a simple qualitative model on the chemism of the process.