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Ceramics of compositions represented by (Na1/2La1/2)xBa1−xTiO3 are prepared and their dielectric and structural properties are investigated. The solid solutions with 0 ≦ × ≦ 0.3 are ferroelectric at room temperature. The ferroelectric phases assume a tetragonal structure below the Curie temperatures (≈ 305 K).

The Curie temperature (T c) data on a number of tetragonal tungsten bronze (TTB) ferroelectrics are successfully explained on the basis of the rotational mode proposed recently.1) The mode arises out of the localized dynamical configurations viz. TTB and perovskite and couples with one of the low frequency lattice modes. This lattice mode presumably is the conventional soft mode that is known as the vibration of the cationic sublattice against the anionic sublattice. The mode is identified with increased Raman spectral widths with increasing Li+ ion concentration in the 12 co-ordinated A-cation site for the compositions Li5La5Ti10O30 and Li6La4 Ti8Nb2O30 and is compared with a similar phenomena observed in morphotropic PZT composition PbZr0.51Ti0.49O3.

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