Showing papers on "Single crystal published in 1971"
TL;DR: In this article, the atomic positions of Ferroelectric BiFeO 3 were determined using both X-ray single crystal and neutron powder diffraction using the multiple film technique using a Weissenberg camera.
450 citations
TL;DR: In this paper, a simple collision model involving only the primary ion and a single isolated surface atom is proposed to identify surface impurity atoms, which can be used for characterizing thin films.
299 citations
TL;DR: In this paper, a method for the preparation of appreciable quantities of large crystals of sodium A and sodium X zeolites is presented for single crystal X-ray diffraction studies and for diffusion measurements.
241 citations
01 Oct 1971
TL;DR: The premonitory events leading to the thermal martensite transformation in nearequiatomic TiNi were studied by transmission electron microscopy, single crystal X-ray diffraction, warm and cold stage light microscopy and electrical resistivity.
Abstract: The premonitory events leading to the thermal martensite transformation in near-equiatomic TiNi were studied by transmission electron microscopy, single crystal X-ray diffraction, warm and cold stage light microscopy, and electrical resistivity. Well above theM
s temperature (as defined by surface relief) {111} planes of diffuse intensity begin to form in reciprocal space and slowly intensify with further cooling. Within 20° to 30°C ofM
s the {111} planes diminish in intensity and new discrete maxima in reciprocal space are formed. These intensify rapidly with further cooling down to theM
s temperature where a discontinuous change in crystal structure occurs as indicated by surface relief. The premartensitic phenomena are discussed in terms of lattice vibrations reflecting an incipient mechanical instability of theB2 lattice. Some observations on the martensite transformation itself are also presented.
237 citations
TL;DR: Anisotropic and isotropic elastic properties are computed and compared with similar properties derived from experimental observations of the anisotropic behavior of bone.
230 citations
TL;DR: In this article, the authors investigated the dispersion characteristics of the refractive indices, the optical rotatory power, associated temperature coefficients, and the photoelastic constants, and found that the contribution of the former oscillator to the latter is larger than that of the latter.
Abstract: Absorption at the fundamental band edge, the dispersion characteristics of the refractive indices, the optical rotatory power, associated temperature coefficients, and the photoelastic constants have been investigated. Absorption at the band edge has been found to obey the exponential Urbach rule up to 5 \ifmmode\times\else\texttimes\fi{} ${10}^{2}$${\mathrm{cm}}^{\ensuremath{-}1}$. Refractive-index data between 0.4 and 1.0 \ensuremath{\mu}m are excellently fitted to the two-term Sellmeier dispersion formula with oscillators located at 9.24 and 4.70 eV. The contribution of the former oscillator to the refractive index in the visible to infrared region is larger than that of the latter. The dispersion energy ${\mathcal{E}}_{\mathrm{di}}=\frac{{\mathcal{F}}_{i}}{{\mathcal{E}}_{i}}$ (where ${\mathcal{F}}_{i}$ is the oscillator strength factor and ${\mathcal{E}}_{i}$ is the oscillator position) defined by Wemple and DiDomenico has been determined as \ensuremath{\sim} 25 eV for the transition at 9.24 eV, and is in agreement with the value derived for the average single oscillator. Dispersion of the rotatory power has been also explained by the two-term Chandrasekhar's formula with oscillator positions nearly equal to those found from the refractive indices. Dispersion measurements of the photoelastic constants reveal that a large anisotropy exists between the changes of ${\mathcal{F}}_{i}$ and ${\mathcal{E}}_{i}$ induced by the strain ${S}_{1}$ and those induced by ${S}_{3}$. The main contribution to the positive value of the temperature coefficient of the refractive indices comes from an intrinsic temperature effect, and the contribution of the photoelastic effect associated with the thermal expansion is negative. Anomalous behavior has been observed in $\frac{\mathrm{dn}}{n}\mathrm{dT}$ and $\frac{d\ensuremath{\rho}}{\ensuremath{\rho}}\mathrm{dT}$ between 0.5 and 0.6 \ensuremath{\mu}m, and is probably attributable to extremely weak absorption peaks located in this wavelength region.
184 citations
TL;DR: Using inelastic neutron scattering, the frequency and wave vector dispersion relations for the lattice vibrations in a single crystal of palladium have been determined at 120, 296, 673, and 853 °K.
Abstract: Using inelastic neutron scattering, the frequency – wave vector dispersion relations for the lattice vibrations in a single crystal of palladium have been determined at 120, 296, 673, and 853 °K. A...
