Abstract
The phase transitions and thermal effects occurring during annealing in air of material with general formula CrOx (x≥2.4) have been investigated. The investigations were performed with TG, DTA, DSC, EGA, XRD and other spectral techniques. The formation of an amorphous phase with average composition Cr5O12 in the range 300-400°C has been observed. Further heating leads to partial loss of oxygen, simultaneous decay of Cr2O5 and CrO2 phases and formation of nonstoichiometric Cr2O3+x. The distinct loss of mass is observed in the range 415-428°C, connected with evolving oxygen and small amount of nitric oxides. Thermal effects accompanying the mass changes depend on the mass of the sample. When the mass decreases, the transition from exothermic to endothermic effects is observed. This phenomenon can be explained as the competition between two processes: reconstruction of the crystalline lattice (endothermic effect) and recombination of the evolved atomic oxygen (exothermic effect).
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
T. V. Rode, Oxygen compounds of chromium catalysts, Izd. Akad. Nauk SSSR, Moscow 1962, Macmillan, London (1965).
R. Richelmi and M. Laffitte, C. R. Acad. Sci. Paris, 265 (1967) 541.
O. Fukunaga and S. Saito, J. Am. Chem. Soc., 51 (1968) 362.
C. P. Poole and D. S. Maciver, Adv. Catal., 17 (1967) 223.
B. M. Weckhuysen and R. A. Schoonheydt, Catal. Today, 51 (1999) 223.
P. D. Ownby and G. E. Jungquist, J. Am. Ceram. Soc., 55 (1972) 433.
T. Komeda, Y. Fukumoto, M. Yoshinaka, K. Hirota and O. Yamaguchi, Mat. Res. Bull., 31 (1996) 965.
T. Tsuzuki and P. G. McCormick, Acta Mater., 48 (2000) 2795.
M. Ocaña, J. Europ. Ceram. Soc., 21 (2001) 931.
M. Maciejewski, K. Koehler, H. Schneider and A. Baiker, J. Solid State Chem., 119 (1995) 13.
A. Małecki, B. Małecka, R. Gajerski and S. Łabuś, J. Therm. Anal. Cal., 72 (2003) 135.
P. Moriceau, B. Grzybowska, L. Gengembre and Y. Barbaux, Appl. Catal., 199 (2000) 73.
Z. V. Marinković, L. Mančić, R. Mariæ and O. Miloševic, J. Eu. Ceram. Soc., 21 (2001) 2051.
I. Takahara, W.-C. Chang, N. Mimura and M. Saito, Catal. Today, 45 (1998) 55.
D. D. Berger, I. Jitaru, N. Stanica, R. Perego and J. Schoonman, J. Mater. Synth. &; Proces., 9 (2001) 137.
L. Gubrynowicz and T. Strömich, Thermochim. Acta, 115 (1987) 137.
S. Łabuś, VII Conference of Calorimetry and Thermal Analysis, Zakopane, Poland, Abstracts 1997, p. 309.
N. E. Fouad, S. A. Halawy, M. A. Mohamed and M. I. Zaki, Thermochim. Acta, 329 (1999) 23.
A. Małecki, Ceramika-Materia'y Ogniotrwałe, 4 (2000) 123.
J. Stoch, J. Thermal Anal., 37 (1991) 1415.
J. Stoch, Thermochim. Acta, 203 (1992) 259.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Labus, S., Malecki, A. & Gajerski, R. Investigation of thermal decomposition of CrOx (x≥2.4). Journal of Thermal Analysis and Calorimetry 74, 13–20 (2003). https://doi.org/10.1023/A:1026309315556
Issue Date:
DOI: https://doi.org/10.1023/A:1026309315556