Neutron and X-ray diffraction study of ferrite nanocrystals obtained by microwave-assisted growth. A structural comparison with the thermal synthetic route

Neutron and X-ray powder diffraction have been used to investigate the differences between the crystal growth of ferrite magnetic nanoparticles (MFe₂O₄ with M = Mn, Fe, Co, Ni, Zn) by two methodologies: microwave radiation and thermal decomposition routes. Rietveld refinement has been used to extract the cationic distribution, the microstructure and magnetic information. Results for the nanoparticles produced by the two procedures evidence similar cationic distribution, microstructure and magnetic properties: complete cationic disorder for M = Mn and Co, crystal size around/below 10 nm etc. It is thus proven that microwave-assisted growth is a promising eco-friendly synthetic technique for the generation of high-quality nanocrystals with comparable structure and properties to those produced by the thermal methodology, even though the microwave route needs a shorter time and lower annealing temperature to obtain the final crystal nanoparticles.

Computing details

Program(s) used to refine structure: FULLPROF.

Fe2O4Zn1

Crystal data

Fe2O4Zn	V = 590.80 (5) Å^3
Mr = 241.07	Z = 8
Cubic, Fd3m	Constant Wavelength Neutron Diffraction radiation
Hall symbol: -F 4vw 2vw 3	T = 300 K
a = 8.3910 (4) Å

Data collection

Radiation source: nuclear reactor

2θmin = 1.066°, 2θmax = 128.966°, 2θstep = 0.100°

Refinement

Rp = 0.939	χ^2 = NOT FOUND
Rwp = 1.198	1280 data points
Rexp = 0.814	23 parameters
RBragg = 0.995	0 restraints

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Fe1	0.12500	0.12500	0.12500	0.00887*	0.621 (16)
Zn1	0.12500	0.12500	0.12500	0.00887*	0.379 (16)
Fe2	0.50000	0.50000	0.50000	0.00887*	0.689 (8)
Zn	0.50000	0.50000	0.50000	0.00887*	0.311 (8)
O1	0.2535 (3)	0.2535 (3)	0.2535 (3)	0.00887*	0.99994

Geometric parameters (Å, º)

Fe1—O1	1.8676
O1—Fe1—O1^i	109.5

Symmetry code: (i) x, −y+1/4, −z+1/4.