Thermochemische Untersuchungen zu den Systemen SE2O3-SeO2. II. Samariumselenoxide auf dem Schnitt Sm2O3-SeO2 / Thermochemical Investigations of Systems SE2O3-SeO2. II. Samarium Selenium Oxides on the Line Sm2O3-SeO2

2001 ◽  
Vol 56 (9) ◽  
pp. 917-926 ◽  
Author(s):  
H. Oppermann ◽  
M. Zhang-Preβe
Keyword(s):  
Phase Diagram ◽  
Thermal Decomposition ◽  
Solid State ◽  
Ir Spectroscopy ◽  
Total Pressure ◽  
Solid State Reactions ◽  
Pressure Measurements ◽  
X Ray ◽  
Dsc Measurements ◽  
Decomposition Properties

Abstract The pure ternary phases on the line Sm2O3-SeO2: Sm2SexO3+2x in thermodynamical equilibri­um have been synthesizied by solid state reactions and characterized by X-ray powder diffrac­tion, IR spectroscopy and DSC measurements. The existence of two new phases Sm2Se1,5O6 and Sm2Se4O11 was demonstrated besides the known phases Sm2Se3,5O10, Sm2Se3O9 and Sm2SeO5. The thermal decomposition properties of all compounds have been determined by total pressure measurements and the thermodynamical data of the compounds have been derived from their decomposition function and Cp-values. The phase diagram and the phase barogram have been estabilished using the results of DSC and total pressure measurements.

Thermochemische Untersuchungen zu den Systemen SE2O3-SeO2. V. Ytterbiumselenoxide auf dem Schnitt Yb2O3-SeO2/Thermochemical Investigations of Systems RE2O3-SeO2. V. Ytterbium Selenium Oxides on the Line Yb2O3-SeO2

2002 ◽  
Vol 57 (8) ◽  
pp. 868-876 ◽  
Author(s):  
H. Oppermann ◽  
M. Zhang-Preße ◽  
P. Schmidt
Keyword(s):  
Thermal Analysis ◽  
Phase Diagram ◽  
Solid State ◽  
Ir Spectroscopy ◽  
Powder Diffraction ◽  
Solid State Reaction ◽  
Total Pressure ◽  
Pressure Measurements ◽  
Thermodynamical Equilibrium ◽  
X Ray

The pure ternary phases on the line Yb2O3-SeO2 in thermodynamical equilibrium have been synthesized by solid state reaction and characterized using X-ray powder diffraction and IR-spectroscopy. There exist three phases: Yb2SeO5, Yb2Se3O9 and Yb2Se4O11, the last one with a homogeneiety range extending a higher SeO2-content. The thermal decompositions have been determined by total pressure measurements, and the thermodynamical data of the compounds have been derived. The phase diagram and the phase barogram have been established using the results of thermal analysis and total pressure measurements.

Untersuchungen zum ternären System Bi/Te/O, II. Thermisches Verhalten und Koexistenzbeziehungen von Bi2O2Te/Investigations of the Ternary System Bi/Te/O, II. The Thermal Behaviour and the Relations of Phase Coexistences of Bi2O2Te

1997 ◽  
Vol 52 (12) ◽  
pp. 1461-1466 ◽  
Author(s):  
P. Schmidt ◽  
O. Bosholm ◽  
H. Oppermann
Keyword(s):  
Solid State ◽  
Ternary System ◽  
Thermal Behaviour ◽  
Total Pressure ◽  
Chemical Transport ◽  
Solid State Reactions ◽  
Pressure Measurements ◽  
Pseudobinary System ◽  
X Ray ◽  
Solid Phases

Abstract The phase Bi2O2Te exists in the pseudobinary system Bi2O3/Bi2Te3. The thermal behaviour of Bi2O2Te was determined by DTA and X-ray analysis: The phase exists up to 620 °C and decomposes into the solid phases Bi12TeO20, Bi10Te2O19 [1] and liquid BiTe. The relations of the phase coexistences in the pseudobinary system and in the ternary area Bi2O3/TeO2/Bi2Te3/Te were investigated by solid state reactions, chemical transport reactions, and by total pressure measurements.

scholarly journals Early stages of solid state reactions: insights from micro-XRD and XAS

2014 ◽  
Vol 70 (a1) ◽  
pp. C1519-C1519
Author(s):  
Serena Tarantino ◽  
Paolo Ghigna ◽  
Elisabetta Achilli ◽  
Sonia Pin ◽  
Michele Zema ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Solid State ◽  
Equilibrium Phase ◽  
Experimental System ◽  
Equilibrium Phase Diagram ◽  
Solid State Reactions ◽  
Reactive System ◽  
X Ray ◽  
Early Stages ◽  
Intermediate Phases

