Sintesis Bahan Magnet BaFe12-2xMgxAlxO19 (x=0-0.5%mol) Berbasis Bahan Baku Komersil dan Pasir Besi Alam Sumatera Barat untuk Material Penyerap Gelombang Mikro

Abstract

Barium hexa-ferrite (BaFe12O19) is hard magnetic materials, which is based on iron oxide. The synthesis of BaFe12-2xMgxAlxO19 of magnetic materials for microwave absorption has been done using the solid state reaction and co-presipitation methods for absorbing microwave. Mixing and milling processes of BaFe12O19 MgO, Al2O3 was held using wet High Energy Milling (HEM). The pollen of BaCl2, FeCl3, MgCl2, AlCl3 and natural iron sand from Sumatera Barat Province, Indonesia were mixed and precipitated by using of NaOH 4M. Sintering process was done at 1200ºC for 2 hours for solid state reaction. Calcination proscess was done at 900, 1050, and 1200ºC for 2 hours for co-precipitation method. The effect of %mol dopant and calcination temperature on the structure, morphology and magnetic characteristic was characterisized by using XRD, SEM-EDS, FE-SEM, VSM and VNA. The effect of ions Mg and Al addition was not change the M-hexagonal structure of barium hexaferrite. The Mg and Al ions have been substituted by Fe ion in barium hexaferrite system which is indicated by change of lattice parameters. Besides that, the substitution decreases saturation (Ms), remanence (Mr) and energy product (BHmax) values, but increases coercivity (Hc). Optimum condition was obtained on x=0.1 %mol (Tc = 1050oC) with Ms = 44.75 emu/g, Mr = 21.86 emu/g, Hc = 2358 kOe, dan BHmax = 73558 GOe. Moreover, the value of the maximum reflection loss is -70.14 dB at frequency of 10.8 GHz and microwave absorption as much as 99.99%.

Barium hexa-ferrite (BaFe12O19) merupakan material magnet permanent yang mengandung besi oksida. Telah dilakukan sintesis serbuk BaFe12-2xMgxAlxO19 untuk aplikasi material microwave absorber dengan metode solid state reaction dan metode co-presipitasi. BaFe12O19 teknis, MgO, Al2O3 dimilling dan dikeringkan menjadi serbuk BaFe12O19. BaCl2, FeCl3, pasir besi alam dari Sumatera Barat, MgCl2 dan AlCl3 dicampur dan diendapkan dengan menggunakan presipitan larutan NaOH 4M. Selanjutnya dilakukan proses sinter pada suhu 1200ºC selama 2 jam untuk metode solid state reaction. Proses kalsinasi pada suhu 900oC, 1050oC, dan 1200oC selama 2 jam untuk metode co-presipitasi. Pengaruh dari doping dan suhu kalsinasi pada struktur, morfologi dan sifat magnet dikarakterisasi menggunakan XRD, SEM-EDX, VSM, dan VNA. Efek penambahan ion Mg2+ dan Al3+ tidak mengubah struktur kristal barium heksaferrite. Perubahan parameter kisi mengindikasikan telah terjadi subsitusi ion ion Mg2+ dan Al3+ terhadap ion Fe3+. Analisis sifat magnetik menunjukkan terjadi penurunan nilai saturasi (Ms), remanence (Mr) dan energy product (BHmax) tetapi meningkatkan nilai koersivitas (Hc). Kondisi optimum diperoleh pada sampel dengan komposisi x= 0.1 %mol di suhu kalsinasi 1050oC dengan Ms = 44.75 emu/g, Mr = 21.86 emu/g, Hc = 2358 kOe, dan BHmax = 73558 GOe. Selain itu, nilai reflection loss maksimum diperoleh sebesar -70.14 dB pada frekuensi 10,8 GHz dan absorbsi gelombang mikro sebesar 99,99%.