Effect of PbO excess on the formation of lead magnesium niobate perovskite by the columbite method

Abstract

The effect of lead excess on the pyrochlore-type formation in Pb(Mg 1/3 Nb 2/3 )O 3 (PMN) powders has been investigated. The polymeric precursor method was used in the synthesis of the columbite in association to the partial oxalate method to synthesize the PMN powder samples. Structure refinement of the columbite precursor and PMN powders was carried out using the Rietveld method. The quantitative phase analysis showed that the amount of perovskite phase is not affected by PbO excess, but a great excess drives the pyrochlore-type formation so that 3 wt.% of PbO causes the predominance of Mg-containing pyrochlore phase. Using the refined data obtained from the Rietveld refinement, the compositional fluctuation in the perovskite phase was calculated from Nb/Mg ratio values and Pb occupation factor. Mg inclusion occurs concomitant with Pb one into PMN perovskite phase and this effect is directed by PbO excess during powder synthesis.

Effect of cadmium doping on electrical properties of lead nickel niobate–lead zirconate titanate [Pb1.0(Ni0.167Nb0.333Zr0.155Ti0.345)O3] ceramics

“…In the present case, the pyrochlore phase appeared due to the excess PbO added during the synthesis process. Similar phases due to excess PbO have been observed in the earlier reported work on PNN-PZT [20] and PMN perovskite [26]. However, in our earlier work [27], we have reported 100% perovskite phase content in 0.5PNN(1/3)-0.5PZT, whereas for other compositions the perovskite phase content decreases.…”

Study of microstructure and dielectric properties of PMN–PZT ceramics via a mixed powder method including sol–gel precursor

“…activation [7,8] or sol-gel [9][10][11] methods. Synthesis of single phase PMN requires more specified processing routes, such as columbite route [12][13][14][15], mechanical activation process [16][17][18], reaction sintering process [19][20][21] and sol-gel method [22,23]. There are also more routes proposed by other authors for PMN-PZT production such as mixed oxide method [24], columbite or corundum routes [25] and wet chemical routes [26,27].…”

Synthesis of pyrochlore free PMN–PZT ceramics via a seeding method

“…The PZT single-phase ceramics can be synthesized by solid state [6], mechanical activation [7,8] or sol-gel [9][10][11] methods. With respect to the PMN powder, the processing routes for single-phase PMN production will limit the more specific routes, which are columbite route [12][13][14][15], mechanical activation process [16][17][18], reaction sintering process [19][20][21] and sol-gel method [22,23].…”