178 citations
TL;DR: In this paper, it was shown that under favorable conditions these crystal planes can be identified, and their extent estimated, from photoelectric emission measurements on heterogeneous nickel surfaces, and that these surfaces are usually not sufficiently homogeneous to permit the work function of the preferred orientation to be determined accurately.
134 citations
TL;DR: In this paper, the deuteron-ordered structure of D2O ice II has been shown to be stable in the donor O···O−O angles, but not exactly symmetrical in the O−O −O angles.
Abstract: D2O ice II has a fully deuteron‐ordered structure in which two crystallographically independent types of water molecule form a tetrahedrally linked network of H bonds, with the deuterons lying near but not on the O···O centerlines. Orientation of the molecules is nearly, but not exactly, symmetrical in the donor O···O···O angles. The D–O–D angles (average, 105.4°) do not differ significantly from the angle in D2O vapor (104.5°) although the corresponding O···O···O angles are smaller (average, 93.8°). Agreement between D–O–D and O···O···O angles is improved about 6° (on average) by a distortion of the bond network, from symmetry R3c to R3. The approach to a match between D–O–D and O···O···O angles is only partly responsible for the existence of proton ordering in ice II. Twinning of R3 individuals is established by variations in certain diffraction intensities from crystal to crystal. Mean O–D bond length (0.98 A) is slightly longer than in the vapor (0.957 A). Variations among the individual O–D distan...
127 citations
TL;DR: In this article, electrical conductivity and weight change measurements were made on single crystal and polycrystalline nickel oxide as a function of temperature from 900 to 1400°C and oxygen partial pressure from 1 atm to 10 −4 atm.
115 citations
TL;DR: The preparation and properties of the perovskite-type metavanadates, CaVO3 and SrVO3, are reported in this article, where it is shown that the BaVO3 composition was only obtained at high pressure and may be nonstoichiometric.
TL;DR: In this article, the phase transformations in Zn2SiO4 and ZnSiO3 have been investigated at high pressure up to 170 kbar and temperature to 1500°C.
TL;DR: In this paper, the authors measured the angular distribution of photoelectrons ejected from a gold single crystal by 1.25keV X-rays and found that the distributions for photo-electrons from the Au4f levels show strong modulation due to electron-diffraction effects.
TL;DR: In this paper, the surface structures are double-spaced along [001] directions on each plane, and single-spaces along the next most closely packed surface directions, [0 1 1], [ 1 31] and [ 1 20] respectively.
TL;DR: In this paper, the spectral line intensities and shapes of Raman lines in an oriented single l-alanine crystal were studied in detail at temperatures ranging from 120 to 300°K.
Abstract: Spectral line intensities and shapes of Raman lines in an oriented single l‐alanine crystal were studied in detail at temperatures ranging from 120 to 300°K. It has been found: (1) Although most of the vibrational modes are polar, the effects of long‐range electrical force on the internal vibration modes are not large. For the lattice modes, the electric dipolar interaction tends to induces coupling between modes of different symmetries; (2) the molecular configuration of an l‐alanine molecule in crystal remains unchanged in the 120–300°K temperature range although crystalline strain and ahnarmonic interaction between molecules significantly affect the Raman spectral lines; (3) for temperature above 220°K, the line shape of the −NH3+ torsional mode becomes a sensitive function of temperature. The linewidth study of this mode shows that the breaking of a second H bond is an important mechanism for broadening the torsional mode at T above 220°K.
TL;DR: In this article, single crystal epitaxial layers of gallium nitride have been grown on α-SiC and α-Al2O3 substrates in the temperature range 1000-1150 °C.
TL;DR: In this article, the internal friction and Young's modulus of a hydrogen doped niobium single crystal were measured in the temperature range 20 to 370°K and the activation energy of the peak was found to be about 0·27 eV.
TL;DR: In this article, the structure of the trans-PtII carbene complex was established by a single crystal X-ray analysis, and the structure was shown to isomerise thermally to the cis-isomer.
Abstract: Interaction of the appropriate electron-rich olefin and chloride bridged PtII dimer has yielded the unreactive trans-PtII carbene complex (I) which is belived to isomerise thermally to the cis-isomer; the structure of the trans-complex is established inter alia by a single crystal X-ray analysis.
Snam1
TL;DR: In this article, the synthesis of a π-arene uranium(III) complex with aluminium chloride obtained from UCl 4, AlCl 3 and Al in benzene is reported.
