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61.
Andrij Stetskiv Beata Rozdzynska‐Kielbik Renata Misztal Volodymyr Pavlyuk 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(6):506-510
A ternary hexaerbium triacontacobalt enneakaidecasilicide, ErCo5Si3.17, crystallizes as a combination of disordered variants of the hexagonal UCo5Si3 (P63/m) and Yb6Co30P19 (P) structure types and is closely related to the Sc6Co30Si19 and Ce6Rh30Si19 types. The Er, Co and three of the Si atoms occupy sites of m.. symmetry and a fourth Si atom occupies a site of .. symmetry. The environment of the Er atom is a 21‐vertex pseudo‐Frank–Kasper polyhedron. Trigonal prismatic coordination is observed for the Si atoms. The Co atoms are enclosed in heavily deformed cuboctahedra and 11‐vertex polyhedra. Crystallochemistry analysis and the data from electronic structure calculations (TB–LMTO–ASA) suggest that the Er atoms form positively charged cations which compensate the negative charge of the [Co12Si9]m− polyanions. 相似文献
62.
Pavlo Solokha Serena De Negri Volodymyr Pavlyuk Adriana Saccone 《Solid State Sciences》2009,11(4):801-811
Single crystals of the Y5Cu5Mg8, Y5Cu5Mg13, Y5Cu5Mg16 and YCuMg4 compounds were synthesized by heating in a resistance furnace evacuated quartz vials containing Ta-crucibles with element pieces. SEM-EDXS analyses were performed to check phases composition. The structures were refined from X-ray single crystal diffraction data. Y5Cu5Mg8, Y5Cu5Mg13 and Y5Cu5Mg16 represent new structure types: Y5Cu5Mg8 – orthorhombic, Pmma, oP36, a = 2.63723(15), b = 0.40066(2), c = 0.74115(6) nm, Z = 2, wR2 = 0.0597, 939 F2 values, 60 variables; Y5Cu5Mg13 – orthorhombic, Cmcm, oS92, a = 0.40973(2), b = 1.92794(8), c = 2.57907(11) nm, Z = 4, wR2 = 0.1134, 1208 F2 values, 75 variables; Y5Cu5Mg16 – orthorhombic, Cmcm, oS104, a = 0.41360(8), b = 1.9239(4), c = 2.9086(6) nm, Z = 4, wR2 = 0.0760, 1383 F2 values, 84 variables. YCuMg4 crystallizes in the TbCuMg4 structure type (Cmmm, oS48, a = 1.35754(4), b = 2.03153(6), c = 0.39060(1) nm, Z = 8, wR2 = 0.0401, 661 F2 values, 45 variables). The crystal chemistry of these two-layer structures is comparatively discussed. Majority of novel compounds were characterized as members of inhomogeneous 2D intergrowth structure series of R5M5X5, X4 (Mg4) and empty Mg octahedra building blocks of general formula R5kM5kX5k + 4l + m. The common pentagonal prism derivative structural fragments around the most electropositive yttrium atoms were outlined in all these intermetallics. 相似文献
63.
M. M. Mazur D. Yu. Velikovskii F. A. Kuznetsov L. I. Mazur A. A. Pavlyuk V. E. Pozhar V. I. Pustovoit 《Acoustical Physics》2012,58(6):658-665
The elastic and photoelastic properties of a potassium-gadolinium tungstate KGd(WO4)2 crystal are determined. A complete matrix of elastic constants for the material is obtained for the first time and the velocity diagrams in the five most practically important planes are constructed on its basis. The coefficients of acoustooptic quality M 2 are measured for the first time for the crystal in the case of isotropic diffraction for all basic configurations of acoustooptic interaction, which makes it possible to reveal the directions of the most effective interaction. 相似文献
64.
P. A. Loiko I. A. Denisov K. V. Yumashev N. V. Kuleshov A. A. Pavlyuk 《Applied physics. B, Lasers and optics》2010,100(3):477-483
A comparative experimental study of laser performance and thermal lensing properties in a flashlamp pumped Nd:KGW crystal
cut for the light propagating along the optical indicatrix axes N
p and N
g is presented. It was found that for both, the N
p-cut Nd:KGW and N
g-cut Nd:KGW thermal lens is astigmatic with astigmatism degree being determined mainly by the thermal expansion anisotropy
in KGW. The thermal lens in the N
g-cut Nd:KGW is positive, while in the N
p-cut Nd:KGW it has different signs for rays lying in two different meridional planes. The sensitivity factors show how much
the thermal lens optical power of a laser rod changes with pump power are determined. The results show that the N
g-cut Nd:KGW allows one to obtain higher average output powers at high pump levels as compared to the N
p-cut Nd:KGW. 相似文献
65.
