Materials Literature
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Using a capillary technique for small samples, the isothermal compressibility κT of water has been measured to −26°C. Accelerating increases of κT at the lower temperatures can be described by an expression of the form κT=Aεγ [where ε= (T−Ts)/Ts], which is known to describe anomalies encountered in the vicinity of a t…
Magnetic heat pumping can be made practical at room temperature by using a ferromagnetic material with a Curie point in or near the operating temperature range and an appropriate regenerative thermodynamic cycle. Rare earths are found to be much more effective in this application than transition elements, and measurem…
This review treats the little-studied magnetic phase transitions of the order-order, spin-reorientation type, in which a rotation of the magnetization vector (or of die antiferromagnetism vector) with respect to the crystallographic axes occurs upon change of temperature, magnetic field, or external pressure. It prese…
A self-consistent formula, which corrects a persistent mistake in the literature, has been developed for the optical joint density-of-states (OJDS) function. A way of linking valence- and conduction-bands densities of states to produce an average density or optically linked states function (ADOLS) for comparison with…
We report magnetic-form-factor measurements for Ir in the cubic antiferromagnet ${\mathrm{K}}_{2}$Ir${\mathrm{Cl}}_{6}$ (${T}_{N}=3.05$ K). Even though the Ir ions lie on an fcc lattice and are surrounded by octahedra of Cl, the magnetization density deviates strongly from the cubic symmetry that the charge density sh…
The spectral response from shallow negative donor ions in silicon has been studied over a range of donor concentrations between 1\ifmmode\times\else\texttimes\fi{}${10}^{14}$ and 1\ifmmode\times\else\texttimes\fi{}${10}^{17}$ ${\mathrm{cm}}^{\ensuremath{-}3}$. At low donor concentrations the binding energy of the nega…
Use of a computer-assisted normalization procedure and a resonant reabsorption technique has permitted frequency resolution of two central peaks in the quasielastic-light-scattering spectrum of KTa${\mathrm{O}}_{3}$ in the 0 to 3 ${\mathrm{cm}}^{\ensuremath{-}1}$ range. The intensities, and the polarization, temperatu…
Relations for the extrapolation of interatomic distances in 2H β-type GaSexS1−x are given for 0 ≦ x ≦ 0.7. This method is based on experimental results and allows to determine these distances, if for the investigated crystal the chemical composition or the lattice parameters are known. The interatomic distance Ga–Ga =…
An investigation is made of magnetic, magnetoelastic, and elastic properties of erbium orthoferrite in the region of the phase transitions. The first and the second magnetoelastic constants of this orthoferrite, and the first and the second anisotropy constants of the iron sublattice are determined. It is shown that t…
By ultrasonic methods the elastic constants of V, Nb, and Ta are determined at room temperature after loading with hydrogen and deuterium. For Nb and Ta also the change of the temperature dependence of the elastic constants on alloying are determined up to 300°C. All measurements are performed in the cubic α-phases. T…
The perovskite-type layer structure compound (CH3NH3)2CdCl4 exhibits an unusual phase sequence:
Hyperfine coupling elements, energy levels, and ESR transition frequencies have been computed for the methyl radical taking into account the large anisotropy of the proton hyperfine couplings. The interpretation of low-temperature ESR and ENDOR spectra of methyl radical is discussed with particular attention to the tu…
The optical spectra of single crystals of Cs2NaPrCl6 are reported. A complete f2 analysis gives the parameters: F2=302.0 cm−1, F4/F2=0.1600, F6/F2=0.01596, ξ4f=754.8 cm−1, α=19. cm−1, A4〈r4〉=288.6 cm−1 and A6〈r6〉=39.6 cm−1. A comparison of these parameters with those of the free Pr+3 ion indicates a covalency of 3%. T…
Frozen aqueous solutions (FAS) of Fe3+ salts have been investigated by use of Mössbauer spectroscopy in order to study the conditions for formation of glasses. A general discussion of spin–spin relaxation in glasses is given, and we discuss how changes in the spin–spin relaxation time can be attributed to changes in t…
The reflectivity of single-crystal, orthorhombic GeS has been measured at 300\ifmmode^\circ\else\textdegree\fi{}K for all three polarizations in the photon energy range 0.1-30 eV. Eleven distinct peaks or shoulders are observed, about half of which can be associated with known structure in the valence-band density of…
Cu 50- x Ni x Zn 50 β phase alloys undergo a martensitic transformation from the CsCl-type ordered cubic (B2 structure) to the AuCuI-type tetragonal (Li 0 structure). The martensite L1 0 phase appears at room temperature when Ni composition x becomes larger than 32.5 at.%, i.e. when electron atom ratio ( e / a ) becom…
The intensity, frequency shift, and linewidth of the longitudinal Brillouin lines have been measured from 4 to 300 K in crystal quartz, fused quartz, and borosilicate glass. Differences in intensity between Stokes and anti-Stokes components have been found, extending to low temperatures the observation of long-lived v…
A selective laser excitation technique has been used to study energy transfer between the individual ions of specific crystallographic sites in charge compensated CaF2:Er3+. Unique energy transfer rates have been obtained directly from the fluorescent transients of the selectively excited sites. No energy transfer pro…
An SCF method is derived for doublet states with one vacancy in an orbital within the occupied manifold (hole states). This method gives an upper bound to an excited state energy. Hence it is a stable procedure which is bounded from below and cannot collapse to a lower energy SCF state. This new procedure is compared…
The potential, charge density, energy spectrum, and occupied surface density of states are calculated selfconsistently for two currently popular structural models of the stable 2 \ifmmode\times\else\texttimes\fi{} 1 reconstruction of the Si (100) surface. The features which emerge are discussed in terms of their relat…