Physical Chemistry of the PbO-MgO-Nb2O5-TiO2 System for Ferroelectric Relaxors

This project was devoted to evaluating the phase chemistry and thermochemistry of the quaternary lead-magnesium-niobium titanate system (PbO-MgO-Nb2O5-TiO2). It is technologically relevant to the development of ferroelectric relaxors with the perovskite crystal structure and of the general compositi...

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Bibliographic Details
Main Author: Petuskey, William T.
Other Authors: ARIZONA STATE UNIV TEMPE DEPT OF CHEMISTRY
Format: Text
Language:English
Published: 2004
Subjects:
Physical Chemistry
Electricity and Magnetism
*FERROELECTRIC MATERIALS
*PHYSICAL CHEMISTRY
*LEAD OXIDES
CRYSTAL STRUCTURE
THERMODYNAMICS
THERMOCHEMISTRY
GRAVIMETRY
TERNARY COMPOUNDS
QUATERNARY COMPOUNDS
TITANATES
SOLID SOLUTIONS
CHEMICAL EQUILIBRIUM
PHASE DIAGRAMS
VAPORIZATION
SOLID PHASES
PEROVSKITES
MAGNESIUM OXIDES
NIOBATES
KNUDSEN GAGES
LEAD MAGNESIUM NIOBIUM TITANATE SYSTEM
*RELAXORS
Knudsen
Orca
Online Access:http://www.dtic.mil/docs/citations/ADA420896
http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA420896
Description
Summary:This project was devoted to evaluating the phase chemistry and thermochemistry of the quaternary lead-magnesium-niobium titanate system (PbO-MgO-Nb2O5-TiO2). It is technologically relevant to the development of ferroelectric relaxors with the perovskite crystal structure and of the general composition Pb(Mg(0.33-0.33)xNb(0.67-0.67x)Ti(x))O. This project also evaluated the phase chemistry of most of the remaining compositions of the system. The four ternary phase diagrams of PbO-MgO-Nb2O5, PbO-MgO-TiO2, PbO-Nb2O5-TiO2 and MgO-Nb2O5-TiO2 at 1000 degrees C were determined in some detail. The quaternary phase diagram was evaluated for relatively PbO-poor compositions. In addition, the thermochemistry of the overall system was also evaluated between about 800 and 1000 degrees C, characterized in the form of equilibrium vaporization rates of lead oxides. This was accomplished by Knudsen cell gravimetry on binary, ternary and quaternary phase states that were thermodynamically well defined. From this, the formation thermodynamics of a number of solid phase compositions were determined for the first time. Moreover, trends were evaluated of the equilibrium vapor pressures over perovskite solid solutions as a function of composition. ORCA proposal: 01-1198.

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