Infrared‐to‐visible conversion in strontium sulphate through a defect‐based infrared stimulated visible emission phenomenon

Strontium sulphate (SrSO4 ) is a defect-based photoluminescence material, generally used in thermoluminescence applications, and has been studied for infrared (IR) stimulated visible emission. The SrSO4 particles were synthesized using a precipitation method. The orthorhombic phase of SrSO4 was confirmed from the X-ray diffraction pattern and the formation of micron-sized particles was authenticated from field emission scanning electron micrographs. The elemental composition of oxygen and strontium was determined using energy-dispersive X-ray analysis measurement that confirmed the presence of VO•• and VSr'' intrinsic defects in the material. Photoluminescence investigations showed the presence of various defect bands in the band gap giving rise to intrinsic luminescence in SrSO4 . The emission in the visible region was attributed to the defect band arising due to VO•• . Photoluminescence lifetime measurement confirmed the presence of stable defect states with a lifetime in microseconds. The SrSO4 sample was tested using IR lasers and a red-orange emission spot was observed from the powder sample when excited with IR lasers. The underlying principle for IR-to-visible conversion in the material is a defect-mediated phenomenon that has been described through the energy level diagram of the material.