Dariusz Bochenek

Influence of the processing conditions on the properties of the biferroic Pb(Fe1/2Nb1/2)O3 ceramics

Abstract. The PbFe1 - xNbxO3 ferroelectromagnetic ceramic for x=0,5 (PFN) was obtained by one and two stage method and examined in the work. Synthesizing of ceramic powder was conducted as a result classic solid-state sintering methods (compacting method) and by powder calcinations method. Densification was carried out by free sintering and the hot uniaxial pressing method. The obtained specimens were subjected to microstructure and dielectric examinations and tests of direct current conductivity. The tests have shown that synthesizing a powder by a two stage columbite method through calcinations creates favorable conditions for obtaining the PbFe1 / 2Nb1 / 2O3 ceramic with the optimum applied parameters. PFN classified into smart materials can be used for building elements and components in electronic engineering and electrical engineering [1,2].

Structure and magnetic properties of perovskite-like multiferroic PbFe0.5Nb0.5O3

PbFe0.5Nb0.5O3 compound (PFN) is a well-known multiferroic material undergoing a paraelectric(PE)-to-ferroelectric(FE) phase transition at ~ 380 K. The cubic structure in the PE state is distorted in the FE state to the tetragonal (below 376 K), and subsequently to the monoclinic structure. Inspecting magnetism, two diffuse magnetic phase transitions were reported at TN = 150 K and Tm = 10 K. In our work, we have investigated samples derived from the PFN, prepared by different methods. The crystal structure, grain size and phase composition of the materials was determined by powder XRD and SEM analysis. Study of magnetization and a.c. susceptibility confirmed presence of the two anomalies of magnetic origin at 150 K and 10 K, respectively, in most of the samples.

Dielectric and electromechanical behaviors of PMN-PT ceramic samples

The results of the investigations on (1 — x)PMN-xPT ceramic samples obtained by sol—gel (SG) technology are presented in this study. In the (1 — x)PMN-xPT samples, the temperature Tm (at which real part of dielectric permittivity reaches its maximum) increases from ~270 K for x = 0 to ~500 K for x = 0.5. At room temperature, the samples with low values of x exhibit relaxor properties, while with increasing x the transition to normal ferroelectric properties takes place. Usually 0.9PMN-0.1PT or 0.925PMN-0.075PT solid solutions are considered as boundary compositions between relaxor and ferroelectric properties at room temperature.This study presents the analysis of X-ray diffraction patterns, fracture microphotographs, electromechanical parameters, and hysteresis loops for ceramics obtained from SG PMN—PT powders densified by the hot pressing method with a composition range, x = 0—0.37.

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

Piezoceramic Transducers with High Thermal Stability of the Resonance Frequency

Methods for increasing thermal stability of the resonance frequency f r of the PZT-based piezoceramic resonators are shown. An influence of ( x )PbTiO 3 content and an effect of doping ions on j f r / f r in the PZT solid solution has been considered. Correlation between qualities of the domain structure, spontaneous deformation parameters i T , i Re , degree of domain reorientation m , internal friction Q m m 1 and mechanical quality factor Q m , has been revealed. An impact of electronegativity of the doping ions on f r thermal stability have been cleared up. Ferroelectric hardness has also been considered. The piezoceramic band filters exhibiting j f r / f r <0.2% and Q m =3225 have been thus obtained.

Structure and physical properties of PZT-type ceramics with cadmium and tungsten dopants

Ceramics of Pb (Zr0.56Ti0.44)O3 with 2.0 at% cadmium and 2.0 at% tungsten dopants (PZT-CW) were created using hot-pressing method. Next, the basic properties of PZT-CW ceramics were investigated. An analysis of the crystallographic structure, tests of dielectric and piezoelectric parameters of the ceramics, as well as internal friction measurements were performed. The PZT-CW ceramics obtained using the hot-pressing method have the microstructure of regularly crystallized grain. For this reason, it holds a set of electrophysical parameters illustrating the possibilities of its application in electrical engineering.

