Hexagonal phase NaY(OH)(x)F4-x: Sm (x <= 0.5) with spindle shape has been successfully synthesized via a facile hydrothermal method. Influence of alkaline environment on the lattice parameters, thermal decomposition, morphology evolution and luminescence properties has been systematically investigated. The spindle shape is controlled by the intrinsic electric field, which is created by the replacement of F-with OH- and the crystallization process is involved in intermediate mesocrystals. In addition, the influence isomorphous anion substitution exerts on photoluminescence properties has been explored. The potential applications of NaY(OH)(x)F4-x: Sm (x <= 0.5) have been pointed out. (C) 2015 Elsevier Ltd. All rights reserved.