Determination of the potassium activity in the heterogeneous phase system K-beta-Al2O3/borate glass, MeO/Me

By potentiometric measurements using the electrochemical cell: Au, O2, CO2|K2CO3(Au)|KBA(Au)|YSZ|KBA(Au)|Borateglass, NiO, FeO|FeNi|Au the potassium activity of the heterogeneous phase system K-beta-Al2O3(KBA)/borate glass, MeO/Me has been determined between T=(350 and 670) deg. C. It is given bylgaK=4.590+/-0.42-(17044.44+/-318.6K)/T.The establishment of the potassium chemical potential within the phase system results from the interaction between the borate glass and K-beta-Al2O3 yielding a defined content of potassium oxide that in its turn equilibrates with the oxygen potential coming from the interaction between Me and MeO