Crystal microstructure, infrared absorption, and microwave electromagnetic properties of (La1−x Dy x )2/3Sr1/3MnO3

Abstract

The manganite perovskite polycrystal samples of (La 1−x Dy x ) 2/3 Sr 1/3 MnO 3 (x = 0, 0.1, 0.2, 0.35, and 0.5) doped with Dy were prepared by solid state reaction in atmosphere to measure their X-ray diffraction (XRD) patterns, scanning electric microscope (SEM) images, infrared absorption spectra, and microwave electromagnetic properties. The displacement of the XRD peaks of the samples was found, and the 2θ increases from 0.05º to 0.5º. The grains of undoped La 2/3 Sr 1/3 MnO 3 not only have the greatest size, but also the most regular shape. The size of the grains decreases as the Dy doping content increases from 0 to 0.5. The infrared absorption spectra of all samples were measured at room temperature. An absorption peak corresponding to the stretching vibration mode of Mn−O bonds appears within the range of 591-629 cm −1 . The absorption peak shifts from a higher frequency to a lower one with the decrease of the average ionic radius of A-site. The frequency dependence of microwave-absorbing properties, imaginary components of the complex magnetic permeability μ" and dielectric permeability ε" for all samples was measured at room temperature from 8 to 13 GHz. The results show that the loss of microwave absorption can be attributed to both the magnetic and electric losses. The increase of Dy content not only enhances the microwave absorption but also causes the displacement of the absorption peaks.

Microstructure and microwave electromagnetic properties of Dy3+-doped W-type hexaferrites

“…For this reason, the replacement of rare earth (RE) ions that have unpaired 4f electrons and the strong spin-orbit coupling of the angular momentum for Ba 2+ ions (ion magnetic moment is 0) will improve M s of ferrite system. RE ions have been used to improve magnetic properties of spine, M-type ferrites, and W-ferrite [6][7][8][9][10]. It is reasoned that there is a relationship between magnetic properties and microwave-absorbing performance.…”