Enhancement of ferro magnetic and dielectric prop erties in barium an d lanthanum dop ed nano powedrs BiFeO۳ by sol-gel synthesis

Multiferroic Bi۱-x.Bax.Fe۱-y.L ay.O۳ (x = ۰.۰, ۰.۰۵, ۰.۰۸, ۰.۱۲ an d ۰.۱۵) microparticles were succes sfully synthesized by a Solgel techn ique at the temperature as low as ۶ ۰۰ ºC.The obtained sol was transparent and ho mogenous w hen the mix ture ionic c oncentratio n was prope rly controll ed with the help of ethylene glycol alcohol. The prepa ration proce ss of crystalline BiFeO۳could be divided into three stages: (i) the evaporation of organics and decom position of nitrogenco ntaining org anics below ۲۰۰ ºC ; (ii) the collapse of BiF e gel network in the temperature range of ۲۰۰-۳۰۰ ºC and (iii) the form ation of BiFeO۳ nanopowders by the solidstate reaction between Fe۲ O۳ and Bi۲C O۳O۲.Multiferroic mat erials, which exhibit both ferroelectric and magnetic ordering, have attracted broad interests d ue to their potential ap plications for novel ma gnetoelectri c devices an d for exploring fundam ental science in the coupling mechanism betwe en electronic and magnetic order pa -rameters. S olgel proces s is widely used for preparing pure phase powd ers and thin films. In the sol-gel synthesis of BFO, the sol i s usually prepared based on citric acid route. In order to compensa te the evaporation loss of bismuth d uring postannealing pro cess, the exc ess bismuth source is u sually added to the solution. In the present paper, a simple solgel method based on ethylene alcohol is use d to prep are BFO nanop owders. The process fr om the sol t o the final inorganic materials is inve stigated in detail. A mi cromechanism for crysta llization of BFO gels is proposed.

کلیدواژه ها:

BiFeO۳ ، Nano P owedrs ، ferromagnetic ، dielectric ، sol-gel ، Barium doped ، Lanthanum doped.