In the last decades, the interest to the PZT solid solution has grown sharply. The most contradictory is information about the structure of the PZT with Ti concentration below 6% [1]. In our combined inelastic and diffuse scattering study of PZT we have addressed the critical instability close to the Γ-point and to the BZ boundary. In the first case, in contrast to the Ref.1 we found lattice instability at q ≈ (0.2 0.2 0) in some cases resulting in the formation of the incommensurate structure. For the BZ vicinity, we found that the temperature dependent diffuse scattering is observed aside of the M-point. Also it is extinct at h = k (Q=(1.5 1.5 0)). Such extinction rule indicates that this component is related to the oxygen octahedra tilts. Our IXS measurements have revealed strong asymmetry of the scattering intensity in respect to the Brillouin zone boundary. Intensity of the central peal (CP) at Q1 = (1.55 0.45 0) is very low, while at Q2 = (1.45 0.55 0) it is high. This is similar to the results reported in the Ref. [3]. Observed scattering pattern can be tentatively described as the result of the coupling of the M3 and M2’ modes. Interference term in this case can suppress the scattering at the one side of the zone boundary and enhancing it at the other side.
References
[1] J Ricote et al., Phys.: Condens. Matter 10, 1767–1786 (1998).
[2] A.K. Tagantsev et al., Nature Communications 4 2229 (2013).
[3] M. Paściak et al., Phase transitions 88, 273 (2015).