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Synthesis, Structure And Properties Of MPB Composition In PZT- Type Ceramics

Electronic Theses of Indian Institute of Science

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Title Synthesis, Structure And Properties Of MPB Composition In PZT- Type Ceramics
 
Creator Geetika, *
 
Subject Perovskite Lead Zirconate Ceramics
Ceramic Composite Structure
Lead Zirconate Titanate Ceramics
PZT Ceramics
PZT-PZN Ceramics
PZT-PMN Ceramics
Morphotropic Phase Boundary
PZT System
Chemical Engineering
 
Description The first chapter introduces the basic principles governing the phenomenon like ferroelectricity, piezoelectricity and pyroelectricity, which influences the material properties for its device applications. An effort is made to examine the present status of material issues, measurement techniques and applications pertaining to the lead based PZT type systems. This chapter also highlights the objectives and the scope of work.
The second chapter deals with the various basic experimental techniques and principles adopted for the synthesis and characterizations of materials which include phase and quantitative analysis by X-ray diffraction, density measurements, microstructures by scanning electron microscopy, electrical properties such as dielectric permittivity, dielectric loss, and piezoelectricity by impedance analyzer and piezometer etc. The materials were synthesized via two step solid state reaction by adopting a low temperature calcinations route. Further, hot processing was employed for densification and better control of microstructure of the ceramics.
In the third chapter PZT1-x –PZNx (x=0, 0.1, 0.2 & 0.3) compositions prepared by the single step low temperature calcination method have been described. It is seen that the pyrochlore free perovskite phase could be obtained up to x=0.2 compositions. The effect of additives like Li and Mn on the structure, sinterability, microstructure, density and dielectric properties has been investigated. The improvement in densification and ferroelectric properties were observed for Li addition favor tetragonal phase while Mn addition compositions were inclined to pseudocubic phase. Further, the addition of Mn led to the significant decrease in Tc than the parent compositions compared to Li added compositions.
In the fourth chapter, the X-ray diffraction data on pbzrx Ti1-x O3 (PZT) for x=0.48 to 0.52 are presented. High resolution x-ray studies for composition x=0.5 show the MPB which consists of monoclinic Zr rich studies and tetragonal Ti rich phase at room temperature. The refined structural parameters for MPB compositions have been obtained using least square Rietveld refinement program, FULLPROF 2006. The evolutions of lattice parameters of the system were also studied with respect to the temperature. The phase transformation in the system has been analyzed by x-ray diffraction pattern and dielectric measurements. The monoclinic phase transforms to tetragonal phase at 270oC after which the tetragonal phase transforms to paraelectric cubic phase at 370DoC. Dielectric properties show signature of the phase transformation. Hence, it is concluded to pole the MPB samples below 270o C to gain the advantage of increased ease of polarization reorientation for monoclinic phase.
The fifth chapter deals with the systematic structural investigation on PZT1-y-PNZy (PZT-PNZ) and PZT1-y-PMNy (PZT-PMN) systems. In this chapter, an effort has been made to determine quantitatively the MPB phase contents and variation in Zr/Ti ratio of PZT-PZN and PZT-PMN systems. High resolution XRD data has been used for quantitative phase analysis using FULLPROF 2006. The correlation between the width of MPB and grain size has also been discussed for these systems. It is found that the addition of PMN and PZN to PZT system shifts the MPB towards pbZrO3 (PZ). The MPB can be regained by tuning the Zr/Ti ratio in the system. Further, there exists an inverse relation between the grain size and coexistence region in the system. It is seen that the MPB range is from x=0.48 to 0.58 and x=0.44 to 0.58 for 10% and 20% PZN concentration respectively. Similar trend has been obtained for the PZT-PMN system. The MPB ranges from x=0.46 to 0.53 and x=0.42 to 0.50 for 10% and 20% PMN respectively. The broadening of coexistence width is attributed to the lower grain size of our samples synthesized by adopting low temperature calcinations route.
The sixth chapter deals with the hot pressing technique employed (adopting low temperature calcinations) for the synthesis of various PZT-PMN compositions with an intention of obtaining highly dense piezoceramics with fine, homogeneous and uniform microstructure. It also describes the dielectric, pyroelecrtic and pi ezoelectric properties were enhanced by hot processing technique. Li and Mn addition further improved the properties of the system.
The seventh chapter investigates various nominal compositions of PZT-(Li, Nb) compositions based on certain assumptions. The attempt was made to introduce Li at A site and B site of ABO3 perovskite lattice. The ball milled, calcined powders were densified at
 
Contributor Umarji, A M
 
Date 2013-05-01T06:50:43Z
2013-05-01T06:50:43Z
2013-05-01
2009-07
 
Type Thesis
 
Identifier http://etd.iisc.ernet.in/handle/2005/1982
http://etd.ncsi.iisc.ernet.in/abstracts/2567/G23650-Abs.pdf
 
Language en_US
 
Relation G23650