| Description |
xi, 91 leaves : illustrations ; 29 cm |
| Summary |
"It is well known that perovskite lead magnesium niobate (PMN) must undergo unusual processing techniques to be reproducibly synthesized. This research successfully used the Columbite precursor method to produce 98% pyrochlore-free perovskite PMN. Annealing of the samples to eliminate excess lead oxide from the grain boundary was rendered unnecessary when powders were properly dispersed and filtered. Thus, it was unnecessary to add excess PbO to achieve high density PMN with superior electrical properties. An excess of 0.5 wt% MgO was added to all compositions to reduce pyrochlore formation, to improve densification, and to improve electrical properties. Lead titanate (PT) was added to the PMN compositions in amounts ranging from 11 to 14 mole%. These additions resulted in improvement in both dielectric and pyroelectric properties. The temperature where the maximum dielectric constant occurred also increased, corresponding to an upward shift in the phase transition, while dielectric losses were unaffected. Improvements were also seen in the remnant polarization and maximum pyroelectric coefficient. Additions of lead tungstate (PW) were also studied in two of the PMN-PT solid solutions. These samples showed lower values of the maximum dielectric constant, as well as lower temperatures of this maximum. Likewise, remnant polarization and maximum pyroelectric coefficient decreased"--Abstract, leaf iii. |
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