66.
1-Allyl-4-aminopyridinium chloride reacts with Cu(NO3)2 · 3H2O in an ethanolic solution under the conditions of ac electrochemical synthesis at copper electrodes to form crystals of compound
[(NH2C5H4N(C3H5))2Cu3Cl3(NO3)2] (I). The crystals of compound I are monoclinic: space group P21/c, Z = 4, a = 25.770(7), b = 7.230(4), c = 12.505(5) ?, β = 92.58(3)°, V = 2328(2) ?3. The direct interaction of 1-allylquinolinium nitrate with Cu(NO3)2 · 3H2O in a methanolic solution in the presence of metallic copper yields crystals of compound [C9H7N(C3H5)Cu(NO3)2] (II). The crystals of compound II are triclinic: space group P
, a = 6.756(3), b = 8.391(4), c = 12.489(5) ?, α = 77.18(3)°, β = 89.48(4)°, γ = 73.32(3)°, V = 662.0(5) ?3. The structure of compound I is built of infinite linear anions: polymeric fragments {(NH2C5H4N(C3H5))2Cu3Cl3(NO3)2}
n
. Each of two copper atoms (Cu(1) and Cu(2)) π-coordinates the C=C bonds of the allyl groups of the 1-allyl-4-aminopyridinium
cations, the oxygen atom of the nitrate ions, and two chlorine atoms. The third copper atom Cu(3) is linearly linked with
two chlorine atoms. Particular polymeric fragments are additionally joined by the N-H…O, C-H…O, C-H…Cl hydrogen bonds. The
crystal structure of compound II is built-up of the isolated L2Cu2(NO3)4 fragments (L is the 1-allylquinolinium cation). The metal atom is localized in the trigonal pyramidal coordination environment
of three oxygen atoms of the nitrate ions and of the C=C bond of the allyl group of the cation. The particular L2Cu2(NO3)4 fragments are additionally joined by the C-H…O hydrogen bonds.
Original Russian Text ? A.V. Pavlyuk, T. Lis, M.G. Mys’kiv, 2009, published in Koordinatsionnaya Khimiya, 2009, Vol. 35, No.
6, pp. 458–462. 相似文献
67.
Volodymyr Pavlyuk Ewa Rozycka‐Sokolowska Bernard Marciniak 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(3):i25-i28
The new ternary intermetallic title compounds, namely trilanthanum undeca(zinc/magnesium), La3(Zn0.874Mg0.126)11, (I), and tricerium undeca(zinc/magnesium), Ce3(Zn0.863Mg0.137)11, (II), are isostructural and crystallize in the orthorhombic La3Al11 structure type. These three phases belong to the same structural family, the representative members of which may be derived from the tetragonal BaAl4 structure type by a combination of internal deformation and multiple substitution. Compared to the structure of La3Al11, in (I), a significant decrease of 11.9% in the unit‐cell b axis and an increase in the other two directions, of 3.6% along a and 5.2% along c, are observed. Such an atypical deformation is caused by the closer packing of atoms in the unit cell due to atom shifts that reflect strengthening of metallic‐type bonding. This structural change is also manifested in a significant difference in the coordination around the smaller atoms at the 8l Wyckoff position (site symmetry m). The Al atom in La3Al11 is in a tricapped trigonal prismatic environment (coordination number 9), while the Zn atoms in (I) and (II) are situated in a tetragonal antiprism with two added atoms (coordination number 10). 相似文献
68.
69.
K.V. Yumashev V.G. Savitski N.V. Kuleshov A.A. Pavlyuk D.D. Molotkov A.L. Protasenya 《Applied physics. B, Lasers and optics》2007,89(1):39-43
A comparative study of the flash-lamp pumped laser performance of standard b-grown Nd:KGW and Nd:KGW grown for propagation
along the optical axis Ng is presented. The results show that, in comparison with b-grown crystal, the Ng-grown Nd:KGW is very promising for use at high repetition flash-lamp pumping rates. With the same laser cavity configuration,
the Ng-grown Nd:KGW can operate at an average flash-lamp input power of at least 1.4 kW, while the b-cut one ceases lasing at average
flash-lamp input power of ∼0.5 kW. The reason for this is that the thermal lens induced in the Ng-oriented Nd:KGW rod under pump radiation is relatively weak, nearly spherical and positive, whereas the b-grown Nd:KGW rod
acts as a quite weak positive lens for radiation with radial polarization, and as a much stronger negative lens for tangentially
polarized radiation.
PACS 42.60.Jf; 42.70.Hj 相似文献
70.