CaO melting
Dear all,
I would appreciate suggestions and references on the melting temperature of CaO at room pressure and, eventually, at high pressure.
To my knowledge, material scientists mostly refer to data reported in the literature of the Am. Ceramic Society; computed phase diagrams are then sort of (from FactSage web page):
http://www.crct.polymtl.ca/fact/phase_diagram.php?file=Ca-Mg-O_CaO-MgO.jpg&dir=FToxid
where melting of CaO occurs at approx. 2850 K
However, calculations on the melting of CaO at high pressure (Sun et al. Solid State Communications 150 (2010) 1785–1788) refer to the room temperature melting of CaO at 3200 K, reported in M.W. Chase Jr., NIST-JANAF, Thermochemical Tables, 4th ed., American Chemical Society, American Institute of Physics, New York, 1998.
Difference is remarkable; is that related to uncertainties in attaining such challenging temperature conditions in "oxidised" atmosphere? or am I wrong somewhere? Thank you for comments on this.
Regards
Stefano
--
Stefano Poli
Dipartimento di Scienze della Terra
Università degli Studi di Milano
Via Botticelli 23, 20133 Milano
ph. +390250315595
Dear Stefano,
the atmosphere (e.g. air, N2, Ar, vacuum) has a strong influence on the melting point of an oxide.
The stoichiometry is influenced by loss of O; sometimes white oxides turn black at very high temperatures due to the presence of such defects.
In other oxides, e.g. CeO2, there are autoreduction effects depending on p(O2).
Cheers, Uwe
Priv.-Doz. Dr. Uwe Kolitsch
Kurator der Mineralien- und Lagerstättensammlung
Mineralogisch-Petrographische Abt.
Naturhistorisches Museum
Burgring 7
A-1010 Wien, Austria
Tel +43-1-52177-274, Fax +43-1-52177-263
E-mail: uwe.kolitsch@nhm-wien.ac.at
Website: http://www.nhm-wien.ac.at/uwe_kolitsch
-----Ursprüngliche Nachricht-----
Von: msa-talk-bounces@minlists.org [mailto:msa-talk-bounces@minlists.org] Im Auftrag von Stefano Poli
Gesendet: Mittwoch, 05. November 2014 18:03
An: msa-talk@minlists.org
Betreff: [MSA-talk] CaO melting
Dear all,
I would appreciate suggestions and references on the melting temperature of CaO at room pressure and, eventually, at high pressure.
To my knowledge, material scientists mostly refer to data reported in the literature of the Am. Ceramic Society; computed phase diagrams are then sort of (from FactSage web page):
http://www.crct.polymtl.ca/fact/phase_diagram.php?file=Ca-Mg-O_CaO-MgO.jpg&dir=FToxid
where melting of CaO occurs at approx. 2850 K
However, calculations on the melting of CaO at high pressure (Sun et al. Solid State Communications 150 (2010) 1785-1788) refer to the room temperature melting of CaO at 3200 K, reported in M.W. Chase Jr., NIST-JANAF, Thermochemical Tables, 4th ed., American Chemical Society, American Institute of Physics, New York, 1998.
Difference is remarkable; is that related to uncertainties in attaining such challenging temperature conditions in "oxidised" atmosphere? or am I wrong somewhere? Thank you for comments on this.
Regards
Stefano
--
Stefano Poli
Dipartimento di Scienze della Terra
Università degli Studi di Milano
Via Botticelli 23, 20133 Milano
ph. +390250315595
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