Determination of Na2O activities in silicate melts by EMF measurements

Thermodynamic and Kinetic Behavior of B and Na Through the Contact of B-Doped Silicon with Na2O-SiO2 Slags

“…In order to verify the calculated activities, selected experimentally measured activities in the literature [32] are also shown in Figure 6. The measured Na 2 O activities by Zaitsev et al for the temperatures between 1373 K and 1673 K (1100°C and 1400°C) are consistent with regard to the dependence of a Na 2 O on temperature as observed by Zaitsev et al [32] and recently Abdelouhab et al [33] . This is confirmed considering the experimentally measured activities by Goto et al [34] for 1773 K (1500°C), as seen in Figure 6.…”

Na2O solubility in CaO–MgO–SiO2 melts

“…The EMF cell design used in this study is the same that used by Abdelouhab (2005) and Abdelouhab et al (2008). It consists of a Na-b 00 -alumina electrolyte (Na + conductor), and platinum electrodes in both half-cells containing the reference and working melts.…”

“…The log(aNa 2 O) values in the "EDiAn melt with 12.5 wt% Na 2 O" are directly calculated using the data recorded in the temperature domain ranging from 1200 to 1325°C and the Na 2 O activities in the Na 2 O-2SiO 2 melt determined by Abdelouhab (2005) and Abdelouhab et al (2008), for each temperature. The obtained data relative to the "EDiAn melt with 12.5 wt% Na 2 O" are reported in Fig.…”

“…Several experimental approaches have been used to measure alkali metal oxide activities in molten silicates at low pressure, including EMF measurements in galvanic cells (Neudorf and Elliott, 1980;Yamaguchi et al, 1983;Pak et al, 1989;Kim et al, 2004;Abdelouhab et al, 2008) or vaporization processes such as Knudsen effusion cell mass spectrometry (Zaitsev et al, 1999;Mueller et al, 2004;Willenborg et al, 2006) and gravimetric method (Steiler, 1976;Kawahara, 1984). These techniques can be very accurate but they require considerable effort for each composition, making it difficult to study a large range of compositions.…”

“Free” oxide ions in silicate melts: Thermodynamic considerations and probable effects of temperature

“…The volatility of alkali oxides enables vapor pressure measurements to be made over wide compositional and temperature ranges; electrochemical measurements can also be standardized back to pure Na 2 O and thus provide an alternative measure of the component activity. Results are wide and complex, but as summarized recently (Abdelouhab et al, 2008), point to very low activities in normal glass-forming alkali silicate melts, e.g. 10 -6 or less.…”