Band 235, Heft 4-5

Orientated ilmenite inclusions have been discovered in amphibole of hornblendite from the Zhujiapu area, Dabie ultra-high-pressure (UHP) metamorphic terrane, China. In order to characterize the crystallographic orientation relationships between ilmenite inclusions and amphibole host and reconstruct the mechanism of their formation, we present an electron backscatter diffraction (EBSD) analysis combined with energy dispersive spectroscopy (EDS) analysis and electron microprobe analysis (EPMA) for ilmenite inclusions and amphibole host. The inclusions can be subdivided into four groups: (1) 60.2% of ilmenites have the crystallographic orientation {0001} Ilm // {100} Amp , (101̅0) Ilm // {010} Amp , [112̅0] Ilm // <001>  Amp and [112̅0] Ilm // <012 >  Amp . (2) 16.5% of ilmenites have <0001>  Ilm // <001>  Amp , (101̅0) Ilm // {010} Amp , (112̅0) Ilm // {100} Amp and [3̅031] Ilm // <012>  Amp . (3) 13.8% of ilmenites have <0001>  Ilm // <012>  Amp , (112̅0) Ilm // {100} Amp and [3̅031] Ilm // <001>  Amp . (4) 9.5% of ilmenites have <0001>  Ilm // [1̅12] Amp , (101̅0) Ilm // {201} Amp , [112̅0] Ilm // [1̅12] Amp and [1121¯]Ilm${[11\overline {21} ]_{Ilm}}$// <010>  Amp . By comparing the lattice relationship between ilmenite inclusions and amphibole hosts, it is shown that the frequency of the ilmenite inclusions in different groups is related to the lattice coherency and oxygen packing. Group-1 of the ilmenite inclusions was most likely be formed via a solid-state exsolution process by cooling of the hornblendite after the intrusion was emplaced. The other three groups of ilmenite inclusions were probably formed via reduction reaction in an open system. The formation temperature of the ilmenite inclusions is estimated by using the TiO 2 solubility geothermeter in amphibole. The minimum formation temperature of the ilmenite inclusions is about 1025 °C, and the maximum formation temperature of the ilmenite inclusions is about 1126 °C.

The quaternary gallium-rich intermetallic phases RE 2 Pt 3 Ga 4 In with RE  = Y and Gd-Tm were synthesized by arc-melting of the elements and subsequent annealing. Small single crystals were obtained by high-frequency annealing of the samples in sealed tantalum ampoules. The polycrystalline samples were characterized through their X-ray powder patterns. The RE 2 Pt 3 Ga 4 In phases crystallize with a site ordering variant of the orthorhombic Y 2 Rh 3 Sn 5 type, space group Cmc  2 1 . The structures of Gd 2 Pt 3 Ga 4 In, Dy 2 Pt 3 Ga 4.14 In 0.86 , Er 2 Pt 3 Ga 4.17 In 0.83 and Tm 2 Pt 3 Ga 4.21 In 0.79 were refined from single-crystal X-ray diffraction data. The single crystals reveal small homogeneity ranges RE 2 Pt 3 Ga 4±x In 1±x . The striking geometrical structural building units are slightly distorted trigonal prisms around the three crystallographically independent platinum atoms: Pt1@ RE 4 Ga 2 , Pt2@ RE 2 Ga 4 and Pt3@ RE 2 Ga 2 In 2 . Based on these prismatic building units, the RE 2 Pt 3 Ga 4 In structures can be described as intergrowth variants of TiNiSi and NdRh 2 Sn 4 related structural slabs. Temperature dependent magnetic susceptibility studies of Gd 2 Pt 3 Ga 4 In and Tb 2 Pt 3 Ga 4 In show Curie-Weiss behavior and the experimental magnetic moments confirm stable trivalent gadolinium respectively terbium. Gd 2 Pt 3 Ga 4 In and Tb 2 Pt 3 Ga 4 In order antiferromagnetically at T N  = 15.8(1) and 26.0(1) K. Magnetization curves at 3 K show field-induced spin reorientations.

