Pulling growth technique towards rare earth single crystals

Abstract

Pulling growth technique serves as a popular method to grow congruent melting single crystals with multiscale sizes ranging from micrometers to centimeters. In order to obtain high quality single crystals, the crystal constituents would be arranged at the lattice sites by precisely controlling the crystal growth process. Growing interface is the position where the phase transition of crystal constituents occurs during pulling growth process. The precise control of energy at the growing interface becomes a key technique in pulling growth. In this work, we review some recent advances of pulling technique towards rare earth single crystal growth. In Czochralski pulling growth, the optimized growth parameters were designed for rare earth ions doped Y₃Al₅O₁₂ and Ce:(Lu_1−xY_x)₂SiO₅ on the basis of anisotropic chemical bonding and isotropic mass transfer calculations at the growing interface. The fast growth of high quality rare earth single crystals is realized by controlling crystallization thermodynamics and kinetics in different size zones. On the other hand, the micro pulling down technique can be used for high throughput screening novel rare earth optical crystals. The growth interface control is realized by improving the crucible bottom and temperature field, which favors the growth of rare earth crystal fibers. The rare earth laser crystal fiber can serve as another kind of laser gain medium between conventional bulk single crystal and glass fiber. The future work on pulling technique might focus on the mass production of rare earth single crystals with extreme size and with the size near that of devices.