Fabrication of perovskite Pb(Fe1/2Nb1/2)O3and reaction mechanism

Abstract
A double-calcination process is proposed to eliminate the stable Lead-niobate pyrochlore phase presented during calcining Pb(Fe1/2Nb1/2)O3. Nearly pure perovskite Pb(Fe1/2Nb1/2)O3, could be obtained by doubly calcining the mixture of 4PbO/Fe2O3/Nb2O5 at temperature of 700°C and then 900°C for 2 hours, respectively. X-ray powder diffraction pattern of calcined sample is carefully analyzed to identify intermediate phases and sequence of reaction. The effect of double calcination on obtaining Pb(Fe1/2Nb1/2)O3 is based on the fact that nucleation of Pb(Fe1/2Nb1/2)O3 is accelerated by the appearance of Pb2Fe2O5. Possible reaction mechanism of Pb(Fe1/2Nb1/2)O3 at each different calcining cycle is also given.