Materials Literature
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Dicalcium aluminate (Ca 2 Al 2 O 5 ) was prepared in a piston cylinder apparatus at 1250 °C and 2.5 GPa. The compound is orthorhombic with space group symmetry /2mb, a = 5.2281(1) Å, b = 14.4686(2) Å, c = 5.4004(1) Å (Z = 4, D calc = 3.481 g/cm3), and belongs to the brownmillerite structure family. Main building units…
In this paper, the calculation of the Cosserat constant l for a polycarbonate honeycomb is carried out experimentally. Circular-cell honeycomb plates were compressed under uniaxial loading for two different boundary value problems. The first configuration was a plate with a centrally located circular hole while the se…
Smectic mesophases in the calamitic liquid crystalline materials such as 2-phenylnaphthalene derivatives exhibit fast ambipolar carrier transport, whose mobility is up to 10−2 cm2/Vs. For these mesophases, we have investigated the effect of defects in the bulk and at the domain boundary on these carrier transport by m…
The crystallization of a new macromolecule is still very much a trial-and-error process. As is well known, it requires the search of a large parameter space of experimental settings to find the relatively few idiosyncratic conditions that lead to diffraction-quality crystals. Crystallographers have developed a variety…
Despite the recent progress in the synthesis of new germanates, no zinc germanate has been synthesized by using a molecular templating route. A unique type of zincogermanate framework has now been prepared by using ethylenediamine as the structure-directing agent. The three-dimensional framework can be simply describe…
The crystal structures of stuffed derivatives of quartz within the Li 1-x Al 1-x Si 1+x O 4 system have been refined by Rietveld analysis of powder synchrotron X-ray diffraction (XRD) data. Our results reveal an Al-Si order-disorder transition at x = ~0.3 and a β-α displacive transformation at x = ~0.65. Structural va…
Permittivity dispersion and transient current profiles of two classes of liquid crystal substances were analyzed, providing an idea of probable mechanisms of ion generation. Due to the strong local field caused by the electric double layers by ions, Schottky injection at electrodes can play an important role even unde…
Iron losses in electrical machines are evaluated and analyzed in this work using the time-stepping finite elements method. The three components of total losses, i.e., eddy currents, excess or anomalous and hysteresis are considered. Concerning hysteresis losses, the influence of minor loops are considered. In order to…
Detailed investigations of the atomic and electronic structures of decagonal AlNiCo alloys have been performed. Several different models for the decagonal structure have been investigated: A model based on a rhombic-hexagon tiling proposed by Henley and models based on a cluster decoration of the Penrose tiling with l…
The structural and dielectric properties of sol-gel derived barium-strontium-titanate (Ba(0.4)Sr(0.6)TiO(3 )) thin films have been investigated. The as-fired films are found to be amorphous, and films crystallize to a cubic phase after a post deposition annealing at 700 degrees C for one hour in air. The variation of…
Crystal transformation behavior and structural changes for the planar zigzag form (form III) of syndiotactic polypropylene, which is spontaneously crystallized at 0 °C from the melt, have been investigated in the heating process by DSC, wide-angle X-ray diffractometry, and high-resolution solid-state 13 C NMR spectros…
We report measurements of the thermal conductivity $\ensuremath{\kappa}(T)$ of a single-grain icosahedral ${\mathrm{Y}}_{8.6}{\mathrm{Mg}}_{34.6}{\mathrm{Zn}}_{56.8}$ in the temperature range between 0.1 and 300 K. The quasilattice thermal conductivity ${\ensuremath{\kappa}}_{\mathrm{ph}}$ increases monotonically with…
Large pore defects clearly develop in Al 2 O 3 ceramics during sintering. These large pores originate from voids caused by the incomplete deformation and adhesion of powder particles in collapsed dimples at the centers and boundaries of granules in the green compacts. The coalescence of pores, with limited shrinkage,…
The dc conductivities of ZrO 2 –Y 2 O 3 ceramic alloys (in the range 3–12 mol% of Y 2 O 3 ) have been obtained from ac impedance measurements at temperatures between 250° and 370°C. The Almond–West ac conductivity model has been applied to evaluate hopping rates in this system. The migration enthalpies were evaluated…
The sintering of alumina doped with magnesia‐based additives to translucency previously has been possible only in atmospheres of hydrogen or oxygen or under vacuum. This paper reports on the sintering of alumina in N 2 –H 2 atmospheres that contain as little as 2% H 2 , where optical transparency that is equivalent to…
Polarization switching and dielectric relaxations have been investigated in two novel ferroelectric liquid crystal mixtures. The samples of helical pitch ∼12 µm and 0.43 µm respectively were sandwiched in planar cells of 5 µm thickness. P S , τ r and γ have been evaluated using polarization reversal current technique.…
The chemical structure of aluminum phosphate binder, which is used as a sealant for thermally sprayed coatings, was studied. Powder X‐ray diffraction (XRD) analysis showed that the binder was a mixture of several phases. None of these phases could be identified from the powder XRD data only. Electron diffraction revea…
We describe a drug-delivery vehicle that combines the sustained release properties of liposomes with the structural advantages of crosslinked gelatin gels that can be implanted directly or coated onto medical devices. Liposome inclusion in gelatin gels does not compromise thermal stability nor does it interfere with t…
Perovskite‐phase developments in partially/fully substituted (Ba,Pb)(Zn 1/3 Nb 2/3 )O 3 , synthesized via B‐site precursor routes, were investigated. The pyrochlore structure, present at no barium content, was immediately replaced by perovskite with a small amount (≥8 at.%) of barium substitution. Variations in the la…
Rare-earth salts of dodecanoic acid (lauric acid) have been prepared and characterized. The compounds have the stoichiometry Ln(C11H23COO)3, where Ln = Y, La, Ce−Lu (except Pm). The thermal behaviour of these rare-earth dodecanoates has been investigated by hot-stage polarized optical microscopy, differential scanning…