29th International Conference on Low Temperature Physics (LT29)/<strong>Cu<sub>7</sub>(SeO<sub>3</sub>)<sub>2</sub>O<sub>2</sub>Cl<sub>6</sub></strong><strong>: a new magnetoelectric compound from CuO</strong><strong><em>–</em></strong><strong>CuCl<sub>2</sub></strong><strong><em>–</em></strong><strong>SeO<sub>2</sub> ternary phase diagram</strong><strong> </strong>