Physicochemical properties of the heterogeneous system Li2CO3-Na2CO3-K2CO3/MgO

Abstract

The structure, conductivity, melting points and caloric melting effects of the (Li2CO3–Na2CO3–K2CO3)eut melt/MgO nanopowder heterogeneous system with MgO concentration up to 70 vol. % have been investigated. A wide variety of methods (DSC, XRD, BET, high resolution scanning electron microscope, AC impedance method, IR and Raman spectroscopy) were used to evaluate samples and research. It is revealed that at the values of effective thickness of the salt phase interlayer between MgO particles below 100 nm there is an abrupt decrease in the melting points of the salt and the normalized phase transition enthalpy of the heterogeneous system. The activation energy of the electrical conductivity rises as the values of effective thickness of the melt phase interlayer between MgO particles decreases. The study established the lack of any chemical interaction between MgO and carbonate melt at 400–600ºС. In situ Raman spectroscopy of the (Li2CO3–Na2CO3–K2CO3)eut melt/MgO nanopowder systems revealed the solvation of solid particles by salt-melt ions.

Keywords

• molten carbonate
• composite
• conductivity
• melting points