Materials Literature
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Complete structural analysis of a Mo bicrystal containing a Σ = 3, [101](121)A grain boundary (GB) was achieved by means of transmission electron microscopy from the microscopic to the nanoscopic level. Secondary GB dislocations compensating a small deviation from the exact Σ = 3 concidence were observed and their cha…
Several Co−Ni−Mg−Al-layered double hydroxides (LDH) have been synthesized by coprecipitation at constant pH = 9. All samples present well crystallized, layered structures, no excess phases were detected by X-ray diffraction, and the lattice a parameter followed the Vegard correlation. The cations thus belong to the sa…
Lead magnesium niobate (Pb(Mg 1/3 Nb 2/3 )O 3 , or PMN) is a relaxor ferroelectric with many potential applications. As a relaxor ferroelectric, PMN displays a diffuse phase transition and its temperature of maximum relative permittivity ( T m ) shifts to higher temperatures as the frequency increases. When 10 mol% of…
Various compositions of the ZrO2/Nb2O5 system were synthesized and the experimental conditions for obtaining reproducible results were established. The gel was precipitated at constant pH = 10, aged at room temperature for 18 h and, after filtration, dried at 110 °C for 24 h. The phase diagram of the ZrO2/Nb2O5 system…
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…