DIELECTRIC PROPERTIES OF LEAD MAGNESIUM NIOBATE-LEAD TITANATE CERAMICS PREPARED BY MIXED-OXIDE METHOD

2009 ◽  
Vol 23 (03) ◽  
pp. 403-410 ◽  
Author(s):  
RATTIKORN YIMNIRUN
Keyword(s):  
Dielectric Properties ◽  
Mixed Oxide ◽  
Relaxor Ferroelectric ◽  
Lead Magnesium Niobate ◽  
Gradual Transition ◽  
Cubic Phase ◽  
Ferroelectric Behavior ◽  
Lead Magnesium ◽  
The Difference ◽  
Titanate Ceramics

In this study, the (1-x) Pb ( Mg 1/3 Nb 2/3) O 3-x PbTiO 3 (when x=0.1, 0.3 and 0.5) ceramics were prepared from PMN and PT powders by a mixed-oxide method. The dielectric properties of the ceramics were measured as functions of both temperature (-150–400°C) and frequency (100 Hz–1 MHz). The results indicated that the dielectric properties of pseudo-cubic phase 0.9PMN-0.1PT and tetragonal phase 0.5PMN-0.5PT ceramics followed that of relaxor and normal ferroelectric behaviors, respectively, while the dielectric behaviors of a near MPB phase 0.7PMN-0.3PT ceramic showed a mixture of normal and relaxor ferroelectric behaviors. In addition, the Curie temperature (TC) increased with increasing PT contents, while the diffusivity decreased. This confirmed a gradual transition from a relaxor ferroelectric behavior in 0.9PMN-0.1PT to a normal ferroelectric behavior in 0.5PMN-0.5PT. The difference in dielectric behaviors was attributed to the structural symmetry of the ceramics.

Chemical reactions of lead magnesium niobate titanate in the presence of a glass

1991 ◽  
Vol 6 (6) ◽  
pp. 1308-1323 ◽  
Author(s):  
V. Srikanth ◽  
E.C. Subbarao
Keyword(s):  
Phase Composition ◽  
Dielectric Properties ◽  
Perovskite Phase ◽  
Relaxor Ferroelectric ◽  
Lead Magnesium Niobate ◽  
Relaxor Behavior ◽  
Glass Addition ◽  
Pure Perovskite Phase ◽  
Lead Magnesium ◽  
Sealing Glass

A relaxor ferroelectric of composition 0.93Pb(Mg1/3Nb2/3)O3-0.07PbTiO3 was sintered with 3 wt.% commercial sealing glass at 750 °C for 30 min to achieve ≥95% of theoretical density and a nearly pure perovskite phase. At higher glass additions (up to 20 wt.%), higher sintering temperatures (up to 800 °C), and longer sintering times (up to 4 h), the amount of perovskite (PMN type) decreases and that of pyrochlore (6PbO · MgO · 3Nb2O5 or 3PbO · 2Nb2O5) increases. On sintering at 800 °C for 4 h no perovskite phase is present in compositions with even 1% glass addition. The reaction of glass with the PMN phase was found to lead to the disappearance of the perovskite. Addition of 0.1 to 0.6 wt.% MgO to compositions containing 1 and 3 wt.% glass (and balance PMN-PT) results in essentially pure PMN perovskite phase on sintering at 700–800 °C for 30–240 min, confirming that the reaction of glass with PMN and depletion of MgO from PMN can be arrested. The sintered ceramics exhibit relaxor behavior and possess dielectric properties essentially commensurate with the phase composition.

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