XANES Studies at N and C K-Edge of Compounds in the Ternary System Si-C-N

1996 ◽  
Vol 437 ◽  
Author(s):  
P. Kroll ◽  
A. Greiner ◽  
R. Riedel ◽  
S. Bender ◽  
R. Franke ◽  
...  
Keyword(s):  
Ternary System ◽  
Room Temperature ◽  
Structural Models ◽  
Silicon Tetrachloride ◽  
Structural Effects ◽  
Structural Increments ◽  
Solid Phases ◽  
Atomic Excitations

AbstractWe report on XANES-investigations at the nitrogen and carbon K-edge of Si-C-N containing solid phases prepared by the reaction of silicon tetrachloride with bis(trimethylsilyl)carbodiimide and annealing the reaction product at temperatures between room temperature (RT) and 1600°C. From the spectra it is possible to evidence the evolution of four phase regions and their different structural increments. We can relate the observed changes of atomic excitations to chemical and structural effects. By that means proposed structural models for the different phases are testified.

X-Ray Absorption at Si K-Edge for Novel Compounds in the Ternary System Si-C-N

1996 ◽  
Vol 437 ◽  
Author(s):  
P. Kroll ◽  
A. Greiner ◽  
R. Riedel ◽  
S. Bender ◽  
R. Franke ◽  
...  
Keyword(s):  
Composite Material ◽  
Ternary System ◽  
Crystalline Phase ◽  
Room Temperature ◽  
X Ray ◽  
Solid Phases ◽  
X Ray Absorption

AbstractWe present results of Si K-edge XANES-investigations for novel Si-C-N containing solid phases prepared by annealing of Si(NCN)2 at temperatures between room temperature (RT) and 1600°C. The chemical equivalence of the NCN-group arid oxygen as a ligand of silicon is confirmed. The spectra show the presence of an intermediate crystalline phase and its decomposition. Furthermore the recrystallisation of a Si3N4/SiC composite material and its dependence on temperature can be seen.

STRUCTURAL AND ELECTRONIC PROPERTIES OF THE Li/Si(001) SURFACE

1996 ◽  
Vol 03 (03) ◽  
pp. 1487-1494
Author(s):  
J.W. CHUNG
Keyword(s):  
Electronic Properties ◽  
Binding Sites ◽  
Room Temperature ◽  
Structural Models ◽  
Metallic Phase ◽  
Surface Band ◽  
Ordered Structures ◽  
Initial Stage ◽  
Structural And Electronic Properties ◽  
Characteristic Features

Atomic arrangements and electronic properties of the Li-adsorbed Si(001) surface are briefly reviewed. Characteristic features of a series of ordered structures with increasing Li coverage at room temperature are described. Structural models invoking a dimer flipping mechanism are discussed for the first two ordered structures, (2×2)-Li and (2×1)-Li, which are proposed as reconstructions of the silicon substrate. It is shown that the metallic phase found at an initial stage of adsorption is a result of substrate metallization, which explains the presence of an intraband surface plasmon. The features of the surface band structures for the first two ordered structures are discussed in terms of variation of the binding sites with coverage. All the unique features of the Li/Si(001) surface essentially exhibit the size effects of Li.

Analysis and Interpretation of Microstructures after Liquid Oxide Corrosion

2010 ◽  
Vol 70 ◽  
pp. 114-129
Author(s):  
Jacques Poirier
Keyword(s):  
Experimental Data ◽  
High Temperature ◽  
Room Temperature ◽  
Local Thermodynamic Equilibrium ◽  
High Alumina ◽  
Essential Information ◽  
Phase Rule ◽  
Liquid Oxide ◽  
Chemical Profiles ◽  
Solid Phases

Corrosion by liquid oxides is one of the most severe modes of degradations which limit the lifetime of the refractory linings. The study of the microstructures of corroded refractories provides essential information. However, the interpretation of the microscopic observations is difficult : - The refractories are multi-component and heterogeneous ceramics, - The microscopic observations are carried out at room temperature. They are not representative of the mineral and vitreous phases existing at high temperature, - During cooling, new solid phases appear by crystallization of liquid oxides. The composition of the vitreous phases also evolves with the temperature. Consequently, the information obtained is often limited. In this paper , we will present a method to analyse and interpret the microstructures of refractories after use. The concept of local thermodynamic equilibrium and the use of the phase rule make it possible to interpret the microstructures of corroded refractories, to explain the observed mineral zonation and to quantify the composition of the liquid phase at high temperature from chemical profiles established by S.E.M. Experimental data from corrosion of MgO-C, Al2O3-MgO and high alumina refractories will illustrate and validate this theoretical approach.

