Stabilization of perovskite phase and dielectric properties of Pb(Zn, Mg)_1/3Nb_2/3O₃-PbTiO₃ ceramics prepared by excess constituent oxides

Abstract

The perovskite phase in PZN-PMN-PT pseudoternary ceramics was stabilized by the addition of excess constituent divalent oxides (PbO, MgO, and ZnO). 5 mol % excess MgO or 7.5 mol % excess PbO was sufficient to eliminate the remnant cubic pyrochlore phase after sintering at 1100 C C for 1 h. The enhanced diffuse phase transition (DPT) and the decrease in the electrical resistivity were observed in the presence of excess ZnO or MgO. These were interpreted in terms of the additional formation of negatively charged, short-range ordered 1:1 domains with a concomitant generation of charge carriers (holes). The behavior of excess MgO or ZnO at concentrations above 5 mol % was studied by examining complex impedance patterns.

Progress in synthesis of ferroelectric ceramic materials via high-energy mechanochemical technique

“…The electrical properties of relaxor ferroelectrics can be significantly modified using multi-component compositions [163,164]. Representative ternary systems prepared by the high-energy mechanochemical process are 0.54PZN-0.36PMN-0.1PT and 0.48PFN-0.36PFW-0.16PZN, reported by Wang's group [131,[165][166][167][168].…”

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

“…PbO volatilization is the main occurrence factor when the pyrochlore amount increases in PMN powders, and in this way, many artifices can be used to avoid the formation of the pyrochlore phase [12][13][14]. PbO excess is one of them, because it aims to compensate PbO volatilization during heat treatment [15][16][17].…”

“…The role of PbO excess on the general characteristics of PMN powders is not clear and some authors reported only indirect effects on PMN bulk ceramics, as variations of the dielectric properties and microstructure [14][15][16]. However, an improvement or impoverishment of the final properties depends much more directly on the processing, firing conditions and apparatus used in sintering stage, making the use of PbO excess a secondary controller parameter and less important [18].…”

Microstructures and electrical properties of lead zinc niobate–lead titanate–lead zirconate ceramics using microwave sintering

“…It was reported that PbO might segregate to form the amorphous layer or second phases. [35][36][37] Fig. 8 and Table 2 display the corresponding EDS spectra of the CS and MW specimens.…”

“…This result indicates that higher dielectric constant of the grain boundary phase may not be that detrimental to dielectric properties in PZN-base materials, comparing with other lead-based systems with excess lead oxide addition. 35,36,42 More importantly, microwave sintering reduces the PbO/ZnO evaporation and segregation effectively, and therefore greatly enhances reliability of the material processing and material properties. The results imply potential applications of microwave sintering in future devices and materials processing for material systems with high vapor pressure.…”