Low-Temperature Densification of Lead Zirconate Titanate With Vanadium Pentoxide Additions
Wittmer, Dale Edward
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Permalink
https://hdl.handle.net/2142/68537
Description
Title
Low-Temperature Densification of Lead Zirconate Titanate With Vanadium Pentoxide Additions
Author(s)
Wittmer, Dale Edward
Issue Date
1980
Department of Study
Ceramics Engineering
Discipline
Ceramics Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Materials Science
Language
eng
Abstract
The addition of 0.1 to 6.0 w/o V(,2)O(,5) to lead zirconate titanate (PZT) ceramics promoted rapid densification below 975(DEGREES)C, thereby eliminating the need for PbO atmosphere control. The base PZT, Pb (Zr(,0.53)Ti(,0.47))O(,3), was prepared by coprecipitation from mixed oxides and butoxides. V(,2)O(,5) was incorporated as mill additions to the precalcined base PZT, as batch additions to the PZT during the coprecipitation process, and as mill additions to a commercially available PZT powder. Densification rates were enhanced by the additions of V(,2)O(,5). Densities greater than 98% of theoretical were obtained in (TURN) 15 minutes of 960(DEGREES)C for additions of 0.1 to 1.0 w/o V(,2)O(,5), compared to 4 hours at 1280(DEGREES)C for the base PZT. Dielectric properties and piezoelectric coefficients varied only slightly within the optimum range of 0.25 to 1.0 w/o V(,2)O(,5) addition and were at least comparable to the base PZT. Indications are that accelerated densification is due to a combined surface activated-liquid phase mechanism. It was proposed that the V(,2)O(,5) becomes incorporated into the surface layers of the oxide powders during mixing or in the coprecipitation process. Upon heating, the V(,2)O(,5) reacts with the surface layers to form a low-melting vanadate phase and surfaces of high defect concentration, primarily in regions of particle-particle contacts. Rapid densification, by almost immediate particle rearrangement and pore removal, occurs with melting of the lead vanadate phase due to the large cohesive forces generated. The rate of densification is further increased by the enhancement of grain-boundary and/or bulk diffusion which are enhanced by the presence of a high defect concentration and reactive liquid phase at the grain contact areas.
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