Search results for "Structure type"
showing 10 items of 15 documents
Crystal Structure and Host-Guest Binding Ability of Three Types of Pillar[5]arenes
2015
A systematic research of the structural characterization and the host-guest binding abilities between three types of pillar[5]arenes 3–5 (3 for Structure Type I, 4 for Structure Type II and 5 for Structure Type III) is carried out by 1H NMR measurements and X-ray study. The results show that the configurations or symmetry of their cavities not only have large difference in these three types of pillar[5]arenes, but also have more or less variations even in the same structure type or the same host locked different guests such as crystals of 3a–3b, 4a–4d. On the other hand, the complexation behavior of pillar[5]arenes with 1,4-dibromobutane (DBB) is affected by the different symmetrical struct…
Hf27Si6P10, a novel metal-rich compound with P2 groups
2000
The new ternary metal rich compound Hf27Si6P10 has been synthesized by reduction of HfP with Hf and Si; Hf27Si6P10 crystallizes in a new structure type, a characteristic and unexpected feature of which is the presence of P2 groups; the structural results are interpreted with the aid of high-level band structure calculations.
Semiconducting half-Heusler and LiGaGe structure type compounds
2009
Compounds with LiAlSi (half-Heusler) and LiGaGe structure types have been investigated by means of band structure calculations. The LiAlSi structure type is known as the half-Heusler structure type, whereas LiGaGe is a closely related hexagonal variant. A remarkable feature of some XYZ half-Heusler compounds with 8 and 18 valence electrons is, that despite being composed of only metallic elements, they are semiconductors. More than 100 semiconducting compounds within these structure types are known. LiGaGe compounds have an additional degree of freedom, namely the degree of puckering of the layers. These compounds can become semiconducting at a certain degree of puckering. Half-metallic beh…
Bellbergite?a new mineral with the zeolite structure type EAB
1993
The new mineral bellbergite, (K, Ba, Sr)2Sr2Ca2(Ca, Na)4Al18Si18O72 · 30H2O, has been found in Ca-rich xenoliths at the Bellberg volcano near Mayen, Eifel, Germany. It occurs as well formed bipyramids with a length up to 0.3 mm. Possible space groups are P63/mmc, P62c and P63mc with a = 13.244(1) A, c = 15.988(2) A, V = 2429 A3, Z = 1. The density is: Dm, = 2.20(2) Mg/m3, Dc = 2.19 Mg/m3. The empirical formula based on 72 oxygen atoms is: Ba0.26Na0.72K1.33Sr2.36Ca5.32Al17.55Si18.36O72 · 30H2O. The mineral is uniaxial negative with ω = 1.522(2) and e = 1.507(2) (λ = 589 nm). The strongest lines in the X-ray powder pattern are (d (A), I, hkl): 3.80 (100) (300, 212, 104), 6.58 (80) (102), 2.95…
Antimykotische wirkstoffe. XIX. 4,6-Disubstituierte 2-(cyanamino)pyrimidine
1985
Aus der Umsetzung von Dicyandiamid (1) mit β-Diketonen (2a-c) gehen die 2-Cyanaminopyrimidine (3a-c) hervor. Strukturtyp 3 wird durch spektroskopische Daten gestutzt, wahrend gleichzeitig eine 1-Cyan-2-imino-struktur (4) ausgeschlossen wird. Verbindung 3a zeigt fungistatische und nematizide Wirkungen. The reaction of city dicyandiamide (1) with β-diketones 2a-c leads to 2-(cyanoamino)pyrimidines 3a-c. Structure type 3 is supported by spectroscopic data, while at the same time a 1-cyano-2-imino structure (4) is excluded. Compound 3a exhibits fungistatic and nematicidal activity.
Structural study of gallium oxynitrides prepared by ammonolysis of different oxide precursors
2009
International audience; A comparative structural study has been carried out on gallium oxynitride powders using XRD and Raman spectroscopy. Gallium oxynitrides have been prepared by ammonolysis of either NiGa2O4 ternary oxide or the citrate method-derived amorphous oxide. Their crystal chemistry is different and appears to be influenced by the nature of the oxide precursor: whereas gallium oxynitride obtained from amorphous gallium oxide crystallizes with the common wurtzite structure, gallium oxynitride obtained from NiGa2O4 crystallizes with an original structure that we have identified as the carborundum II (B6) structure type or 6H-SiC. As far as we know, this is the first 6H-SiC struct…
Crystal structures of new ternary compounds in RE–Pt–Pb and RE–Au–Pb systems (RE=rare earth metal)
2012
Abstract The crystal structures of the compounds RE 2 Pt 2 Pb (RE = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; Mo 2 FeB 2 structure type, space group P 4/ mbm , Pearson code tP10 ), REPtPb (RE = La, Ce, Pr, Nd, Sm; ZrNiAl structure type, space group P 6 ¯ 2 m , Pearson code hP9 ), RE 2 Au 2 Pb (RE = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; Er 2 Au 2 Sn structure type, space group P 4 2 / mnm , Pearson code tP20 ) and REAuPb (RE = Tm, Yb and Lu) were determined using X-ray powder diffraction.
ChemInform Abstract: Crystal Structures of New Ternary Compounds in RE-Pt-Pb and RE-Au-Pb Systems (RE = Rare Earth Metal).
2012
Abstract The crystal structures of the compounds RE 2 Pt 2 Pb (RE = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; Mo 2 FeB 2 structure type, space group P 4/ mbm , Pearson code tP10 ), REPtPb (RE = La, Ce, Pr, Nd, Sm; ZrNiAl structure type, space group P 6 ¯ 2 m , Pearson code hP9 ), RE 2 Au 2 Pb (RE = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; Er 2 Au 2 Sn structure type, space group P 4 2 / mnm , Pearson code tP20 ) and REAuPb (RE = Tm, Yb and Lu) were determined using X-ray powder diffraction.
ChemInform Abstract: Hf27Si6P10, a Novel Metal-Rich Compound with P2 Groups.
2010
The new ternary metal rich compound Hf27Si6P10 has been synthesized by reduction of HfP with Hf and Si; Hf27Si6P10 crystallizes in a new structure type, a characteristic and unexpected feature of which is the presence of P2 groups; the structural results are interpreted with the aid of high-level band structure calculations.
ChemInform Abstract: Nb2Te3, a Niobium Sesquitelluride with Te22- Groups.
2010
The new binary compound Nb2Te3 was synthesized by reduction of NbTe2 with Ga metal; different from the formally analogous Ta2Te3 it crystallizes in the Mo2As3 structure type; based on the results of band structure calculations Nb2Te3 is metallic with quasi one-dimensional metal electronic properties.