Prediction on dielectric strength and boiling point of gaseous molecules for replacement of SF6

• Published in: Journal of computational chemistry Vol. 38; no. 10; pp. 721 - 729
• Main Authors: Yu, Xiaojuan, Hou, Hua, Wang, Baoshan
• Format: Journal Article
• Language: English
• Published: New York Wiley Subscription Services, Inc 15.04.2017
• Subjects: boiling point; dielectric strength; Dielectrics; environment‐friendly insulation; Functional groups; Gases; Molecular chemistry; structure–activity relationship; sulfur hexafluoride
• ISSN: 0192-8651; 1096-987X
• DOI: 10.1002/jcc.24741

Developing the environment‐friendly insulation gases to replace sulfur hexafluoride (SF6) has attracted considerable experimental and theoretical attentions but without success. A computational methodology was presented herein for prediction on dielectric strength and boiling point of arbitrary gaseous molecules in the purpose of molecular design and screening. New structure–activity relationship (SAR) models have been established by combining the density‐dependent properties of the electrostatic potential surface, including surface area and the statistical variance of the surface potentials, with the molecular properties including polarizability, electronegativity, and hardness. All the descriptors in the SAR models were calculated using density functional theory. The substitution effect of SF6 by various functional groups was studied systematically. It was found that CF3 is the most effective functional group to improve the dielectric strength due to the large surface area and polarizability. However, all the substitutes exhibit higher boiling points than SF6 because the molecular hardness decreases. The balance between Er and Tb could be achieved by minimizing the local polarity of the molecules. SF5CN and SF5CFO were found to be the potent candidates to replace SF6 in view of their large dielectric strengths and low boiling points. © 2017 Wiley Periodicals, Inc. New structure‐activity relationship models have been established for predicting dielectric strengths and boiling points of gaseous molecules using the ab initio calculated descriptors, which are combinations of the density‐dependent statistical properties of the electrostatic potential surface with molecular polarizability, electronegativity, and hardness. The novel theoretical model is capable of screening and designing new environment‐friendly dielectrics as alternatives to sulfur hexafluoride.