Rich Coordination of Nd³⁺ in Mg₂Nd₁₃(BO₃)₈(SiO₄)₄(OH)₃, Derived from High-Pressure/High-Temperature Conditions

A neodymium borosilicate, Mg2Nd13(BO3)8(SiO4)4(OH)3 (MgNdBSi-1), was obtained from a high-temperature (1400 °C), solid-state reaction under high-pressure conditions (4.5 GPa). MgNdBSi-1 contains six different types of Nd3+ coordination environments with three different ligands: BO3, SiO4, and OH groups. Mg2+ cations are only bond to BO3 groups and form porous two-dimensional layers based on 12-membered ring fragments. Surprisingly, the OH groups are retained at high temperature and reside at the center of Mg–BO3 rings.