AC electric field‐induced softening of alkali silicate glasses

• Published in: Journal of the American Ceramic Society 2018-06, Vol.101 (6), p.2277-2286
• Main Authors: McLaren, Charles T., Heffner, William R., Raj, Rishi, Jain, Himanshu
• Format: Article
• Language: English
• Subjects: Electric fields; Electric potential; electrical properties; Glass; ionic conductivity; Lithium; migration; Reduction; Softening
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/jace.15387

Electric field‐induced softening (EFIS) is a recently discovered phenomenon leading to significant reduction in the furnace temperature at which glass softens under the application of DC voltage. Unfortunately, it is accompanied by local compositional changes due to migration of ions that could limit its usefulness. To overcome this drawback, we have investigated the same phenomenon using AC voltage, that is, AC‐EFIS on a sodium disilicate glass and a 50/50 mixed lithium‐sodium disilicate glass of very different ionic resistivity yet similar network structure. The results show that the magnitude of EFIS temperature reduction is significantly greater for AC compared to DC for both glass compositions. The enhancement of EFIS under AC voltage appears to be due to a more uniform power dissipation and self‐healing of changes than under DC voltage. This uniformity allows for the overall sample temperature to increase throughout the bulk and provides a better technique for practical applications than the DC case which produces potentially undesirable changes, especially in the anode region.