Showing papers on "Lattice constant published in 1973"
TL;DR: In this article, the lattice constants of tetragonal CuGaS2 are a = 5.34741 ± 0.00006 A at 298 °K, and of CuInS2, the GaÕS distance is 2.335 ± 0.001 A in CuS2.
Abstract: CuGaS2 and CuInS2 are typical AIBIIIC2VI members of the chalcopyrite structure family. The lattice constants of tetragonal CuGaS2 are a = 5.34741 ± 0.00007 and c = 10.47429 ± 0.00006 A at 298 °K, and of CuInS2 are a = 5.52279 ± 0.00007 and c = 11.13295 ± 0.00022 A at 298 °K. Both materials have four formulas in a unit cell with space group I 42d. A total of 984 reflections for CuGaS2 and 1413 for CuInS2 were measured with PEXRAD, and the resulting 134 symmetry‐independent CuGaS2 and 310 CuInS2 structure factors, in least‐squares refinement, led to final agreement factors of 0.029 and 0.038, respectively. Both materials are slightly nonstoichiometric. Final x coordinates are 0.2593 ± 0.0004 for CuGaS2 and 0.2295 ± 0.0004 for CuInS2. As was also found with AgGaS, these values are significantly different from those expected for a geometrically regular B atom tetrahedron. The resulting sublattice distortion is predictable from a linear sum of atomic electronegativities, which is also used to predict the x coordinate and interatomic bond lengths in 17 other AIBIIIC2VI chalcopyrites. The sublattice distortion in AIIBIVC2V chalcopyrites is generally small, but also significant. The experimental Cu–S distance is 2.312 ± 0.001 A in CuGaS2 and 2.335 ± 0.001 A in CuInS2, the Ga–S distance is 2.288 ± 0.001, and In–S is 2.464 ± 0.002 A. The amplitudes of thermal vibration for the A and B atoms in AgGaS2, CuGaS2, and CuInS2 are essentially isotropic, with considerable anisotropy in the C atom motion.
236 citations
TL;DR: In this paper, an X-ray diffraction analysis has been performed on superlattice crystals which were grown epitaxically by alternately depositing GaAs and GaAs 0.5P0.5 layers on a gallium arsenide substrate.
Abstract: An X-ray diffraction analysis has been performed on superlattice crystals which were grown epitaxically by alternately depositing GaAs and GaAs0.5P0.5 layers on a gallium arsenide substrate. The periodic change of compositions causes a one-dimensional periodic lattice distortion along the direction of growth. The periodic lattice distortion gives rise to satellite peaks close to the Bragg reflections of the sphalerite-type lattice of gallium arsenide. Two models are employed to calculate the X-ray diffraction intensities: in one the lattice distortion is described by two longitudinal phonons with frequency ω = 0, in the other a periodic step function is used. The X-ray diffraction data obtained on two samples show that the two alternating layers of different composition are coherent and, therefore, constitute one single-crystal with its unit cell large (g 100 A) along the growth direction. From the fit of the two models to the data one can determine the period and amplitude of the lattice distortion, the relative thickness of the two layers and the size of the domains which diffract coherently. These parameters are discussed in relation to the physical growth conditions.
167 citations
TL;DR: In this paper, the initial stages of the oxidation of (110 and (100) chromium surfaces have been studied using low energy electron diffraction and Auger electron spectroscopy.
137 citations
TL;DR: In this paper, the authors investigated the effect of vanadium on the order and antiphase domain coalescence of quenched equiatomic equiaomic iron and cobalt alloys in the range 400-600°C.
Abstract: The rates of ordering and antiphase domain coalescence during isothermal annealing of quenched equiatomic iron–cobalt and iron–cobalt–vanadium alloys have been studied in the range 400–600° C. Experimental techniques included X-ray diffraction (superlattice line intensity and breadth, and lattice parameter) and measurement of magnetic saturation moment. Amounts of vanadium up to 2.5% do not significantly affect the ordering kinetics in these alloys. It is suggested that the transformation bcc → L20 in this system occurs by a homogeneous process rather than by nucleation and growth of ordered domains. Rates of antiphase domain coalescence are affected by vanadium. Coalescence is very rapid in FeCo below 550°C but is relatively slow in FeCo and FeCo-V above 550°C, when a linear (domain size) vs. time relationship is obeyed. The effect of vanadium on the equilibrium degree of order in the range 300–900°C has been assessed on the basis of specific-heat, lattice-parameter, and magnetic-saturation measu...
106 citations
TL;DR: AgGaS2 is a representative member of the AIBIIIC 2VI family with chalcopyrite structure and is strongly piezoelectric and phase matchable for second harmonic generation.
