ChemInform Abstract: TRANSFORMATION TOUGHENING IN CERAMICS: MARTENSITIC TRANSFORMATIONS IN CRACK‐TIP STRESS FIELDS
Abstract Review: 21 Literaturhinweise vo und HEUER, A. H.; J. Am.
Materials Literature
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Symmetry Specification of Bands in Solids
Band representations of space groups are defined and they are used for the symmetry specification of bands in solids. While the symmetry of atomic orbitals is specified around a single center, the band symmetry of a solid is defined with respect to a whole lattice of centers.
Observation of a Biaxial Nematic Phase in Potassium Laurate-1-Decanol-Water Mixtures
The phase diagram of the ternary system potassium laurate-1-decanol-D$_{2}\mathrm{O}$ was studied over concentration ranges where nematic phases are likely to occur. Two uniaxial nematic phases which are separated by a biaxial nematic phase are found. In limited concentration range the following phase sequence may be…
Structural studies of RbH2PO4in its paraelectric and ferroelectric phases
The crystal structure if RbH 2 PO 4 has been determined by neutron diffraction at room temperature and T c +5K in the tetragonal (paraelectric) phase using single-crystal samples. The techniques of constrained refinement and statistical testing have been used to examine carefully the significance of some pertinent str…
Thermal conductivity of SnO2single crystals
SnO 2 single crystals have been grown by use of vapour-phase reaction method. The crystals obtained are characterised by chemical analysis and electrical measurements. The density of the crystals was determined as 6.994+or-0.001 g cm -3 . The thermal conductivity measured is discussed for different orientations of the…
The crystal structure of IV-VI compounds. I. Classification and description
It is shown that the crystal structures of the binary IV-VI compounds can be classified by parameters derived from a Pauli-force model potential, which has previously been used successfully for the octet and suboctet materials (A N B P-N with P=8 and 2<or=P<or=6). Trends in the transverse effective charges, in the hea…
Synthese von optisch aktiven, natürlichen Carotinoiden und strukturell verwandten Naturprodukten. IV. Synthese von (3R, 3′R, 6′R)‐Lutein. Vorläufige Mitteilung
Synthesis of optically active natural carotenoids and structurally related compounds. IV. Synthesis of (3 R , 3′ R , 6′ R )‐lutein The synthesis of (3 R , 3′ R , 6′ R )‐lutein ( 19 ) according to the building principle C 25 +C 15 C 40 is reported utilizing ( R )‐4‐hydroxy‐2,6,6‐trimethyl‐2‐cyclohexen‐1‐one ( 4 ) as a…
Gradient-Index Optics: A Review
The subject of gradient-index optics dates from the 1850s. However, only in the last 10 years has it been possible to design lenses, manufacture materials, measure the properties, and fabricate lens elements. The current status of gradient-index optics is reviewed.
Dielectric behaviour of layered antiferroelectric squaric acid in the microwave region
The complex dielectric constant ϵ = ϵ′– jϵ″ of single crystals of squaric acid C4H2O4(H2SQ) was examined at around 100 MHz and between 2 and 8 GHz as a function of temperature. In the GHz range the imaginary part ϵ″ can be well described by the beginning of a monodispersive relaxation, whose relaxation frequency slows…
Anomalous photovoltaic effect in ferroelectric SbSI and cubic piezoelectric ZnS
The anomalous photovoltaic effect referred to here is obtained fro crystals without a centre of symmetry. The spatially oscillatory photovoltaic current is investigated and the photovoltaic coefficients kijk for SbSI and ZnS determined. These coefficients are k31 = 4 × 10−8 Acm/W, k32 = 3 × 10−8 Acm/W, and k33 = (2 to…
New cleavable photoreactive heterobifunctional cross linking reagents for studying membrane organization
The synthesis is described of four new cleavable, photosensitive, heterobifunctional cross-linking reagents for use in examining membrane organization: 4'-azidoazobenzene-4oxysuccinimide ester (1), N-[4-(p-azidophenylazo)benzoyl]-3-aminopropyl-N'-oxysuccinimide ester (2), N-[4-(p-azidophenylazo)benzoyl]-6-aminohexyl-N…
Use Of Chalcogenide Glass In Thermal Infrared Telescopes
Optical materials for the 8 - 13 micron waveband are discussed and a range of high performance infrared telescopes incorporating chalcogenide glass is described.
The valence change of Fe in BaTiO3 studied by Mössbauer effect and gravimetry
The valence states of Fe and the charge compensation by oxygen vacancies of Fe57-doped BaTiO3 are studied by the Mössbauer effect and gravimetry as a function of O2 partial pressure. By preparational and analytical effort, it is ensured that the dopant homogeneously substitutes Ti4+ in the BaTiO3 lattice (up to 1.2 mo…
Order–disorder reactions in the ferroelectric perovskites Pb(Sc1/2Nb1/2)O3 and Pb(Sc1/2Ta1/2)O3. I. Kinetics of the ordering process
The perovskites Pb(Sc1/2Nb1/2)O3 and Pb(Sc1/2Ta1/2)O3 can be obtained in a disordered state by means of a synthesis at high temperature (1250 to 1500°C). Ordering of the trivalent and pentavalent ions occurs during annealing at lower temperatures. The kinetics of this ordering process are investigated by means of X-ra…
Electro-optical surface flashover measurements
Electro-optical measurements of the electric field along solid insulator/vacuum interfaces have been made to determine the mechanisms associated with fast (ns) insulator flashover. Data showing the temporal and spatial performance of the insulator surface fields prior to and at flashover are presented. The results sho…
Thickness measurement of ultrathin films on metal substrates using ATR
By modifying the surface plasma mode on a bare metal surface with an ultrathin film deposited on the metal, we measured the film thickness by attenuated total reflection (ATR). Various factors causing measurement errors are estimated with numerical examples. As a result, for example, it is shown that for some thicknes…
Vibrational contribution to molecular polarizabilities and hyperpolarizabilities
The vibrational averaging theory of Kern and Matcha is extended, at the harmonic level of approximation, to the case where the molecular property under investigation can itself lead indirectly to a perturbation of the vibrational levels of the molecule. It is found that contributions arising from this perturbation can…
Frequency-Dependent Conductivity in NbSe3
The observation of a frequency-dependent conductivity ($\ensuremath{\sigma}$) and dielectric constant ($\ensuremath{\epsilon}$) in Nb${\mathrm{Se}}_{3}$ is reported. In both charge-density-wave phases a strong frequency dependence and huge dielectric constant are observed below 100 MHz, with greatest effects observed…
Experimental heat capacities of LaNi5, α-LaNi5H0.36, and β-LaNi5H6.39 from 5 to 300 °K. Thermodynamic properties of the LaNi5–H2 system
The heat capacities of LaNi5, α-LaNi5H0.36, and β-LaNi5H6.39 were measured from 5 to 300 °K, and in the case of LaNi5 also from 300 to 350 °K. Various special techniques and unusual circumstances involved in the measurements and calculations are described. A slight enhancement of the heat capacity of β-LaNi5H6.39 was…
High-temperature contact structures for silicon semiconductor devices
While thin films of TiN and TaN are good diffusion barriers in contact structures which use nickel or gold as a top layer, they show poor barrier properties if aluminum is used as a top layer. It is shown in this letter that stable high-temperature contacts on silicon semiconductor devices can be produced by using int…