Nano-shorts

Micro-Raman and electron nano-probe techniques are used to show that lead zirconatetitanate (PZT) and samarium-doped bismuth titanate undergo local phase transformations during electrical shorting. In PZT dendrite-like shorts of a few microns diameter, produced by extreme bipolar voltage cycling fatigue, are mapped spectroscopically in 1 μ ² areas and exhibit almost pure regions of α-PbO, β-PbO and rutile TiO₂. [Note that β-PbO is not the stable ambient phase.] Similarly, the Sm-doped bismuth titanate converts under large dc voltages from layered-perovskite structure to a pyrochlore-like structure during filamentary electrical breakdown, with the loss of Bi.