Crystal structure of bismuth gallium aluminium oxide, Bi-2(GaxAl1-x)(4)O-9, x=0.4, 0.6, 0.8

Al-2 4Bi2Ga1 O-6(9), orthorhombic, pbam (no 55), a = 7 79697(7) angstrom, b = 8.16575(7) angstrom, c = 5 75442(5) angstrom, V = 366.4 angstrom(3), Z = 2, Rw(P) = 0.067, R(P) = 0 048, R(l) = 0 022, T = 293 K. Al16Bi2Ga24O9, orthorhombic, Pbam (no 55), a = 7.83752(8) angstrom, b = 8 20096(8) angstrom, c = 5 79475(6) angstrom, V = 372 5 angstrom(3), Z = 2, Rw(P) = 0 081, R(P) = 0 057 R(l) = 0.031 T = 293 K. Al08Bi2Ga32O9, orthorhombic, Pbam (no 55), a = 7 88345(6) angstrom, b = 8 24579(6) angstrom, c = 5.84335(4) angstrom, V = 379 9 angstrom(3), Z = 2, Rw(P) = 0 075, R(P) = 0 054, R(l) = 0 028, T = 293 K

Investigations of the Anisotropic Optical Reflectivity of Binary and Ternary Nb-W Oxides Possessing Block-Type Crystal Structure

We have studied the anisotropic optical properties of binary NbO2.5-δ (0 8) in the infinite block direction only

Synthesis and Characterization of Vanadium Substituted Potassium Tungsten Bronzes, K x V y W 1-y O 3

A series of vanadium substituted potassium hexagonal tungsten bronzes KxVyW1-yO3 (K-HTB) were prepared by conventional solid state method at 800 °C with compositions of x = 0.30 and 0.00 ? y ? 0.15. A mixture of K-HTB and non bronze phases with y ? 0.20 was observed. The proportion of this non bronze phase increases with increasing vanadium content. The non bronze phases in the mixture could not be indexed yet. In contrast, a very small amount of vanadium can be substituted in potassium tetragonal tungsten bronzes (K-TTB) at 800 °C with x = 0.50 and 0.00 ? y ? 0.02, however at 700 °C vanadium substituted K-TTB can be prepared with 0.00 ? y ? 0.05. Further substitution of vanadium in K-TTB decomposes to K-HTB and non-bronze phases

Investigation of the relationship between the condensed structure and the chemically bonded water content in the network of geopolymer cements

The main objective of this work was to investigate the relationship between the condensed structure and the chemically bonded water content in the metakaolin-based geopolymer network. The kaolinite clay used in this work as an aluminosilicate source was transformed to metakaolin by calcination at 700 °C. The powder of the waste glass and the silica fume were used as silica sources for the synthesis of the hardeners. The obtained hardeners were characterized by infrared spectroscopy and MAS-NMR 29Si. The metakaolin and the hardeners were used for producing geopolymers cements. The synthesized products were characterized by X-ray diffractometry, infrared spectroscopy, mercury intrusion porosimetry, scanning electron microscopy, MAS-NMR 29Si and 27Al, thermal analyses (TG and DSC) and compressive strength. The results show that the compressive strength of geopolymer cements using hardener from silica fume and the one from waste glass are 62 and 26 MPa, respectively. The microstructure (SEM observations) geopolymer cements obtained using hardener from silica fume are homogeneous, compact and dense with an average pore diameter around 10 nm. Whereas, the one obtained using hardener from waste glass are heterogeneous and contains larger pores (170 nm). MAS-NMR 29Si and 27Al results show that the specimen obtained using hardener from the silica fume contains more aluminum in four-fold coordination in its network than waste glass geopolymer, GWG. This indicates a higher degree of crosslinking of poly(sialate-siloxo) chains which could lead to a smaller pore sizes and a higher water uptake in the structure of the sample. The amount of chemically bonded water contained in the network of geopolymer cements using hardeners from waste glass and silica fume were 6.82 and 11.23%, respectively, as determined from weigth loss in the range 100-300 °C. All these results indicate that the higher content of chemically bonded water in the network of geopolymer obtained using hardener from silica fume is related to the much smaller average pore size diameter and the hydrophilic character of aluminum, which reveals obviously better mechanical and microstructural properties of the specimen. This could indicate here a higher degree of condensation using silica fume based hardeners for geopolymerisation. Please click Additional Files below to see the full abstract

Legislative Documents

Also, variously referred to as: House bills; House documents; House legislative documents; legislative documents; General Court documents

Crystal structure of caesium niobium tungsten bronzes, Cs-0.23(Nb0.09W0.91)O-3 andCs(0.29)(Nb0.10W0.90)O-3

Cso.23Nbo.09O3Wo.91 (1) hexagonal, P63/mcm (No. 193), a = 7.3998(2) Å, c = 7.5732(2) Å, V = 359.1 ų, Ζ = 6, wR(P) =0.062, R(P)=0.044,R(I)=0.023, R(F)=0.012, T= 293 K. Cs0.29Nb0.10O3W0.90 (2), hexagonal, P63/mcm (No. 193), a = 7.3992(2) Å, c = 7.5867(2) Å, V = 359.7 ų, Ζ = 6, wR(P)=0.080, R(P)=0.057, R(I)=0.028, R(F)=0.014, T= 293 K

Comparison of metakaolin-based geopolymer cements from commercial sodium waterglass and sodium waterglass from rice husk ash

Abstract: Three sodium waterglass (NWG) such as commercial NWG (S1), NWG from pure rice husk ash (S2) and NWG from raw rice husk ash (S3) were applied for producing geopolymer cements using metakaolin (MK) as aluminosilicate source. Geopolymers (Geo1, Geo2 and Geo3) were prepared using each NWG with the molar ratios SiO2/Na2O and H2O/Na2O kept constant at 1.5 and 12, respectively. It could be observed that the water absorption of Geo1, Geo2 and Geo3 is 7, 9 and 13.2 % and the mass loss is 15.8, 14.7 and 12.4 %, respectively. Their compressive strength at 20 days (37.5/34.3/29.6 MPa) and 28 days (43.3/40.3/33.2 MPa) increases with increasing the aging and decreases in the course Geo1/Geo2/Geo3. Their average pore radius (6/8/20 nm) and cumulative pore volumes (155/205/245 mm3/g) increase in the course Geo1/Geo2/Geo3. It is discussed that the presence of phosphate known as corrosion inhibitors in raw rice husk ash hinders the dissolution of SiO2. It entails the formation of NaH2PO4 in S3 which reduces the soluble Si atoms. Therefore, less amount of metakaolin could be dissolved leaving thus a higher amount of unreacted metakaolin particles in Geo3. The reacted volumes and compositions of the geopolymers are different in the three cases, too. A content of approximately 20, 25 and 35 % of unreacted metakaolin was proved for Geo1, Geo2 and Geo3, respectively. Graphical Abstract: [Figure not available: see fulltext.