Structural refinement of Nd[Fe(CN)6]·4H2O and study of NdFeO3 obtained by its oxidative thermal decomposition at very low temperatures

2005 ◽  
Vol 178 (3) ◽  
pp. 847-854 ◽  
Author(s):  
M. Carolina Navarro ◽  
Elisa V. Pannunzio-Miner ◽  
Silvina Pagola ◽  
M. Inés Gómez ◽  
Raúl E. Carbonio
Keyword(s):  
Thermal Decomposition ◽  
Low Temperatures ◽  
Structural Refinement

Analysis of nitromethane thermal decomposition at low temperatures

2013 ◽  
Vol 54 (2) ◽  
pp. 131-138 ◽  
Author(s):  
N. M. Kuznetsov ◽  
Yu. P. Petrov ◽  
S. V. Turetskii
Keyword(s):  
Thermal Decomposition ◽  
Low Temperatures

The photochemical and thermal decompositions of hydrogen sulphide

1953 ◽  
Vol 216 (1126) ◽  
pp. 344-361 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Quantum Yield ◽  
Hydrogen Sulphide ◽  
Low Temperatures ◽  
Room Temperature ◽  
Large Fraction ◽  
Kcal Mole ◽  
Hydrogen Atoms ◽  
Photochemical Decomposition ◽  
Bimolecular Mechanism

The photochemical decomposition of hydrogen sulphide has been investigated at pressures between 8 and 550 mm of mercury and at temperatures between 27 and 650° C, using the narrow cadmium line ( λ 2288) and the broad mercury band (about λ 2550). At room temperature the quantum yield increases with pressure from 1.09 at 30 mm to 1.26 at 200 mm. Above 200 mm pressure there was no further increase in the quantum yield. Temperature had little effect on the quantum yield at λ 2550, but there was a marked increase in the rate of hydrogen production between 500 and 650° C with 2288 Å radiation. This may have been caused by the decomposition of excited hydrosulphide radicals. The results are consistent with a mechanism involving hydrogen atoms and hydrosulphide radicals. The mercury-photosensitized reaction is less efficient than the photochemical decomposition, the quantum yield being only about 0.45. The efficiency increased with temperature and approached unity at high temperatures and pressures. This agrees with the suggestion that a large fraction of the quenching collisions lead to the formation of Hg ( 3 P 0 ) atoms. The thermal decomposition is heterogeneous at low temperatures and becomes homogeneous and of the second order at 650° C. The experimental evidence suggests the bimolecular mechanism 2H 2 S → 2H 2 + S 2 . The activation energies are 25 kcal/mole (heterogeneous) and 50 kcal/mole (homogeneous).

THE THERMAL DECOMPOSITION OF HYDROGEN PEROXIDE VAPOUR. II.

1947 ◽  
Vol 25b (2) ◽  
pp. 135-150 ◽  
Author(s):  
Paul A. Giguère
Keyword(s):  
Activation Energy ◽  
Hydrogen Peroxide ◽  
Thermal Decomposition ◽  
Low Temperatures ◽  
Hydrocyanic Acid ◽  
Quartz Surface ◽  
First Order ◽  
Acid Washing ◽  
Reaction Vessels ◽  
Low Pressures

The decomposition of hydrogen peroxide vapour has been investigated at low pressures (5 to 6 mm.) in the temperature range 50° to 420 °C., for the purpose of determining the effect of the nature and treatment of the active surfaces. The reaction was followed in an all-glass apparatus and, except in one case, with one-litre round flasks as reaction vessels. Soft glass, Pyrex, quartz, and metallized surfaces variously treated were used. In most cases the decomposition was found to be mainly of the first order but the rates varied markedly from one vessel to another, even with vessels made of the same type of glass. On a quartz surface the decomposition was preceded by an induction period at low temperatures. Fusing the glass vessels slowed the reaction considerably and increased its apparent activation energy; this effect was destroyed by acid washing. Attempts to poison the surface with hydrocyanic acid gave no noticeable result. The marked importance of surface effects at all temperatures is considered as an indication that the reaction was predominantly heterogeneous under the prevailing conditions. Values ranging from 8 to 20 kcal. were found for the apparent energy of activation. It is concluded that the decomposition of hydrogen peroxide vapour is not very specific as far as the nature of the catalyst is concerned.

