The influence of thermal annealing on the optical properties of nanocrystalline zinc sulfide films

The influence of thermal annealing on the photoluminescence, electroluminescence, and the transmission and reflection spectra in nanocrystalline zinc sulfide films has been studied. All the samples exhibit a broad emission band, the intensity of which depends on the annealing temperature. It is shown that luminophors, the crystal lattice of which includes imperfections that appeared in the transition from wurtzite to sphalerite, feature the highest emission intensity.     

Potential-flow studies of steady two-dimensional jets, waterfalls, weirs and sprays

Various numerical and analytical calculations of jets, waterfalls, weirs and sprays are discussed. Steady planar potential flows are considered. Boundary-integral-equation methods, series-truncation techniques and slender-body theory are among the methods to be used. The connections between the various results are stressed. Joint work with Professor E. O. Tuck as well as research inspired by him are presented.     

Processing and electromechanical properties of lanthanum-doped Pb(Zr,Ti)O<Subscript>3</Subscript> extruded piezoelectric fibres

This article describes the processing and characterisation of lanthanum-doped lead zirconate titanate (PLZT)-based ferroelectric fibres for composite transducer applications. X-ray diffraction of the extruded and sintered fibres indicated some lead loss during sintering; however, the fibres exhibited low porosity (1.54%), high maximum piezoelectric strain (4041 ppm) and relatively low coercive field (0.77 kV/mm). The low coercive field of the lanthanum-doped fibres may be advantageous in terms of facilitating polarization of the fibres in composite architectures.     

Determination of Se,As, Sb,Te, and Bi in wastewaters of mining-and-processing integrated works with the use of AAS-ETA

The procedure of analysis of wastewaters of mining-and-processing integrated works on the content of Se, As, Sb, Te, and Bi with the use of an atomic absorption method with electrothermal atomizer, which involves the preliminary sample preparation and choice of temperature program, modifier, and corrector of nonselective absorption, was described. The conditions were matched for the determination of low concentrations of these elements in natural waters.     

High-pressure volume magnetostriction in the diluted magnetic semiconductor Cd1 ? xMnxGeAs2 (x = 0.06–0.3)

The specific volume of the diluted magnetic semiconductor Cd_{1 − x} Mn _x GeAs₂ (x = 0.06–0.3) has been determined for the first time by strain measurements at pressures of up to 7 GPa. From the pressure dependences of the relative specific volume, we evaluated the volume magnetostriction (spontaneous magnetization coefficient). A scaling relation was used to estimate the bulk modulus of the magnetically ordered and disordered phases.     

Phase relations in the Nb-Cr-Sb and Nb-Mn-Sb systems

The 970-K phase relations in the Nb-Cr-Sb and Nb-Mn-Sb systems have been studied by X-ray diffraction. The systems contain no ternary compounds. There are substitutional solid solutions based on binary antimonides. The Nb₅Sb₄-based solid solution (Ti₅Te₄ structure) extends to the composition Nb_4.1Mn_0.9Sb₄; the Nb₃Sb-based solid-solution series (Cr₃Si structure) is bounded by the compositions Nb_2.6Cr_0.4Sb and Nb_2.4Mn_0.6Sb; the Cr_{1.04 − x} Sb_{0.96 + x} -based solution with x = 0.08 (NiAs structure) exists between the compositions Cr_0.94Nb_0.10Sb_0.96 and Cr_0.70Nb_0.30Sb_1.00; and the Mn_{1.00 + x} Sb_{1.00 − x} -based solution with x = 0.1 extends to the composition Mn_0.9Nb_0.2Sb_0.9. In addition, there is an interstitial solid solution (Ni₂In structure), which extends to MnNb_0.25Sb. The 970-K isothermal sections of the Nb-Cr-Sb and Nb-Mn-Sb phase diagrams are mapped out in the region 0–80 at % Sb.     

Probing of wood–cement interactions during hydration of wood–cement composites by proton low-field NMR relaxometry

Proton NMR T ₂ relaxometry has been applied to investigate phenomena involved in wood–cement composites during hydration. The transformation of capillary pore water into hydrates and gel pore water, as well as the microstructural changes occurring in the cement matrix, was continuously monitored during the first 28 days of hydration. Water in wood and its transfer into the matrix as cement hardens were also evidenced with the method. It has been found, for example, that some of the water in the mixture is retained in wood in the form of bound or free water, depending on the initial water content. By measuring the area under the different peaks, the consumption of water during hydration can be measured and the advancement of the hydration process can be evaluated via the hydration advancement coefficient α. The cement hardening within the composite has been also studied in the presence of calcium chloride, an accelerating agent. The acceleration was clearly evidenced at the early stage of the hydration process. The influence of extractives has been evaluated by comparing the hydration behaviour of composites prepared from Eucalyptus saligna (low extractives content) and Afzelia bipendensis (high extractives content), and a new compatibility index based on NMR relaxometry measurements has been proposed.     

Split Hopkinson pressure bar testing of 3D woven composites

Results from a series of split Hopkinson pressure bar (SHPB) tests on 3D woven tetxile composites (3DWC) are presented. These tests were done to determine the rate dependent compression response of 3DWC. Three different configurations of the 3DWC, corresponding to compression response in the plane of the material and through-the-thickness direction (out-of-plane) were studied. The rate dependent responses were compared against quasi-static test results and it was found that 3DWC showed an increase in strength in all three directions studied, however, accompanied by a transition in the failure mechanism. The in-plane orientations showed the largest increase in (about 100%) strength at the elevated rates of loading. A follow-on paper provides finite element based results that correspond to the experimental results presented here.