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Piezoelectric micro machined ultrasonic transducers (pMUT) are piezoelectric laminated plates operating at flexural modes. The pMUT's fabricated in this work contained a 4 mum thick lead zirconate titanate (PZT) thin film deposited by a sol-gel technique, and exhibiting a permittivity of epsivr = 1200, and an effective transverse piezoelectric coefficient e31,f of 12 C/m2 . A further optimization of the sol-gel process yielded larger grain diameters and consequently improved properties: epsivr = 1600, e31,f of 16 C/m2 . A design and micromachining concpet for easy scaling in frequency has been developed. The electromechanical coupling coefficient (k2 ) and the quality factor (Q) of rectangular clamped elements (with former PZT process) were measured as k2 = 4.4% and Q = 145 in air for a low frequency transducer (@240 kHz). The 16.9 MHz transducer yielded values of Q = 25 and k2 = 3% in air. The effect of DC bias voltage on frequency and k2 has been studied.