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Abstrak :
Information about magnetic structure can not be obtained through X ray diffraction method. Therefore data from neutron diffraction are needed to find out substance magnetic structure. From that structure, we can get information about magnetic crystal structure and magnetic momentum or the structure of the spin. The research is aimed to find out magnetic structure at CaMnO3 dan LaMnO3 in powder. The preparation of CaMnO3 and LaMnO3 substance is made through powder method and stoikiometric calculation. Basic substance of CaMnO3 is CaCO3 and MnO2, while basic substance of LaMnO3 is La2O3 and MnO2. After the substances are mixed, time varied milling, temperature varied sintering and annealing are conducted. It is hoped that the substances will be united or form a new phase. The magnetic structure study of CaMnO3 and LaMnO3 at this research are explained by neutron powder diffraction. CaMnO3 is good analisis at crystal system on orthorhombic space group Pnma with lattice parameter at 12 k is a = 5.2692 Å, b = 7.4403 Å, c = 5.2596 Å. LaMnO3 is good analisis at crystal system on monoklinik space group P1121/a with lattice parameter at 12 K is a = 5.4726 Å, b = 7.7613 Å, c = 5.5324 Å. Magnetic parameter Mn atomic has charge ordered of CaMnO3 and LaMnO3 is Mn4+ ion and Mn3+ ion. Result at research with High Resolution Powder Diffractometer, HRPD to find, CaMnO3 has properties magnetic at Mn atomic with indeks miller hkl (011) angle θ 2 = 24.486 on 12 K. LaMnO3 has properties magnetic at Mn atomic with indeks miller hkl (200) and angle θ 2 = 38.966°. Magnetic structure Mn atomic at 4b(0,0, 2 1 ) simetri of CaMnO3 is four possible nonkolinear ferromagnetic, with value magnetic momen is m(Mn) = 1.73 B µ . Magnetic structure Mn atomic of LaMnO3 at 2c(0,0, 2 1 ) is two possible (antiferomagnetik and ferromagnetic) and 2d( 2 1 , 2 1 ,0) simetri is two possible antiferromagnetic, with value magnetic momen is m(Mn) = 2.23 B µ .

Abstrak :
Penelitian tentang fenomena kemagnetan telah berkembang cukup pesat, seiring dengan pesatnya perkembangan penerapannya dalam Teknologi Informasi dan Komunikasi. Material yang akhir-akhir ini banyak diteliti oleh para ahli adalah material perovskite oksida manganite yang didop dengan tanah jarang La1-xCax MnO3 . Penelitian banyak dilakukan, didorong oleh ditemukannya fenomena-fenomena CMR, transisi semikonduktor-metal dan lain-lain. Riset ini bertujuan untuk meneliti struktur magnetik dari bahan La1-xCaxMnO3 (untuk x = 0,1 dan x = 0,5 ) dengan difraksi netron metode serbuk, menggunakan alat High Resolution Powder Diffractometer (HRPD). Riset dimulai dengan mencampur bahan-bahan dasar La2O3 , MnO2, CaCO3 , dengan perbandingan massa yang sesuai. Selanjutnya campuran bahan ditreatment melalui milling dan perlakuan panas . Tujuan milling dan pemanasan adalah untuk mempermudah dan mempercepat pembentukan fasa baru La1-xCax MnO3, serta menghilangkan impuritas. Untuk mengetahui terbentuknya fasa baru La1-xCaxMnO3, maka dilakukan karakterisasi dengan XRD dan dicocokkan dengan standar ICDD (International Center for Diffraction Data). Selanjutnya bahan dikarakterisasi dengan HRPD pada suhu diatas dan dibawah temperatur kritisnya (TC ≈ 270 K) untuk meneliti struktur magnetiknya. Data-data yang diperoleh dari karakterisasi dengan HRPD dianalisa dengan program Fullprof untuk mengetahui besar dan arah moment magnetik, disamping untuk mengetahui posisi atom, dan parameter kisi. Untuk La0.5Ca0.5MnO3, dari analisis dengan BasIreps diperoleh moment magnetik sebesar 0.5383 µB untuk k = ( ½ , 0 , ½ ) , dan 4,0069 µB. untuk k = ( 0,49 ; 0 ; 0 ) dengan empat kemungkinan struktur magnetik. Untuk La0.1Ca0.9 MnO3 diperoleh nilai moment magnetik untuk k = ( ½ , 0 , ½ ) adalah sebesar 0,3055 µB , dan untuk k = ( ¼ , 0 , ½) adalah sebesar 2,0151 µB , dan juga memiliki 4 kemungkinan struktur magnetik. ......Research about magnetic phenomena has been developed rapidly, since aplication of Information and Comunication Technology had been developed simultaneous. Recently, most of research materials were Oksida Manganite perovskite that had dopped with rare earth La1-xCax MnO3 . Many research have been done by scientist, motivated by discovery of many phenomenon like CMR, semiconductor ?metal transition, etc. The purpose of this research is to find a magnetic structure of La1-xCaxMnO3 material (for x = 0.1 and x = 0.5) with neutron difraction powder method, using High Resolution Powder Diffractometer (HRPD). This research start by mixing materials of La2O3 , MnO2, CaCO3 , with an appropriate mass composition. Furthermore, the materials were mixed by milling and heat treatment. The purpose of milling and heat treatment is to make easy and fast the establishment new phase La1-xCaxMnO3 , and to vanish impurity. To know the establishment of new phase La1-xCaxMnO3 , the samples characterized using XRD and agreed with ICDD (International Center for Diffraction Data) standard. Then the materials were characterized by HRPD (High Resolution Powder Diffractometer) both at upper and lower the critical temperature (TC ≈ 270 K) to investigate the magnetic structures. The data got from characterized by HRPD was analysed by Fullprof progam to study magnitude and direction of magnetic moment, as well as to study atomic position, and lattice parameter. From BasIreps analysis, the magnetic moment m(Mn) of La0.5Ca0.5MnO3 was 0.5383 µB for k = ( ½ , 0 , ½ ), and 4,0069 µB. for k = ( 0,49 ; 0 ; 0 ), with 4 magnetic structures probabilities. While the magnetic moment m (Mn) of La0.1Ca0.9MnO3 was 0,3055 µB for k = ( ½ , 0 , ½ ) , and and 2,0151 µB for k = ( ¼ , 0 , ½ ) with 4 magnetic structures posibilities too.