The Structural behaviour of tetrahedral framework compounds—a review. Part I. Structural behaviour

1983 ◽  
Vol 47 (344) ◽  
pp. 319-326 ◽  
Author(s):  
D. Taylor
Keyword(s):  
Atmospheric Pressure ◽  
Room Temperature ◽  
Critical Size ◽  
Smooth Transition ◽  
Structural Effects ◽  
Structural Behaviour ◽  
Tetrahedral Framework ◽  
Displacive Transformation ◽  
Alkali Feldspars ◽  
Framework Compounds

AbstractTetrahedral framework compounds, as defined in this paper, generally exist as tilted and distorted versions of ideal fully expanded structures at room temperature and atmospheric pressure. How pressure, temperature, and composition (P, T, and X) affect the tilting and distortion is critically reviewed. Although P, T, and X are generally regarded as analogous variables in their effect on framework structures there is reason to believe that they have different structural effects. In particular, an important, and frequently neglected, thermal effect is the apparent shortening of the framework bonds by the anisotropic thermal motion of the framework oxygens. The effects of P, T, and X on displacive transformations in framework compounds are reviewed with particular reference to the disordered alkali feldspars and the leucites. It seems probable from the available evidence that displacive transformations do not take place at a critical size of the framework. Displacive transformations can take place with or without a volume discontinuity and hysteresis. Furthermore, the effects of P, T, and X on a solid-solution series with a displacive transformation can be different, one variable causing a volume discontinuity and another a smooth transition.

The structural behaviour of tetrahedral framework compounds — a review Part II. Framework structures

1984 ◽  
Vol 48 (346) ◽  
pp. 65-79 ◽  
Author(s):  
D. Taylor
Keyword(s):  
Thermal Expansion ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Structural Changes ◽  
Structural Data ◽  
Structural Behaviour ◽  
Tetrahedral Framework ◽  
Cell Parameters ◽  
Silicon And Germanium ◽  
Framework Compounds

AbstractTetrahedral framework compounds, as defined in this paper, generally exist as tilted and distorted versions of ideal fully expanded structures at room temperature and atmospheric pressure. How pressure, temperature, and composition (P, T, and X) affect the tilting and distortion is critically reviewed. It is shown that although the effects of P, T, and X on the cell parameters are broadly analogous, the underlying structural changes are generally different. An important, and frequently neglected thermal effect is the apparent shortening of the framework bonds by the anisotropic thermal motion of the framework oxygens. Tilting models of framework compounds are critically examined and their failure to match the observed structural behaviour is attributed to changes in tetrahedral distortion. For quartz it appears that during compression the change in tetrahedral distortion is virtually all angular (O-Si-O angles), whereas during thermal expansion the change in distortion is in the Si-O distances. Such behaviour may typify the behaviour of many other framework compounds but the structural data needed to establish this are lacking. The review is illustrated by reference to the quartz and cristobalite analogues; to the sodalite, leucite, nepheline, scapolite, and feldspar families; and to the nitrides and oxynitrides of silicon and germanium. It is concluded that our understanding of the structural behaviour of framework compounds is still superficial and that much theoretical and experimental work remains to be done.

scholarly journals Magnetic and Magneto-Optical Oroperties of Iron Oxides Nanoparticles Synthesized under Atmospheric Pressure

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1888
Author(s):  
Aleksandr Spivakov ◽  
Chun-Rong Lin ◽  
Yu-Chuan Chang ◽  
Cheng-Chien Wang ◽  
Dmitriy Sarychev
Keyword(s):  
Thermal Decomposition ◽  
Structural Analysis ◽  
Reaction Temperature ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Critical Size ◽  
Average Crystallite Size ◽  
Thermal Decomposition Process ◽  
Nitrate Nonahydrate ◽  
Superparamagnetic State

Magnetite nanoparticles were synthesized by a simple thermal decomposition process, involving only iron (III) nitrate nonahydrate as a precursor, and hexadecylamine as a solvent and stabilizer at reaction temperatures varied from 200 to 380 °C. The results of the structural analysis showed that the average crystallite size depends on the reaction temperature and increases from 4.8 to 13.3 nm. The behavior of the coercivity indicates that all synthesized samples are single domain; herewith, it was found that the critical size corresponding to the transition to the superparamagnetic state at room temperature is about 9 nm. The effect of the reaction temperature on changes in the saturation magnetization was studied. It was found that the size effect in the MCD spectra is observed for the IVCT transition and one ISCT transition, and the influence of the reaction temperature on the change in the MCD spectra was discussed.

