Fabrication And Properties Of 1-3-2 Piezoelectric Composites

1-3-2 piezoelectric composite is a special type of 1-3 piezoelectric composite, which combines the structure of both parallel 1-3 connectivity and series 2-2 connectivity composites. It is composed of upper electrode, 1-3 piezoelectric composite, base plate and bottom electrode. This structure makes it be supported by ceramic framework in three dimensions, which leads to a steady fabric comparing with 1-3 piezoelectric composite material. Meanwhile, 1-3-2 composite not only has the merits of 1-3 composite, but also has more steady properties, and a more simple fabrication craft. In order to extending the application of 1-3-2 piezoelectric composite, and promote the development of piezoelectic composite material, it's very important to explore and research this composite.In this paper, the development of 1-3-2 piezoelectric composites was discussed. 1-3-2 piezoelectric composites were fabricated by dice and filling technique. The influences of [P(MN)]ZT volume fraction, base thickness, [P(MN)]ZT ceramic pole highness, different matrixes and different ceramic cutting direction on piezoelectric properties, dielectric properties, electromechanical properties and acoustic impedance properties of composites were analyzed and discussed.The influences of [P(MN)]ZT volume fraction on the piezoelectric properties, dielectric properties, the electromechanical properties and acoustic impedance of composites were studied. The results show that as the [P(MN)]ZT volume fraction increases, the piezoelectric stain factor d33, the relative dielectric constantεr and acoustic impedance Z increase evidently, while the piezoelectric voltage factor g33 and the dielectric loss tanδdecrease. The thickness mode of composites is strengthened, and the mechanical quality factor Qm are reduced. Meanwhile, the thickness electromechanical coupling coefficient Kt of the composite increase comparing with the [P(MN)]ZT ceramic.The influences of base thickness on piezoelectric properties, dielectric properties and electromechanical properties of the composites were studied. The results show that, as the base thickness increases, the piezoelectric stain factor d33 increases gradually, while the piezoelectric voltage factor g33 decreases. The relative dielectric factorεr increases,εr is the minimum(1406) when base thickness is 0.50 mm. While the dielectric loss tanδdecreases, and the tanδreaches the minimum value of 0.251 when base thickness is 3.00 mm. The planar electromechanical coupling coefficient Kp exhibits the trend of decrease, while the thickness electromechanical coupling coefficient Kt and acoustic impedance show the increasing trend. The mechanical quality factor Qm reaches the minimum value of 1.49 when base thickness is 2.0 mm.The influences of [P(MN)]ZT ceramic pole highness on piezoelectric properties, dielectric properties and electromechanical properties of the composites were studied. The results show that, with increasing [P(MN)]ZT pole highness, piezoelectric stain factor d33 and piezoelectric voltage factor g33 increase. Dielectric constantεr and dielectric loss tanδall increase. The resonance frequency of dielectric constant becomes diminution. The value of plannar electromechanical coupling coefficient Kp is between 40 % and 45 %, thickness electromechanical coupling coefficient Kt increases, acoustic impedance Z is between 12.50 M rayl and 13.20 M ray. The Qm is between 1.40 and 2.70.The influences of different matrixes on piezoelectric properties, dielectric properties and electromechanical properties of the composites were studied. The results show that, different matrixes have obvious effect on the properties of the composite. The d33,εr, tanδand Kt of portland cement-based piezoelectric composite are higher than those of other composites. Polymer-based composite has a smaller g33 comparing other composites. High-temperature gel-based composite has a smaller Qm. Cement has little influence on the acoustic impedance Z.The influences of different ceramic cutting direction(45°and 90°) on piezoelectric properties, dielectric properties and electromechanical properties of the composites were researched. The results show that, Composite whose cutting direction is 45°has good piezoelectric properties. At the same time, it shows lowerεr and tanδ. Comparing with [P(MN)]ZT ceramic, the two stype composites only have thickness vibration and radial vibration, and the space of them is obvious, which makes the interference on thickness vibration be reduced. Kt and Qm of 45°cutting composite is larger than that of the other composite. It also has a smaller acoustic impedance Z.