Critical radii of ferroelectric domains for different decay processes in LiNbO3 crystals

The LiNbO3 crystals were polarized at fixed points and characterized by means of scanning probe microscope. The growth evolution and the decay process of the fabricated domains were carefully studied. Two critical radii rC and Rc that determine a different decay behavior of domains were put forward, where rC is considered to correspond to the point when the domains just penetrate the crystal. Those domains with radius larger than rC could exist beyond 5days, those between rC and Rc experienced a distinct metastable state before completely disappearing, while those smaller than Rc were even invisible under piezoresponse force mode.