Abstract: Silver thiogallate, AgGaS2, is a representative member of the AIBIIIC 2VI family with chalcopyrite structure. AgGaS2 is strongly piezoelectric and is phase matchable for second harmonic generation. The lattice constants of this tetragonal crystal are a = 5.75722 ± 0.00003 and c = 10.3036 ± 0.0002 A at 298 °K. The space group is I 42d, with four formulas per unit cell. The integrated intensities of 1978 reflections were measured within a hemisphere of reciprocal space having radius (sin θ)/λ = 1.02 A−1 using PEXRAD, resulting in 268 symmetry‐independent structure factors. The x coordinate of sulfur (0.2908 ± 0.0004) is 0.088 A less than the value calculated on the assumption of a geometrically regular tetrahedral bond distribution about the B atom. By contrast, four AIIBIVC2V compounds previously reported have x coordinates for the Cv atom either slightly greater than (for ZnSiP2, CdSiP2, and ZnSiAs2), or not significantly different from (for ZnGeP2) that calculated. The experimental Ag–S distance is 2.556...
104 citations
TL;DR: In this paper, it was found that the solid solubility of Ce3+ in varies with the atmosphere during firing, and that only 2 mole per cent (m/o) of C3+ can be dissolved in the yttrium aluminum garnet in air while almost 6% of C 3+ enters the garnet lattice when fired at 1450°C under a hydrogen atmosphere.
Abstract: The systems , , and were studied. It was found that the solid solubility of Ce3+ in varies with the atmosphere during firing. Only 2 mole per cent (m/o) of Ce3+ can be dissolved in the yttrium aluminum garnet in air while almost 6% Ce3+ enters the garnet lattice when fired at 1450°C under a hydrogen atmosphere. Complete solid solutions were observed in the systems and . The cathodoluminescence emission‐peak position of the Ce3+ ion in host shifted to a longer wavelength while the latttice parameter of the solid solution expanded when Gd3+ ions were substituted for Y3+. On the other hand, the emission‐peak position shifted to a shorter wavelength when the garnet host contained Ga3+ ions in the Al3+ position. The lattice parameter of the solid solution increased with Ga concentration.
101 citations
TL;DR: In this paper, a double-crystal X-ray diffraction technique has been applied to the lattice constant measurement of SrTiO 3 in the temperature range 17 to 300 K.
100 citations
TL;DR: In this paper, the Curie temperature and the saturation magnetization of the pseudobinary system LaCo 5x Ni 5−5x have been determined as a function of composition and the variation of the lattice constants suggests an anisotropic magneto-volume effect accompanying the paramagnetic-ferromagnetic transition.
Abstract: The lattice constants, the Curie temperature and the saturation magnetization of the pseudobinary system LaCo 5x Ni 5−5x have been determined as a function of composition. The variation of the lattice constants suggests an anisotropic magneto-volume effect accompanying the paramagnetic-ferromagnetic transition. The hydrogen absorption capacity decreases markedly with x in the series LaCo 5x Ni 5−5x . The nature of the hydride phases corresponding to the various plateau pressures of the absorption isotherms has been studied by X-ray diffraction. The hydrogen equilibrium pressure at the first hydride is strongly reduced when x increases. Dependent on x one can discern two regions where this equilibrium pressure varies as In p = Cx + q , the absolute value for C being largest for small x values.
95 citations
TL;DR: In this paper, a good correlation exists between superconducting Tc's and film structure and composition regardless of the sputtering conditions used to achieve this structure, and the most important parameters affecting Tc are lattice parameter, crystal structure, island structure and impurity content.
Abstract: Superconducting properties and electrical resistivities of NbN thin films have been studied as a function of sputtering parameters, film structure, and composition. A good correlation exists between superconducting Tc's and film structure and composition regardless of the sputtering conditions used to achieve this structure. The most important parameters affecting Tc are lattice parameter, crystal structure, island structure, and impurity content. Substrate temperature, Ar/N2 ratio, and impurity content are the principal sputtering parameters affecting film structure, and thus Tc.
91 citations
TL;DR: In this paper, the distribution coefficient for Nd in these garnet systems indicate that it is a linear function of the host lattice parameter and independent of the rare-earth ion.
89 citations
TL;DR: The lattice parameter and the crystal structure of SrO (NaCl-type structure) have been investigated to 340 kb at 23° ± 3°C by means of X ray diffraction employing a diamond-anvil press as mentioned in this paper.
Abstract: The lattice parameter and the crystal structure of SrO (NaCl-type structure) have been investigated to 340 kb at 23° ± 3°C by means of X ray diffraction employing a diamond-anvil press. Silver mixed with the sample served as a pressure transmitting medium and an internal pressure calibrant. The compressional data fitted to two forms of the Birch equation yield the bulk modulus and its pressure derivative, K0 = 913 ± 27 kb, K0′ = 4.3 ± 0.3 and K0 = 906 ± 24 kb, K0′ = 4.4 ± 0.3, respectively. Between 70 and 307 kb, a splitting of the diffraction lines indicates a tetragonal distortion of the NaCl-type structure with an axial ratio of c/a = 1.005–1.008. No volume discontinuity accompanies this phenomenon, and its cause is not understood.
