Study of dielectric relaxations in co-precipitated Sr–Fe(Cr) nanoferrites

Abstract

Chromium (Cr) doped strontium hexaferrites with nominal composition SrFe 12-x Cr x O 19 (x = 0.0, 0.1, 0.2, 0.3) were prepared using co-precipitation method. Thermal analysis of the samples was carried out using thermogravimetric analysis and differential scanning calorimetry to study the thermal stability as well as the transitions within the samples with variation in temperature. Structural analysis of the samples was carried out using X-ray diffraction (XRD). XRD revealed that all the samples possess hexagonal structure with space group P63/ mmc. AC electrical properties including dielectric constant (e 9), dielectric loss tangent (tan d) and ac electrical conductivity (r ac ) were studied as a function of frequency (1 kHz-3 MHz) at temperatures 100-700°C. The dielectric losses tend to decrease with increasing Cr content. AC conductivity could be very well explained by Jonscher power law. These materials have applications in high frequency devices with reduced energy losses.

Ferroelectric, Magnetic and Dielectric Properties of SrCo0.2Zn0.2Fe11.6O18.8 Hexaferrite Obtained by “One-Pot” Green Sol-Gel Synthesis Utilizing Citrus reticulata Peel Extract

“…This is similar to previous research on M-type strontium hexaferrites [50]. This type of behavior of the dielectric constant is in accordance with the Maxwell-Wagner type of interfacial polarization applied for heterogeneous systems [51,54]. In the lower frequency domain, the dielectric behavior is influenced by the heterogeneous system composed of grains and grain boundaries with different conducting properties [50].…”

“…The determined conductivity for SrCo 0.2 Zn 0.2 Fe 11.6 O 18.8 hexaferrite is shown in the inset in Figure 6b. It changes according to the Jonscher power law, being relatively constant in the lower frequency range and increasing with frequency increase as [53,54]:…”

Resistivity Enhancement of Sr-Hexaferrite Using Rare Earth Dopant to Minimize Energy Losses

“…5 showed AC Conductivity (σ ac ) of SrFe 12-x Gd x O 19 (x = 0.0, 0.1) as a function of frequency ranges from 20Hz to 3MHz at room temperature. The trend of the graphs can be explained using jump relaxation model and similar behavior is reported for undoped sample [14].…”

Electromagnetic Interference Shielding and Characterization of Ni2+ Substituted Cobalt Nanoferrites Prepared by Sol-Gel Auto Combustion Method

“…Te value of AC conductivity increases linearly with frequency for all the samples, which is the expected characteristic of ferrites Figure 13(c). It can be explained by Verwey's hopping mechanism [51], which states that electrical conductivity in ferrites is mostly caused by electron hopping between ions of the same element in more than one valence state [52]. Conductive grains become increasingly active at higher frequencies of the applied feld, also the conductivity increases due to an increase in the hopping frequency [53].…”