Releasing behavior of different oxides in Nd₂Fe₁₄B

High content of oxygen in NdFeB magnet is one of the essential factors that hinder its large-scale industry production and cause its low grade in magnetism performance. Therefore, how to control the total oxygen content and oxygen states in NdFeB becomes an important issue brought to analysts. Based on different binding energies of oxides with graphite in the sample, releasing behaviors of different oxides in NdFeB were investigated by both qualitative and quantitative methods in this article. Inert gas fusion infrared absorption method was used in the article. As verified by ramp heating mode, two kinds of oxides were found to exist in Nd₂Fe₁₄B under different analyzing heating powers. Based on releasing conditions derived from ramp heating mode, two releasing peaks of different oxides obtained from segmented heating mode were completely separated. Then, X-ray diffraction, SEM, Electrolyte distillation and Photoelectron Spectroscopy were used on Nd₂Fe₁₄B sample and the 1st-step-heated sample individually. Qualitative analysis results were obtained. The first peak was released from deoxidization of Nd_xFe_yO_z compound. The second one was released from Nd₂O₃ deoxidization. Based on the above results, seriatim calibrated method was used to calibrate the two peaks respectively. Accurate quantitative results of them were obtained.