The mechanism of a solid state reaction in its early stages can be explored by investigating the time evolution of a model reactive system made of a thin layer of one reagent deposited onto a single crystal slab of the other reagent. Insights can be retrieved by comparing results at both local and long length scales obtained with films of different thicknesses and deposited onto different crystal orientations. In particular, reaction between ZnO and Al2O3has been chosen, as the spinel-forming reactions have been and still remain a model experimental system for investigating solid state reactions and because in the ZnO/Al2O3phase diagram, spinel is the only stable compound. The reaction initial steps have been investigated by using synchrotron X-ray diffraction, atomic force microscopy and X-ray absorption spectroscopy at the Zn-K edge starting from zincite films deposited onto (110)-, (012)-, (001)-oriented corundum single crystals [1,2]. The reaction eventually yields ZnAl2O4spinel but via a complex mechanism involving side and intermediate non-equilibrium compounds that do not appear in the equilibrium phase diagram of the pseudo-binary system. Spinel, when occurs, is polycrystalline at the end but initially forms with a few preferred orientations. Intermediate phases form before and in parallel with the growth of the spinel. Their number, composition, structure and kinetic role strongly depend on substrate orientation and film thickness. A more detailed understanding of the reactivity can be inferred by comparing EXAFS results to those of grazing incidence diffraction experiments of the films deposited on the (001) face of Al2O3and heat-treated at 10000C for different lengths of time. Information on the structure of the intermediate phases is given and results are discussed by comparing different films thickness to clarify the role of interfacial free energy and crystallographic orientation.

X-ray topographic investigations of solid state reactions. I. Changes in surface and bulk substructure during incipient thermal decomposition in sodium chlorate monocrystals

1983 ◽  
Vol 386 (1791) ◽  
pp. 431-442 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Solid State ◽  
Mass Loss ◽  
Crystal Surface ◽  
Sodium Chlorate ◽  
Solid State Reactions ◽  
Dislocation Loops ◽  
Etch Pits ◽  
X Ray ◽  
Surface Decomposition

On heating, sodium chlorate monocrystals undergo a limited degree of thermal decomposition in the solid state (0.1-1 % mass loss) between 450 K and the melting point, ca . 535 K. The degree to which this occurs depends on the perfection of the sample, the more perfect crystals suffering lower mass loss. Examination of thermally treated pristine surfaces with a microscope reveals distributions of decomposition sites characteristic of the reaction initiating where emergent dislocations intersect the crystal surface. There is little correlation, however, between dislocation etch-pits and decomposition centres. X-ray topographic studies of changes in bulk substructure during thermal treatment confirm that ‘grown in’ dislocations play little or no part in the nucleation of the decomposition process in the bulk. There is some evidence, however, that they may contribute to the surface reaction. In the bulk, the potential nuclei are strained regions in the lattice. From these, and possibly as a consequence of decomposition, dislocation loops are punched out into the surrounding lattice along <100> and <110> directions. Similar defects are emitted from localized regions at the surface and it is possible that these give rise to the surface decomposition patterns. Impurity doped crystals show considerably enhanced decomposition.

Preparation of Bi-Pb-Sr-Ca-Cu-O Superconductor By Thermal Decomposition of an Edta Colloid

1990 ◽  
Vol 180 ◽  
Author(s):  
H.S. Koo ◽  
C.K. Chiang ◽  
Y.T. Huang ◽  
G.C. Tu
Keyword(s):  
Thermal Decomposition ◽  
Solid State ◽  
Solid State Reactions ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
Microstructural Characteristics ◽  
High Tc ◽  
X Ray ◽  
Metal Nitrates ◽  
Zero Resistance

ABSTRACTHigh-Tc superconducting Bi-Pb-Sr-Ca-Cu oxide with zero resistance temperature at above lOOK has been synthesized via the use of ethylenediamine-tetra-acetate(EDTA) colloid and corresponding metal nitrates. Remarkable sinterability of the precursor requires shorter time to achieve superconducting phases than conventional solid-state reactions. Superconducting properties were measured electrically and magnetically. The thermal decomposition, X-ray diffraction and microstructural characteristics of the precursor and the sintered samples were also discussed.

