Materials Literature
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Existing experimental data for the antiferroelastic phase transition in strontium titanate are reviewed and analysed using a Landau free energy of the form ΔG = 1/2Aθs (cothθs/ Tc-colb.θ/T)Q2 + 1/4BQ 4 + 1/6CQ 6, with A = 0·6472 J K−1mol−1, B = 29·12 Jmol−1, C = 39·27 Jmol, T c= 105·6 K, θ S = 60·8 K. The temperature…
We report on the temperature dependence of the crystal and magnetic structure of the layered colossal magnetoresistive manganite, ${\mathrm{La}}_{2\ensuremath{-}2x}{\mathrm{Sr}}_{1+2x}{\mathrm{Mn}}_{2}{\mathrm{O}}_{7}, x=0.3$. Neutron-diffraction measurements show that the insulator-metal (IM) transition ${(T}_{\mathr…
In this study, atomistic finite deformation calculations employing the Embedded Atom Method show three items of interest related to continuum field theory. First, a spatial size scale effect on the yield stress is found. In these calculations, mechanical yield point occurred from dislocation initiation at the edge of…
Isothermal transformation kinetics and coarsening rates were studied in unseeded and alpha‐Al 2 O 3 ‐seeded γ‐Al 2 O 3 powders heated in dry air and water vapor. Unseeded samples heated in dry air transformed to alpha‐Al 2 O 3 with an activation energy of 567 kJ/mol. Seeding with alpha‐Al 2 O 3 increased the transform…
The packet-like space-charge behaviour in an oxidized crosslinked polyethylene (XLPE) film doped with antioxidant is discussed through computer simulation. The model is based on the following assumptions, (1) both electrons and holes are injected from the electrodes and they migrate to the opposite electrodes by hoppi…
The mixed ionic‐electronic conductor (LSCF) is a candidate for use as the membrane material in the pressure‐driven air separator. However the long‐term stability of these materials is a major concern for the commercial realization of these devices. In an attempt to assess the stability of the material under realistic…
Cosmo-mimetic carbon microcoils with a three-dimensional helical/spiral structure similar to deoxynucleic acid, having coil diameters of 3–6 μm and coil lengths of 5–8 mm could be obtained by the catalytic pyrolysis of acetylene. A three-dimensional growth model of the carbon coils, based on the anisotropy for the car…
High alloyed stainless steels (Fe20Cr20Ni, Fe20Cr20Ni6Mo, and Fe20Cr20Ni6Mo0.2N) were polarized in 0.1 M HCl + 0.4 M NaCl solution for 10 min and 2 h between {minus}75 and 800 mV vs. saturated calomel electrode (SCE). The composition of the passive films was analyzed by angle-resolved X-ray photoelectron spectroscopy,…
A new energy-dispersive X-ray diffraction (EDXD) method to study the kinetics of the phase transitions (PTs) is reviewed. It enables one to follow the evolution of systems undergoing structural transformations in real time. It is based on a novel approach to PTs and provides several advantages with respect to the conv…
2- and 3-Dimensional crystalline arrangements of metal nanoparticles are of interest because of their unique optical and electronic behavior. Discrete assemblies of nanoclusters (e.g. dimers, trimers) studied in this paper allow the effects of local symmetry on collective particle properties to be studied. The distanc…
A simple technique for crystallizing spherical nanoparticles into 3D opaline structures, which can be of use as diffractive elements in the fabrication of optical or electro-optical devices, is presented. Both polystyrene beads and silica colloids within the size range 50–100 nm have been successfully ordered and it i…
1. The avian eggshell is a biomineralised composite ceramic consisting of calcium carbonate embedded in an organic matrix. Matrix components are supposed to be involved in the control of mineralisation, crystallographic texture and biomechanical properties of eggshell. 2. The structure and eggshell matrix composition…
The intercalation of inorganic materials into organized organic assemblies presents many opportunities for the development of new functional materials with superior physicochemical properties. We have designed a composite material comprising Prussian blue intercalated into photoresponsive organic molecules (azobenzene…
A series of polyhedral oligomeric silsesquioxanes (POSS) monomers bearing silane or α-olefin substituents have been prepared and their chemistry explored. Both the POSS silanes and α-olefin monomers readily participate in hydrosilation chemistry and have been used as starting materials for the preparation of POSS sol–…
A novel interatomic potential energy function is proposed for condensed systems composed of silicon and oxygen atoms, from SiO 2 to Si crystal. The potential function is an extension of the Stillinger-Weber potential, which was originally designed for pure Si systems. All parameters in the potential function were dete…
${\mathrm{CaMnO}}_{3\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ with $\ensuremath{\delta}=0,$ 0.06, and 0.11 was prepared by the Pechini citrate gel process at 1100 \ifmmode^\circ\else\textdegree\fi{}C. Oxygen defects were created by quenching the sample from high temperature. Chemical analysis and x-ray abs…
Dense BaTiO 3 ceramics consisting of submicrometer grains were prepared using the spark plasma sintering (SPS) method. Hydrothermally prepared BaTiO 3 (0.1 and 0.5 µm) was used as starting powders. The powders were densified to more than similar/congruent95% of the theoretical X‐ray density by the SPS process. The ave…
This paper considers a mixture of sedimenting particles at low Reynolds numbers and volume fractions. Simple theoretical arguments have long suggested that for a random suspension of particles in an infinite system, the fluctuations in the velocity about the mean should diverge with system size. On the other hand, exp…
Macromolecular phase-refinement and phase-extension calculations using real-space electron-density averaging techniques require accurate envelopes (or masks) to define the boundaries of each domain or molecule whose density is to be averaged. An extensive set of tools, implemented in four computer programs (O, MAMA, C…
Activated sintering in Bi 2 O 3 ‐doped ZnO has been studied with emphasis on the mechanistic role of intergranular amorphous films. The atomic‐level microstructures and bismuth solute distributions in doped powders have been investigated using high‐resolution electron microscopy and scanning transmission electron micr…