Low‐Temperature Route to Lead Magnesium Niobate

Lead magnesium sniobate, Pb(Mg 1/3 Nb 2/3 )O 3 (PMN), was prepared by a sol‐gel technique using alkoxide precursors. The hydrolysis‐condensation mechanism leads to a translucent gel which is dried under hypercritical conditions to avoid collapse of the porous texture. After drying, the aerogel exhibits a B‐deficient pyrochlore structure which progressively inserts magnesium oxide when the temperature increases. Near 700°C, this pyrochlore phase completely transforms into the PMN‐perovskite phase. Above 1000°C, the loss of lead oxide leads to the destabilization of the PMN‐perovskite with formation of an A‐deficient pyrochlore phase.