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

Strontium sulphate (SrSO 4 ) is a defect-based photoluminescence material, generally used in thermoluminescence applications, and has been studied for infrared (IR) stimulated visible emission. The SrSO 4 particles were synthesized using a precipitation method. The orthorhombic phase of SrSO 4 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 V O • • $$ {V}_O^{\bullet \bullet } $$ and V Sr ' ' $$ {V}_{Sr}^{\prime \prime } $$ intrinsic defects in the material. Photoluminescence investigations showed the presence of various defect bands in the band gap giving rise to intrinsic luminescence in SrSO 4 . The emission in the visible region was attributed to the defect band arising due to V O • • $$ {V}_O^{\bullet \bullet } $$ . Photoluminescence lifetime measurement confirmed the presence of stable defect states with a lifetime in microseconds. The SrSO 4 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.