Preparation And Properties Of LTCC Single And Multilayered PNN-PZN-PZT Thick Films

The past few decades have witnessed a wide application of lead zirconate titanate(PZT),including transdusers,actuators and sensors due to its excellent piezoelectric and ferroelectric properties,such as large displacement,quick response time,low power consumption and high force generation.Piezoelectric thick films with the thickness of 10-100 ?m fill the gap between processing capabilities of thin films and bulk ceramics and combine their advantages of larger actuating force and displacement,lower working voltage,wider working frequency and compatibility with semiconducting integrated circuit.Consequently,PZT thick films have been promisingly applied to micromotors,ultrasonic transducers and energy harvesters.In this paper,screen printing and tape casting PNN-PZN-PZT single layer and multilayer thick films were successfully prepared on Al2O3 substrate by using one step co-firing method.During the process of screen printing method,the effects of calcined temperature,addition of sintering aids,sintering temperature,ball milling time and poling method on the micro-structure and electrical properties of single layer piezoelectric thick films have been investigated.After processes of calcined at 850 °C for 2 h,adding1 wt.% sintering aids(Pb-B-Si-Al),ball milling for 10 h,sintered at 850 °C and finally poled at 130 °C,keeping the electric field of 6 kv/mm until room temperature,single layer PNN-PZN-PZT thick films exhibits markedly enhanced piezoelectric and dielectric properties: d33 = 202 pC/N,?33~T/?0 = 987,tan? = 1.8 %,Tc = 295 °C,and Pr = 14.02 ?C/cm~2.Furthermore,Ag element distribution at a cross section of the PZT-Ag-Al2O3 interface through linear EDX scanning.It can be observed that there is no obvious interface between thick film and Ag electrode layer,indicating fine coherence of interface.And stainless steel and titanium substrate were adopted in this research.Finally screen printed multilayer thick films were successfully fabricated.Multilayer thick films with 5 layers showed optimal electric properties: d33,?33T/?0,tan ?,and Pr of 1021 pC/N,1167,1.92 % and 56.44 ?C/cm~2.And 11 layered specimens exhibited giant d33 and strain of 1883 pC/N and 0.66 % at 4 kV/mm.The applied voltage to obtain the same displacement was decreased from 3072 to 180 V for 11 layered specimens,compared to bulk ceramics.Such prominent properties indicate that co-fired PNN-PZN-PZT multilayer thick films are suitable for applications like micro-actuators and micro-transdusers in MEMS system.During the research of tape casting single and multilayer PNN-PZN-PZT thick films,the preparation of tape casting slurry,and the effects of value and rising rate of sintering temperature on the micro-structure and electrical properties of tape casting single layer PNN-PZN-PZT thick films have been investigated.The optimal piezoelectric properties of single layer and three layers thick films were a little higher than screen printed thick films,with the values of 258 pC/N and 725 pC/N,respectively.