Materials Literature
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The authors provide a brief history of the art of calligraphy in Muslim cultures, highlighting examples of tessellations of words. The underlying principles for designing a word tessellation inscribed in a hexagon are discussed, and a test for determining which words can be tessellated is provided. The authors demonst…
Mn-Al thin films with the composition of 31-68 at.% Mn were prepared by rf magnetron sputtering at various substrate temperatures then annealed in vacuum. Effects of the chemical composition, substrate temperature and annealing temperature on the magnetic properties of Mn-Al films have been investigated. The analysis…
The perovskite-related oxide Ca2Fe2O5 takes up additional oxygen under high pressure and elevated temperature. The Mössbauer spectra from a number of preparations establish the existence of new phases which are structurally related to the original lattice. The latter features an ordered arrangement of oxygen vacancies…
An earlier statistical model for the spatial arrangement of isotopically labelled ‘stems’(single molecular traverses) within single crystals has been extended, with the probability of deposition of a labelled stem following another labelled stem (PA), the probability of labelled stem deposition after an unlabelled one…
The structures of the two fast ion conducting glass systems (AgI) x (Ag 2 O–2B 2 O 3 ) 1- x and (LiCl) x (Li 2 O–2B 2 O 3 ) 1- x have been examined. The neutron diffraction experiments revealed large similarities in the short range order of the B–O network for the two glass systems. However, remarkable differences are…
A new dynamic mechanical rheological tester called the RPA 2000 rubber process analyzer by Monsanto can analyze rubber masterbatches as well as rubber compounds before, during and after cure. It requires no special sample preparation, is easy to operate, and can apply a wide range of dynamic test conditions to a rubbe…
SiC bulk material is manufactured in the desired shape from an organopolysiloxane‐based pre‐ceramic polymer by pyrolysis. For an evaluation prototype, an emitter was made in form of a 7’’ tube with 1.5’’ diameter for operation at 1400 °C–1700 °C in conjunction with a GaSb photovoltaic cell (Eg=0.67 eV). The spectral d…
The effects of Ta addition on the resistivity and hillock suppression were studied in Al-Ta sputtering films in comparison with Al-Cu alloy films. Ta was dissolved in the Al matrix of the as-deposited films. The metastable AlTa solid solution was decomposed into Al3Ta during annealing at more than 573 K. As the Ta con…
The effect of talc grain size on the microstructure of cordierite ceramics prepared from the talc, kaolin and alumina was studied. Six kinds of talc materials with various grain size distributions were prepared by classification and grinding. Enstatite formed by decomposition of fine talc grains contributed to the cor…
Zeolite A (NH4-A) exchanged with NH4+ was used as a precursor of mullite. NH4-A was dehydrated and deammoniated by heating up to 300°C and it entered an amorphous state. Mullite crystallized directly from the amorphous phase at above 950°C without forming a spinel phase as an intermediate phase. Since the starting mat…
The fine particles of yttrium oxide containing europium are very important for the fabrication of red phosphor. In this study, the synthesis of the fine monodispersed particles containing yttrium and europium from the homogeneous solution using urea as a precipitant generator was investigated. The obtained precipitate…
Abstract The phase diagram of the model of spinless fermions with repulsive nearest neighbour interaction is calculated analytically on a hypercubic lattice in infinite dimensions ( d → ∞). In spite of its simplicity the model displays a rich phase diagram depending on the doping δ, the interaction U and the temperatu…
Two basic mechanisms which operate in the functioning of reactive armour are presented. Both the explosive effect and cutting of metal plates by a jet have been investigated. The angle of attack and the confinement of the explosive have been found most significant factors in reducing the penetrating power of the jet.…
The wettability of glass, carbon, and organic fillers (in the form of fibres or fabrics) by powder thermoplastic polymers has been studied. Wettability is the first step in the interaction between the components, a necessary condition for forming an interface, so as to achieve high levels of physico-mechanical propert…
Comparisons of the magnetoelastic responses of the highly magnetostrictive compound Terfenol-D (Tb/sub 0.3/Dy/sub 0.7/Fe/sub 1.95/) with aluminium substituted compounds Tb/sub 0.3/Dy(Fe/sub 1-x/Al/sub x/)/sub 1.95/ where 0.05/spl les//spl times//spl les/0.10 in the temperature range 20-300/spl deg/C have been made. In…
The polymerization of hydroxyalkylacetylenes [HC°C(CH2)n-OH, n = 1–4) was carried out with various transition metal catalysts. Mo-based catalysts and PdCl2 were very effective for the polymerization of hydroxyalkylacetylenes. The polymer yields generally decreased as the number of methylene units between the hydroxy a…
Abstract The catalytic activity of binary oxides of Al2O3–Eu2O3, Al2O3–Sm2O3, Al2O3–Nd2O3, Al2O3–Pr6O11, and Al2O3–Y2O3 were checked in the transformations of α and β-pinene oxides. Al2O3–Eu2O3 and Al2O3–Nd2O3 are found to be best catalysts for α-pinene oxide isomeriztion. Among the oxiranes, α-pinene oxide showed mor…
Nickel-containing zirconia samples (Ni⩽16.85%), prepared by contacting hydrous zirconium oxide with an Ni2+ solution to a given pH were studied by various techniques (XRD, DTA, TG, XPS) to investigate the incorporation of Ni2+ in the zirconia structure in relation to the dispersion degree of the transition-metal ions.…
Local structures around Si, Ca, Mg, Co, and Ni atoms in CaMgSi2O6, CaCoSi2O6, and CaNiSi2O6 glasses were investigated by X-ray diffraction, XAFS, and optical absorption spectra measurements. Si–O interatomic distances of these three glasses are 1.62 Å and coordination numbers of Si atoms are 4. Mg–O, Co–O, and Ni–O in…
Abstract The general theory of a third‐order generalized photoconductivity in glass is developed using a density matrix approach in the generalized master equation approximation. The theory is applied to third‐order photogalvanic effect in glass in connection with photoinduced second‐harmonic generation in silica.