Energy transfer from Mn4+ to Mn5+ and near infrared emission with wide excitation band in Ca14Zn6Ga10O35:Mn phosphors

Ca14Zn6Ga10-xO35:xMn(CZG:xMn) phosphors were synthesized by high temperature solid state reaction. High doping concentration as 30 mol% for Mn ions can be realized in the compounds due to the existence of the multiple valance of Mn ions. Both red emission from Mn4+ and near infrared (NIR) emission from Mn5+ were observed from CZG:xMn phosphors. The energy transfer from Mn4+ ions to Mn5+ ions was detected, which makes it possible for CZG:xMn phosphors to emit 1152 nm light under the excitation of the whole visible light region, especially under the commercial blue chips (450 nm). This means the CZG: xMn phosphors can be used in the manufacture of NIR sources with small size, simple structure and low cost. Because CZG:xMn can be excited by 600 similar to 700 nm and emits 1152 nm, the phosphors show the application in the real-time biochemical detection because of the excellent penetration capacity of biological tissue for 600 similar to 700 nm and 1152 nm light. With the aid of low-temperature PL spectra, it was found that two zero phonon lines and multiple vibration bands are responsible for the five compact emission band from 650 similar to 750 nm of Mn4+ ions. The results are helpful to comprehend the mechanism of the emission of Mn ions in CZG:xMn and promote the phosphors application.