Synthesis of chromium-nickel nanoparticles prepared by a microemulsion method and mechanical milling

A chemical and a physical method have been applied for the preparation of chromium-nickel alloy nanoparticles. These particles were designed to be used for controlled magnetic hyperthermia applications. Microemulsions with $Ni^{2+}$ and $Cr^{3+}$ and/or $NaBH_4$ as precursors were prepared using the isooctane/CTAB, n-butanol/$H_2O$ system. The samples of $Cr_xNi_{1-x}$ nanoparticles with the desired composition were obtained after the reduction of their salts with $NaBH_4$ and afterwards heat treated in a TGA in a $N_2$ atmosphere at various temperatures. The $Cr_xNi_{1-x}$ materials were also prepared by mechanical milling. Utilizing a ball-to-powder mass ratio of 20 : 1 and selecting the proper alloy compositions we were able to obtain nanocrystalline $Cr_xNi_{1-x}$ particles. Thermal demagnetization in the vicinity of the Curie temperature of the nanoparticles was studied using a modified TGA-SDTA method. The alloyʼs phase composition, size and morphology were determined with XRD measurements and TEManalyses.Za pripravo nanodelcev zlitine $Cr_xNi_{1-x}$ smo uporabili kemijsko in fizikalno metodo. Delci so namenjeni uporabi v biomedicini, zlasti na področju kontrolirane magnetne hipertermije. Najprej smo pripravili mikroemulzije z $Ni^{2+}$, $Cr^{3+}$ in/ali $NaBH_4$ prekurzorji v sistemu izooktan/CTAB, n-butanol/$H_2O$. Vzorce $Cr_xNi_{1-x}$ nanodelcev z željeno sestavo smo dobili po redukciji njihovih soli z $NaBH_4$ in naknadnem segrevanju v TGA v atmosferi $N_2$ pri različnih temperaturah. Nanodelce $Cr_xNi_{1-x}$ smo sintetizirali tudi s pomočjo mehanskega mletja zmesi kromovih in nikljevih prahov. Mleli smo v visokoenergijskem krogličnem mlinu SPEX 8000M. Z uporabo primernega masnega razmerja med mlevnimi kroglicami in prahom 20:1 in izbiro primerne sestave smo dobili nanodelce zlitine $Cr_xNi_{1-x}$. Curiejevo temperaturo nanodelcev smo določili z uporabo modificirane TGA-SDTA metode. Sestavo nanozlitine, velikost in morfologijo delcev smo določili s pomočjo meritev XRD in TEM analize