Materials Literature
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We present an integrodifferential-operator formulation of the problem of linear stability around the selected needle crystal pattern in dendritic crystal growth. We show by explicit computation that (a) all members of the discrete set of allowed steady states aside from the fastest are unstable and (b) the fastest suc…
High-resolution measurements of the ir stretching bands of OH and OD at about 3500 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ and 2600 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ in monodomain ${\mathrm{SrTiO}}_{3}$ crystals yield spectroscopic data for a local anharmonic-oscillator model. The optical polarization depe…
A quantum-mechanical approach for surface-enhanced optical processes is given, which may solve an old controversy regarding the surface enhancement mechanisms: The present formalism contains three terms: The first is equivalent to the classically derived electromagnetic enhancement; the second represents a loss term d…
The local electronic structure of bulk and defect sites has been calculated for nine amorphous III-V compound semiconductors and for two amorphous II-VI compound semiconductors using the tight-binding recursion method. We find that structural disorder in a chemically ordered, tetrahedrally coordinated network causes a…
Magnetic properties of a layered compound MnPS 3 were investigated by means of magnetic susceptibility, high field magnetization and electron spin resonance. Temperature and angular dependence of EPR line width are characteristic of 2D-antiferromagnet. The main exchange interaction in the a b -plane is estimated to be…
Using rigorous coupled-wave analysis, high spatial-frequency rectangular-groove surface-relief phase gratings are shown to be capable of exhibiting zero reflectivity. Thus these corrugated surfaces may act as antireflection coatings in a variety of applications. The diffraction characteristics of rectangular-groove su…
By means of permittivity, spontaneous polarisation and polarisation reversal measurements the authors studied the influence of the substitution of deuterium atoms for hydrogen on the ferroelectric properties of tris-sarcosine calcium chloride (TSCC). Although most of the protons in the hydrogen bonds were substituted…
Deviations to Paschen's law for SF 6 at high pressures are commonly explained by field enhancement due to protrusions supposed to exist at the surface of the electrodes. New experiments for positive polarity allow the authors to draw a different conclusion, i.e. to ascribe these deviations to the impurities of the gas…
For pt.I see ibid., vol.12, p.2351 (1986). This second paper on the breakdown mechanisms in electronegative gases under non-uniform field conditions deals with the development of the leader type of discharge, the emphasis being laid on details of the streamer to leader transition, which is found to be very much differ…
Streamer propagation and the streamer to leader transition have been thoroughly investigated for SF 6 and air/SF 6 mixtures under positive impulse conditions. This paper, being the first of two related papers on the matter, concentrates on the streamer corona. Streamer propagation in strongly electronegative gases is…
Using a general expression for the spatial dependence of the temperature determined by a steady-state heat flow equation for a cylindrical X-ray target anode with dimensions much larger than the incident electron beam radius, the radius of the melt region on the anode surface has been calculated as a function of the t…
Stable colour centres can be introduced in single crystals of alkali halides using electrolytic coloration. The powders obtained by crushing these single crystals lose colour very rapidly. Mobile dislocations which are present in far greater abundance in the powders are responsible for the reduced stability. Results o…
Abstract The three ligands H 4 dota, H 4 teta, and H 4 heta give binuclear complexes with Cu 2+ and Ni 2+ , the spectral properties of which have been studied. The structures of Cu 2 (dota)·5H 2 O and Cu 2 (teta)·6H 2 O have been established by X‐ray diffraction analysis.
Abstract The two tetraazamacrocycle‐ N , N ′, N ″, N ‴‐tetraacetic acids H 4 dota and H 4 teta form with Ni 2+ , Cu 2+ , and Zn 2+ (M 2+ ) mononuclear complexes MLH 2 and M′[ML], M′ being an alkaline earth ion. The structures of Ni(H 2 dota) and Cu(H 2 dota) have been solved by X‐ray structure analysis. The metal ions…
The 5RL centre has been produced in natural semiconducting diamond by radiation damage and annealing to about 300 degrees C. The 5RL system is observed in both absorption and cathodoluminescence, and is of interest because the zero-phonon transition couples to local-mode phonons with energies well above those of the l…
Using optical second-harmonic generation as a probe, we have observed polar ordering of ${4}^{\ensuremath{'}}\ensuremath{-}n\ensuremath{-}\mathrm{octyl}\ensuremath{-}4\ensuremath{-}\mathrm{cyanobiphenyl}$ (8CB) molecules in a monolayer at an 8CB-glass interface, but nonpolar ordering at the free surface of 8CB as well…
Durable electrochromic coatings of hydrated nickel oxide were produced by reactive rf magnetron sputtering of Ni followed by treatment in KOH. Spectrophotometry was used to assess the achievable modulation of luminous and solar transmittance and to verify that the studied material is interesting for ‘‘smart window’’ a…
A fundamental limitation of LEED as a surface-structure probe is the complexity of the theory compared with x-ray scattering from solids. By making one full dynamical calculation for a reference structure we express diffraction from modifications of this structure in first-order perturbation theory. This gives a theor…
Abstract A method is described for growing single crystals from a solution where a base’s concentration is controlled so that an adduct to be grown is equilibrated with the solution. A slight difference in its solubilities at two different temperatures is responsible for their growth process. The technique is valuable…
The effects of two commercial chitin synthesis inhibitors, dimilin and polyoxin D, on chitin fiber formation and cell sedimentation for the diatoms Thalassiosira fluviatilis and Cyclotella cryptica (Bacillariophyceae) were investigated. Dimilin treatments for both diatom species were indistinguishable from controls in…