Bulk Moduli of (MgO,CaO,SrO,BaO)- Na2O-SiO2 Melts
published: May 1, 1998
ArtNo. ESP154017202003, Price: 29.00 €
The effect of composition and temperature on the compressibility of melts in the XO-Na2O-SiO2 (X = Mg, Ca, Sr, Ba) system has been investigated. The relaxed bulk moduli were measured using ultrasonic interferometric methods at frequencies of 3-7 MHz in the temperature range of 1000 to 1600 °C. For these melts, the bulk modulus decreases with replacement of XO with Na2O as expected from previous observations that alkaline-earth silicate melts display anomalously high bulk moduli in comparison to alkali-silicate melts. It would appear that the bulk moduli of XO-Na2O-SiO2 melts follow a simple linear trend as a function of the number of cations per oxygen - similar to the observed behaviour for CaO-AlO3-SiO2 and Na2O-SiO2 melts. The trend-line for the present xXO · (1-X)Na2O · SiO2 melts connects the separate trends for XO-SiO2 and Na2O-SiO2 at the XO · SiO2 and Na2O · SiO2 compositions. This simplification for estimating the compressibility of melts in the XO-Na2O-SiO2 system, however, does not apply to the XO-Na2O-Al2O3-SiO2 system as the addition of alumina significantly changes the structure of sodium-silicate melts and Na2O-Al2O3-SiO2 melts do not follow the same systematic bulk moduluscations per anion behaviour.