Effect of Zr⁴⁺ Addition on Photoluminescence Properties of YPO₄:Mn²⁺

Photoluminescence (PL) properties of YPO 4 :Mn 2+ and Zr 4+ -doped YPO 4 :Mn 2+ have been investigated by measuring PL and PL excitation (PLE) spectra and electron spin resonance (ESR) spectra. The PL spectrum at 9 K is dominated by a red (R) emission band at 1.91 eV for YPO 4 :Mn 2+ and a blue-green (BG) emission band at 2.52 eV for YPO 4 :Zr 4+ ,Mn 2+ . The R and BG bands are caused by the d–d transition in Mn 2+ ions, in analogy with PL spectra of Mn 2+ -doped inorganic compounds. The PLE spectra for the R and BG bands are different from each other, suggesting that the Zr 4+ addition changes the environment of Mn 2+ ions. The ESR spectra revealed that Mn 2+ ions can occupy interstitial sites without Zr 4+ addition and Y 3+ lattice sites with Zr 4+ addition. It is thus supposed that the R and BG bands originate in an interstitial Mn 2+ ion and a Y 3+ -substituted Mn 2+ ion, respectively. The increase in the BG emission intensity caused by Zr 4+ addition can be explained as an increase in the number of Mn 2+ ions at Y 3+ sites.