La0.7Sr0.3MnO3의 합성, 특성 평가 및 전자기파 흡수 특성 (Synthesis, Characterization, and Electromagnetic Wave Absorbing Properties of La0.7Sr0.3MnO3)

서지정보

· 발행기관 : 대한금속·재료학회
· 수록지 정보 : 대한금속·재료학회지 / 61권 / 3호 / 183 ~ 189페이지
· 저자명 : 허재희, 강영민

초록

Perovskite manganese La0.7Sr0.3MnO3 (LSMO) powders were prepared by sol-gel synthesis andcalcination in the temperature (T) range of 500~1200 oC and their structures and electromagnetic (EM)wave absorption properties were investigated. X-ray diffraction (XRD) analysis revealed that thecrystalline perovskite phase can be formed at T ≥ 600 oC. The average grain size was ~15 nm at thecalcination temperature (Tcal) = 600 oC and it increased to ~1 μm when Tcal increased up to 1200 oC. MHcurves of the samples showed soft magnetic behaviors for all the crystallized samples, and the valueof saturation magnetization increased with increasing Tcal. The real and imaginary parts of permittivitiesand permeabilities were measured on LSMO powder-epoxy (10 wt%) composites using a network vectoranalyzer in the frequency range of 100 MHz ≤ f ≤ 18GHz. The complex permittivities (ε', ε") increasedsignificantly in samples calcined above 800 oC because the concentration of free electrons increased, dueto the LSMO's unique magnetotransport effect, as the crystallinity and the MS value increasedsignificantly. As the Tcal increased, the height of the μ' and μ" spectra also gradually increased. The largevalues of ε', ε" of the LSMO-epoxy are dominant factors in the EM wave absorption characteristics, andit showed good absorption characteristics when it had a thickness of 1.5 mm or less at a frequency of 12GHz or higher. At the same time, it also exhibited EM wave shielding ability by reflection in the severalGHz band.

영어초록

Perovskite manganese La0.7Sr0.3MnO3 (LSMO) powders were prepared by sol-gel synthesis andcalcination in the temperature (T) range of 500~1200 oC and their structures and electromagnetic (EM)wave absorption properties were investigated. X-ray diffraction (XRD) analysis revealed that thecrystalline perovskite phase can be formed at T ≥ 600 oC. The average grain size was ~15 nm at thecalcination temperature (Tcal) = 600 oC and it increased to ~1 μm when Tcal increased up to 1200 oC. MHcurves of the samples showed soft magnetic behaviors for all the crystallized samples, and the valueof saturation magnetization increased with increasing Tcal. The real and imaginary parts of permittivitiesand permeabilities were measured on LSMO powder-epoxy (10 wt%) composites using a network vectoranalyzer in the frequency range of 100 MHz ≤ f ≤ 18GHz. The complex permittivities (ε', ε") increasedsignificantly in samples calcined above 800 oC because the concentration of free electrons increased, dueto the LSMO's unique magnetotransport effect, as the crystallinity and the MS value increasedsignificantly. As the Tcal increased, the height of the μ' and μ" spectra also gradually increased. The largevalues of ε', ε" of the LSMO-epoxy are dominant factors in the EM wave absorption characteristics, andit showed good absorption characteristics when it had a thickness of 1.5 mm or less at a frequency of 12GHz or higher. At the same time, it also exhibited EM wave shielding ability by reflection in the severalGHz band.

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