TL;DR: The crystal structure of acetyl-L-proline-N-methylamide has been determined by the symbolic addition method as discussed by the authors, where the molecules are bound together through N H.. O hydrogen bonds to form a chain about the twofold screw axis parallel to c.
Abstract: The crystal structure of acetyl-L-proline-N-methylamide has been determined by the symbolic addition method. The crystal is orthorhombic, space group P21212x with four molecules in a cell of dimensions a = 9.74_+ 0.01, b = 13.20 +__ 0.01, c = 7.17 _+ 0.01/~. Refinement was carried out by the full-matrix leastsquares method including anisotropic thermal parameters. The final R value for 1213 reflexions was 0.098. The main chain of the molecule containing two trans planar peptide groups takes a folded conformation, the dihedral angle between the two peptide planes being 69.4 °. The two imino nitrogen atoms are arranged nearly in cis position and the torsion angles, tp and g are 103.7 and 164.2 ° respectively, indicating that the conformation is fairly close to that of the right-handed e-helix. The molecules are bound together through N H . . . O hydrogen bonds to form a chain about the twofold screw axis parallel to c.
TL;DR: In this article, the magnetic moment per formular unit was measured of single crystal spheres of Y, Ce, Pr, Nd and SmCo5 compounds and the anisotropy constants were estimated from the K1 and K2 vs temperature curves.
Abstract: Magnetization measurements of single crystal spheres of Y, Ce, Pr, Nd and SmCo5 compounds yield the magnetic moment per formular unit 7.9, 6.6, 10.4, 10.4 and 7.7 µB, respectively. The anisotropy constants K1 (0) and K2 (0) at 0 °K estimated from the K1 and K2 vs temperature curves measured are 6.5 and ~ 0, 5.5 and ~ 0, - 7 and 18, - 40 and 19, 10.5 and ~ 0 (x 107 ergs.cm-3) for the above compounds, respectively. Linear variation of K1 (0) and K2 (0) with x obtained in Y1-xNdxCo5 gives evidence in support of single ion model.
TL;DR: The obtained results allowed us to assess the importance of knowing the carrier and removal status of canine coronavirus, as a source of infection for other animals, not necessarily belonging to the same breeds.
Abstract: 8 8 8 10 11 13 15 18 21 21 23 23 23 27 27 30 31 II. PHYSICAL STUDIES ON DRY PHOSPHOLIPIDS A. Introduction to polymorphism and thermotropic mesomorphism I. Polymorphism 2. Nomenclature of the polymorphic forms 3. Thermotropic mesomorphism 4. State of the hydrocarbon chains in mesomorphic phases B. Thermal analysis C. Infrared spectroscopy D. X-ray studies I. Single crystal 2. Powder studies on synthetic phospholipids (a) Phosphatidic acids (b) 1,2-diacylphosphatidylethanolamines ( cephaIins ) (c) 1,3-diacylphosphatidylethanolamines (cephalins) (d) 1,2-diacylphosphatidylcholines (lecithins) ( e) 1,2-diacylphosphatidylserines 3. Powder studies on natural phospholipids
TL;DR: In this paper, the Raman spectrum of an oriented single crystal of CaSO4∙2H2O has been recorded from 20 to 3600 cm−1 at 300 °K and 77 °K using polarized laser excitation.
Abstract: The Raman spectrum of an oriented single crystal of CaSO4∙2H2O has been recorded from 20 to 3600 cm−1 at 300 °K and 77 °K using polarized laser excitation. The symmetries of the observed Raman line...
TL;DR: In this article, thin iron films were grown on (110) copper single crystal substrates and examined by reflection electron diffraction and found to be f.c. in parallel orientation with the copper substrate.
Abstract: Thin iron films, ∼ 30 A thick, have been grown on (110) copper single crystal substrates. The structure of the films was examined by reflection electron diffraction and found to be f.c.c. in parallel orientation with the copper substrate. The specimens were examined by electron spin resonance and found to be ferromagnetic.
TL;DR: In this paper, the frequency wave vector dispersion relation for the normal vibrations of a CuCl single crystal at room temperature has been measured for the [100]-, [110]-, and [111]-symmetric directions using inelastic neutron scattering.
Abstract: The frequency-wave-vector dispersion relation $\ensuremath{
u}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}})$ for the normal vibrations of a CuCl single crystal at room temperature has been measured for the [100]-, [110]-, and [111]-symmetric directions using inelastic neutron scattering.