Untersuchungen zum quasibinären System Bi2Te3/BiBr3 / Investigations on the Pseudobinary System Bi2Te3/BiBr3

1999 ◽  
Vol 54 (4) ◽  
pp. 487-490 ◽  
Author(s):  
U. Petasch ◽  
H. Oppermann
Keyword(s):  
Phase Diagram ◽  
Total Pressure ◽  
Ternary Phase ◽  
Heat Of Formation ◽  
Standard Entropy ◽  
Pressure Measurements ◽  
Pressure Data ◽  
Pseudobinary System ◽  
Vapor Pressure Data ◽  
X Ray

The phase diagram of the pseudobinary sytem Bi2Te3/BiBr3 was investigated by DTA, total pressure measurements and X-ray phase analysis. Only BiTeBr exists as a ternary phase in this system. The compound melts congruently at 526 °C. The heat of formation and standard entropy were calculated from vapor pressure data:ΔH(BiTeBr, f, 298) = (-30,4 ± 1,4) kcal/mol; S°(BiTeBr, f, 298) = (36,2 ± 2,9) cal/K·mol.

TEM studies of solid-state reactions in sputter-deposited Nb/Al multilayer thin films

1996 ◽  
Vol 54 ◽  
pp. 1020-1021
Author(s):  
F. Ma ◽  
S. Vivekanand ◽  
K. Barmak ◽  
C. Michaelsen
Keyword(s):  
Thin Films ◽  
Solid State ◽  
Stoichiometric Composition ◽  
Analytical Electron Microscopy ◽  
Grain Structure ◽  
Solid State Reactions ◽  
Multilayer Thin Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sputter Deposited

Solid state reactions in sputter-deposited Nb/Al multilayer thin films have been studied by transmission and analytical electron microscopy (TEM/AEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The Nb/Al multilayer thin films for TEM studies were sputter-deposited on (1102)sapphire substrates. The periodicity of the films is in the range 10-500 nm. The overall composition of the films are 1/3, 2/1, and 3/1 Nb/Al, corresponding to the stoichiometric composition of the three intermetallic phases in this system.Figure 1 is a TEM micrograph of an as-deposited film with periodicity A = dA1 + dNb = 72 nm, where d's are layer thicknesses. The polycrystalline nature of the Al and Nb layers with their columnar grain structure is evident in the figure. Both Nb and Al layers exhibit crystallographic texture, with the electron diffraction pattern for this film showing stronger diffraction spots in the direction normal to the multilayer. The X-ray diffraction patterns of all films are dominated by the Al(l 11) and Nb(l 10) peaks and show a merging of these two peaks with decreasing periodicity.

scholarly journals Zur Kenntnis eines Barium-Oxoniobat-Tellurats: Ba2Nb2TeO10 / On a Barium-Oxoniobate-Tellurate: Ba2Nb2TeO10

1996 ◽  
Vol 51 (10) ◽  
pp. 1407-1410 ◽  
Author(s):  
B. Wedel ◽  
Hk. Müller-Buschbaum
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Single Crystals ◽  
Solid State Reactions ◽  
Orthorhombic Symmetry ◽  
X Ray ◽  
Lattice Constants ◽  
Group D ◽  
Symmetry Space ◽  
Symmetry Space Group

Single crystals of Ba2Nb2TeO10) have been prepared by solid state reactions in air. X-ray investigations led to orthorhombic symmetry, space group D152h-Pbca, a = 7.242(4), b = 12.433(3), c = 9.932(3) Å. Z = 4. Nb5+ and Te6+ show octahedral coordination by O2- . The crystal structure is characterized by planes of edge- and corner-sharing NbO6- and TeO6octahedra. It is shown that in spite of nearly identical lattice constants of Ba2Nb2TeO10 with compounds of the composition M0,5BaNbTe2O9 the so far unknown crystals of these substances may not be derived from the Ba2Nb2TeO10 type.

Zur Kenntnis quaternärer Telluride Cu2MM′Te4 mit Tetraederstrukturen / Quaternary Tellurides Cu2MM′Te4 with Tetrahedral Structures

1991 ◽  
Vol 46 (8) ◽  
pp. 1049-1052 ◽  
Author(s):  
H. Haeuseler ◽  
F. W. Ohrendorf ◽  
M. Himmrich
Keyword(s):  
Solid State ◽  
Type Structure ◽  
Solid State Reactions ◽  
X Ray

Quaternary tellurides Cu2MM′Te4 (M = Zn, Cd, Hg and M′ = Si, Ge, Sn) have been prepared by solid state reactions and characterized by X-ray powder methods. All 9 compounds crystallize in a stannite type structure.

Sign in / Sign up

Export Citation Format

Share Document