Luminescence of YAG doped with Eu,Yb, and Mn ions under VUV excitation

Hydrothermal synthesis has been successfully used to obtain fine-crystalline powders of yttrium aluminum garnet (YAG) doped with manganese ions and codoped with cerium and manganese ions. Using the method of high-temperature solid-state synthesis, ceramic specimens of YAG that contain europium and ytterbium ions have been obtained. In synthesized YAG:Eu and YAG:Yb ceramics, no luminescence that can be attributed to 5d-4f transitions in Eu²⁺ or Yb²⁺ ions has been detected, even though the scheme of energy levels of these ions constructed with respect to YAG energy bands indicates that there is a potential possibility of the occurrence of 5d-4f luminescence for Eu²⁺ ions in YAG. At room temperature, the luminescence spectrum of hydrothermally synthesized YAG doped with manganese ions consists of two broad bands with maxima at ～600 and ～750 nm and does not contain any narrow bands in the red or IR range. Therefore, the spectrum contradicts to the properties of the luminescence of Mn²⁺, Mn³⁺, or Mn⁴⁺ ions in YAG described in the literature, even though the obtained hydrothermal specimens can contain noticeable concentrations only of Mn³⁺ ions.