Microstructure and dielectric properties of ion-doped La0.7Sr0.3MnO3 lossy ceramics at radio frequencies

Abstract

In this paper, the microstructure and dielectric properties of ion-doped La 0.7 Sr 0.3 MnO 3 are investigated in detail. The polycrystalline ceramics of La 0.7 Sr 0.3 Mn 1Ày M y O 3 (M ¼ Fe, Ni, Cu; y ¼ 0.3 or 0.5) are prepared by the sol-gel/sintering method. The symmetry of the crystal structure is improved and the dielectric properties obtained in the frequency range from 80 MHz to 1 GHz can be tuned by the doping of Fe, Ni, and Cu ions. With regard to the dielectric properties in lossy ceramics, the decrease of real permittivity 3 0 r for the doping of Fe and Ni will be effective for impedance-matching; the enhanced dielectric losses in the Ni and Cu doping samples will promote stronger absorption. Thus, the improved dielectric properties make ion-doped La 0.7 Sr 0.3 MnO 3 promising candidates for lossy ceramics in microwave electronics. In addition, the experimental results of permittivity were checked by K-K relations, and the frequency dispersion behaviors of the conductivity within a certain frequency range accord with the Jonscher's power law in the form of s 0 ac (f) f (2pf) n , demonstrating that the conductive mechanism is hopping conduction.

Experimental realization of tunable negative permittivity in percolative Fe78Si9B13/epoxy composites

“…4, the increasing of the Fe 78 Si 9 B 13 content results in the improvement of conductivity. It also can be found that the frequency dispersion behavior of the conductivity within a certain range of frequency, represents the Jonscher power law 22 in the form of s 0 ac (f) f (2pf) n with a different powerlaw index of n. The s 0 ac (f) exhibits a characteristic of plateau in the low-frequency region and a frequency dispersion in the high-frequency region with an onset frequency. The value of the exponent n for FSB71 and FSB76 is 0.39 and 0.20 respectively, shows that the conductive mechanism is hopping conduction.…”

Kondo-like electronic transport and ferromagnetic cluster-glass behavior in La0.7Sr0.3MnO3nanostructures

“…Among the doped perovskite manganites, La 1-x Sr x MnO 3 (0.17 ≤ x ≤ 0.33) system has received a lot of attention because of high Curie temperature (T c ), excellent metallic/magnetic behavior, nearly 100 % spin polarization etc. It became a model system for potential applications in terms of Spintronics, sensors, memories, and fuel cell types of devices [4][5][6][7][8] . This system coupled with recent advances in nanomaterials synthesis created new cognizance for materials science research.…”

“…It became a model system for potential applications in terms of spintronics, sensors, memories, and fuel cell types of devices. [4][5][6][7][8] This system coupled with recent advances in nanomaterials synthesis created new cognizance for materials science research. The most intriguing topics regarding the electrical and magnetic behavior of this system are nite size or low dimensionality effects.…”

Graphene–Epoxy Composites with High Dielectric Constant Prepared by Cryomilling

“…It was determined by the formula of σ' ac =d/RA, where d is the sample thickness and R is the resistance, A is the electrode plate area. [13] As it is possible to observe, GNPs can be considered one of the good fillers in increasing the electrical conductivity of the epoxy resin. The result shows that there is a better exponential relationship between electrical conductivity and frequency.…”