scholarly journals Cat-CrNP as new material with catalytic properties for 2-chloro-2-propen-1-ol and ethylene oligomerizations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jacek Malinowski ◽  
Dagmara Jacewicz ◽  
Artur Sikorski ◽  
Mariusz Urbaniak ◽  
Przemysław Rybiński ◽  
...  
Keyword(s):  
Complex Compound ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Organometallic Compounds ◽  
Ethylene Oligomerization ◽  
High Catalytic Activity ◽  
New Material ◽  
Activity Requirement ◽  
Olefin Oligomerization ◽  
Xrd Method

AbstractThe contemporary search for new catalysts for olefin oligomerization and polymerization is based on the study of coordinating compounds and/or organometallic compounds as post-metallocene catalysts. However known catalysts are suffered by many flaws, among others unsatisfactory activity, requirement of high pressure or instability at high temperatures. In this paper, we present a new catalyst i.e. the crystalline complex compound possesing high catalytic activity in the oligomerization of olefins, such as 2-chloro-2-propen-1-ol and ethylene under very mild conditions (room temperature, 0.12 bar for ethylene oligomerization, atmospheric pressure for 2-chloro-2-propen-1-ol oligomerization). New material—Cat-CrNP ([nitrilotriacetato-1,10-phenanthroline]chromium(III) tetrahydrate) has been obtained as crystalline form of the nitrilotriacetate complex compound of chromium(III) with 1,10-phenanthroline and characterized in terms of its crystal structure by the XRD method and by multi-analytical investigations towards its physicochemical propeties The yield of catalytic oligomerization over Cat-CrNP reached to 213.92 g · mmol−1 · h−1· bar−1 and 3232 g · mmol−1 · h−1 · bar−1 for the 2-chloro-2-propen-1-ol and ethylene, respectively. Furthemore, the synthesis of Cat-CrNP is cheap, easy to perform and solvents used during preparation are environmentally friendly.

Proliferation assay of mouse embryonic stem (ES) cells exposed to atmospheric-pressure plasmas at room temperature

2014 ◽  
Vol 47 (44) ◽  
pp. 445402 ◽  
Author(s):  
Taichi Miura ◽  
Ayumi Ando ◽  
Kazumi Hirano ◽  
Chika Ogura ◽  
Tatsuya Kanazawa ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Room Temperature ◽  
Es Cells ◽  
Embryonic Stem ◽  
Proliferation Assay ◽  
Atmospheric Pressure Plasmas

Apparatus for Measuring Dynamic Bulk Compliance of Time-Dependant Materials

2014 ◽  
Vol 601 ◽  
pp. 3-6
Author(s):  
Alen Oseli ◽  
Igor Emri
Keyword(s):  
Atmospheric Pressure ◽  
Room Temperature ◽  
Polyvinyl Acetate ◽  
Thermoplastic Polyurethane

This paper describes a novel apparatus for measuring dynamic bulk compliance B*(ω) of time-dependant materials. System can measure dynamic bulk compliance at room temperature, at pressures up to 100 ± 1,5 bar and frequencies from 100 Hz to 1000 Hz. Functionality of the apparatus is demonstrated by performing measurements of dynamic bulk compliance for two different materials, i.e., polyvinyl acetate (PVAc) and thermoplastic polyurethane (TPU). Measurements were conducted at room temperature, atmospheric pressure and frequencies from 100 Hz to 1000 Hz.

l-Asparagine-assisted synthesis of flower-like β-Bi2O3 and its photocatalytic performance for the degradation of 4-phenylphenol under visible-light irradiation

RSC Advances ◽  
2015 ◽  
Vol 5 (91) ◽  
pp. 74977-74985 ◽  
Author(s):  
Xin Xiao ◽  
Shunheng Tu ◽  
Chunxia Zheng ◽  
Huan Zhong ◽  
Xiaoxi Zuo ◽  
...  
Keyword(s):  
Visible Light ◽  
Visible Light Irradiation ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Photocatalytic Performance ◽  
Light Irradiation ◽  
Temperature Range

By introducing l-asparagine as a ligand, a flower-like precursor of Bi2O3 was prepared by a simple reflux process under atmospheric pressure. β-Bi2O3 was then conveniently obtained by decomposing the precursor and stabilized in a temperature range from room temperature to 420 °C due to the surface-coordination effects of CO32− derived from l-asparagine.

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