SQUARE HYSTERESIS LOOPS IN PHASE-SWITCHING NB-DOPED LEAD ZIRCONATE STANNATE TITANATE THIN-FILMS

Niobium-doped lead zirconate stannate titanate thin films have been prepared by a modified sol-gel spin on technique, utilizing the hydrolysis-resistant precursor lead acetylacetonate. Films of compositions in the antiferroelectric tetragonal and antiferroelectric orthorhombic phases were prepared and phase-switched with the application of appropriate electric fields. A distinctly ''square'' hysteresis response was observed in a low titanium, low tin, orthorhombic composition, with a maximum polarization, P-max, of 40 mu C/cm(2) and switching field values of E(f) = 175 kV/cm and E(a) = 75 kV/cm, while varying degrees of squareness, along with lower polarizations and switching fields, were observed in the higher tin, tetragonal compositions. Electric field-induced strains of up to 0.33% have been measured in the orthorhombic composition, with tunable electromechanical coefficients. Film properties showed only slight variation with electrode size over a range of diameters from 0.8 mm to 6.35 mm; large area electrodes are vital for practical actuator and sensor devices. With a capacitance density of 30-35 mu F/cm(2), films of the orthorhombic composition are promising as power plane decoupling capacitors in multichip modules.