Calorimetric studies of the energetics of order-disorder in the system Mg{sub 1{minus}x}Fe{sub x}Ca(CO{sub 3}){sub 2}

Journal Article · Fri Oct 01 00:00:00 EDT 1999 · American Mineralogist

DOI:https://doi.org/10.2138/am-1999-1016· OSTI ID:20000953

Navrotsky, A; Dooley, D; Reeder, R; Brady, P

Calorimetric studies by Chai and Navrotsky (1996) on dolomite-ankerite energetics have been extended by including two additional types of samples: a very disordered stoichiometric MgCa(CO{sub 3}){sub 2} prepared from low-temperature aqueous solution and three largely ordered natural samples of intermediate iron content. Combining these data with previous work, the authors see three distinct energetic trends. These represent samples with nearly complete order, nearly complete disorder, and intermediate order. From these trends, the enthalpy of complete disordering is estimated to be 33 {+-} 6 kJ/mol for MgCa(CO{sub 3}){sub 2} and 18 {+-} 5 kJ/mol for FeCa(CO{sub 3}){sub 2}.

• Research Organization: Univ. of California, Davis, CA (US)
• Sponsoring Organization: USDOE
• OSTI ID: 20000953
• Journal Information: American Mineralogist, Vol. 84, Issue 10; Other Information: PBD: Oct 1999; ISSN 0003-004X
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
ANKERITE
DOLOMITE
ORDER-DISORDER TRANSFORMATIONS
TRANSITION HEAT