Luminescent properties of Cr-doped gallium garnet crystals grown by the micro-pulling-down method

Abstract Cr-doped (Gd x Y 1− x ) 3 Ga 5 O 12 crystals ( x =0.00, 0.25, 0.50, 0.75 and 1.00) were grown by the micro-pulling-down method and examined for their possible application as red and infrared scintillating detectors in medical field. Although Cr:(Gd 0.75 Y 0.25 ) 3 Ga 5 O 12 and Cr:Gd 3 Ga 5 O 12 had similar X-ray diffraction patterns, other samples showed some change in lattice constant. All the crystals had broad emission bands in the red and infrared region when excited by either 450 nm photons or X rays. These bands were associated with 4 T 2 →A 2 transitions. Moreover, redshift of the emission-peak wavelengths ( 4 T 2 → 4 A 2 ) and absorption peaks ( 4 A 2 → 4 T 1 and 4 T 2 ) was observed with increase of Gd content ( x ) in Cr-doped (Gd x Y 1 −x ) 3 Ga 5 O 12 due to the change of the crystal fields. The crystals had scintillation emissions in the wavelength region suitable for the real time dose monitoring in radiation therapy.