Temperature-Dependent Domain Dynamics and Electrical Properties of Nd-doped Bi₄Ti 2.99 Mn 0.01 O 12 Thin Films in Fatigue Process.

Bi₄Ti _2.99 Mn _0.01 O ₁₂ (BTM) thin films with different ratio of neodymium (Nd) doping were prepared on Pt(111)/Ti/SiO₂/Si(100) substrates through a sol-gel method. The effects of Nd doping on domain dynamics and temperature-dependent fatigue behaviors of BTM thin films were systematically studied. The polarization fatigues of BTM (not doped) and Bi _3.5 Nd _0.5 Ti _2.99 Mn _0.01 O ₁₂ (BNTM05) thin films first get better with the increasing temperature ( T ) from 300 to 350 K and then become worse from 350 to 400 K, while Bi _3.15 Nd _0.85 Ti _2.99 Mn _0.01 O ₁₂ (BNTM85) thin films show enhanced fatigue endurance from 300 to 400 K. It can be shown that the long-range diffusion of oxygen vacancies in BTM thin film happens more easily through the impedance spectra analysis with T from 300 to 475 K, which can be verified by a lower activation energies (0.13⁻0.14 eV) compared to those of BNTM05 and BNTM85 (0.17⁻0.21 eV). Using a temperature-dependent piezoresponse force microscopy (PFM), we have found more responsive domain fragments in Nd-substituted films. The microscopic domain evolution from 298 to 448 K was done to further explain that the domain wall unpinning effect has been enhanced with increasing T . The correlation between microscopic domain dynamics and macroscopic electrical properties clearly demonstrates the effects of charged domain wall in Nd-doped BTM thin films during the fatigue tests.