Materials Literature
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Thermoluminescence properties of Li2B4O7 polycrystalline powder undoped and doped with Cu or Eu impurities are investigated. Glow curves of ß irradiated samples are recorded and the dependences of their shapes and of the peak intensities on the dopant concentrations are determined. The results obtained for Li2B4O7:Cu…
Techniques of electron microscopy and specimen preparation of polymers for studying morphology and interfacial layers are briefly reviewed, including a discussion of general problems of electron microscopic investigations of polymers arising from irradiation sensitivity and low contrast. To improve contrast, some irra…
This experiment describes the synthesis of 1,4,8,11-tetraazacyclotetradecane and its nickel(II and III) complexes avoiding the use of percholrate anion. The paramagnetic effects in solution and solid state are described for the nickel(III) dihalo derivatives along with a spectrophotometric study.
Stress corrosion experiments were carried out on oriented single crystals of copper-gold and copper-zinc (α-brass) using constant and slow strain rate (SSR) loading modes under various chemical conditions in which passive oxides were present on the surface or dealloying occurred in the absence of such films. Results s…
Abstract A first-principles method for the computation of electric field gradients (EFG) is illustrated for various borides. It is based on energy band calculations using the full-potential linearized aug-mented plane wave (LAPW) method within density functional theory. From the self-consistent charge density distribu…
Internal photoemission is a photoelectric characterization technique commonly used to study semiconductor heterojunction characteristics. Previous analyses of internal photoemission including those of Fowler, Kane, and Powell have been well accepted and applied; however, the quantum effects were not fully taken into a…
A novel multipulse laser technique has been used to study the crystallization behavior of the GeTeSe ternary system, and the dependence of the nucleation and growth rates on composition has been related to the optical and structural properties. We show that the Se content is dominant in determining both the nucleation…
The anodic reaction on spectrally pure graphite (SPG) and pyrolytic graphite was studied in the potential range from 1.2 to 1.8 V vs. an aluminium reference electrode in alumina‐saturated cryolite melts at 1000°C by means of electrochemical impedance spectroscopy. It has been found that the total electrode reaction ca…
1,5-Dioxepane-2-one (DXO) was coordinatively ring-opening polymerized with different Lewis acids in bulk and solution. The reactivities of a series of initiators (SnCl4, FeCl3, AlCl3, BCl3, and BF3OEt2) at different temperatures and reaction times were analyzed. Polymerization of DXO in bulk with SnCl4, FeCl3, AlCl3,…
Real-space observations of gasification reaction of graphite surface caused by UV irradiation were made using scanning tunneling microscopy (STM). The formation of etch pits on highly oriented pyrolytic graphite (HOPG) surface during gasification reaction was investigated. At the beginning of gasification reaction, do…
Abstract Sedimentary zeolites clinoptilolite, mordenite and erionite occur as diagenetic products of ash falls of rhyolitic composition from the Oligocene Chichindaro Formation at the limits of the Mexican Volcanic Belt with the Mexican Highland. These zeolitic tuffs were formed from open hydrologic environments where…
TL emission characteristics have been studied from LiF(Mg,Cu,P) samples prepared at the Institute of Nuclear Physics in Krakow, Poland in which the Cu concentration has been varied from 0.002 mol% to 0.5 mol% while the Mg content (0.2 mol%) and P content (1.25 mol%) were kept constant. Thermoluminescence has been reco…
Thermal quenching of TL processes in dosimetric anion-defective a-Al2O3 single crystals was studied by investigating the temperature dependence of radioluminescence and photoluminescence in the range of 77-550 K. It is established that the process of quenching is most effective in the temperature range of the dosimetr…
Abstract Nine new compounds AMX with A: Ca, Sr, Ba, M: Pd, Au and X:P, As were prepared by heating mixtures of the elements and investigated by Xray methods. They crystallize in modified AIB 2 - type structures, for the present examples in the ZrBeSi- and SrPtSb-types, with an ordered distribution of the atoms
The relaxation of density fluctuations in charge-stabilized colloidal suspensions is characterized by the dynamic structure factor S(q,t), which can be measured by dynamic light scattering. Whereas the short-time behavior of this quantity is well understood, its characteristics at longer times are more difficult to de…
Abstract A comparative study is reported in which kaolinite has been hydrothermally synthesized at several pH conditions. The syntheses were carried out at 220 °C for 3 to 10 d with distilled water or acidic solutions using a mixture of silica-gel derived from alkoxide and gibbsite with a Si/Al ratio of 1:1 as the sta…
In Buenos Aires province, the river Samborombón, which is typical of the plain, was sampled monthly during 1986-1987 in research carried out both on its physico-chemical characteristics and the communities present - plankton, phytobenthos, zoobenthos -. In this paper the structure and function of phytoplankton and ben…
Abstract Die bislang unbekannte Kristallstruktur der schwarzen, binären Verbindung Al 2 Te 5 wird durch Rietveld‐Verfeinerung an Röntgen‐Pulverdaten aufgeklärt: a = 1359,29(3) pm, b = 415,27(1) pm, c = 983,92(2) pm, β = 126,97(1)°, Raumgruppe: C2/m (Nr.12), Z = 2. Al 2 Te 5 ist im Unterschied zu Ga 2 Te 5 und In 2 Te…
The physical interactions of polymers with inorganic substrates are determined by two major contributions: Van der Waals forces and acid-base interactions, taken in the most general “Lewis” electron acceptor-donor sense. The present work shows that the work of adhesion can be very appreciably increased by the creation…
The modal analysis of samples belonging to the zeolite-rich pyroclastic formation named “Neapolitan yellow tuff” (Central and Southern Italy) has been determined by full-profile refinement of X-ray powder diffraction (XRPD) data using a combined Rietveld–RIR method. The quantitative analysis and especially the zeolite…