Ordering Behavior of Lead Magnesium Niobate Ceramics with A‐Site Substitution

The ordering behavior of lanthanum‐modified lead magnesium niobate ceramics was investigated over a wide range of lanthanum content (from 0 to 50 at.%). The ordering of magnesium and niobium ions in the B site was examined by X‐ray diffraction, and the superlattice reflection was associated with the A(B′ 1/2 B″ 1/2 )O 3 ‐type partial ordering structure. Moreover, the ordering degree increased pronouncedly with respect to lanthanum content of the sample and almost reached unity at [La] = 50 at.%. Finally, a comparison of the ordering behavior was performed among several lead magnesium niobate (PMN) samples with different A‐site substitutional ions. The mechanism used to enhance the ordering of PMN by A‐site substitution is then described by the effect of high valence.