纯钙钛矿相PMN-PT的改进铌铁矿法合成

ynthesis of Pure Perovskite Phase PMN-PT by Modified Columbite Precursor Method

以碱式碳酸镁代替氧化镁,在1 100℃×6 h条件下合成出纯的铌铁矿相,从而避免了第二步预烧过程中焦绿石相的形成。以碱式碳酸铅代替氧化铅,在650-1 150℃不同温度下预烧2 h后的XRD相组成分析表明:预烧粉体主相为钙钛矿相的PMN-PT,随预烧温度提高,PMN-PT固溶体不断形成,同时PbO发生四方相-正交相转变,但均未出现焦绿石相。因此,该工艺特别适合在需要过量PbO来实现低温烧结制备PMN-PT陶瓷的情况。

Using MgCO3 · Mg （ OH）2 · 4H2O instead of MgO, the pure columbite phase is synthesized at 1100oC for 6 hrs, consequently the formation of pyrochlore phase is avoided in the second step calcinations process. Using （ PbCO3 ）2 · Pb （OH）2 instead of PbO, the X - ray diffraction analysis is investigated for the precursor powders calcined at 650 - 1150oC for 2 hrs, the result shows that the main phase composition of the precursor powders is perovskite PMN -PT, and the PMN - PT solid solutions are continuously formed with the calcined temperature elevation, at the same time the tetragonal PbO phase is transformed in orthogonal PbO phase, whereas the pyroehlore phase does not arise in all calcined powders. Therefore, this synthesis technology of PMN - PT using （PbCO3 ）2 · Pb （OH）2 is especially adapted to the condition of low temperature sintering of PMN -PT ceramics by using excess PbO as sintering aids.