Investigation of the luminescence properties and thermal stability of dysprosium, terbium, and europium ions singly- and co-doped strontium yttrium borate phosphors

A series of trivalent rare-earth element ions (europium, terbium, dysprosium) singly- and co-doped strontium yttrium borate phosphors was synthesized via the sol–gel method. The phase formation, luminescence properties, decay times, and energy transfer behaviors from terbium ions to europium ions, the thermal stability, and the Commission Internationale de L’Eclairage coordinates were investigated. Under the excitation of ultraviolet light, the singly doped phosphors exhibited green emission of terbium ions, white emission of dysprosium ions, and red emission of europium ions, respectively. For the terbium and europium ions co-doped strontium yttrium borate samples, a white emission can be realized by blending the doping concentration of terbium and europium ions. The critical distance between terbium and europium ions has been calculated to be about 14.52 Å and the energy transfer from terbium to europium occurred through the dipole–quadrupole interaction. At 150°C, the emission intensity of terbium and europium in the 12 mol% terbium and 14 mol% europium co-doped strontium yttrium borate sample was maintained at about 74% and 87% of their corresponding initial values, respectively, and the dysprosium ions singly doped strontium yttrium borate sample showed about 70% of its initial emission intensity at room temperature. The above results suggested that europium, terbium, dysprosium ions singly- and co-doped strontium yttrium borate phosphors have potential applications as ultraviolet-convertible phosphors.