Materials Literature
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Electric-field-induced first-order Raman scattering (FIFORS) by the normally Raman inactive LO and TO phonons is observed in the pure alkali halide crystals KCl and KBr under electric fields of 2.5\ifmmode\times\else\texttimes\fi{}${10}^{5}$ V/cm. Cross sections for the FIFORS--active modes are calibrated and the resu…
The effect of pressure on the optical absorption and Raman spectra of 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) and on the optical absorption edge in 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) was investigated, using a diamond anvil cell. In NTCDA the absorption edge shifts red by about 8000 cm−…
Recombination of carriers in semi-insulating undoped CdSe was studied using infrared absorption and both the polarization and excitation power dependence of the photoluminescence spectra. The photoluminescence measurements showed that a deep donor and a shallow-acceptor state dominate the recombination process, which…
At excitation energies corresponding to definite extrinsic transitions in ${\mathrm{CdIn}}_{2}$${\mathrm{S}}_{4}$, the photoconductivity is investigated as a function of light intensity over a maximum of 12 orders of magnitude ${(10}^{16}$ to ${10}^{28}$ photons/${\mathrm{m}}^{2}$ sec). For certain wavelength ranges a…
The electronic contribution to the thermal conductivity in degenerate semiconductors has been measured at low temperature in fine-grained ceramic samples in which the lattice thermal conductivity is reduced by grain-boundary scattering of the phonons. The validity of the Wiedemann-Franz-Lorenz law has been demonstrate…
The temperature dependence of the dielectric dispersion of KOH-doped ice was measured at the temperature range from 55 K to 90 K at frequencies 0.002 Hz∼1 Hz. The phase transition at 72 K was clearly observed only at the heating stage from the temperature dependence of the dielectric constant and the relaxation time.…
Time-resolved site-selection spectroscopy techniques using a pulsed tunable dye laser were used to investigate the spectral structure and dynamics of Eu3+ ions in six oxide and one fluoride glass hosts. Network modifier ions were found to be important in determining the details of the spectral structure which can be r…
Conductivity and magnetoconductivity have been measured for various kinds of graphite crystals at low temperatures down to 0.03 K. Anomalous behaviours have been found in polycrystalline (but well oriented) specimens of graphite. At low temperatures below 0.1 K, the conductivity shows T 1/2 dependence in and without m…
Anharmonic decay of high-energy transverse acoustic (TA) phonons satisfying \ensuremath{\Elzxh}\ensuremath{\omega}\ensuremath{\gg}${k}_{B}$T is studied taking account of the elastic anisotropy of real crystalline solids. Dispersive effects are assumed to be small. We find that the decay rate is very anisotropic. The p…
Photoelectron spectroscopy, including emission from the Si 2p core level, was used to investigate the orientation dependence of the photoionization threshold \ensuremath{\xi}(\ensuremath{\alpha}) and the surface position of the valence-band edge below the Fermi level, ${E}_{\mathrm{VFS}}$(\ensuremath{\alpha}), on a cy…
The conduction of diamond implanted with carbon ions, at a target temperature of 250 \ifmmode^\circ\else\textdegree\fi{}C, was studied as a function of ion energy using the electrical sheet resistance of these implanted layers as a probe. It was found that ion doses at which the onset of hopping conduction occurs incr…
High-resolution angle-resolved photoemission has been used to study Al(111) and Al(001). Two new surface states at \ensuremath{\Gamma}\ifmmode\bar\else\textasciimacron\fi{} and K\ifmmode\bar\else\textasciimacron\fi{} of Al(111) were observed and characterized. Their energy positions are in good accord with recent self…
The superconducting transition temperature T c and the sizes of the resistive anomalies due to both the q 1 - and the q 2 -CDW formations are examined on single crystals of Ta-doped NbSe 3 . With addition of Ta, T c increases steeply from below 70 mK to 1.7 K but turns to decrease at 5 at%Ta. The sizes of the resistiv…
Ultraviolet-light excitation of thermochemically reduced ${\mathrm{MgAl}}_{2}$${\mathrm{O}}_{4}$ single crystals below room temperature produces a luminescence band with a peak at 2.69 eV. The excitation spectrum of the 2.69-eV band coincides with the broad F-center absorption band at 5.30 eV. The 2.69-eV band is also…
The band structures and density of states of all polycrystalline forms of ${\mathrm{SiO}}_{2}$ with known crystal structures are calculated using a first-principles orthogonalized linear combination of atomic orbitals method. These include 4:2-coordinated polymorphs of \ensuremath{\alpha}-quartz, \ensuremath{\beta}-qu…
The spontaneous decay rates of LA phonons are calculated in terms of the second- and third-order elastic constants in the isotropic model. It is shown that the dominant decay channel is LA\ensuremath{\rightarrow}TA+TA but not LA\ensuremath{\rightarrow}LA+TA and total decay rates at 1-THz frequency range from ${10}^{5}…
Thermal coupling and etch rate measurements are reported for polyethylene terephthalate and polyimide films irradiated at excimer laser wavelengths of 193, 248, and 308 nm. Thermal energy balance is observed up to a threshold fluence but above this the energy absorbed remains approximately constant, the excess energy…
Neutron and X-ray diffraction studies and magnetization measurements were carried out on single crystals of (Ba 1- x Sr x ) 2 Zn 2 Fe 12 O 22 . The substitution of Ba by Sr produces two effects on the crystal structure: a lattice deformation around the Sr ions and a redistribution of the Zn and Fe ions in the tetrahed…
Self-consistent, spin-polarized energy-band calculations have been performed for MnSb, for both ferromagnetic and antiferromagnetic spin alignments. For ferromagnetic MnSb we find a 3${d}^{5.5}$ configuration on the Mn atom, with a magnetic moment of 3.3${\ensuremath{\mu}}_{B}$ on the Mn sites, and -0.06${\ensuremath{…
The crystal structure of low cristobalite (SiO2) was refined at 10, 293, and 473 K from time-of-flight neutron powder diffraction data. One of the Si-O distances and one Si-O-Si angle change considerably: 10 K, 1.602(1) and 1.617(1) Å, 144.7(1)°; 473 K, 1.605(2) and 1.590(2) Å, 148.4(1)°. The angular distortion of the…