REECOB: 20 years of rare earth element calcium oxoborates crystal growth research

Rare earth element calcium oxoborates (REECOB, REECa4O[BO3]3) represent a group of materials for non-linear optics and with useful piezoelectric properties under high-pressure and high-temperature conditions making it applicable as sensor materials in extreme environments. High-quality crystals with appropriate size are generally grown from a melt by the Czochralski method. This paper presents a compilation and comparison of crystal growth parameters and properties of members of the REECOB group from the literature with those of own growth experiments. Recent studies provided new data concerning the melting temperature of REECOB members, such as ca. 1475 °C for SmCa4O(BO3)3 (SmCOB).

► The paper comprises a comprehensive compilation of crystal growth methods and parameters for members of the REECOB group. ► Different growth methods and parameters and also selected properties are discussed. ► The melting point of SmCOB is reevaluated with regard to the melting points of other REECOB compounds. ► Furthermore, the thermal expansion coefficients of the known members of the REECOB family are also widely discussed.