Highly uniform microsphere of broadband near-infrared-emitting Ba(Hf1-xCrx)O3 perovskite phosphors

Chromium activated BaHfO3 (BHOC) perovskite phosphor with varying amount of Cr3+ ion (1–10 %) was prepared by hydrothermal synthesis and was characterized systematically using x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), positron annhilation lifetime spectroscopy (PALS) and time resolved photoluminescence (TRPL). FESEM show the formation of highly uniform microsphere of BHOC with very smooth surface texture. XPS showed the stabilization of chromium in +3 oxidation states, formation of oxygen vacancies and improved crystallinity in 6 % doped in BHOC sample. Under 500 nm excitation, BHOC perovskite demonstrated a very broad near infrared (NIR) emission band (700–1050 nm) centered at 815 nm with a full width at half-maximum (FWHM) of ∼150 nm and a wide absorption band, suggesting its potential application in NIR spectroscopy. The fraction of positrons getting trapped in the defects and vacancy clusters decreased with increase in Cr3+ doping and showed minima at 6.0 % doping and this sample also showed highest NIR light emission.