Rare‐Earth Ion Local Environments in Nd:Al₂O₃‐P₂O₅‐K₂O Glass Studied by Electron Paramagnetic Resonance Spectroscopies

The rare‐earth local environments of Nd:Al₂O₃‐P₂O₅‐K₂O glass with different P/Al ratios are analyzed using electron paramagnetic resonance (EPR). The echo‐detected field sweep (EDFS) line‐shape change hints at a modification of the local environment around Nd³⁺ion by various P/Al ratios. The coordination sphere structure of Nd³⁺ion is determined by three and four pulse electron spin echo envelope modulation (ESEEM) spectra. The off‐diagonal signal corresponding to³¹P Larmor frequency confirms that the second‐order coordination sphere of Nd³⁺ion is almost occupied by P atoms. Al is located at the higher‐order Nd³⁺coordination sphere as only diagonal resonance corresponding to the²⁷Al was detected, the content of which rapidly increases with decreasing P/Al ratio.