Laser-diode-heated floating zone (LDFZ) method appropriate to crystal growth of incongruently melting materials

We have developed a laser-diode-heated floating zone (LDFZ) method, in order to improve the broad and inhomogeneous light focusing in the conventional lamp-heated floating zone method, which often causes difficulties in the crystal growth especially for the incongruently melting materials. We have simulated the light focusing properties of the LDFZ method to make the whole of the molten zone irradiated with concentrated and homogeneous laser lights. We have designed and assembled an LDFZ furnace, and have demonstrated how it works through actual crystal growth. The method is applicable to various kinds of materials, and enables stable and reproducible crystal growth even for the incongruently melting materials. We have succeeded in the crystal growth of representatives of the incongruently melting materials such as BiFeO3 and (La,Ba)2CuO4, which were believed to be difficult to be grown by the conventional method. Tolerance to the decentering of samples and highly efficient heating are also established in the LDFZ method. ► The laser-diode-heated floating zone method have been developed. ► The molten zone is irradiated with concentrated and homogeneous laser lights. ► The temperature gradient at the interface between the liquid and the solid is steep. ► Stable and reproducible crystal growth is realized even for the incongruently melting materials. ► Tolerance to the decentering of samples and highly efficient heating are established.