Tiny cubes of magnetite form superstructures under a magnetic field
Scientists have been coaxing nano-sized cubes of magnetite (Fe3O4) into larger, more complex structures like helices without using a template by exposing them to a magnetic field.
A team led by Rafal Klajn at the Weizmann Institute of Science in Israel found that by varying the density of the cubes and the size and direction of the magnetic field they can control the kind of structure the cubes self-assemble into, which depends on the interplay between intermolecular forces and magnetic interactions. Under an increasing magnetic field the nanocubes line up to make a ‘belt’, while under a constant magnetic field at high density they curl round and form a helix. Single helices tend to clump together to make double helices (like the rope-like structure shown above) or even triple helices.
Although at the moment there is no obvious use for the structures, the team say they could have interesting magnetic properties. They are now exploring the effects of using other magnetic nanomaterials, such as nickel or iron nanoparticles, and decorating the nanocube surfaces with functional ligands to see what other shapes can be made.
Kwa mfano, magineti ya aina ya nanocrystalline (Fe3O4) hufanyiza muundo wa magineti (magnetite) kwa kutumia magnetol, na kwa kutumia magnetol, magineti ya aina ya nanocrystalline (Fe3O4) hufanyiza muundo wa maginiti (magnetol) kwa kutumia magnetol. Rafal Kline, mwanasayansi wa Israel, alisema kuwa kwa kubadilisha unene wa cubes na ukubwa na mwelekeo wa uwanja wa sumaku, wanaweza kudhibiti aina ya muundo wa cubes kujikusanya katika, ambayo inategemea mwingiliano kati ya nguvu za intermolecular na mwingiliano wa sumaku. Chini ya kuongezeka kwa uwanja wa sumaku nanocubes line up kufanya <unk> ukanda<unk>, wakati chini ya uwanja wa sumaku mara kwa mara katika wiani wa juu wao curl pande zote na kuunda helix. Helices moja huwa na clump pamoja kufanya helices mara mbili (kama muundo kamba-kama iliyoonyeshwa hapo juu) au hata helices mara tatu. Ingawa kwa sasa hakuna matumizi ya wazi kwa miundo hiyo, timu hiyo inasema inaweza kuwa na mali za kushangaza za sumaku. Sasa wanachunguza athari za kutumia nanomaterials nyingine za sumaku, kama vile nanoparticles za nikeli au chuma, na kupamba nyuso za nanocubes na ligands za kazi ili kuona ni aina gani nyingine za umbo zinaweza kufanywa.