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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Langmuir 3 (1987), S. 973-975 
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract It is shown that the massicot/litharge ratio of the lead monoxide yielded from the thermal decomposition of ground samples of PbCO3 decreases from 1 to 0 by increasing the grinding time of the above salt. The conclusion has been drawn that the PbO keeps a sort of “memory” of the lattice imperfections of the PbCO3 specimen used as precursor. Both the crystalline size and the root-mean square strain data reported in the present paper support this conclusion.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Physics and chemistry of minerals 27 (2000), S. 495-503 
    ISSN: 1432-2021
    Keywords: Key words Thermal decomposition ; Kinetics ; Siderite ; CRTA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The mechanism of the thermal decomposition of two siderites (a pure synthetic and a natural Mg-containing sample) has been determined from comparison of the results obtained from linear heating rate (TG) and constant rate thermal analysis (CRTA) experiments in high vacuum. The thermal decomposition of the synthetic siderite takes place approximately 200 K below the decomposition temperature of the natural sample. The mechanism and the product of the thermal decomposition are different for the siderite samples. In fact, an A2 kinetic model describes the thermal decomposition of the synthetic siderite, whereas the thermal decomposition of the natural sample obeys an F1 kinetic law. Decomposition products of the synthetic siderite are iron and magnetite, those of the natural siderite are wüstite and minor magnetite.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 36 (1990), S. 2531-2537 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Unter der Annahme der Proportionalität der partiellen Drücke der während der Reaktion entstehenden Gase zur Reaktionsgeschwindigkeit wurde eine theoretische Analyse des Einflusses von Stoffübergangserscheinungen auf die Gestalt von EGA-Kurven bei der thermischen Zersetzung von Feststoffen durchgeführt. Werden gasförmige Produkte vom System weniger wirksam abgegeben, verschieben sich die EGA-Kurven zu höheren Temperaturen und die scheinbare Reaktionsordnungn nähert sich Null, während die Aktivierungsenergie annähernd konstant bleibt. Die Feststellungen wurden experimentell überprüft.
    Notes: Abstract A theoretical analysis of the influence of mass-transfer phenomena on the shape of EGA traces of the thermal decompositions of solids has been carried out by assuming that the partial pressures of the gases generated in the reactions are proportional to the reaction rate. It has been shown that the EGA curves move to higher temperatures and the apparent reaction ordern approaches zero as the efficiency of the system for removing the gas product decreases, while the activation energy remains nearly constant. These statements have been checked experimentally.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 38 (1992), S. 313-319 
    ISSN: 1572-8943
    Keywords: CRTA ; synthesis of silicon nitride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Bei 1 atm Druck wurde im Stickstoffflu\ die carbothermische Reduktion von Silika mittels eines CO IR Detektors verfolgt, der am Gas-Output eines Hochtemperaturröhrenofens angeschlossen wurde. Die Reaktionstemperatur wird kontrolliert, indem das Analogsignal des IR-Detektors über ein Interface an eine Kontrolleinheit geleitet wird, welche die Verfolgung der Probentemperatur auf die Art ermöglicht, da\ die Konzentration des bei der Reaktion entstehenden CO auf einem konstanten Wert gehalten wird, den der Anwender zuvor einstellt. Die Reaktionsgeschwindigkeit kann bei einer ganz bestimmten CO-Konzentration durch entsprechende Wahl des Volumendurchsatzes des reaktiven Gases fixiert werden. Es wurde der Einflu\ von Reaktionsgeschwindigkeit und CO-Konzentration sowohl auf die Reaktionstemperatur als auch auf die Struktur der Reaktionsendprodukte untersucht.
