The Laser Furnace(LF)method has been applied to directionally solidify NiFe_(2)O_(4)spinel disks from a mixture of Fe and Ni oxides in order to obtain uniform,dense targets for controlled synthesis of spinel nanoparti...The Laser Furnace(LF)method has been applied to directionally solidify NiFe_(2)O_(4)spinel disks from a mixture of Fe and Ni oxides in order to obtain uniform,dense targets for controlled synthesis of spinel nanoparticles via Laser Ablation.Application of a CO2 laser in Line Scan mode onto a sample with the desired stoichiometry,enabled melt processing above 1580C at its outer surface layer.This process was carried out inside a continuous roller furnace at a maximum volume temperature of 1000C.Such combination helps avoid excessive thermal stress,crack formation and catastrophic failure of these magnetic ceramic monoliths.Higher energy incubation values yield increased molten volumes and a thicker resolidified surface layer with a dense microstructure.Despite the high solidification rates imposed,NiFe2O4 spinel is the main phase obtained according to X-Ray Diffraction(XRD)and magnetization studies.LF processed samples exhibit a reduction of the coercive fields and an increase of the saturation magnetization values,evidence for soft ferromagnetism and characteristic of the magnetic behaviour associated with this spinel.This work demonstrates the convenience of the LF method for preparation of uniform,dense targets for Laser Ablation and other evaporation based techniques used in the fabrication of nanoparticles.展开更多
基金The authors acknowledge financial support from MINECO-AEIFEDER,EU(projects MAT2016-79866-R and ENE2017-83669-C4-1-R)SPRINT(EU H2020-FET-OPEN/0426)projects and from Gobierno de Aragon“Construyendo Europa desde Aragon”(research group T54_17R).
文摘The Laser Furnace(LF)method has been applied to directionally solidify NiFe_(2)O_(4)spinel disks from a mixture of Fe and Ni oxides in order to obtain uniform,dense targets for controlled synthesis of spinel nanoparticles via Laser Ablation.Application of a CO2 laser in Line Scan mode onto a sample with the desired stoichiometry,enabled melt processing above 1580C at its outer surface layer.This process was carried out inside a continuous roller furnace at a maximum volume temperature of 1000C.Such combination helps avoid excessive thermal stress,crack formation and catastrophic failure of these magnetic ceramic monoliths.Higher energy incubation values yield increased molten volumes and a thicker resolidified surface layer with a dense microstructure.Despite the high solidification rates imposed,NiFe2O4 spinel is the main phase obtained according to X-Ray Diffraction(XRD)and magnetization studies.LF processed samples exhibit a reduction of the coercive fields and an increase of the saturation magnetization values,evidence for soft ferromagnetism and characteristic of the magnetic behaviour associated with this spinel.This work demonstrates the convenience of the LF method for preparation of uniform,dense targets for Laser Ablation and other evaporation based techniques used in the fabrication of nanoparticles.
