Materials Literature
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Two iron(III) chloride solutions, prepared in suitable chemical conditions, have been examined by the x-ray diffraction technique. The two solutions are isoelectronic (i.e., they have the same average scattering power per chlorine atom) with the hydrated FeCl3⋅6H2O melt previously examined [J. Chem. Phys. 71, 4255 (19…
The polarized Raman and infrared reflectivity spectra of single crystal LiNaSO4 are reported. Symmetry-based vibrational band assignments are given for both the internal and external optic models. The spectra of 6LiNaSO4 clearly identify higher frequency external modes as originating in lithium ion motion essentially…
The radiative lifetimes and collisional deactivation rate constants of Ar[3p5(2P01/2)5p] and Ar[3p5(2P03/2)5p] levels with argon atoms have been measured by time resolved laser induced fluorescence combined with a pulsed discharge for preparation of populations in the Ar(4s) precursor levels. The radiative lifetimes o…
The time dependence of the specific heat of several amorphous materials, such as $a$-Si${\mathrm{O}}_{2}$, $a$-${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$, and $a$-As, has been studied in the temperature range 0.1-1 K. It is found that below 0.3 K in all the materials studied the short-time specific heat at about 10 \ensure…
We have studied the quasiperiodic noise generated in Nb${\mathrm{Se}}_{3}$ above the critical electric field where the charge-density waves (CDW's) are depinned. The Fourier spectrum of the noise can be totally described with three fundamental frequencies and their harmonics. At high electric fields the fundamental fr…
Absorption of photons at low power levels below the band edge reversibly alters the molecular structure of Ge${\mathrm{Se}}_{2}$ glass. These structural changes have been analyzed by continuously monitoring the Raman scattering spectrum as a function of time and laser power level. At sufficiently high power levels irr…
Germanium disulfide exhibits three solid forms: an amorphous form ($a$-Ge${\mathrm{S}}_{2}$), a layer-structure crystalline form (2D-Ge${\mathrm{S}}_{2}$), and a quartzlike crystalline form (3D-Ge${\mathrm{S}}_{2}$). We have carried out a series of experiments to determine the effect of pressure on the optical-absorpt…
We have measured the variation of the differential resistance as a function of the electric field for temperatures below those at which the two charge-density waves (CDW) form in Nb${\mathrm{Se}}_{3}$. The shape of the $\frac{\mathrm{dV}}{\mathrm{dI}}$ variation is very sensitive to temperature, particularly below tha…
We report a theoretical survey of defect energetics in $\ensuremath{\alpha}$-${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$ and rutile Ti${\mathrm{O}}_{2}$ which we relate to structural and transport properties of these materials. The study of these crystals has required us to modify our computational methods based on the Mott…
The photoelectronic properties of nominally pure SrTi${\mathrm{O}}_{3}$ single crystals were studied in detail. A sharp narrow peak near the fundamental absorption edge was observed in both photoconductivity and photoluminescence excitation spectra, although it was not detected in the absorption spectrum. The temperat…
The total energy for Si with various lattice distortions has been calculated using a first-principles linear-combination-of-atomic-orbitals method. The physical properties derived from these calculations include not only the equilibrium lattice constant, cohesive energy, and bulk modulus, but also the internal strain…
The room-temperature polarized reflectance of a potassium-deficient platinum chain salt ${\mathrm{K}}_{1.75}$Pt${(\mathrm{CN})}_{4}$\ifmmode\cdot\else\textperiodcentered\fi{}1.5${\mathrm{H}}_{2}$O [K(def)CP] has been measured in the infrared and visible. The reflectance is strongly anisotropic, with a plasma edge in t…
Crystalline powder pellets of MoO3 and WO3 were irradiated with 253.7 nm radiation at room temperature in vacuum, in the presence of H2 and in the presence of Hg vapor and H2. Electronic changes induced in the surface of the solids were studied by x-ray photoelectron spectroscopy. In vacuo both MoO3 and WO3 turned blu…
The structures of the paraelectric (tetragonal) phase of KH 2 PO 4 (KDP) and 95% deuterated KD 2 PO 4 (DKDP) have been investigated as a function of pressure and temperature using high-resolution (sin theta max / lambda >1 AA -1 ) single-crystal neutron-diffraction techniques. Data have been collected for both KDP and…
The structures of the paraelectric (tetragonal) phase of KH 2 PO 4 (KDP) and 95% deuterated KD 2 PO 4 (DKDP) have been investigated using high-resolution (sin theta b max / lambda >1.1 AA -1 ) single-crystal neutron-diffraction techniques. Full three-dimensional data have been collected at T c +5K and T c + approximat…
Some brown gem-quality diamonds exhibit bright yellow luminescence when excited with a long-wave ultraviolet (365 nm) mercury lamp. The authors describe detailed absorption and luminescence measurements in the visible spectral region, and absorption measurements in the defect-induced one-phonon region, using a large n…
Because the distances between atoms vary with direction within a crystal, the properties of a crystal also vary with direction. Such property variations are called crystalline anisotropy, and the amount of anisotropy depends on the symmetry of the crystal structure. The alpha-phases of uranium depends on the symmetry…
Abstract In measurements of grain boundary transport it is the product of the grain boundary enrichment ratio and the grain boundary diffusivity that is usually obtained. This work presents the first study in which these two terms are separated and in which the role of the grain boundary composition in grain boundary…
The commensurate charge-density-wave state of $2H$-${\mathrm{TaSe}}_{2}$ can have hexagonal ($H$) or orthorhombic ($O$) symmetry. With use of a Landau theory it is shown that near the boundary between $H$ and $O$ states a discommensuration splits into two $H\ensuremath{-}O$ interfaces and thereby greatly lowers its en…
一般式 (Bi2O2)2+(Mem-1RmO3m+1)2-で表されるBi層状化合物の中, 一致溶融し, しかも比較的高いキュリー点を有する7種の化合物の組成, 及びこれに少量のPbO, Bi2O3, B2O3などを添加した組成の融液を, 白金るつぼ中で70°-140℃/cmの温度こう配下で0.7-2.9mm/hの速度で下から上に向け一方向に凝固した. その結果, いずれの組成, いずれの凝固条件の場合も, 分極軸のa軸あるいはb軸を凝固進行方向にほぼ完全にそろえたBi層状化合物の配向性多結晶体が得られた. これらの多結晶体の多くは, 空げき及びき裂をいくらか含んでいたが, (Bi2O2)(PbNb2O7) にPbO-Bi2O3-B…