In the present study we analyze the thermal and dielectric behavior from 292 to 930 K of BNN doped with Nd3+ (1 at.%). The crystal was grown by the Czochralski method along the tetragonal axis. The complicated dielectric permittivity epsilon'(r) behavior, which depends on the cooling or heating process, was compared with the pure crystal. Two unexpected epsilon'(r) anomalies were detected around 318 and 847 K while the remaining transitions are in good agreement with the thermal expansion measurements. (c) 2007 Elsevier B.V. All rights reserved.