TL;DR: In this paper, the suitability of applying the well-known Morse function φm(r) to the description of mechanical properties of cubic crystals was examined, and the theoretical model of the crystal was found to be mechanically stable for arbitrary (i.e., m>1) exponentially attractive and repulsive interactions and the elastic moduli C11 and C12 of the theoretical fcc crystals were found to conform to the respective experimental values of fcc metals.
Abstract: The well‐known Morse function φ(r) = D {exp [−2α(r−r0)] −2 exp [−α(r−r0)]} can be considered to be a particular case of the general family of potential functions with exponential attraction and exponential repulsion, viz., φm(r) = [D/(m−1)] {exp[−mα(r−r0)] −m × exp[−α(r−r0)]}. This study examines the suitability of applying the functions φm (r) to the description of mechanical properties of cubic crystals. For bcc lattices, the ratio C11/C12 for the theoretical model of the crystal made up of atoms with φm (r) interatomic interactions is shown to be too small to provide a realistic description of bcc metals; also, the bcc crystals are found to be inherently unstable for larger values of αa0, where a0 is the lattice parameter of the crystal. For fcc lattices, however, the theoretical model of the crystal is found to be mechanically stable for arbitrary (i.e., m>1) exponentially attractive and repulsive interactions and the elastic moduli C11 and C12 of the theoretical fcc crystals are found to be capable of conforming to the respective experimental values of fcc metals. The results are in agreement with Born's analyses of lattice stability. Numerical values of D, α, and r0 are calculated for several different values of the parameter m for fcc Ni using experimental values of C11, C12, and lattice parameter. The element Ni is selected because, among the fcc metals, Ni most closely obeys the Cauchy condition C12 = C44. The functions φm are then used to calculate theoretical pressure versus volume (P‐V) behavior (at pressures large enough to produce considerable anharmonicity) and the results are compared with experiment; good agreement is found between the calculated and experimental P‐V relations.
TL;DR: In this article, the spontaneous volume magnetostriction of Fe-Ni and Ni-Cu alloys at 0 K evaluated from their thermal expansion curves can be quantitatively explained on the basis of the collective electron model, using the density of states curve for nickel.
Abstract: Thermal expansion measurements were made on f.c.c. Fe-Ni and Ni-Cu alloys from liquid helium temperature up to 1000 K. The spontaneous volume magnetostriction of these alloys at 0 K evaluated from their thermal expansion curves can be quantitatively explained on the basis of the collective electron model, using the density of states curve for nickel. The lattice constants of these alloys at various temperatures evaluated from their thermal expansion curves deviate from Vegard's law in the Invar region. This deviation is discussed in connection with the magnetic state of the Invar alloy and with the origin of the Invar effects.
TL;DR: In this paper, the existence of compositional shifts due only to Ga 2 O 3 vaporization losses in gadolinium gallium garnet single crystals grown by pulling from the melt was confirmed.
TL;DR: The empirical relation between the energy gap and lattice constant has been found for a wide range of semiconductors with the cubic NaCl crystal structure as mentioned in this paper, and the empirical relation has been shown to hold for a variety of semiconductor architectures.
Abstract: The empirical relation ${E}_{0}\ensuremath{\propto}(\frac{1}{{a}_{0}^{2}})$ between the energy gap ${E}_{0}$ and lattice constant ${a}_{0}$ has been found to hold for a wide range of semiconductors with the cubic NaCl crystal structure.
TL;DR: In this article, lattice constants, grain size, electrical conductivity, and luminescence were measured for sintered BaTiO3 ceramics doped with 0 to 1.2% rare-earth ions.
Abstract: Lattice constants, grain size, electrical conductivity, and luminescence were measured for sintered BaTiO3 ceramics doped with 0 to 1.2 at.% rare-earth ions. BaTiO3 doped with low levels of rare-earth ions contains grains 10 μm in size and has lattice constants nearly equal to those of undoped ceramics. In this case, rare-earth ions occupy Ba2+ sites and yield donors. When grain growth is inhibited by high doping levels or by insufficient sintering, the lattice constants change, the rare-earth ions occupy both Ba2+ and Ti4+ sites, and, consequently, BaTiO3 becomes insulative because of charge compensation.
TL;DR: In this article, the lattice parameter of NaCl, KCl, LiF, NaF and KI was measured using high temperature X-ray diffractometry, and an orthogonal polynomial of second order with least square error approximation was fitted to the parameter versus temperature data to obtain the thermal expansion coefficient.
