Determination of the Bromley contributions to estimate the activity coefficient of neodymium electrolytes

► Bromley model is used to calculate activity coefficients of neodymium compounds. ► Nd contributions are adjusted from experimental data of Nd(NO3)3 and NdCl3 solutions. ► Experimental acquisitions are carried out on Nd(NO3)3/HNO3/H2O ternary mixtures. ► Bromley model and the new Nd contributions are also applied to these mixtures. ► Comparison shows a good agreement for ionic strengths up to 6 mol kg−1.