Impact of strontium substitution on the structural, magnetic, dielectric and ferroelectric properties of [formula omitted](x = 0.0–0.8) hexaferrites

Abstract

Strontium substituted barium hexaferrites i.e., Ba1-xSrxFe11Cr1O19 with x = 0.0–0.8 were prepared via co-precipitation technique. Single-phase magnetoplumbite structure was confirmed for all samples by X-ray diffraction, whereas scanning electron microscopy showed the variation in microstructure on Sr2+ substitution. Magnetic measurements revealed that the substitution causes prominent enhancement in saturation magnetization and coercive field for x = 0.4 sample. However, under same condition, decrease in real part of dielectric permittivity, dielectric loss tangent and ac conductivity were observed by impedance spectroscopy, while these parameters started to increase for x > 0.4. The dielectric permittivity exhibited frequency-dependent dispersive behavior due to Maxwell-Wagner interfacial polarization whereas weak ferroelectric hysteresis loops were obtained for the prepared samples. Moreover, it was found that the Sr2+ substitution substantially enhanced the resistive properties which is elucidated in term of localization of charge carrier’s mobility due to reduction in Fe3+-O-Fe2+ network and microstructural variations. Here, it is proposed that x = 0.4 sample exhibits maximum magnetization (64 emu/g), moderate real part of dielectric permittivity at low frequency (>103), diminished dielectric loss tangent (~0.05) and colossal value of resistance (~1010 Ω) which makes this material interesting for high frequency applications.