Materials Literature
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Excitation of Tm 3+ to 3 H 4 using the 791 nm pump source showed the frequency up‐converted blue emission (∼480 nm) due to the Tm 3+ : 1 G 4 → 3 H 6 transition in Tm 3+ /Nd 3+ codoped CaO·Al 2 O 3 glasses. Intensity and lifetime changes with rare‐earth concentrations suggested the efficient energy transfer of Tm 3+ :…
An Al-Ni-Co pentagonal quasicrystal, showing electron diffraction patterns with pentagonal symmetry and including so-called superlattice reflections, has been examined by the high-angle annular detector dark-field technique with scanning transmission electron microscopy. Columnar clusters with a pentagonal arrangement…
A superplastic β‐SiAlON was used as an interlayer to diffusionally bond a hot‐pressed silicon nitride to itself. The bonding was conducted in a graphite furnace under a constant uniaxial load of 5 MPa at temperatures varying from 1500° to 1650°C for 2 h, followed by annealing at temperatures in the range of 1600° to 1…
Convergent‐beam electron diffraction has been used to determine the space groups of β‐ and γ‐Zn 3 (VO 4 ) 2 particles in vanadium oxide‐doped zinc oxide varistors. The crystal structure of β‐Zn 3 (VO 4 ) 2 has been determined to be monoclinic with space group P 2 1 and lattice parameters of a = 9.80 Å, b = 8.34 Å, c =…
We have found that the structure of an Al-Ni-Co decagonal quasicrystal, which shows a diffraction pattern with many superlattice reflections (called a 'type I superlattice'), can be described as an ordered arrangement of two kinds of atomic columnar cluster with different orientations of their pentagonal symmetry. The…
Shape Memory Alloy (SMA) can be easily deformed to a new shape by applying a small external load at low temperature, and then recovers its original configuration upon heating. This unique shape memory phenomenon has inspired many novel designs. SMA based heat engine is one among them. SMA heat engine is an environment…
The crystallization kinetics, electrical and optical properties of as-prepared and annealed GexSb40—xSe60 (22.5 at% ≤ x ≤ 32.5 at%) chalcogenide system have been studied. The kinetic studies using differential scanning calorimetry technique and X-ray diffraction examinations revealed that all the considered glasses ca…
Creatine kinase (CK) catalyses the reversible transfer of the phosphate moiety from phosphocreatine (PCr) to ADP, generating creatine and ATP. The crystal structure of a cytosolic brain-type creatine kinase is reported at 2.3 A. The biological dimer sits on a crystallographic twofold axis. The N-terminal residues of b…
Analysis of the atomic arrangement in anhydrous aminoguanidinium hexafluorozirconate, CN 4 H 8 ZrF 6 , reported by Bukvetskii, Gerasimenko & Davidovich [ Koord. Khim. (1990), 16 , 1479–1484], led to the prediction that it is a new ferroelectric [Abrahams, Mirsky & Nielson (1996). Acta Cryst. B 52 , 806–809]. I…
Electron paramagnetic resonance (EPR) room‐temperature observation of trivalent titanium in sol–gel titania has been reported. This unprecedented detection of stable paramagnetic signals in this titania, which was treated at 200°–800°C, occurred regardless of whether the atmosphere was reducing, inert, or oxidating. T…
The microstructural evolution and mechanical properties of Si 3 N 4 –SiC composites obtained by the sinter–post‐HIP process were investigated. SiC addition prohibited β‐Si 3 N 4 grain growth; however, the grain growth followed the empirical growth law, with exponents of 3 and 5 for the c ‐ and the a ‐axis directions,…
There is an urgent need to improve the methods to estimate solute fluxes in soil, e.g. cumulative capture of leaching ions by exchange resin cores. We compared the suitability of different resin materials, core sizes, and installation procedures to assess nutrient leaching in a highly permeable, tropical Xanthic Ferra…
In this article we present the synthesis of three‐dimensionally ordered ternary BC 2 N crystals produced under high‐temperature and high‐pressure conditions. Unit cell dimensions are a = 2.4820 ± 0.0007 Å and c = 6.620 ± 0.003 Å. The composition BC 2 N is derived from Vegard's law and quantitative electron energy loss…
Recent experiments have shown that heavy ion or electron irradiation induces the nucleation of diamond crystallites inside concentric nested carbon fullerenes, i.e., bucky onions. This suggests that the fullerene acts as a nanoscopic pressure shell. In this paper we study the formation of tetrahedrally bonded carbon i…
RATIONALE AND OBJECTIVES: Slow water exchange in Gd3+ complexes is generally considered detrimental to their use as MR contrast agents. The objective of this work was to demonstrate how this feature may serve as a useful template for the design of responsive MR agents. METHODS: Lanthanide (Ln) complexes of two 1,4,7,1…
The phenomenon of ant nest (formicary) corrosion is reviewed. Current theories indicate that attack requires the simultaneous presence of moisture, oxygen and a corrodent, usually an organic acid, such as formic acid. Morphological features are presented using several recent case studies as examples. This paper seeks…
Near-infrared (IR) spectroscopy has been used to distinguish between alumina oxo and hydroxy phases. Two near-IR spectral regions are identified for this function: (1) the high-frequency region between 6400 and 7400 cm −1 , attributed to the first overtone of the hydroxyl stretching mode, and (2) the 4000–4800 cm −1 r…
We show experimentally that spontaneous decay of highly non-equilibrium domain state in ferroelectric is achieved through the formation of self-organized nanoscale domain structures. The nanodomain structures have been observed by SEM and SFM in uniaxial ferroelectric lithium niobate during spontaneous backswitching a…
In the light of recent studies, we summarize our present theoretical understanding of insulating oxides in low dimensionality, including unsupported clusters, planar or stepped surfaces and ultrathin films. We review the various theoretical approaches, their efficiency in calculating ground and excited state propertie…
Polarization effects are studied in surface-enhanced resonant Raman scattering (SERRS) experiments on single-wall carbon nanotubes (SWNT's) in contact with silver colloidal clusters. For metallic SWNT's the very low depolarization ratio of the G band observed in normal resonant Raman scattering (RRS) is nearly complet…