Electrochemical determination of activity of Na2O in Na2Ti6O13-TiO2 two phase system between 803–1000 K

Sodium oxide (Na 2 O) activity in NT6-TiO 2 was measured using the EMF method with test electrode Pt,Na 2 Ti 6 O 13 +TiO 2 (NT6-TiO 2 ). NASICON (Na 2 Zr 2 Si 2 PO 12 ) was used as the solid electrolyte in conjunction with a biphasic mixture of alpha alumina (α-Al 2 O 3 ) and sodium beta alumina (Na 2 O.x Al 2 O 3 (8.5≤x < 11)) as the reference electrode and measurements taken over the temperature range of 803≤T≤1000 K. Internal consistency of the cell was ensured by approaching the equilibration target temperature from both sides, during cooling and heating. EMF measurements showed linear dependency with temperature in the temperature range under study. The activity of Na 2 O in NT6-TiO 2 in the temperature range under study was determined. This was found to be loga Na 2 O(NT6−TiO 2 ) =1.20−[Formula presented]. This data is important in the determination of theoretical EMF for the calibration electrochemical sensors employing NT6-TiO 2 electrode. Furthermore, it was found that, a Na 2 O(NT6−TiO 2 ) > a Na 2 O(NASICON) indicating chemical stability when in contact with NASICON at higher temperatures.