Pyroxene-type compounds NaM³⁺Ge₂O₆, with M = Ga, Mn, Sc and In

The structures of the two new pyroxene-type compounds, NaGaGe₂O₆ and NaInGe₂O₆, have been determined, and new data for NaMnGe₂O₆ and NaScGe₂O₆ are reported. The compounds adopt the high-temperature structure of the pyroxene-type chain germanates, with monoclinic symmetry and space group C2/c. The lattice parameters, the individual and average bond lengths involving M1, and the distortion parameters scale well with the ionic radius of the M1 cation.