J. Ilczuk

Influence of the Technology Conditions on the Mechanical and Dielectric Properties of the PZT-Base Piezoceramic Transducers

Application of the piezoceramics produced on the base of the PZT-type s olid solution in modern electroacoustics depends primary on its mechanical and electr ica pa ameters. Multicomponent ceramic materials of the PZT-type are characterized by the occurrence of the morphotrophy area, it means the area of the rhombohedral and tetragonal phase coexistence. T he position and width of the area depends on the solid chemical solution and the technology used for obtai ning it. Therefore, selecting the suitable methods and conditions for producing piezoceramics is very impo tant since it has a direct influence on its properties. This work presents results of the investigations of the piezocerami c samples of the PZT-type received by the hot pressing method and the conventional sintering in different condi ions. The results obtained will be used to optimize the technological process and will indicate possibilities of wider applications of PZT-type piezoceramics in modern technology. Introduction Apart from the chemical composition and microstructure of ferroelec tric eramics temporary and temperature stability of their mechanical and dielectric param eters constitute important factors influencing their range of application. This has been confirmed by invest gations of the multicomponent solid state solutions of the PZT-type, conducted by differ ent methods [1 6]. Mechanical spectroscopy due to its high sensitivity to changes taking place in the real structure of materials has been more often used in recent investigations [6]. To observe changes occurring in the domain structure and to determine the stability of mechanical and die lectric parameters, the application of mechanical spectroscopy and the resonance-anti-resonance method is used. The influence of the conditions of the technological process on the stabil ity of temperature, on the mechanical properties and on the basic dielectric parameters of t he multicomponent piezoelectric ceramics of the PZT-type is shown. These investigations were ai m d at controlling the manufacturing process of ceramics to be used in ultrasound generators of high power e ngines and in piezoelectric transformers. Experimental The material used in this study was the ceramics belonging to te rnary solid solutions of the PZT-type with the following chemical composition: Pb (Zr 0.51 Ti0.49) O3 + Pb (Nb0.5 Mn0.5) O3 + 2.15 wt % Bi 2O3; its dielectric parameters show that it belongs to ceramics of medium ferroe lect ic hardness. The ceramics was obtained in different technological conditions by the hot pressing method in nitrogen or in argon atmosphere, and by the classical sintering method. A synthesized powder of the Solid State Phenomena Online: 2003-02-13 ISSN: 1662-9779, Vol. 89, pp 303-308 doi:10.4028/www.scientific.net/SSP.89.303

Biferroic electro -acoustic ceramics with BiFeO3 composition

Abstract.Bismuth ferrite, one of a few multiferroics, has attracted much attention for many decades since 1960. BiFeO3 (BFO) belongs to perovskite class of complex oxides. BFO is one of only a few materials in which (anti)ferromagnetism and ferroelectricity coexis in room temperature. Authors prepared BiFeO3 ceramics by solid state reaction method. The synthesized powders were characterized by X-ray diffraction method. Thermogravimetric and differential thermal analysis were investigated. The microstructure of the BFO ceramics was investigated by means of scanning transmission electron microscopy, and the ferroelectric characteristic of BFO ceramics was demonstrated. BFO is very interesting ceramic material for potential applications in the memory devices, sensors, satellite communications, optical filters and smart devices.

Mechanical Spectroscopy and Phase Transformations in PZT-Type Piezoceramics

The dielectric and mechanical loss properties of the PZT-type m ulticomponent piezoceramics are reported. This paper describes two mechanical l oss peaks induced by phase transitions: (1) from the rhombohedral phase into the tetragonal phase, a nd (2) from the ferroelectric phase into the paraelectric phase. It is determined that the trans ition from the ferroelectric phase into the paraelectric phase at the Curie temperature causes a decr e se in dynamic Young’s modulus due to the disappearance of the domain structure. Introduction For several years ferroelectric ceramic materials have be en carefully investigated because of their many applications in modern technology and electroacoustics. PZT multicomponent ceramics, based on the PbTiO 3-PbZrO3 solid solution, are highly effective piezoelectric materials. T hese materials have to meet strict quality requirements and must have certain desired properties [1-6]. Therefore, it is important to investigate the physical, chemical and mechanical properties of the materials, along with their dielectric and mechanical losses. T o tailor high-quality ferroelectric ceramic materials, a good knowledge about the relationships between c h mical compositions, crystalline structures, electrophysical properties, and domain structures is required. Mechanical spectroscopy (internal friction) is highly sensitive to changes in both the concentration of structural defects and in the real structure of ce ramic materials. The purpose of this work is to study the kinetics of phase transformations in PZT-type m ulti-component ceramics through the use of rezonant mechanical spectroscopy. Specimens and Experimental Procedure The material used in this study was the PbSr(ZrTi)O 3 piezoceramic modified with cobalt (CTS-23) and the so-called CTS-83G piezoceramic with the following chemical omposition: Pb0.97Ba0.01Ca0.01Sr0.005(Zr0,52Ti0.47)O3 + 1.4%wt. Bi 2O3 + 0.3%wt. GeO (the CTS-83G and CTS23 refer to Russian patents). These materials are widely used i n vibration detectors, pressure pickups, and accelerometers working in severe climate conditions. The diel ectric and piezoelectric parameters of the investigated ceramics are collected in Table 1. The structure of the PZT-type multicomponent piezoceramics is dete rmined by the chemical composition of the solid solution. For different PbTiO 3 concentrations the following structures can be observed: rhombohedral (R), tetragonal (T), or dualphase (R+T) morphotropic systems [ 9]. Solid State Phenomena Online: 2003-02-13 ISSN: 1662-9779, Vol. 89, pp 309-314 doi:10.4028/www.scientific.net/SSP.89.309