Materials Literature
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Abstract It has long been the bane of analytical electron microscopy (AEM) that the use of focused probes during microanalysis of specimens increases the local rate of hydrocarbon contamination. This is most succinctly observed by the formation of contamination deposits (fig.l) during focused probe work typical of AEM…
Pure and doped (Benzophenone and Urea) triglycine sulphate (TGS) crystals have been grown from aqueous solution by slow cooling method. The influence of doping of benzophenone and urea on the growth and electrical properties have been investigated. The pyroelectric coefficient increases with the addition of benzopheno…
Ba 6 CoNb 9 O 30 and Ba 6 FeNb 9 O 30 in space group P 4 bm are shown to satisfy the structural criteria for ferroelectricity. Ba 6 CoNb 9 O 30 undergoes a diffuse phase transition at 660 (11) K, as observed calorimetrically, in addition to a dielectric permittivity anomaly with an onset temperature of 685 (10) K. The…
Abstract Treatment of a C222‐vanadyl‐AMP complex (C222 = cryptand‐222, AMP = adenosine monophosphate) with Me 2 NH in the presence of air yielded centrosymmetric dihydrogen‐decavanadate H 2 V 10 O 4 28 , sandwiched by two diprotonated C222 molecules. An X‐ray crystal‐structure analysis was performed of this compound w…
The desorption processes of adsorbed impurity ions on various alignment layers in nematic liquid crystal cells have been studied by measuring ac conductivity of the cells. The liquid crystal used here is 4-cyano-4′-pentyl biphenyl. The adsorption of the ions is induced by the application of dc voltage to the cells. It…
Four major cardenolide glycosides of Xysmalobium undulatum (L.) R. Br. roots (Uzara) have been isolated for the first time in pure form. The structures were elucidated by spectral analyses and determined as sophorosides and their 17-epimers, respectively. Thus, the structural elucidation of uzarin and xysmalorin, the…
A thermal conductivity augmentation technology for zeolite beds has been studied in this paper. To enhance the effective thermal conductivity of zeolite, the zeolite particle was coated with a thermal polymer material in a new synthesis process. It was found that the effective thermal conductivity of the polymerzeolit…
Statistical properties of well-defined fully conjugated poly(3-octylthiophene) (POT) gels are explored above glass transition and fusion temperatures by varying the cross-link functionality, f, and the cross-link concentration, R i . Four series of gels are prepared using four different cross-linking agents. The state…
The article deals with ionic crystals of the type A+B− where the cations are alkali, NH+ 4 or TI+ ions and the anions are the triatomic linear entities SCN−, OCN−, N− 3 and HF− 2. These crystals show a large variety of crystallographic phases which are based on the orientational degrees of freedom of the linear anions…
The grain size distribution of copper and nickel processed by severe plastic deformation was studied by transmission electron microscopy. The temperature dependence of electrical resistivity in the temperature range from 20 to 300 K is presented. The tunnel model of electrical resistivity of grain boundaries is discus…
The analytical models already developed by Smith and Roylance for impact in yarns and impact in textiles have been used, together with a new failure criterion based on the energy that crosses each yarn, to build a simple analytical model of impact in textiles. This model has been checked with Dyneema armours and predi…
The room-temperature phases of sodium potassium molybdates K 3 Na(MoO 4 ) 2 and K 2.5 Na 1.5 (MoO 4 ) 2 are isostructural with the monoclinic low-temperature phases of KaNa(SeO 4 ) 2 and K 3 Na(CrO 4 ) 2 , which are twinned distorted glaserite structures. In the molybdates there are two crystallographically independen…
Abstract A general synthetic route toward symmetric and asymmetric side‐on and end‐on carbazolyl monomers has been developed. The effect of the nature of the core on the induction of liquid‐crystal phases in side‐on carbazolyl polysiloxanes has been studied. Chromophores have been introduced into the carbazole core to…
Solventothermal reaction of certain binary alloys and quaternary alloys with tetraalkylammonium salts in ethylenediamine yielded K6In2Te6·4C2H8N2 and (Ph4P)2In2Te6, respectively. A highly charged dimer, [In2Te6]6-, is observed in the former, while the latter adopts a one-dimensional [In2Te6]2- chain structure in which…
Depending on the operating temperature, gas sensors that are based on n‐type‐semiconductor, polycrystalline gallium oxide (Ga 2 O 3 ) thin films are used to detect oxygen (at temperatures, T, of 850°C) or reducing gases (T 900°C). At high temperatures (T 900°C), beta‐Ga 2 O 3 has an oxygen deficiency in the crystal la…
Mixed phthalocyanines carrying one anthracene (Pc 3 An) or substituted naphthalene nucleus (Pc 3 NcR 2, R = H, OCH 3, or SC 12 H 25 ) are proposed as low-temperature photochroms for spectral hole burning. Solubility of these compounds in polymers was greatly enhanced by introducing the 2,4-dimethyl-3-pentoxy substitue…
Thin films of Ni-Zn ferrite have been epitaxially grown in situ on basal plane sapphires at room temperature by pulsed laser deposition in high vacuum. The films deposited at oxygen pressures of 1×10 -5 to 1×10 -6 Torr grew with spinel-type crystal structure and (111) planar orientation. X-ray phi scan analysis showed…
Hysteresis of the temperature of jumps in the cholesteric pitch in planar layers of cholesteric liquid crystals (CLCs) has been observed in the temperature dependence of the optical transmission spectra measured in a 4.8 ¼ m thick specimen of a 60% chiral racemic mixture of CE6. The temperature difference for the pitc…
The molecular and supramolecular structure of poly( n -hexyl isocyanate) in n -octane has been studied in the sol state and in the gel state by neutron and light scattering. In the sol state the chains appear stiff with dimensional characteristics consistent with the literature on this polymer. The gel consists of a n…
For Na0.5Bi0.5TiO3 single crystals the time dependencies of dielectric and structural properties were investigated. The obtained results reveal that phase transformation in Na0.5Bi0.5TiO3 between tetragonal and rhombohedral symmetries disclosed a time dependent character. This transformation was completed after about…