The detail investigation of the samples with nanodimensional anatase, formed by hydrolysis of TiOSO 4  ×  x H 2 O without or in the presence of polymer poly( N -vinyl caprolactam), physical precipitation of the polymer followed by the capture of commercial Hombifine N are performed by X-ray powder diffraction using laboratory and synchrotron radiation sources, transmission electron microscopy with the diffraction, and elemental analysis. The two «core»-«shell» models with nanoparticles and their associates as a core can be applied to samples produced. The synchrotron and electron radiation change the degree of crystallinity and the imperfection of anatase, isolate of TiO 2−x (OH) 2x  ×  y H 2 O from the nanoparticle shell with a decrease in its thickness, lead to the anatase – rutile phase transition. The double diffraction effect on the appearance of kinematically forbidden reflections caused by the dynamic character of the electron diffraction. The photoactivity depends on microstructural characteristics (specific surface, nanoobjects sizes). The structure and elemental composition of nanoparticles (associates) affect antimicrobial activity against Staphylococcus aureus and Escherichia coli.

The copper-rich intermetallic compounds CaCu 9 Mg 2 and SrCu 9 Mg 2 were synthesized by induction melting of the elements and subsequent annealing in a muffle furnace. CaCu 9 Mg 2 and SrCu 9 Mg 2 crystallize with the TbCu 9 Mg 2 type structure, space group P  6 3 / mmc , which is a ternary ordered variant of CeNi 3 . The polycrystalline samples were characterized through their X-ray powder patterns. The CaCu 9 Mg 2 structure was refined from single-crystal X-ray diffraction data. a =  504.13(9), c =  1622.5(3) pm, wR 2 = 0.0635, 302 F 2 values and 19 variables. The two striking coordination polyhedra in the CaCu 9 Mg 2 structure are Ca@Cu 18 Mg 2 and Mg@Cu 12 Mg 3 Ca. These polyhedra condense to layers which are stacked in ABA′B′ sequence. The X-ray data give no hint for Ca/Mg mixing.

Although γ / η -Mo 4 O 11 and Mo 2 Ta 2 O 11 are used in a variety of industrial applications and can easily be synthesized in a chemical vapour transport (CVT) process or reactions in silica ampoules, respectively, only few data are available concerning their physical properties. In this paper, we further explore the properties of the three compounds with respect to their thermal and magnetic behavior, surface composition, and Raman spectroscopic properties.

Explicit formulas for coordination sequences of all 20 plane 2-uniform graphs are proved. The proof is based on the concept of layer-by-layer growth and on the canonical representation of geodesic chains in terms of special chains called as rays. The method works for a wide class of plane periodic graphs satisfying the following condition: for each sector of layer-by-layer growth there exists a graph vertex that is initial for two rays determining the sector. This generaizes the previous results where it is required that all vertices are initial for all rays.

A new silicate-germanate K 2 Y[(Si 3 Ge)O 10 (OH)] was synthesized hydrothermally in a system Y 2 O 3 :GeO 2 :SiO 2  = 1:1:2 (T = 280 °C; P = 90–100 atm.); K 2 CO 3 was added to the solution as a mineralizer. Single-crystal X-ray diffraction experiment was carried out at low temperature (150 K). The unit cell parameters are a  = 10.4975(4), b  = 6.9567(2), c  = 15.4001(6) Å, β  = 104.894(4)°; V  = 1086.86(7) Å 3 ; space group is P  2 1 / c . A novel complex anion is presented by corrugated (Si,Ge) tetrahedral layers connected by couples of YO 6 octahedra into the mixed microporous framework with the channels along b and a axes, the maximal size of cross-section is ~5.6 Å. This structure has similarity with the two minerals: ring silicate gerenite (Ca,Na) 2 (Y,REE) 3 Si 6 O 18  · 2H 2 O and chain silicate chkalovite Na 2 BeSi 2 O 6 . Six-member rings with 1̅ symmetry as in gerenite are distinguished in the new layer. They are mutually perpendicular to each other and connected by additional tetrahedra. Straight crossing chains in chkalovite change to zigzag four-link chains in the new silicate-germanate layer.