Influence of the magnitude of the ferroelectric ordering on the optical properties of Pb(Ti Ni)O3 and (K Ba)(Nb Ni)O3

Reference Presenter Authors
08-123 Manuel Henrique Lente Lente, M.H.(Universidade Federal de São Paulo); Eiras, J.A.(Universidade Federal de São Carlos); de Abreu, P.T.(Universidade Federal de São Paulo); Vargas, N.F.(Universidade Federal de São Paulo); Gennari, R.C.(Universidade Federal de São Paulo); Lang, R.(Universidade Federal de São Paulo); Ferroelectric perovskite ceramics are massively used in a very wide range of technological applications, such as piezoelectric ultrasonic transducers, nonvolatile random-access memories and piezoelectric actuators. Recently, ferroelectrics materials have also emerged as a promising alternative to traditional semiconductor junctions for photo-excited carrier separation and, thus, for photovoltaic solar energy conversion. The ferroelectric polarization direction can drive the charges carries separation thus preventing their recombination. However, the inherent large band gap of ferroelectric oxides is still a challenge to be overcome. Recent works have revealed that suitable doping or ceramic processing can tailor the optical properties of ferroelectric oxides, increasing their viability for visible wavelength-absorbing materials. On the other hand, few attention has been paid to the influence of the intrinsic BIAS field from the ferroelectric axis to the optical properties of ferroelectric oxides. In this work, the optical properties of (K Ba)(Nb Ni)O3 - KBNN - and Pb(Ti Ni)O3 - PTN - ceramics were investigated. The results revealed that the Ni2+ doping broken the long-range ferroelectric order for the KBNN, leaving the KBNN system in a pseudo-cubic symmetry, whereas the ferroelectric ordering for the PTN was maintained with high c/a distortion. Moreover, it was observed that while the optical properties of the PTN ceramics were independent of the ceramic processing, the optical ones for the KBNN were strongly dependent of the sintering temperature. The difference between the optical properties for both ferroelectric oxides was associated with the magnitude of the intrinsic BIAS field due to the ferroelectric axis. Therefore, it is suggested that Ni2+ doping may differently tailor the optical properties of ferroelectric ceramics, depending on the magnitude of the ferroelectric order.
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