  Polycrystalline Ba4NbIr3O12 has recently been shown to be a promising spin
liquid candidate. We report an easy and reliable method to grow
millimeter-sized single crystals of this trimer based spin liquid candidate
material with the actual stoichiometry of Ba4Nb0.8Ir3.2O12. The growth of large
crystals is achieved using BaCl2 as flux. The crystals show hexagonal
plate-like habit with edges up to 3 mm in length. The structure is confirmed by
single crystal X-ray diffraction and is found to be the same as of previously
reported phase Ba12Nb2.4Ir9.6O36 [Ba4Nb0.8Ir3.2O12], indeed with a mixed
occupancy of Nb/Ir at 3a site. The magnetic and calorimetric study on the
individual single crystals confirms the possibility of a spin liquid state
consistent with a recent report on a polycrystalline sample
