  We have investigated the effect of synthesis and growth conditions on the
magnetic, structural, and compositional properties of pyrochlore oxide holmium
titanate and demonstrate a method for growing high quality stoichiometric
single crystals. A series of polycrystalline samples with various contents of
Ti (-0.08 \leqslant x \leqslant 0.08, and nominal compositions of Ho2Ti2+xO7)
were synthesized at different temperatures, and characterized using powder
X-ray diffraction. The results show that synthesizing powders at a higher
temperature of 1500 {\deg}C yield single phase compounds. Ti deficient powders
showed an increase of lattice constant due to stuffing (Ho into Ti positions),
while Ti rich powders showed a decrease in lattice constant due to
anti-stuffing (Ti into Ho positions). A post annealing in O2 was found to be
necessary to accomplish the anti-stuffing process. Use of the conventional
floating zone (FZ) technique introduced Ti deficiency, stuffing, and oxygen
vacancies in the grown crystal. Growth of high structural quality and
stoichiometric single crystals of Ho2Ti2O7 by the traveling solvent floating
zone (TSFZ) is reported. AC susceptibility measurements revealed that the
stoichiometric crystal shows a higher ice freezing temperature, indicating that
crystal quality and stoichiometry play a key role on low temperature spin ice
properties of this compound.
