Nanocrystaline samples of transition-metals (Fe, Mn) doped ZnO are synthesized by wet chemical method. Samples are characterized by X-ray diffraction in order to determine composition of the samples and the mean crystallite size (8-52 nm). Raman spectroscopy and the magnetic measurements were performed too.

In this paper we report experimental spectra of low-frequency Raman scattering (below 100 cm^-1) at low temperatures, from these doped ZnO nanoparticles. In order to make low-frequency Raman modes visible we subtracted the intensity of the elastic scattering background by A/ωⁿ approximation. Observed modes are deconvoluted using the Lorentzian line profile technique. In almost all samples, two low-frequency Raman modes are identified. For example: in a case of (ZnO)_0.95(Fe₂O₃)_0.05 with mean crystallite size ~10 nm , modes are at about 19 cm^-1 and 39 cm^-1; in a case of (ZnO)_0.05(MnO)_0.95 with mean crystallite size ~43 nm modes are at about 22 cm^-1 and 46 cm^-1. Position of these modes is connected to the dimension of particles and dopant concentration. Low-frequency modes are analyzed as confined acoustic vibrations of nanoparticles.

As the dimension of the particles is already determined and having in mind specific frequency to diameter dependence, we established material parameters and analyzed behavior of these nanocrystaline doped ZnO samples.