Materials Literature
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Results are presented of an investigation on the origin of the low temperature coefficient of resistance in NiCr thin films. It is shown that this low temperature coefficient is an intrinsic property of the alloy. Besides NiCr a large number of disordered alloys containing transition metals have similar conduction pro…
Raman spectra of polycrystalline films of CHCl3 and CDCl3 have been recorded at 77°K. Splittings due to the four chlorine siotropic molecules have been resolved for the ν3(A1) bands of both CHCl3 and CDCl3. After taking isotopic effects into account, further splittings of the fundamentals in the Raman spectra together…
Vibrational frequencies of the NO3− ion in matrix-isolated monomers of several nitrates MNO3 are shown to correlate with the polarizing power of the cation M+, P≡ (z/r)/Seff, properly defined as the quotient, rather than the product, of the ionic potential, z/r, and a factor Seff= (5z1.27)/(r(1/2)I) (Ahrens, 1954) rep…
Measurements have been made of the transit times of pulses of longitudinal and transverse ultrasonic waves in single-crystal samples of ${\mathrm{Ti}}_{2}$${\mathrm{O}}_{3}$ having appropriate orientations at various temperatures between 75 and 580 K. Sample-length-versus-temperature data were also obtained using a di…
Magnetic domains of a press-sintered SmCo5 magnet with a high intrinsic coercivity (IHc = 12 700 Oe) and energy product [(BH)max = 18.0 MGOe] were observed in the demagnetized state by the powder pattern technique. The domains on the surfaces parallel and perpendicular to the alignment direction and at grain boundarie…
The Raman spectra of B2F4 have been recorded from 25 to 1500 cm−1 with the sample in both the gaseous and crystalline states. An assignment of the normal vibrations of the molecule in the planar form is presented. No evidence could be found for the conversion from the D2h form in the solid to a nonplanar D2d form in t…
The luminescence properties of phthalocyanine complexes of platinum metals with d6 and d8 electron configurations were investigated in dilute solutions between room temperature and 1.6°K. For the first time it was possible to study the magnetic sublevels of the triplet state of aromatic molecules in zero field through…
The experimental information available from x-ray photoemission spectroscopy regarding the electron correlation energy $U$ of $3d$ and $4f$ electrons in solids is considered. It is found that $U$ is of the order of 7 eV for $4f$ electrons and \ensuremath{\sim} 2 eV for $3d$ electrons.
The thermal conductivity, electrical resistivity, and thermoelectric power of well-characterized, polycrystalline specimens of pure Co have been determined in the temperature range of 90 to 1250 K. Additionally, the measurements of the electrical resistivity have been extended to 1750 K, and the coefficient of thermal…
Cation self-diffusion coefficients have been obtained for MgO in an argon atomosphere over a temperature range 1000–2400°C from concentration gradients determined with the aid of mass spectrometry. The problems associated with use of the short-lived radioisotope 28Mg were avoided by employing the stable isotope 26Mg a…
The high-resolution x-ray-photoemission-spectroscopy (XPS) valence-band spectrum from a cleaved natural-diamond single crystal is reported. The absence of extrinsic structure allows a reliable comparison with band theory. The XPS molecular-orbital spectra of methane, silane, and germane are also given. The modulation…
The design and operation of a magnetocalorimeter for the highly accurate measurement of the enthalpy increase and magnetic properties of CMN over the range 0.0006 to 0.01°K are described. The essentials were as follows: A Pyrex calorimeter equipped with a Pt-9%W noninductively wound heater and carbon thermometers, and…
The pressure and temperature dependence of the refractive index and absorption edge have been measured for a group of amorphous semiconductors with average coordination number between two and four, all containing group-VI elements in twofold coordination (lone-pair semiconductors). Clear compositional trends are obser…
The theory of the thermal resistivity of dielectric crystals at ordinary and high temperatures in terms of anharmonic three-phonon interactions is reformulated. The resistivity is similar in form to that obtained by Leibfried and Schl\"omann, but larger by a factor of 6.8. The theory is then extended to crystals where…
For pt. I see abstr. A7013 of 1972. Expressions for the g-values and hyperfine structure parameters of Cu 2+ ions in tetragonally distorted tetrahedral sites are derived by including the effects of covalency, 4p mixing and the dynamic Jahn-Teller effect. The results are applied to Cu:Cs 2 ZnCl 4 where agreement with E…
The ESR spectra of several brown diamonds measured at 77 K show a central group of three equally strong lines, with two groups of six closely spaced anisotropic lines of equal intensity at about 30-40 G on either side of the central group. The central group of lines has double the intensity of the side lines. Spacings…
A simple method is proposed for calculating by hand the thickness of surface films using data obtained from the microprobe analyser. It is shown that, if one exploits the scaling properties of electron scattering distributions, a set of curves may be obtained representing the fraction of characteristic ionization prod…
A critical examination is presented of the available experimental evidence relating to the frequency dependence of the electrical conductivity of a wide range of disordered and amorphous semiconductors and insulators. It is pointed out that there is no justification for regarding these effects as true bulk phenomena,…
An experimental study of critical phenomena in thin ferroelectric films is presented which, for the first time, conclusively demonstrates that the polarization in thin films is drastically reduced as a result of depolarization effects. Other causes, like impurities, structural defects, and domain formation, which can…
The existence of a monoclinic phase of hydroxyapatite, Ca(2)(PO(4))(4)OH, has been confirmed, by single-crystal structure analysis (weighted "reliability" factor = 3.9 percent on |F|(2)). The structure has space group P21/b, a = 9.4214(8) angstroms, b = 2a, c = 6.8814(7) angstroms, and gamma = 120 degrees , and is ana…