Abstract Strontium hexaferrite single crystals, SrFe 12 O 19 , with sizes of up to 5 mm were grown by spontaneous crystallization from sodium oxide based flux. The structural and morphological characterization of the grown samples was performed by powder and single crystal X-ray diffraction and scanning electron microscopy, respectively. X-ray diffraction reveals that all prepared samples are single-phase with magnetoplumbite structure. The unit cell parameters were determined to a = 5.8832(4) Å, c = 23.0361(14) Å, V = 690.51(6) Å3. Magnetic hysteresis curves on single crystals reveal an almost ideal soft magnetic behavior, whereas a ground sample shows an increased value for the coercivity. [ABSTRACT FROM AUTHOR]