Design And Synthesis Of Absorbents Based On LaMnO₃ And Their Microwave Absorbing Property

In this paper,citric acid-assisted sol-gel route method was adopted to synthesize relevant La MnO₃-based microwave absorbing agent.The LaOCl/C,LaOCl/C/MnO composites and LaMnO₃ compounds were prepared by using different reagents and different heat treatment environments.The microstructure and microwave absorption properties of the samples were analyzed by X-ray diffractometer,scanning electron microscope,Raman spectrometer and vector network analyzer.The study shows that different metal salts and heat treatment environment have different influence on the structure and properties of the products.1.The experimental product was LaOCl/C composite while the metal salt used was only lanthanum chloride,the experimental product was La OCl/C/MnO composite while the metal salt used was lanthanum nitrate and manganese chloride.The heat treatment environment of the above-mentioned both products were under the condition of tubular furnace in the air atmosphere.The average grain size of the two samples was21nm and 24nm.The carbon component presence in the as-prepared samples were confirmed by Raman spectram,and the contribution of the carbon component to the two samples was similar.The average particle sizes of the two samples were about 20-80nm and 26-70nm respectively.The analysis of absorbing performance indicates that:the band range with reflection loss below-10dB of LaOCl/C/MnO is 2.2-14.2GHz,corresponding thickness is 2-7.5mm.The optimum reflection loss of LaOCl/C/MnO is acquired-49dB at 9.5GHz,and the corresponding thickness is 2.4mm,which is better than that of LaOCl/C composite material.The good absorbing properties can be attributed to the function of MnO with good dielectric properties.2.The experimental product was LaMnO₃ while the metal salts used were lanthanum nitrate and manganese nitrate and the heat treatment environment is a fully air-filled electric furnace,compound.It can be seen from SEM that the particle size of samples obtained through sintering is about 92nm,108nm and 160nm respectively.All three samples show excellent microwave absorption characteristics,and the effective band width of RL<-10dB is 2-18GHz,and the matching thickness is 1-5.5mm.The best reflection losses of the samples after three different heat treatment were-21.8dB at4.8GHz,-18.3dB at 7.6GHz,and-24.0dB at 8.0GHz.Studies have shown that the LaOCl/C/MnO and LaMnO₃ nanomaterials synthesized in this paper have good absorbability,and they are the microwave absorbing material with development prospect.