Synthesis, Crystal Growth and Characterization of Ho₂Ti₂O₇

Holmium titanate (as a candidate for the spin ice behavior [1]), is a member of the rare-earth titanate family with the A2B2O7 chemical formula and Pyrochlore structure. The ability to show a wide variety of behaviors in the Pyrochlores is due to structure adaptation with different cations' radius ratio. This flexibility can also ease the structural distortion which causes defect formation inside the crystals [2,3]. The wide range of the lattice parameters that are reported for Ho2Ti2O7 in the literature raises doubts as to the quality of previously grown crystals. We grew single crystals of Ho2Ti2O7 (HTO) by floating zone and traveling solvent floating zone methods from high-quality powder to investigate and illustrate the effect of synthesis and growth of the single crystal at the melting point of the Holmium titanate and below their melting point on the compositional and structural properties. We found that the crystal grown by typical floating zone method shows a continuous increase in its lattice parameter from top to bottom, but the crystal is grown by traveling solvent method shows a consistency of the lattice parameter along the crystal, similar to what has been observed for Ytterbium titanate [4].