Uniform field-induced strain in a/b-axes-oriented Bi3.9Pr0.1Ti3O12 thick films on IrO2/Si substrates for lead-free piezoelectric microdevice applications

We grew 1.5-mum-thick Bi3.9Pr0.1Ti3O12 (BPT) polycrystalline films with a/b-axes orientation on IrO2/Si substrates from chemical solutions and measured electric-field-induced strain epsilon by a double-beam laser doppler vibrometer and atomic-force microscopy (AFM). The results reflected uniform film growth and elimination of elastic deformation of the substrate, and the microscopic piezoelectric response in AFM measurements agreed well with the macroscopic response evaluated by laser vibrometer. A large longitudinal epsilon=0.3% was observed at 400 kV/cm and 10 Hz, and the piezoelectric coefficient d(33)=depsilon/dE\(0)=60 pm/V was calculated. X-ray diffraction analyses revealed that the (200)/(020) peak of BPT was comprised of 40% a domain and led to the reduced values of ferroelectric polarizations of 2P(r)=35 and P-sat=23 muC/cm(2). This suggests that applying an electric field did not cause fraction reconfiguration of a- and b-domains, and, therefore, the measured large strain was achieved without contribution from the 90degrees-domain-wall motion in a/b-axes-oriented BPT thick films. (C) 2004 American Institute of Physics.