SYNTHESIS OF DIAMOND FILMS ON MOLYBDENUM SUBSTRATE SURFACE BY COMBUSTION FLAME

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3926-3931 ◽  
Author(s):  
MAMORU TAKAHASHI ◽  
OSAMU KAMIYA ◽  
TADASHI OHYOSHI
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Substrate Surface ◽  
Diamond Films ◽  
Synthesis Temperature ◽  
Interfacial Stress ◽  
X Ray Diffraction ◽  
Thermally Induced ◽  
X Ray ◽  
Combustion Flame

Diamond films were synthesized on a Mo substrate using combustion flame. During the cooling process, most diamond films delaminated. From previous work it was shown that diamond films delaminated at a synthesis temperature less than 1300K (low temperature), and films did not delaminate at synthesis temperature more than 1400K (high temperature). In this study, to clarify the influences on the delamination of the interface, films synthesized at high temperature and low temperature were investigated by SEM and X-ray diffraction. The results show that in the case of low temperature, diamond films were synthesized on the Mo substrate, case of high temperature, Mo 2 C and diamond phases were synthesized on the Mo substrate. Thermally induced interfacial stress occurs due to the thermal expansion mismatch between the synthesized film and the Mo substrate. The interfacial stress by high temperature and low temperature was determined as the cause of the delamination. Thus, the interfacial stress of each synthesized temperature was calculated by a finite element method. The results show that the interfacial stress in the film synthesized by high temperature was smaller than that by the low temperature. As the buffer phases prevent the delamination, synthesized films by high temperature will be useful as hardcoating layer for a metal surface.

The Application of X-Ray Diffraction at Elevated Temperatures to Study the Mechanism of Formation of Sodium Tripolyphosphate

1961 ◽  
Vol 5 ◽  
pp. 276-284
Author(s):  
E. L. Moore ◽  
J. S. Metcalf
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Amorphous Phase ◽  
Elevated Temperatures ◽  
Sodium Tripolyphosphate ◽  
X Ray Diffraction ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Temperature Form ◽  
High Temperature Form

AbstractHigh-temperature X-ray diffraction techniques were employed to study the condensation reactions which occur when sodium orthophosphates are heated to 380°C. Crystalline Na4P2O7 and an amorphous phase were formed first from an equimolar mixture of Na2HPO4·NaH2PO4 and Na2HPO4 at temperatures above 150°C. Further heating resulted in the formation of Na5P3O10-I (high-temperature form) at the expense of the crystalline Na4P4O7 and amorphous phase. Crystalline Na5P3O10-II (low-temperature form) appears after Na5P3O10-I.Conditions which affect the yield of crystalline Na4P2O7 and amorphous phase as intermediates and their effect on the yield of Na5P3O10 are also presented.

scholarly journals X-ray diffraction analysis of kaolin M1 and M2 via the Williamson–Hall and Warren–Averbach methods

2021 ◽  
pp. 174751982098472
Author(s):  
Lalmi Khier ◽  
Lakel Abdelghani ◽  
Belahssen Okba ◽  
Djamel Maouche ◽  
Lakel Said
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Low Temperature ◽  
Diffraction Analysis ◽  
Mechanical Resistance ◽  
X Ray Diffraction ◽  
Integral Breadth ◽  
X Ray ◽  
Mullite Phase

Kaolin M1 and M2 studied by X-ray diffraction focus on the mullite phase, which is the main phase present in both products. The Williamson–Hall and Warren–Averbach methods for determining the crystallite size and microstrains of integral breadth β are calculated by the FullProf program. The integral breadth ( β) is a mixture resulting from the microstrains and size effect, so this should be taken into account during the calculation. The Williamson–Hall chart determines whether the sample is affected by grain size or microstrain. It appears very clearly that the principal phase of the various sintered kaolins, mullite, is free from internal microstrains. It is the case of the mixtures fritted at low temperature (1200 °C) during 1 h and also the case of the mixtures of the type chamotte cooks with 1350 °C during very long times (several weeks). This result is very significant as it gives an element of explanation to a very significant quality of mullite: its mechanical resistance during uses at high temperature remains.

