Ba [ ( Fe 0.9 Al 0.1 ) 0.5 Ta 0.5 ] O 3 ceramics with extended giant dielectric constant step and reduced dielectric loss

Abstract

Structure and dielectric characteristics of Ba[(Fe0.9Al0.1)0.5Ta0.5]O3 solid solution were investigated. The cubic crystal structure in space group Pm3¯m(221) was confirmed in the Al-substituted Ba(Fe0.5Ta0.5)O3 ceramics. The extended giant dielectric constant step and the significantly reduced room-temperature dielectric loss were obtained in the Al-substituted Ba(Fe0.5Ta0.5)O3 ceramics. These improvements of dielectric characteristics have great scientific significance for potential application of giant dielectric constant materials. XPS analysis results confirmed that the low-temperature dielectric relaxation originated from the mixed-valent structure of Fe2+/Fe3+ and the hopping of the charge carriers between them, and the improvements of dielectric characteristics in the Al-substituted Ba(Fe0.5Ta0.5)O3 ceramics were attributed to the modification of such mixed-valent structure of Fe2+/Fe3+.