Effects on the dielectric and ferroelectric properties of an O2 atmosphere during sintering of Pb(Fe0.5Nb0.5)O3 ceramics

Abstract

Multifunctional materials such as the single phase compound Pb(Fe0.5Nb0.5)O3 (PFN), where ferroelectric and magnetic order coexist, are very promising and have great interest from the academic and technological points of view. However, as was established in previous work, the occurrence of Fe2+ and oxygen vacancies originated during the sintering process increase electrical conductivity, dielectric loss, and space-charge accumulation at the grain boundary, all of them detrimental to optimal device performance.1-3 Here, a report on the effects of an O2 atmosphere during the calcination and sintering stages of the preparation process using the traditional ceramic method is presented. A comparative study of structural, morphological and small signal dielectric frequency-temperature response study, where appropriate microstructural and equivalent circuit models were established using the impedance spectroscopy technique is presented. Big differences in the hysteret!ic behavior of the samples prepared in the presence and without the O2 atmosphere were observed and are discussed. The O2 atmosphere improves the dielectric and ferroelectric properties largely, in comparison with previous reports on PFN ceramics where other methods such as sintering in air, Pb atmospheres or fabricated from sol-gel-derived powders were used. 1 O. Raymond et al, J. Appl. Phys. 97, 084107 (2005). 2 O. Raymond et al. J. Appl. Phys. 97, 084108 (2005). 3 O. Raymond et al. J. Appl. Phys. 99, 124101 (2006). This work was partially supported by DGAPA-UNAM Project IN109305-3 and CoNaCyT Projects No. 47714-F and 49986-F. The authors thank E. Aparicio, P. Casillas, I. Gradilla, and J. Peralta for their technical assistance.