    Notes: Abstract The carbothermal reduction of silica under flowing nitrogen at a pressure of 1 atm has been followed by means of a CO IR detector attached to the gas output of a high temperature tubular furnace. The control of the reaction temperature is carried out by interfacing the analogical output of the IR detector to a controller that allows to monitor the sample temperature in such a way that the concentration of CO generated in the reaction is maintained constant at a value previously selected by the user. The reaction rate at a particular concentration of CO can be fixed by properly selecting the flow rate of the reactive gas. The influence of the reaction rate and the CO concentration on both the reaction temperature and the structure of the final product of the reaction are analysed.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1572-8943
    Keywords: Constant Rate Thermal Analysis (CRTA) ; solid state kinetics ; Stepwise Isothermal Analysis (SIA)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The results obtained in this work point out that both SIA and CRTA traces, simulated assuming the same values of the reaction rate, are identical provided that either 'n order’ or diffusion controlled kinetics are concerned. The α-T CRTA plots of solid state reactions fitting an Avrami-Erofeev kinetic model show that the temperature decreases with increasing α until reaching a minimum at a value of the reacted fraction α = αmin characteristic of the Avrami-Erofeev exponent. The shapes of the corresponding SIA diagrams are quite different and a very long isothermal step is obtained. Moreover, the reaction rate is not maintained constant during the isothermal period but it shows a maximum at a value of α depending on the Avrami-Erofeev coefficient. It is important to point out that this αmax value agrees with the corresponding αmin calculated from a CRTA curve by assuming the same Avrami-Erofeev exponent.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 53 (1998), S. 509-517 
    ISSN: 1572-8943
    Keywords: DTA ; EGA ; goethity hematite ; grinding ; mechanochemical decomposition ; thermal behaviour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Effects induced by grinding in synthetic goethite samples were studied. The products of α-FeOOH grinding were characterised by means of DTA, TG/DTG coupled with EGA (Mass spectrometry detection), powder X-ray diffraction analysis, and surface area determination.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 37 (1991), S. 2369-2375 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wurde der Mechanismus der thermischen Zersetzung von Dolomit untersucht. Es wurde gezeigt, daß ein Vergleich der kinetischen Angaben aus einer kinetischen Analyse eines einfachen TG-Durchlaufes und einer mittels CRTA einmal registrierten Kurve die Unterscheidung desjenigen kinetischen Modelles ermöglicht, dem die Reaktion gerade unterliegt und außerdem die Bestimmung der zugehörigen kinetischen Parameter ermöglicht.
    Notes: Abstract The mechanism of the thermal decomposition of dolomite was studied. It was shown that a comparison of the kinetic data obtained from the kinetic analysis of a single TG trace and a single curve recorded using the constant rate thermal analysis (CRTA) method allows discrimination of the actual kinetic model obeyed by the reaction and also determination of its corresponding kinetic parameters.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 49 (1997), S. 1467-1475 
    ISSN: 1572-8943
    Keywords: CRTA ; DSC ; kinetics ; synthetic brochantite ; TG-DTA ; thermal decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The reaction pathway of the thermal decomposition of synthetic brochantite, Cu4(OH)6SO4, to copper(II) oxide was investigated through the detailed kinetic characterization of the thermal dehydration and desulferation processes. The dehydration process was characterized by dividing into two overlapped kinetic processes with a possible formation of an intermediate compound, Cu4O(OH)4SO4. The dehydrated sample, Cu4O3SO4, was found first to be amorphous by means of XRD, followed by the crystallization to a mixture of CuO and CuO-CuSO4 at around 776 K. The specific surface area and the crystallization behaviour of the amorphous dehydrated compound depend largely on the dehydration conditions. The thermal desulferation process is influenced by the gross diffusion of the gaseous product SO3, which is governed by the advancement of the overall reaction interface from the top surface of the sample particle assemblage to the bottom.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 49 (1997), S. 1477-1484 
    ISSN: 1572-8943
    Keywords: CRTA ; kinetics ; particle size distribution ; rate jump method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetic curves at infinite temperature for the solid-state reactions of the interface shrinkage type were drawn theoretically by taking account the particle size distribution in the sample mixture. The CRTA curves for the reactions with the particle size distribution can be drawn by utilizing the universal kinetic curves at infinite temperature. The proper kinetic treatment for the CRTA curves with the particle size distribution is discussed in connection with the property of the kinetic equation with respect to the particle size distribution. The present kinetic consideration is taken as a simulation for the reactions with a certain distribution in α among the reactant particles, produced preferably by the mass and heat transfer phenomena during the thermoanalytical measurements. The merit of the rate jump method by a single cyclic CRTA curve is also discussed on the basis of the present results.
    Type of Medium: Electronic Resource
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