Multiferroic Ceramic Composites Based on PZT Type Ceramic and NiZnFe Ferrite

Multiferroic (ferroelectric–ferromagnetic) ceramic composites were obtained on the basis of a ceramic powder of PZT type, i.e. Pb(Zr0.51Ti0.49)O3 + 0.2% at. Bi2O3 + 0.03% at. Nb2O5 + 0.06% at. MnO2 (marked as PZTBNM) and Pb0.84Ba0.16(Zr0.54Ti0.46)O3 + 1.0% at. Nb2O5 (marked as PBZTN). Admixtured compositions constituted of a PZT type ferroelectric powder with nickel-zinc ferrite (Ni1-xZnxFe2O4) as the magnetic content in the composite. Synthesis of the composite content was performed using compact sintering in the solid phase, while densification of the synthesized powder was achieved using the pressure-less sintering method (conventional sintering method). For the obtained multiferroic ceramic composites XRD investigations were performed, as well as investigations of microstructure, EDS, dielectric and magnetic properties, impedance and electrical hysteresis loop. The tests showed the existence of a correlation between magnetic and electric subsystems in the composites. Thanks to the ferroelectric and magnetic properties of the composites obtained, materials of this type could be applied, for example, in new memory types or magnetoelectric transducers.

Dielectric Properties of Pb0.75Ba0.25(Zr0.65Ti0.35)1-zSnzO3 Ceramics

In this work, the ceramics with the general formula of Pb0.75Ba0.25(Zr0.65Ti0.35)1-zSnzO3 (PBZST) for a constant x = 0.25, constant y = 0.35 and variable z = 0, 0.02, 0.04, 0.06, 0.08, 0.10 were obtained and examined. Powders synthesis was carried out using calcination method in conditions of: Tcalc = 850°C/tcalc = 3 h, and densification using free sintering method in conditions of: Ts = 1250°C/ts = 4h. For the obtained samples of PBZT and PBZTS ceramics, the microstructure and basic dielectric properties in the frequency function tests were performed. The PBZTS ceramics with relaxor properties is an interesting material to use in the modern electrical engineering, for instance as electrostriction transducers, sensors, or pulse capacitors.

Low frequency elastic and anelastic properties of Pb(Fe0.5Nb0.5)O3 ferroelectric ceramics

Abstract.Pb(Fe0.5Nb0.5)O3 is one of the well studied ferroelectric compound. However, different physical properties of this ceramics were investigated in details, mainly at temperatures in the vicinity of the Curie point, whereas many questions remain about the behavior of physical properties in a wide temperature range, the presence of other phase transitions, types of lattice defects and their effect on macroscopic characteristics, etc. The papers devoted to low frequency elastic and anelastic properties of Pb(Fe0.5Nb0.5)O3 are practically non-existant. Nevertheless, the study of internal friction could give valuable information about different kinds (point, linear and plane) of lattice defects and the changes in the properties of the different phases of investigating ceramics which are related with the several mechanisms measured by the mechanical resonance spectrometer [3]. It is difficult to obtain such results by any other method; moreover sometimes it is impossible at all. In the work, we present results of the measurements of low frequency internal friction Q-1, Youngs modulus E, electric permittivity ε and dielectric loss of angle tgδ in the polycrystalline Pb(Fe0.5Nb0.5)O3 ceramic samples in order to understand a nature of lattice defect interactions and mechanism Q-1 at the phase transition in the Curie and Neel points.

The properties of (1-x)(0.5PZT-0.5PFW)-xPFN ceramics

ABSTRACT The ceramic samples of solid solution (1-x)[0.5(PbZr0.53Ti0.47O3)-0.5(PbFe2/3W1/3O3)]-x(PbFe1/2Nb1/2O3) [i.e. (1-x)(0.5PZT-0.5PFW)-xPFN] with x = 0; 0.1; 0.2 have been obtained by conventional ceramic technology using the free sintering (FS) method from PbO, ZrO2, TiO2, Fe2O3, WO3 and Nb2O5 oxides. Basing on the literature data for individual components, it can be expected that this material ought to have interesting multiferroic properties. The presented work is the first step in obtaining and investigating this solid solution. In the presented paper, the technology and the results of investigations of EDS, XRD, the microstructure of fractured samples, dielectric permittivity v.s. temperature, and d.c. electric conductivity are presented.