<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>The title compounds are prepared by reaction of Ln<sub>2</sub>O<sub>3</sub> (Ln: Eu, Gd) and NiO in a LiCl/KCl (4:6) flux (autoclave, 180 bar O<sub>2</sub>, 400 °C, 16 d).</p> </abstract>