Thermal decomposition of hexanitrostilbene at low temperatures

2001 ◽  
Vol 58-59 ◽  
pp. 569-587 ◽  
Author(s):  
Th. Rieckmann ◽  
S. Völker ◽  
L. Lichtblau ◽  
R. Schirra
Keyword(s):  
Thermal Decomposition ◽  
Low Temperatures

The thermal decomposition of ammonium perchlorate at low temperatures

1960 ◽  
Vol 254 (1279) ◽  
pp. 455-469 ◽  
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Kinetic Equation ◽  
Ammonium Perchlorate ◽  
Low Temperatures ◽  
Cold Working ◽  
Experimental Results ◽  
Detailed Model

The thermal decomposition of ammonium perchlorate shows several unusual characteristics. The most striking of these is that at low temperatures it decomposes only to the extent of about 20 to 30 %, leaving a residue which is chemically identical with the original salt. The experimental results for the rate of decomposition of whole crystals, powder and pellets are shown to be well fitted by a kinetic equation which is in accord with a detailed model for the decomposing salt. It is possible to account in terms of this model (which involves the decomposition of intergranular material only) for the observed dependence of the activation energy on the extent of cold-working to which the solid is subjected.

Nanosized Silicon Carbide Obtained from Rice Husks

2010 ◽  
Vol 159 ◽  
pp. 153-156 ◽  
Author(s):  
Dimitar D. Radev ◽  
Ivan Uzunov
Keyword(s):  
Thermal Decomposition ◽  
Silicon Carbide ◽  
Low Temperatures ◽  
Xrd Analysis ◽  
Rice Husks ◽  
Rice Hulls ◽  
High Temperature Materials ◽  
Thermal Regimes ◽  
Scale Properties ◽  
Pure Sio2

Two ways to obtain nanosized silicon carbide (SiC) powders from the products of thermal decomposition of rice hulls and posterior thermal and chemical treatment of SiO2-C precursors are shown in the present paper. The reagents and products were analyzed using BET, DTA, IR, XRD and SEM/TEM. Precursors obtained from rice husks containing pure SiO2 and a controlled SiO2-C ratio were used for the synthesis of SiC. The synthesis of SiC proceeded for 30-45 min in a graphite heater furnace under protective Ar atmosphere at relatively low temperatures (1450oC-1550oC). Nanosized dimensions of reagents obtained from rice husks and their high activity allow obtaining SiC in relatively milder thermal regimes. TEM and XRD analysis revealed synthesis of nanostructured mainly β-SiC with a mean crystallite size of 40-100 nm. Due to their purity and nano-scale properties, the products obtained are appropriate for production of bulk SiC or design of SiC–based ultra high-temperature materials using the methods of powder metallurgy.

Thermal decomposition of expanded polystyrene in a pebble bed reactor to get higher liquid fraction yield at low temperatures

2008 ◽  
Vol 28 (11) ◽  
pp. 2140-2145 ◽  
Author(s):  
R.S. Chauhan ◽  
S. Gopinath ◽  
P. Razdan ◽  
C. Delattre ◽  
G.S. Nirmala ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Low Temperatures ◽  
Liquid Fraction ◽  
Expanded Polystyrene ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Fraction Yield

New Synthesis Process of Li, Na and K Niobates from Metal Alkoxides

2010 ◽  
Vol 63 ◽  
pp. 7-13 ◽  
Author(s):  
Yoko Suyama ◽  
Tetsuya Yamada ◽  
Yosuke Hirano ◽  
Kazuo Takamura ◽  
Kenjiro Takahashi
Keyword(s):  
Thermal Decomposition ◽  
Low Temperatures ◽  
Nano Particles ◽  
Synthesis Process ◽  
Potassium Niobate ◽  
Metal Alkoxides ◽  
Mixed Solution ◽  
Sodium Niobate ◽  
Lattice Constants ◽  
New Synthesis

New synthesis process to prepare nano-particles of lithium niobate, sodium niobate and potassium niobate by thermal decomposition of the constituent double metal alkoxides was developed. Single crystals of such double-metal alkoxides as Na-Nb, Li-Nb and K-Nb ethoxides were newly synthesized from a mixed solution of the constituent metal ethoxides. The doublemetal alkoxides of the Li-Nb, Na-Nb and K-Nb systems decomposed at low temperatures below 673 K to form nano-particles of LiNbO3, NaNbO3 and LiNbO3. The lattice constants and crystallite size of the obtained LiNbO3, NaNbO3 and LiNbO3 particles were elucidated. It was shown that this new synthesis process was useful for preparation of niobate nano-particles at low temperatures.

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