scholarly journals Vapour-phase-transport rearrangement technique for the synthesis of new zeolites

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Valeryia Kasneryk ◽  
Mariya Shamzhy ◽  
Jingtian Zhou ◽  
Qiudi Yue ◽  
Michal Mazur ◽  
...  
Keyword(s):  
Vapour Phase ◽  
Nanoporous Materials ◽  
Trial And Error ◽  
New Materials ◽  
In Situ Xrd ◽  
Significant Difference ◽  
Silica Layers ◽  
Vapour Phase Transport ◽  
Phase Transport

Abstract Owing to the significant difference in the numbers of simulated and experimentally feasible zeolite structures, several alternative strategies have been developed for zeolite synthesis. Despite their rationality and originality, most of these techniques are based on trial-and-error, which makes it difficult to predict the structure of new materials. Assembly-Disassembly-Organization-Reassembly (ADOR) method overcoming this limitation was successfully applied to a limited number of structures with relatively stable crystalline layers (UTL, UOV, *CTH). Here, we report a straightforward, vapour-phase-transport strategy for the transformation of IWW zeolite with low-density silica layers connected by labile Ge-rich units into material with new topology. In situ XRD and XANES studies on the mechanism of IWW rearrangement reveal an unusual structural distortion-reconstruction of the framework throughout the process. Therefore, our findings provide a step forward towards engineering nanoporous materials and increasing the number of zeolites available for future applications.

A radioactive tracer study of the behaviour of long chain organic molecules on solid surfaces

1955 ◽  
Vol 8 (2) ◽  
pp. 173 ◽  
Author(s):  
JE Young
Keyword(s):  
Surface Diffusion ◽  
Quartz Glass ◽  
Radioactive Tracer ◽  
Vapour Phase ◽  
Pure Acid ◽  
Surface Transport ◽  
Short Period ◽  
Vapour Phase Transport ◽  
Phase Transport

The adsorption and possible mechanisms for the surface transport of stearic acid and some of its derivatives on solids have been investigated using radioactive tracers.� mono- and multimolecular layers of these compounds were deposited on quartz glass, mica, and metal specimens, which were then held at various temperatures for a short period. The resulting changes in amount and distribution of activity were determined by autoradiography or an appropriately designed Geiger tube. On unreactive surfaces such as platinum or quartz glass the pure acid is only weakly adsorbed and thermal desorption, in general, readily occurs, especially of layers deposited on an initial monolayer. Layers of copper or calcium soaps on all surfaces, either deposited as such or formed in situ, are very much more stable. There is also some evidence that desorption is favoured by the presence of water vapour. Both pure acid and soap layers have some resistance to mechanical abrasion, but none to dissolution by hot benzene unless the adsorption involves a chemical bond. Part B of the present paper describes an experimental search for a long-range surface diffusion, using the same surfaces and adsorbates. It is shown that, under favourable conditions, material desorbed from one part of a surface will readsorb elsewhere after movement over considerable distances in the vapour phase. This mechanism may account for some examples of apparent surface diffusion reported by earlier workers. If, however, this vapour phase transport is suppressed, then no evidence can be detected of a true surface diffusion over macroscopic distances.

Notizen: The Crystal Structure of MnIn2Se4, a Ternary Layered Semiconductor

1991 ◽  
Vol 46 (8) ◽  
pp. 1122-1124 ◽  
Author(s):  
K.-J. Range ◽  
U. Klement ◽  
G. Döll ◽  
E. Bucher ◽  
J. R. Baumann
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Layered Structure ◽  
Chemical Vapour ◽  
Vapour Phase ◽  
Tetrahedral Coordination ◽  
Layered Semiconductor ◽  
Vapour Phase Transport ◽  
Phase Transport ◽  
Transport Technique

Single crystals of MnIn2Se4 have been grown by the chemical vapour phase transport technique using AlCl3 as the transporting agent. The structure was refined to R = 0.064, Rw, = 0.059 for 609 reflections. MnIn2Se4 (R 3̄m, hexagonal axes a = 4.051(1), c = 39.464(2) Å, c/a = 9.74, Z = 3) crystallizes with a nearly close-packed layered structure (sequence of the Se layers ABCA|CABC|BCAB) with Moct (= 0.56 Mn + 0.44 In) in octahedral coordination (Moct,–Se = 6 × 2.721(1) A) and Mtet (= 0.78 In + 0.22 Mn) in tetrahedral coordination (Mtet-Se = 1 × 2.527(2) and 3 × 2.593(1) Å). The overall layer sequences is ΑβΒαCyA| Cα AγBβC| BγCβAα B.

scholarly journals Enhanced detection of nitrogen dioxide via combined heating and pulsed UV operation of indium oxide nano-octahedra

2016 ◽  
Vol 7 ◽  
pp. 1507-1518 ◽  
Author(s):  
Oriol Gonzalez ◽  
Sergio Roso ◽  
Xavier Vilanova ◽  
Eduard Llobet
Keyword(s):  
Nitrogen Dioxide ◽  
Indium Oxide ◽  
Gas Sensors ◽  
Uv Light ◽  
Vapour Phase ◽  
Uv Light Irradiation ◽  
Combined Operation ◽  
Pulsed Uv Light ◽  
Vapour Phase Transport ◽  
Phase Transport

We report on the use of combined heating and pulsed UV light activation of indium oxide gas sensors for enhancing their performance in the detection of nitrogen dioxide in air. Indium oxide nano-octahedra were synthesized at high temperature (900 °C) via vapour-phase transport and screen-printed onto alumina transducers that comprised interdigitated electrodes and a heating resistor. Compared to the standard, constant temperature operation of the sensor, mild heating (e.g., 100 °C) together with pulsed UV light irradiation employing a commercially available, 325 nm UV diode (square, 1 min period, 15 mA drive current signal), results in an up to 80-fold enhancement in sensitivity to nitrogen dioxide. Furthermore, this combined operation method allows for making savings in power consumption that range from 35% to over 80%. These results are achieved by exploiting the dynamics of sensor response under pulsed UV light, which convey important information for the quantitative analysis of nitrogen dioxide.

GaAs growth by vapour phase transport

1975 ◽  
Vol 29 (2) ◽  
pp. 176-186 ◽  
Author(s):  
J.B. Loyau ◽  
M. Oberlin ◽  
A. Oberlin ◽  
L. Hollan ◽  
R. Cadoret
Keyword(s):  
Vapour Phase ◽  
Vapour Phase Transport ◽  
Phase Transport
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