The phase equilibrium diagram of the ternary system magnesium iodide-iodine-water

1981 ◽  
Vol 34 (11) ◽  
pp. 2449 ◽  
Author(s):  
R Thomas
Keyword(s):  
Phase Equilibrium ◽  
Ternary System ◽  
Equilibrium Diagram ◽  
Phase Equilibrium Diagram ◽  
Solid Phases

The phase equilibrium diagram of the ternary system MgI2-12-H2O has shown a single polyiodide, MgI12,,9H2O), and a new hydrate, MgI2,9H2O, to be stable solid phases at 0°C.

Phase Transitions and Water Dynamics of [Mn(H2O)6](ClO4 )2 Studied by Differential Scanning Calorimetry and Neutron Scattering Methods

2000 ◽  
Vol 55 (9-10) ◽  
pp. 759-764 ◽  
Author(s):  
E. Mikuli ◽  
A. Migdał-Mikuli ◽  
I. Natkaniec ◽  
J. Mayer
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Neutron Scattering ◽  
Structural Phase Transition ◽  
Room Temperature ◽  
Structural Phase ◽  
Water Dynamics ◽  
Water Molecules ◽  
Temperature Phase ◽  
Solid Phases

Abstract DSC measurements performed at 95 -290 K have shown that [Mn(H 2 O) 6 ](CIO 4) 2 possesses, besides a high-temperature phase, existing above 323 K, four low-temperature solid phases. The inelastic incoherent neutron scattering (IINS) spectra and neutron powder diffraction (NPD) pat-terns registered at 20 -290 K have supported the DSC results and provided evidence that the investigated substance possesses even more than five solid phases. The IINS spectra have shown that in the room-temperature phase, water molecules perform fast stochastic reorientation at the picosecond scale. The orientational disorder characteristic for the room-temperature phase can be easily overcooled and frozen. Even by relatively slow cooling at ca. 40 K/hour a metastable, orientational (protonic) glass phase is formed below ca. 160 K. Below ca. 100 K, a structural phase transition was observed by the NPD, however the IINS spectra indicate existence of the pure ordered low-temperature phase only after annealing the sample for a few hours at 100 K. On heating, a structural phase transition takes place at ca. 120 K, and at ca. 225 K water molecules begin fast reorientation.

Phase equilibria in the Gd–Bi–Sb ternary system at room temperature

2007 ◽  
Vol 433 (1-2) ◽  
pp. 125-128 ◽  
Author(s):  
Y.X. Jian ◽  
J.Q. Li ◽  
F.S. Liu ◽  
W.Q. Ao
Keyword(s):  
Ternary System ◽  
Phase Equilibria ◽  
Room Temperature

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 phase equilibrium diagram of the ternary system strontium iodide-iodine-water

1982 ◽  
Vol 35 (1) ◽  
pp. 227 ◽  
Author(s):  
R Thomas
Keyword(s):  
Phase Equilibrium ◽  
Ternary System ◽  
Equilibrium Diagram ◽  
Phase Equilibrium Diagram ◽  
Solid Phases

The phase equilibrium diagram of the ternary system SrI2-I2-H2O has shown a single polyiodide SrI12,7H2O and the hydrate SrI2,7H2O to be stable solid phases at 0�C.

STUDY ON PHASE DIAGRAM OF BaO-Y2O3-CuO TERNARY SYSTEM

1987 ◽  
Vol 01 (02) ◽  
pp. 363-365 ◽  
Author(s):  
Guangcan Che ◽  
Jingkui Liang ◽  
Wei Chen ◽  
Sishen Xie ◽  
Yude Yu ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Phase Diagram ◽  
Ternary System ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
High Tc ◽  
X Ray ◽  
High Tc Superconductor

In Ba-R-Cu-O system (R=La, Y) , high Tc superconductor have been discovered (1–3). The room temperature section of the phase diagram in BaO-Y2O3-CuO system has been completed by means of X-ray diffraction, thermal analysis and superconducting measurements.

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