Ferroelectric properties of tungsten bronze lead barium niobate (PBN) single crystals

Abstract

A ferroelectric tungsten bronze single crystal of Pb_0.33Ba_0.70Nb₂O₆ was grown from a melt using the Czochralski technique. The crystal belongs to the tetragonal point group 4mm with the spontaneous polarization parallel to the ‘c’ axis. The room temperature lattice parameters were a = 12.50 Å and c = 3.995 Å. The spontaneous polarization was found to be 0.40 C/m²°C. The Curie transition was 350°C as determined from the temperature dependence of the dielectric constants. The pyroelectric properties were found to be typical of other tetragonal ferroelectric bronzes. Dielectric constant ϵ₁₁ and piezoelectric constant ^d15 show a strong enhancement from the approach of the tetragonal:orthorhombic morphotropic phase boundary and it is clear that crystals with composition in the tetragonal phase field closer to this boundary will be of major interest for piezoelectric and electro-optic applications.