An in-situ Raman spectroscopic investigation in electric fatigue behaviors of PLZT ceramics

A series of in-situ Raman spectra upon different polarization directions of incident and scattered lights (θ) and the corresponding hysteresis loops of unpoled lanthanum-doped lead zirconate titanate (PLZT) ceramics were simultaneously measured without and with applications of various electric fatigue cycle numbers (N). Accordingly, the relative Raman intensities in optical modes of E(2TO) over E(3TO+2LO)+B1 (IE(2TO)/IE(3TO+2LO)+B1), the maximum changes in IE(2TO)/IE(3TO+2LO)+B1 at θ=0–360° (ΔRmax) and the remnant polarization (Pr) were obtained for the as-received (N=0) and differently electric fatigued (N=100, 104, 105, 106 and 106.2) PLZT specimens. The characteristic electric fatigue behaviors observed for the unpoled PLZT ceramics were quantitatively analyzed by the normalized remnant polarization denoted as Pr, N/Pr, 10° and correlated to the average domain reorientation defined as ΔRmax, N/ΔRmax, 10°. It was concluded that during the electric fatigue process, the randomly orientated domains in the unpoled PLZT specimen as-received might be reoriented preferentially along the direction of the applied electric field initially. The electric fatigue reduced the extent of average domain orientation and significantly deteriorated the ferroelectric properties.