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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Conduction and Excess Charge in Silicate Glass/Air Interfaces

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Author(s):
Paiva, Victor T. C. [1] ; Santos, Leandra P. [1] ; da Silva, Douglas S. [1] ; Burgo, Thiago A. L. [2] ; Galembeck, Fernando [1]
Total Authors: 5
Affiliation:
[1] Univ Estadual Campinas, Inst Chem, BR-13083970 Campinas, SP - Brazil
[2] Univ Fed Santa Maria, Dept Phys, BR-97105900 Santa Maria, RS - Brazil
Total Affiliations: 2
Document type: Journal article
Source: Langmuir; v. 35, n. 24, p. 7703-7712, JUN 18 2019.
Web of Science Citations: 1
Abstract

The glass/air interface shows electrical properties that are unexpected for a widely used electrical insulator. The mobility of interfacial charge carriers under 80% relative humidity (RH) is 4.81 X 10(-5) m(2) s(-1), 3 orders of magnitude higher than the electrophoretic mobility of simple ions in water and less than 2 orders of magnitude lower than the electron mobility in copper metal. This allows the glass/air interface to reach the same potential as a biased contacting metal quickly. The interfacial surface resistance R increases by more than 5 orders of magnitude when the RH decreases from 80 to 2%, following an S-shaped curve with small hysteresis. Moreover, the biased surfaces store charge, as shown by Kelvin potential measurements. Applying an electric field parallel to the surface produces RH-dependent results: under low humidity, the interface behaves as expected for an ideal two-dimensional parallel-plate capacitor, while under high RH, it acquires and maintains excess negative charge, which is lost under low RH. The glass surface morphology and potential distribution change on the glass/air interface under high RH and applied potential, including the extensive elimination of nonglass contaminating particles and potential levelling. All these surprising results are explained by using a protonic-charge-transfer mechanism: mobile protons dissociated from silanol groups migrate rapidly along a field-oriented adsorbed water layer, while the matrix-bound silicate anions remain immobile. Glass may thus be classified as the ionic analogue of a topological insulator but based on structural features and charge-transfer mechanisms different from the chalcogenides that have been receiving great attention in the literature. (AU)

FAPESP's process: 14/50906-9 - INCT 2014: in Functional Complex Materials
Grantee:Fernando Galembeck
Support Opportunities: Research Projects - Thematic Grants