Synthesis and growth mechanism of tubular YAl3(BO3)4 crystals in millimeter diameter

► Hexagonal tubular YAl3(BO3)4 crystals of millimeter diameter were reported for the first time. ► Cooling rate was the key factor to the formation of tubular YAl3(BO3)4 crystals. ► A formation mechanism for tubular YAB crystal was proposed.