[en] The TANDAR accelerator of the National Atomic Energy Commission has been used to obtain the non-conventional radioactive probe ¹⁰⁰Rh embedded in α - Nb₂O₅ allowing the PAC study of the range of high electric field gradients in this semiconductor. A sintered oxide tablet, obtained from metallic Nb powder calcination in air at 1050deg C, was irradiated with a 100 MeV ¹²C6+ beam for 15 hours to produce the ¹⁰⁰Rh probe through the reaction ⁹³Nb (¹²C,5n) ¹⁰⁰Ag → ¹⁰⁰Pd → ¹⁰⁰Rh. The PAC measurements show a non-homogenous distribution of the probes substituting the Nb in lattice sites of high electric field gradient. The range of low electric field gradients was studied using the probe ¹¹¹In incorporated to the samples by diffusion. (Author)