Through the rolled‐up glass: We demonstrate an alkali‐free glass (• in figure) with high permittivity, low dielectric loss, high energy density, and potential self‐healing capabilities that significantly performs better for high temperature–high power capacitor applications prepared through a standard roll‐to‐roll process than currently used polymer films (shown for comparison).

The dielectric breakdown statistics of alkali‐free glass was determined for various thicknesses with electrodes having controlled morphology and continuity. The characteristic electrical breakdown field strength increased from 400 to 1100 MV/m as the glass substrate thickness decreased from 58 to 5 μm, respectively. Surface roughness RMS values of as‐drawn and etched glass substrates were in the 0.9–1.8 nm range, which is small in comparison to the glass substrate thickness. The glass etching, itself did not have significant effect on the dielectric breakdown strength. The dielectric breakdown strength was also independent of the sputtered‐deposited electrode composition (Au, Pt); however, electrode thickness played an important role in controlling the breakdown process. The Au electrode morphology transitioned from a continuous sheet for thicker electrodes to discrete nano‐scale islands for very thin electrodes (<2 nm thick). The thin electrode morphology provides a unique opportunity to explore the intrinsic properties and high dielectric breakdown strength regime (1100 MV/m) in glasses with Weibull modulus values approaching 100.

A new non-destructive gradient scattered light method is presented for micronscale stress profile measurement in chemically strengthened (chemically tempered, ion exchanged) glass. Direct non-destructive stress measurement in the surface layer (\100 lm) of chemically strengthened glass is reported for the first time. This is accomplished by passing a narrow laser beam through the surface layer of the glass at a considerably large incidence angle of 81.9°. The theory of gradient scattered light method is based on the ray tracing of ordinary and extraordinary rays in chemically strengthened glass and calculating the optical retardation distribution along the curved ray path. The experimental approach relies on recording the scattered light intensity and calculating the optical retardation distribution from it. The stress profile is measured in a chemically strengthened (8 h at 480°C in a salt mixture of 80 mol% KNO 3 and 20 mol% NaNO 3 ) lithium aluminosilicate glass plate to illustrate the capability of the method. Measured surface compressive stress was -1053 MPa and case depth 365 lm. Method is validated with transmission photoelasticity. The method could also be used for stress profile measurement in all transparent flat materials (such as very thin thermally tempered glass slabs or polymers). Additional new applications could be: (1) enhanced version of Bradshaw's surface layer etching method for stress profile measurement in case of ultra-thin case depths \20 lm;(2) micron-scale non-destructive tomography of layered polymeric gradient-refractive-index materials. The experimental procedure is developed to the level of full automation and the measurement time is less than 10 s.

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