RESEARCH PAPER Raman study of cations’ distribution in Zn x Mg 12x Fe 2 O 4 nanoparticles S. W. da Silva • F. Nakagomi • M. S. Silva • A. Franco Jr • V. K. Garg • A. C. Oliveira • P. C. Morais Received: 19 September 2011 / Accepted: 25 February 2012 Ó Springer Science+Business Media B.V. 2012 Abstract In a complementary way, Raman and Mo ¨ssbauer spectroscopy were successfully employed to assess the cations’ distribution among the tetrahe- dral (A-site) and octahedral (B-site) sites of nonosized Zn x Mg 1-x Fe 2 O 4 (0 B x B 1) cubic ferrite structure, synthesized by combustion reaction method. Nano- particles with little change in size distributions, in the 40 nm (x = 0.0) up to 42 nm (x = 1.0) were obtained. Mo ¨ssbauer data indicated that as the Zn- content (x) increases in the range 0 B x B 1, the Fe 3? ion monotonically increases (decreases) the A-site (B-site) occupancy up to nearly equal values at the highest end x value. Analysis of the Raman data, however, confirms that the three highest energy modes around 650, 668 and 710 cm -1 are assigned to Zn–O (B-site), Fe–O (A-site) and Mg–O (A-site) vibrations, respectively. Additionally, in agreement with the Mo ¨ssbauer data, the Raman data show that as the Zn-content (x) increases in the range 0 B x B 1, the occupancy of A-sites by Mg 2? ions monotonically reduces with concomitant increase of A- and B-sites occupancy by Fe 3? and Zn 2? ions, respectively. Indeed, combination of the two sets of spectroscopic data (Raman and Mo ¨ssbauer) provides an effective protocol for assessing the cations’ distribution within the crystal structure of nanosized quaternary cubic ferrite samples running for instance from Fe 3þ 0:42 Â Mg 2þ 0:58  A Zn 2þ 0:20 Mg 2þ 0:22 Fe 3þ 1:58 Â Ã B O 2 4 at x = 0.2 up to Fe 3þ 1:0 Â Ã A Zn 2þ 0:60 Mg 2þ 0:40 Fe 3þ 1:0 Â Ã B O 2 4 at x = 0.6. Keywords Raman spectroscopy  Cubic ferrite  Magnetic nanoparticles  Cation’ distribution  Mo ¨ssbauer spectroscopy Introduction The crystal structure of cubic ferrites (MFe 2 O 4 ; M = Fe, Co, Ni, Mn, Mg, Zn,) consist of a face centered cubic (fcc) lattice of oxygen anions within which cations (Fe 3? and M 2? ) occupy tetrahedral (A-sites) and octahedral (B-sites) interstitial sites arranged in two possible extreme patterns: normal and inverse. In the normal cubic ferrite structure, the A-sites are occupied exclusively by M 2? cations while the B-sites are occupied exclusively by Fe 3? cations. In bulk form ZnFe 2 O 4 is a typical normal-like cubic ferrite with all Fe 3? ions on B-sites and all Zn 2? ions on A-sites (O’Neill 1992). In the inverse cubic ferrite Nanoparticles with little change in size distributions, in the 40 (x = 0.0) up to 42. S. W. da Silva (&)  F. Nakagomi  V. K. Garg  A. C. Oliveira  P. C. Morais Instituto de Fı ´sica, Universidade de Brası ´lia, C.P. 04455, Brası ´lia, DF 70919-970, Brazil e-mail: swsilva@unb.br M. S. Silva  A. Franco Jr Instituto de Fı ´sica, Universidade Federal de Goia ´s, Goia ˆnia, GO 74001-970, Brazil 123 J Nanopart Res (2012) 14:798 DOI 10.1007/s11051-012-0798-4