Valence state regulation of Terbium in all-inorganic amorphous solid for magnetic field sensing

Tb3+ doped glass has emerged as a promising magneto-optical (MO) material due to the high transparency, high Verdet constant, as well as easy processing characteristics. Although Tb3+ possesses the highest paramagnetic susceptibility, is usually impacted by inactive Tb4+. Regulating the valence state and quantitatively calculating the effective concentration of the mixed-valence metal elements doped in all-inorganic amorphous matrix is quite difficult. Here, a modified model for quantitatively calculating the effective concentration of Tb3+ was proposed and the oxidation of Tb3+ to Tb4+ was inhibited through controlling the surrounding electron accepter or diminishing the charge transfer activity in all-inorganic amorphous matrix. A high effective concentration of Tb3+ among all valence Tb ions was achieved. Based on it, the assembled magnetic field sensor showed a high Verdet constant of 68.82 rad/(T·m) at 650 nm and a sensing sensitivity of 0.17 rad/T. This work provides insights of ionic valence state regulation to rationally improve the properties of all-inorganic amorphous solid for MO applications, such as magnetic field sensing.