Growth and structure of Ca4La[O|(BO3)3]Ca4La[O|(BO3)3]

The lanthanum oxoborate is a material with a non-centrosymmetric structure which is important for optical and sensorical application. Sintering has been performed to find the best parameters to produce the polycrystalline phase free from phase shift to grow a single crystal. A slight excess of B2O3 is necessary because of the hygroscopic properties of boron oxide.A DSC measurement of the Ca4La[O|(BO3)3]Ca4La[O|(BO3)3] was performed to determine the melting behaviour. LaCOB melts congruently at nearly 1410∘C. By using a [0 1 0] Ca4Gd[O|(BO3)3]‐seedCa4Gd[O|(BO3)3]‐seed a single crystal of high quality had been produced by the Czochralski method. The grown crystal is free from macrodefects like bubbles and cracks with a typical shape of rhombohedral cross section.Single-crystal X-ray diffraction in combination with a powder diffraction measurement showed, that the structure belongs to the monoclinic system with space group Cm and a0=0.817079(8) nm, b0=1.608406(16) nm, c0=0.362844(3) nm and the angle β=101.352(1)∘β=101.352(1)∘. The R-value for the solved structure is 0.0201.