Nanoplasmonics and surface enhanced spectroscopy

Prospective materials based on nickel ferrites
S.M. Lesik1, I.M. Ivanenko1, A.O. Perecos2
1 National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute" 03056, Kyiv, 37 pr. Pеremohy, 4 building, irinaivanenko@hotmail.com
2 G.V. Kurdyumov Institute for Metal Physics, N.A.S. of Ukraine, 03142 Kyiv, 36 Academician Vernadsky Boulevard

Spinel ferrites are important magnetic materials through their magnetic and electrical properties, high chemical and thermal resistance. These materials are technologically important and have found application in many industries such as: media, catalysis, medicine, sensors, pigments, magnetic liquid, and others.
NiFe2O4 is widely used in electrical devices owing to their high permeability at high frequencies, high electrical conductivity, mechanical strength and chemical resistance. It is relatively cheap material with all these benefits. Their properties depend on the shape and size of the particles. 
To obtain the Nickel ferrites are using different methods of synthesis: coprecipitation, sol-gel, hydrothermal, micro-emulsion, mechanical, microwave combustion and others.

(a)	(b)	
Fig 1. Schematic (a) and simulated (b) structure of ferrites [1].	

Nickel ferrite is an inverse spinel in which the unit cell consists of 8 atoms of molecules NiFe2O4. Half of the iron ions occupy tetrahedron plot (A-side) and the other – octahedral (B-side). It can be represented by formula (Fe3+)A(Ni2+Fe3+)BO4, where A and B represent tetrahedron and octahedral sites, respectively.
1.	Perron H., Mellier T., Domain C., Roques J., Simoni E., Drot R., Catalette H. Structural investigation and electronic properties of the nickel ferrite NiFe2O4: a periodic density functional theory approach // J. Phys.: Condens. Matter.- 2007.- Vol.19.-№34.-P. 346219. doi:10.1088/0953-8984/19/34/346219