Single crystal growth of the pyrochlores $R_2$Ti$_2$O$_7$ ($R$ = rare earth) by the optical floating-zone method

摘要

We report a systematic study on the crystal growth of the rare-earthtitanates $R_2$Ti$_2$O$_7$ ($R$ = Gd, Tb, Dy, Ho, Y, Er, Yb and Lu) and Y-dopedTb$_{2-x}$Y$_x$Ti$_2$O$_7$ ($x$ = 0.2 and 1) using an optical floating-zonemethod. High-quality single crystals were successfully obtained and the growthconditions were carefully optimized. The oxygen pressure was found to be themost important parameter and the appropriate ones are 0.1--0.4 MPa, dependingon the radius of rare-earth ions. The growth rate is another parameter and wasfound to be 2.5--4 mm/h for different rare-earth ions. X-ray diffraction datademonstrated the good crystallinity of these crystals. The basic physicalproperties of these crystals were characterized by the magnetic susceptibilityand specific heat measurements.