Synthesis of lithium ferrites from polymetallic carboxylates

Lithium ferrite was prepared by the thermal decomposition of three polynuclear complex compounds containing as ligands the anions of malic, tartaric and gluconic acid: (NH4)2[Fe2.5Li0.5(C4H4O5)3(OH)4(H2O)2]?4H2O (I), (NH4)6[Fe2.5Li0.5(C4H4O6)3(OH)8]?2H2O (II) and (NH4)2[Fe2.5Li0.5(C6H11O7)3(OH)7] (III). The polynuclear complex precursors were characterized by chemical analysis, IR and UV-Vis spectra, magnetic measurements and thermal analysis. The obtained lithium ferrites were characterized by XRD, scanning electron microscopy, IR spectra and magnetic measurements. The single a-Li0.5Fe2.5O4 phase was obtained by thermal decomposition of the tartarate complex annealed at 700?C for 1 h. The magnetization value ? 50 emu g-1 is lower than that obtained for the bulk lithium ferrite due to the nanostructural character of the ferrite. The particle size was smaller than 100 nm. Litijum-ferit je dobijen termickom razgradnjom tri polinuklearna kompleksna jedinjenja koja kao ligande sadrze anjone maleinske, vinske i glukonske kiseline: (NH4)2[Fe2.5Li0.5(C4H4O5)3(OH)4(H2O)2]?4H2O (I), (NH4)6[Fe2.5Li0.5(C4H4O6)3(OH)8]?2H2O (II) i (NH4)2[Fe2.5Li0.5(C6H11O7)3(OH)7] (III). Polinuklerna kompleksna polazna jedinjenja okarakterisana su hemijskom analizom, IR i UV-Vis spektrima, magnetnim merenjima i termogravimetrijskom analizom. Dobijeni litijum-ferit okarakterisan je metodama difrakcije x-zraka i skenirajuce elektronske mikroskopije, kao i IR spektrima i magnetnim merenjima. Registrovano je da je dobijena jedino a-Li0.5Fe2.5O4 faza termickom razgradnjom tartaratnog kompleksa na temperaturi 700?C tokom 1 h. Vrednost magnetizacije od oko 50 emu g-1 manja je od one dobijene za kompaktni litijum-ferit zbog nanostrukturnih karakteristika sintetisanog ferita. Velicina cestica manja je od 100 nm.