Dielectric breakdown of alumina single crystals

Abstract

The bulk breakdown behaviour of alumina single crystals with two different crystal orientations,   0 2 11 -plane (single crystal A) and   1 000 -plane (single crystal C), have been studied. Therefor plan-parallel single crystal samples were electrically loaded until dielectric breakdown was achieved. For each crystal orientation, a characteristic breakdown channel direction through the sample could be defined. In C-oriented crystals the breakdown channel originated parallel to the c-axis. For Aoriented crystals however, the breakdown channel crossed the sample in an oblique direction; the angle between crystal surface and breakdown channel was 60°. Here, the breakdown channel crossed the sample along an A-plane. Although the breakdown channel paths of A and C crystals are different, the observed breakdown strength are identical within the scatter range.

Thickness-dependence of the breakdown strength: Analysis of the dielectric and mechanical failure

“…The dielectric breakdown tests were performed using a rectified AC voltage signal as described by Neusel et al [34]. The voltage signal was realized by a 50 Hz voltage pulse, generated by a function generator (Agilent 33220 A, Agilent Technologies, USA), which was stepwise amplified by vacuum tubes, inductors and a transformer coil from low to high voltage.…”

Electrical conduction mechanism in bulk ceramic insulators at high voltages until dielectric breakdown

“…For 1.5 mm thick alumina single-crystals AO EK-A and EK-C, this behavior has already been shown and described in the previous work. 55 If the channel length of AO EK-A is corrected with respect to the tilted pathway, the breakdown strengths of AO EK-A and AO EK-C are within the standard deviation the same.…”

A Griffith type energy release rate model for dielectric breakdown under space charge limited conductivity

“…A second very pronounced feature of the dielectric breakdown strength is the wide scatter of the observations similar to the fracture strength of ceramics (Owate and Freer, 1991;Kishimoto et al, 1995). In all these cases the damage is a sudden event, which creates a small tubular channel (Neusel et al, 2012) and is the focus of this paper. These experimental results are summarized in the schematic of Fig.…”