Tetragonal alkali metal tungsten bronze and hexagonal tungstate nanorods synthesized by alkalide reduction

2009 ◽  
Vol 19 (33) ◽  
pp. 6029 ◽  
Author(s):  
Olivera Zivkovic ◽  
Chao Yan ◽  
Michael J. Wagner
Keyword(s):  
Alkali Metal ◽  
Tungsten Bronze ◽  
Alkalide Reduction

An Incommensurate Superstructure of Hexagonal Tungsten Bronze

1980 ◽  
Vol 38 ◽  
pp. 166-167 ◽  
Author(s):  
Yoshio Bando ◽  
Sumio Iijima
Keyword(s):  
High Resolution ◽  
Alkali Metal ◽  
Metal Ions ◽  
Diffraction Pattern ◽  
Average Distance ◽  
Tungsten Bronze ◽  
Incident Beam ◽  
Optical Diffraction ◽  
Alkali Metal Ions ◽  
Resolution Electron

Incommensurate superstructures are interesting problems for high resolution electron microscopy. If modulations are formed within a plane of a host lattice parallel to the incident beam direction, their structures can be known directly from images (1,2,3). In this paper, an incommensurate superstructure of hexagonal potassium tungsten bronze, K0.3WO3, is observed by a 100B high-resolution electron microscope and its structure model is proposed. The hexagonal tungsten bronze was determined by Magneli (4) and its structure is shown in Fig. 1. The structure consists of WO6 octahedra and alkali metal ions. The alkali metal ions situated in hexagonal tunnels do not lie at the same level of the WO6 octahedra but at ¼ c above or below them. It was assumed that the alkali metal ions were distributed in a random fashion. Fig. 2 shows a structure image of K0.3WO3, taken along the [100] direction. The white spots correspond to hexagonal tunnels in Fig. 1. Fig. 3 shows an electron diffraction pattern taken along the [010] direction. Some additional weak superstructure spots are observed. The superstructure spot (indicated by A) is situated at a non-integral multiple position of the subcell spots along the c*-axis, indicating that the incommensurate superstructure has a multiplicity of 2.2 x c of the subcell. The non-integral periodicity can be seen in a high-resolution image taken along the [010] direction, as shown in Fig. 4. At the thick crystal regions, some weak dark bands running parallel to the c axis are observed, in which they have two different widths (2 x c or 2.5 x c) along the c axis. An average distance between the adjacent dark bands becomes about 2.2 x c, which is consistent with an optical diffraction pattern (inset in Fig. 4). One of the possible models for the incommensurate superstructure of the hexagonal tungsten bronze is proposed in Fig. 5. The superstructure arises from the local ordering of K ion vacancies located in the tunnels along the c axis. The vacancies are formed at every fourth or fifth site of K ions. We call them structures with n = 4 and n = 5. The incommensurate superstructure results from a mixture of the structure elements with n = 4 and n = 5, causing the formation of a non-integral periodicity observed presently. It should be noted in Fig. 4 that the image from a thin region does not show the superstructure but the image from a thick region does. It seems that this phenomenon arises from dynamical diffraction effects. This will be discussed in detail on the basis of the image calculation.

Alkali metal tungsten bronze-doped energy-saving glasses for near-infrared shielding applications

2021 ◽  
Author(s):  
Guang Yang ◽  
Daming Hu ◽  
Chuanfan Yang ◽  
Yunhang Qi ◽  
Bin Liu ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Energy Saving ◽  
Near Infrared ◽  
Tungsten Bronze

Modeling fine particles and alkali metal compound behavior in a kraft recovery boiler

TAPPI Journal ◽  
2012 ◽  
Vol 11 (7) ◽  
pp. 9-14 ◽  
Author(s):  
AINO LEPPÄNEN ◽  
ERKKI VÄLIMÄKI ◽  
ANTTI OKSANEN
Keyword(s):  
Alkali Metal ◽  
Computational Models ◽  
Fine Particles ◽  
Black Liquor ◽  
Melting Behavior ◽  
Metal Compound ◽  
Effect Of Temperature ◽  
Particle Model ◽  
Boiler Furnace ◽  
Recovery Boiler

Under certain conditions, ash in black liquor forms a locally corrosive environment in a kraft recovery boiler. The ash also might cause efficiency losses and even boiler shutdown because of plugging of the flue gas passages. The most troublesome compounds in a fuel such as black liquor are potassium and chlorine because they change the melting behavior of the ash. Fouling and corrosion of the kraft recovery boiler have been researched extensively, but few computational models have been developed to deal with the subject. This report describes a computational fluid dynamics-based method for modeling the reactions between alkali metal compounds and for the formation of fine fume particles in a kraft recovery boiler furnace. The modeling method is developed from ANSYS/FLUENT software and its Fine Particle Model extension. We used the method to examine gaseous alkali metal compound and fine fume particle distributions in a kraft recovery boiler furnace. The effect of temperature and the boiler design on these variables, for example, can be predicted with the model. We also present some preliminary results obtained with the model. When the model is developed further, it can be extended to the superheater area of the kraft recovery boiler. This will give new insight into the variables that increase or decrease fouling and corrosion

Epitaxial Growth of Sr0.3Ba0.7Nb2O6 Thin Films Prepared by Sol-Gel Process

1999 ◽  
Vol 606 ◽  
Author(s):  
Keishi Nishio ◽  
Jirawat Thongrueng ◽  
Yuichi Watanabe ◽  
Toshio Tsuchiya
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Epitaxial Growth ◽  
Raw Materials ◽  
Substrate Surface ◽  
Sol Gel ◽  
Tungsten Bronze ◽  
Monomethyl Ether ◽  
Tetragonal Tungsten Bronze ◽  
Sol Gel Process

AbstructWe succeeded in the preparation of strontium-barium niobate (Sr0.3Ba0.7Nb2O6 : SBN30)that have a tetragonal tungsten bronze type structure thin films on SrTiO3 (100), STO, or La doped SrTiO3 (100), LSTO, single crystal substrates by a spin coating process. LSTO substrate can be used for electrode. A homogeneous coating solution was prepared with Sr and Ba acetates and Nb(OEt)5 as raw materials, and acetic acid and diethylene glycol monomethyl ether as solvents. The coating thin films were sintered at temperature from 700 to 1000°C for 10 min in air. It was confirmed that the thin films on STO substrate sintered above 700°C were in the epitaxial growth because the 16 diffraction spots were observed on the pole figure using (121) reflection. The <130> and <310> direction of the thin film on STO were oriented with the c-axis in parallel to the substrate surface. However, the diffraction spots of thin film on LSTO substrate sintered at 700°C were corresponds to the expected pattern for (110).

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