TL;DR: In this paper, the optical energy gap and the lattice parameters of ZnSxTe1-x have been measured, and the energy gap bowing is compared with previous theoretical estimates.
Abstract: Thin films of ZnSxTe1-x have been grown in the composition range 0
TL;DR: The lattice constants of more than 40 compounds A 2 BMF 6 are reported in this paper, where the occurence of cubic (type K 2 NaAlF 6 ) and hexagonal (type Cs 2 NaCrF6 ) structures is discussed as governed by the modified Goldschmidt tolerance factor of the compounds.
TL;DR: In this article, the anhydrous iodates of Cr, Mn, Fe, Co and β-Ni form a single isomorphous family, crystallizing in space group P63 or P6322 with lattice constants typified by Mn(IO3)2 of a = 11.178 ± 0.001 A and four formulas per unit cell.
TL;DR: In this article, the authors present results obtained on rapid solidification of aluminium-silicon alloys from the liquid state, and show that the limit of primary solid solubility is extended almost to the eutectic composition and that the large supersaturation is relieved on raising the annealing temperature to the range 110 to 450° C.
Abstract: This paper present results obtained on rapid solidification of aluminium-silicon alloys from the liquid state. It shows that the limit of primary solid solubility is extended almost to the eutectic composition and that the large supersaturation is relieved on raising the annealing temperature to the range 110 to 450° C. This conclusion is based on measurements of lattice parameter and is also supported by corresponding changes in hardness and metallographic features.
TL;DR: In this article, the electronic densities of states functions for the random substitutional alloy system Ag-Pd for a number of compositions across the complete range of concentrations are calculated based on the coherent potential approximation.
Abstract: Electronic densities of states functions are calculated for the random substitutional alloy system Ag-Pd for a number of compositions across the complete range of concentrations. The calculations are based on the coherent potential approximation. It was found necessary to extend the simple model Hamiltonian method previously used to describe Cu-Ni alloys because of the stronger dependence of the lattice constant on composition in the Ag-Pd system. It is shown that the results are consistent with published photoemission and optical absorption data, and low temperature specific heat and Pauli spin susceptibility experiments. The possibility of s-d charge transfer in this alloy system is discussed.
TL;DR: The magnetic properties of rare earth-magnesium compounds with the CsCl structure have been determined in the temperature range 4.2-300 K with applied magnetic fields up to 18 kOe.
Abstract: The magnetic properties of rare earth-magnesium compounds with the CsCl structure have been determined in the temperature range 4.2–300 K with applied magnetic fields up to 18 kOe. There is a change in sign of the asymptotic Curie temperatures in going from compounds with light rare-earth elements to those with heavy rare-earth elements. The temperature dependence of the magnetization in the magnetically ordered region points to antiferromagnetism for the former compounds and to ferromagnetism for the latter compounds. For all compounds investigated the lattice constants have been determined.
TL;DR: In this article, self-consistent spin-polarized APW calculations have been performed to determine the energy band structure of metallic vanadium in an assumed ferromagnetic b.c. structure as a function of lattice parameter.
TL;DR: In this paper, the reflectance R and transmittance T of an infinite square lattice of polarizable nonpolar particles with retarded dipole-dipole interactions are rigorously calculated.
TL;DR: In this paper, the orthorhombic phases of YMnO3, HoMnNO3 and YbNOM3 were made by transformation of the normal hexagonal phases at 1000°C and 35-40 kbar.
TL;DR: Theoretical predictions of void lattices in metals are discussed and related to the observations reported in this paper, where the void concentration is found to be ∼3 × 10 16 / cm 3, and the void lattice parameter ∼ 700 A.
TL;DR: The defect properties of GaAs have been investigated through a process of crystal growth, especially in relation to the change in electrical and luminescence properties and lattice constant due to the deviation from stoichiometry as discussed by the authors.
Abstract: The defect properties of GaAs have been investigated through a process of crystal growth, especially in relation to the change in electrical and luminescence properties and lattice constant due to the deviation from stoichiometry. GaAs crystals were grown from Sn solutions by the temperature gradient method under controlled As pressure from 8.5×10−‐6 to 4.3×10 Torr. From the photoluminescence measurements, the level which is associated with the As vacancy and Sn is found at 1.34 eV in the low As pressure region. With increasing As pressure, the concentration of the Ga vacancies which behave as acceptors increases and carrier compensation proceeds. The lattice constant is increased by the incorporation of Sn. It also is a function of the As pressure, that is, the Ga vacancy is found to make the lattice constant increase. It can be said that GaAs crystals which deviate from stoichiometry can be obtained when they are grown from Sn solutions under controlled As pressure.