Electrical and electromechanical properties of lead–potassium–yttrium–niobate ceramics—piezoelectric applications

Abstract

Tungsten bronze (TB)-type oxide ceramic Pb 0.74K 0.13Y 0.13Nb 2O 6 (PKYN) has been synthesized by the standard solid state reaction method. Single phase formation, orthorhombic crystal structure was confirmed by X-ray diffraction (XRD). The substitution of Y 3+ in Pb 0.74K 0.52Nb 2O 6 (PKN) decreased the unit cell volume and T C=260 °C. PKYN exhibited the remnant polarization, P r=8.5 μC/cm 2, and coercive field, E c=28.71 kV/cm. Electrical spectroscopy studies were carried out over the temperature (35–595 °C) and frequency (45 Hz–5 MHz) ranges, and the charge carrier phenomenon, grain–grain boundary contribution and non-Debye-type relaxation were analyzed. The relaxation species are immobile charges in low temperature and oxygen vacancies at higher temperature. The theoretical values computed using the relations, ε′= ε ∞+sin( n( T) π/2)( a( T)/ ε 0)( ω n( T)−1 ); σ( ω)= σ dc+A ω n are fitted with the experimental one. The n and A parameters suggested that the charge carrier's couple with the soft mode and become mobile at T C. The activation enthalpy, H m=0.38 eV, has been estimated from the hopping frequency relation ω p= ω e exp(− H m/ k B T). The piezoelectric constants K t=35.4%, d 33=69×10 −12 C/N, d 31=−32×10 −3 mV/N, S 11 E=17.8 pm 2/N, etc., achieved in PKYN indicate the material is interesting for transducer applications. The activation energies from different formalisms confirmed the ionic-type conduction.