<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Novel Ba<sub>4</sub>LnTiNb<sub>9</sub>O<sub>30</sub> compounds with Ln: La, Pr, Nd, Sm, Eu, and Gd are prepared by solid state reaction of stoichiometric mixtures of CaCO<sub>3</sub>, Ln<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub>, and Nb<sub>2</sub>O<sub>5</sub> (1300 °C, 8 h, followed by sintering at 1290—1380 °C for 8 h).</p> </abstract>