Effects of Seeding Over the Microstructure and Stresses of Diamond Thin Films

1999 ◽  
Vol 594 ◽  
Author(s):  
S. Gupta ◽  
G. Morell ◽  
R. S. Katiyar ◽  
D. R. Gilbert ◽  
R. K. Singh
Keyword(s):  
Electron Cyclotron Resonance ◽  
Raman Band ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Interfacial Stress ◽  
Intrinsic Stress ◽  
Seeding Density ◽  
X Ray Diffraction ◽  
Total Stress ◽  
X Ray

AbstractWe have studied diamond films grown by electron cyclotron resonance-assisted chemical vapor deposition (ECR-CVD) at low pressure (1.0 Torr) and temperatures (550–700 °C). These films were grown on seeded Si (111) substrates with different diamond seed densities (0.225, 1.5, 2.3, and 3.1 × 109 nuclei/cm2). Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy (RS) were employed to investigate the crystalline quality, diamond yield, and stresses developed in the films as a function of seeding density. Thermal interfacial stress, interactions across grain boundaries, and internal stress were considered in order to account for the total stress observed from the Raman band. We present correlations among seed density, relative amount of non-sp3 phase, O/C ratio, and total intrinsic stress.

Structural chemistry of NaCoPO4

1996 ◽  
Vol 52 (3) ◽  
pp. 440-449 ◽  
Author(s):  
R. Hammond ◽  
J. Barbier
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Large Family ◽  
X Ray Diffraction ◽  
Tetrahedral Framework ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Tetrahedral Sites ◽  
Bond Valence Analysis

Sodium cobalt phosphate, NaCoPO4, occurs as two different polymorphs which transform reversibly at 998 K. The crystal structures of both polymorphs have been determined by single-crystal X-ray diffraction. The low-temperature form α-NaCoPO4 crystallizes in the space group Pnma with cell parameters: a = 8.871 (3), b = 6.780 (3), c = 5.023 (1) Å, and Z = 4 [wR(F 2) = 0.0653 for all 945 independent reflections]. The α-phase contains octahedrally coordinated Co and Na atoms and tetrahedrally coordinated P atoms, and is isostructural with maracite, NaMnPO4. The structure of high-temperature β-NaCoPO4 is hexagonal with space group P65 and cell parameters: a = 10.166 (1), c = 23.881 (5) Å, and Z = 24 [wR(F 2) = 0.0867 for 4343 unique reflections]. The β-phase belongs to the large family of stuffed tridymites, with the P and Co atoms occupying tetrahedral sites and the Na atoms located in the cavities of the tetrahedral framework. The long c axis corresponds to a 3 × superstructure of the basic tridymite framework (c ≃ 8 Å) and is caused by the displacement of the Na atoms, tetrahedral tilts and strong distortions of the CoO4 tetrahedra. A bond-valence analysis of these phases reveals that the polymorphism in NaCoPO4 is due in part to over-/underbonding of the Na atom in the low-/high-temperature structures, respectively.

Modification of Asphalt by Montmorillonite

2011 ◽  
Vol 84-85 ◽  
pp. 662-666 ◽  
Author(s):  
Zeng Ping Zhang ◽  
Yong Wen ◽  
Jian Zhong Pei ◽  
Shuan Fa Chen
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Temperature Sensitivity ◽  
Softening Point ◽  
High Speed ◽  
Melt Blending ◽  
X Ray Diffraction ◽  
Nanocomposite Structure ◽  
X Ray ◽  
Temperature Performance

Montmorillonite (MMT) modified asphalts are prepared by melt blending with the help of high-speed shear mixer. The dispersion of MMT layers in the asphalt matrix are characterized by X-ray diffraction (XRD). The effect of different contents of MMT on physical properties of the base asphalt is studied. These properties include penetration, softening point and ductility. The results indicate that MMT/asphalt may form a nanocomposite structure with MMT layers intercalated by the asphalt molecules. MMT can improve the high temperature performance and temperature sensitivity of the base asphalt. And it can slightly reduce the low temperature performances of matrix asphalt. It is found that low temperature performances, high temperature performance and temperature sensitivity of the modified system achieved balance when the content of MMT is 4 wt%.

