In this paper, GaN nanoparticles were firstly synthesized through a facile solid-state reaction using an organic reagent cyanamide (CN2H2) and Ga2O3 as precursors. The structural properties were investigated in detail. It is found that these nanoparticles having average size of 40 nm were N-deficient with the N vacancies reaching as high as 12%. The Raman scattering spectrum of these nanoparticles presented some interesting features. The room-temperature frequency spectrum of the relative dielectric constant er was measured and indicated that these nanoparticles exhibited sharp enhancement at low frequency range comparing with GaN nanomaterials and N-deficient microparticles. It is thought both the rotation direction polarization (RDP) and the space charge polarization (SCP) process should be responsible for the enhancement of er in these N-deficient GaN nanoparticles. (c) 2008 Elsevier B.V. All rights reserved.