The system Pd–Ag–S: phase relations and mineral assemblages

Phase equilibria in the system Pd–Ag–S were studied using the silica-glass tube method at 400°C and 550°C. In the system we synthesised three ternary phases: coldwellite (Pd3Ag2S), kravtsovite (PdAg2S) and a new phase Pd13Ag3S4. At 400°С, coldwellite forms a stable association with vysotskite (PdS) and vasilite (Pd16S7); vysotskite and kravtsovite; phase Pd4S and a Ag–Pd alloy; it also coexists with a new phase Pd13Ag3S4. Kravtsovite is stable up to 507°C; the presence of kravtsovite in the mineral assemblage reflects its formation below this temperature. The occurrence of coldwellite, vysotskite and Ag2S together in equilibrium reflects the formation of this mineral assemblage above this temperature (507°C). Coldwellite is stable up at 940°С. Mineral assemblages defined in this study can be expected in Cu–Ni–PGE mineral deposits, associated with mafic and ultramafic igneous rocks, in particular in mineralisations with known silver–palladium sulfides.

Powder diffraction study of Pd2HgSe3

The Pd2HgSe3 phase was synthetized from individual elements by the silica glass tube technique and its crystal structure has been refined by the Rietveld method. The Pd2HgSe3 phase crystalizes in P$\bar 3$m1 space group with the unit-cell parameters a = 7.3096(2) Å, c = 5.2829(1) Å, V = 244.45(1) Å3, Dc = 8.84 g/cm3, and Z = 2. In its layered crystal structure, the [PdSe6] octahedra share opposing Se–Se edges with adjacent [PdSe4] squares forming layers parallel with the (001) plane. The layers show AA type stacking along the c-axis. Hg atoms occupy the anti-cubooctahedral voids between two consecutive layers. Pd2HgSe3 is isostructural with Pt2HgSe3 and Pt4Tl2X6 (X = S, Se, or Te) phases. The structure can be viewed as a 2a.2a.c superstructure of PtSe2.

Fabrication of a Porous TiO2-Coated Silica Glass Tube and Its Application for a Handy Water Purification Unit

A simple, handy, reusable, and inexpensive water purification unit including a one-end sealed porous amorphous-silica (a-silica) tube coated with 2 μm of porous TiO2photocatalyst layers has been developed. Both TiO2and a-silica layers were formed through outside vapor deposition (OVD). Raman spectrum of the porous TiO2-coated a-silica glass tube indicated that the anatase content of the TiO2layers of the tube was estimated to be approximately 60 wt%. Developed porous TiO2-coated a-silica glass tube has been assayed for the tube filtering feature againstEscherichia coli(E. coli) solution used as one of the typical bacteria size species or Qβphage also used as typical virus size species and compared with the feature of porous a-silica tubes alone. The tubes removedE. colicompletely from the aqueous suspension which contained 106 CFU/mL ofE. coliwithout UV irradiation. The porous TiO2-coated a-silica glass tube with UV-C lamps successfully reduced the Qβphage amount in the suspension from 109to 103 PFU/mL.

Synthesis and crystal structure of (Ag,Pd)22Se6

The (Ag,Pd)22Se6 phase was synthesized from individual elements by silica glass tube technique and structurally characterized from powder X-ray diffraction data. The (Ag,Pd)22Se6 phase crystallizes in Fm$\overline3$m symmetry, unit-cell parameters: a = 12.3169(2) Å, V = 1862.55(5) Å3, Z = 4, and Dc = 10.01 g/cm3. The crystal structure of the (Ag,Pd)22Se6 phase represents a stuffed 3a.3a.3a superstructure of the Pd structure (fcc), where only 4 from 108 available octahedral holes are occupied. Its crystal structure is related to the Cr23C6 structure type.

Enhancement of green photoluminescence from ZnO:Pr powders

Pr-doped ZnO phosphor powders were prepared by dry reaction within evacuated sealed silica glass tube. Pr2O3 and Pr6O11 were used as additives. Pr concentrations were 0.5, 1, 3, and 5 mol%, and the sintering temperatures were 600, 800, and 1000 °C, respectively. Photoluminescence (PL) and PL excitation (PLE) spectra were measured to study luminescent properties of samples. Some samples showed the enhancement of green emission. This emission is related to native defects in ZnO. Based on the results of PL and PLE, the origin of the enhancement was discussed in view of native defects in ZnO and the defect-related complex in ZnO varistor ceramics. The possible origin is the increase of native defects such as VZn, OZn, and the complex in the vicinity of grain boundaries and ZnO matrix near the surface of grains. The increase of native defects and the complex are probably due to the existence of the Pr3+-ions with binding to native defects, which form the complex by Coulombic potential.

A re-examination of herzenbergite–teallite solid solution at temperatures between 300 and 700°C

In order to investigate the range of the solid solution series in herzenbergite-teallite minerals, samples of different composition were synthesized. Herzenbergite-teallite minerals were synthesized by an evacuated silica glass tube method at 700°C. A linear relationship between cell dimensions, a, b and c and composition is established. Extension of solid solution to the Pb-rich portion of the system PbS-SnS is limited; the solid solution area is between Pb1.060Sn0.940S2 and SnS at 700°C. Teallite coexisting with galena was also synthesized by hydrothermal recrystallization at 300, 400 and 450°C. The compositions of teallite are Pb1.140Sn0.860S2 at 300°C, Pb1.114Sn0.886S2 at 400°C, and Pb1.124Sn0.876S2 at 450°C, respectively. Their compositions shift towards the PbS end-member from stoichiometric teallite. The cell dimensions of teallite, which was synthesized hydrothermally, follow the linear relationship between cell dimensions and composition established at 700°C.

Darstellung und Kristallstruktur von Hexacaesium-hexatelluridodigermanat( III) (Cs6Ge2Te6)

The new compound hexacaesium hexatellurido digermanate(III), Cs6Ge2Te6, has been prepared by reacting the elements in a stoichiometric ratio at 923 K in an evacuated silica glass tube. The title compound crystallizes as black columns and is isostructural to K6G e2Te6 (C2/c, a = 17.027(2), b = 14.237(1), c = 10.104(1) Å, β = 96.701(8)°, Z = 4 (5130 reflections, R1 (I > 2 σ (I)) = 0.042). The structure ist composed of isolated distorted Te6 octahedra, with Ge-Ge dumbbells at the centres. The caesium cations are arranged between the isolated Ge2Te6 octahedra. The Ge-Ge bond lengths in A6Ge2Te6 (A = alkali metal) increase significantly as the counter ions are varied from sodium to caesium.