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Abstract
Pb(Mg 1/3 Nb 2/3 )O 3 ceramics prepared via columbite method by using two types of Mg precursors, i.e. MgO and (MgCO 3 ) 4 ·Mg(OH) 2 ·4H 2 O exhibit high crystallinity and high densification after sintering at 1200°C. Higher amounts of pyrochlore phases were detected in the PMN sample obtained by using (MgCO 3 ) 4 · Mg(OH) 2 .4H 2 O as precursor. This compositional difference, determines, for all frequencies, a shift of ∼ 50 K of the temperature corresponding to the permittivity maximum T m for the sample derived from (MgCO 3 ) 4 ·Mg(OH) 2 ·4H 2 O. From this reason, better dielectric properties were obtained at room temperature for this PMN sample, although a higher dielectric permittivity at T m was obtained for the sample derived from MgO precursor.
Acknowledgments
This work was supported by the Romanian grant CEEX – FEROCER (2006–2008).