Displacive Phase Transformation in Vanadium - Substituted Lanthanum Niobate

1983 ◽  
Vol 24 ◽  
Author(s):  
A. T. Aldred ◽  
S.-K. Chan ◽  
M. H. Grimsditch ◽  
M. V. Nevitt
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Low Temperature ◽  
Raman Scattering ◽  
Transformation Temperature ◽  
Complex Oxides ◽  
Temperature Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Order

ABSTRACTThe displacive transformations in complex oxides of the type LaNb1-xVxO4 has been studied by x-ray diffraction and Raman scattering for 0 < x < 0.3. X-ray diffraction results indicate that the transformation from the tetragonal high temperature structure (C4h6) to the monoclinic low-temperature structure (C2h6) is higher than first order and that the transformation temperature Tc is depressed significantly by V substitution. Raman scattering results show that the force constant between the nearest (Nb, V)O4 tetrahedral units behave uniquely compared to others. It softens at Tc as a function of composition and it also softens as a function of temperature as Tc is approached from above.

Triethanolamine Molybdate, a New Polymeric Precursor for Molybdenum Nitride

2007 ◽  
Vol 29-30 ◽  
pp. 195-198
Author(s):  
S. Mondal ◽  
A.K. Banthia
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Transition Metal ◽  
Niobium Nitride ◽  
Metal Nitrides ◽  
Molybdenum Nitride ◽  
Transition Metal Nitrides ◽  
Polymeric Precursor ◽  
X Ray Diffraction ◽  
X Ray

Nitrides remain a relatively unexplored class of materials primarily due to the difficulties associated with their synthesis and characterization. Several synthetic routes, including high temperature reactions, microwave assisted synthesis, and the use of plasmas, to prepare binary and ternary nitrides have been explored. Transition metal nitrides form a class of materials with unique physical properties, which give them varied applications, as high temperature ceramics, magnetic materials, superconductors or catalysts. They are commonly prepared by high temperature conventional processes, but alternative synthetic approaches have also been explored, more recently, which utilize moderate temperature condition. Transition metal nitrides particularly, molybdenum nitride, niobium nitride, and tungsten nitride have important applications as catalyst in hydrodenitridation reactions. These nitrides have been traditionally synthesized using high temperature nitridation treatments of the oxides. The nitridation temperatures are very high (> 800- 1000 oC). The aim of our work is to synthesize molybdenum nitride by a simple, low-temperature route. The method involves pyrolysis of a polymeric precursor, which was prepared from the condensation reaction between triethanolamine and molybdic acid. The melting point of the product is 180oC. The polymeric precursor and its pyrolyzed products are characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). X-ray diffraction shows that molybdenum nitride (MoN) obtained from this method has hexagonal crystal structure. MoN is obtained by this method at very low temperature (~ 400 oC).

The low-temperature form of calcium gold stannide, CaAuSn

2014 ◽  
Vol 70 (8) ◽  
pp. 773-775 ◽  
Author(s):  
Qisheng Lin ◽  
John D. Corbett
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Single Crystal ◽  
Diffraction Analysis ◽  
Orthorhombic Symmetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Symmetry Space ◽  
High Temperature Polymorph ◽  
Symmetry Space Group

The EuAuGe-type CaAuSn phase has been synthesized and single-crystal X-ray diffraction analysis reveals that it has an orthorhombic symmetry (space groupImm2), witha= 4.5261 (7) Å,b= 7.1356 (11) Å andc= 7.8147 (11) Å. The structure features puckered layers that are connected by homoatomic Au—Au and Sn—Sn interlayer bonds. This structure is one of the two parent structures of its high-temperature polymorph (ca873 K), which is an intergrowth structure of the EuAuGe- and SrMgSi-type structures in a 2:3 ratio.

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