Abstract
The domain orientations’ distributions in the unpoled lanthanum and niobium-doped lead zirconate titanate (La,Nb-doped PZT) ceramics after the application of different poling electric fields (\(E_{{\text{P}}}^{n}\)) were studied based on in situ polarization angle analysis by Raman spectroscopy in a parallel y(zθ,zθ)y configuration. Ten grains were randomly selected within the same polycrystalline La,Nb-doped PZT ceramic specimen, and the polarization angle (θ)—dependent Raman spectra were in situ measured before and after \(E_{{\text{P}}}^{n}\). It was found that the intensity ratio of Raman optical modes IE(2TO)/IE(3TO+2LO)+B1 varied periodically by 180° with the polarized direction of the laser beam. The decreases in the mean orientation angle and the standard deviation revealed that the preferred domain orientation tended to be distributed more and more closely in the direction towards the poled electric field with the enhanced strengths in \(E_{{\text{P}}}^{n}\). Furthermore, the larger linear proportional coefficient \(\alpha_{N} (E)\) indicated that the degree of the preferred domain orientation decayed more slowly with the development of fatigue on the more strongly poled La,Nb-doped PZT ceramic due to a more serious reduction in the ability of 90° domain switching resulted from the easier pining of ferroelectric domains, in the scope of lattice vibration. The method introduced in this work might be applicable to investigate the domain orientation distribution in polycrystalline ferroelectrics and to predict the similar electrical fatigue behavior for other ferroelectric ceramic materials.