Phase transition behaviors of (Na1/2Bi1/2)1−xTiPbxO3 thin films

Ferroelectric thin films of (Na1/2Bi1/2)1−xTiPbxO3 have been synthesized via a sol–gel route. Structural changes of the films were investigated by using X-ray diffraction (XRD) and Raman spectroscopy over the composition range 0 < x < 0.9. There occur different nano-sized clusters in the films. More interestingly, in contrast to the previously reported results on (Na1/2Bi1/2)1−xTiPbxO3 bulk ceramics, the ferroelectric thin films exhibit a rhombohedral–tetragonal structure change at x = 0.4–0.5, together with a long range tetragonal symmetry at x ≥ 0.8. The unique phase transition behaviors are discussed in relation to the growth of Pb2+TiO3 clusters upon the substitution of Pb2+ for Na+/Bi3+ cations in the (Na1/2Bi1/2)1−xTiPbxO3 films.