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

Abstract

The rare-earth local environments of Nd:Al 2 O 3 -P 2 O 5 -K 2 O 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 Nd 3þ ion by various P/Al ratios. The coordination sphere structure of Nd 3þ ion is determined by three and four pulse electron spin echo envelope modulation (ESEEM) spectra. The off-diagonal signal corresponding to 31 P Larmor frequency confirms that the second-order coordination sphere of Nd 3þ ion is almost occupied by P atoms. Al is located at the higher-order Nd 3þ coordination sphere as only diagonal resonance corresponding to the 27 Al was detected, the content of which rapidly increases with decreasing P/Al ratio.Nd-doped phosphate glasses, such as LHG-8, LG760, and N31, have been used in laser confinement fusion facilities. [1,2] Using Nd-doped glass amplifiers, high-intensity ultra-fast lasers have been developed, which are important tools to realize inertial confinement fusion. [3] However, the narrow gain bandwidth of commercially available neodymium glasses hinders further improvement of laser output. Introducing Al 2 O 3 into Nd-doped phosphate glass broadens the effective line-width (Δλ eff ). [4] The Nd 3þ luminescence is greatly influenced by its glass structure and the local environment of Nd 3þ ion. The glass structure of aluminophosphate glass has been investigated by NMR, IR and Raman. [5] The local environment of Nd 3þ ion can be examined by EPR.In aluminophosphate fluoride systems, 27 Al and 31 P signals have been observed under the weak coupling condition. [6,7] However, the distribution of P and Al around the RE ion in aluminophosphate glass is still unclear, especially when the content of P is far greater than that of Al.In this work, we apply EPR technique to characterize of Nd: Al 2 O 3 -P 2 O 5 -K 2 O glasses. The P/Al ratios were set to 11, 5, and 3 in order to examine the effect of the P/Al ratio on the Nd 3þ ion local environments. In addition, the luminescence properties have been correlated to the Nd 3þ ion local environment. On the basis of the experiments mentioned above, we demonstrated that the second-order coordination sphere of Nd 3þ ion is almost occupied by P atoms. Al is located at the higherorder Nd 3þ coordination spheres, the content of which rapidly increases with decreasing P/Al ratio.Experiment Details: xAl 2 O 3 -(60Àx)P 2 O 5 -40K 2 O-0.5Nd 2 O 3 (x ¼ 5, 10, 15) were prepared by the conventional melting procedure. The samples are named PA11, PA5 and PA3 according to their respective P/Al ratios. Stoichiometric amounts of Al(PO 3 ) 3 , Al 2 O 3 , KPO 3 , P 2 O 5 , and Nd 2 O 3 .were mixed. Mixtures were melted in a quartz crucible for 30 min at 900-1400 C, depending on the components. The melts were cast into preheated steel molds and annealed at the corresponding transition temperature in a muffle furnace.All of the solid-state EPR experiments were carried out on an E-580 BRUKER ELEXIS X-band EPR spec...

v-P2O5 micro-clustering in P-doped silica studied by a first-principles Raman investigation

“…In the recent years, the composition of the nearest neighbors shell around a rare-earth ion in RE doped silica fibers (and also in other glasses 19 ) has been investigated 20–22 . Still little is known concerning the formation of the nearest neighbors shell around a RE ion.…”

Effect of Li2O substitution on structures and properties of Nd3+‐doped Al(PO3)3‐Li2O glasses

“…It is known that the optical properties of Nd 3+ ions are highly dependent on the glass structure and their local ligand environment . Glass structure is hard to be comprehensively characterized due to the disorder arrangement of atoms and the low resolution of traditional techniques.…”

“…Schneider et al 8 suggested that six-fold coordinated aluminum (Al Ⅵ ) restricted the migration of phosphate chains resulting in an enhancement of T g in (1−x)NaPO 3 It is known that the optical properties of Nd 3+ ions are highly dependent on the glass structure and their local ligand environment. [11][12][13][14] Glass structure is hard to be comprehensively characterized due to the disorder arrangement of atoms and the low resolution of traditional techniques. The solid-state nuclear magnetic resonance (SSNMR) technique is a powerful tool to characterize the hyperfine structure of glass materials.…”

“…Pulse electron paramagnetic resonance (EPR) technique is an effective way to investigate the local environment of rare‐earth (RE) ions. Yu Yue et al showed that the content of 31 P located in the second‐order shell of Nd 3+ ions increased as P/Al ratio increased in Al 2 O 3 ‐P 2 O 5 ‐K 2 O glasses. This structural evolution was considered to be responsible for the narrowing of effective linewidth (Δλ eff ) of 1053 nm emission.…”

Edge Effect on the Photodetection Ability of the Graphene Nanocrystallites Embedded Carbon Film Coated on p‐Silicon

“…Photodetectors are an indispensable core component in many modern precision analytical, measurement and diagnostic instruments . Photodetectors fabricated using heterojunctions are superior to those fabricated with homojunctions in the aspect of low dark noise, etc . Graphene is a hexagonal 2D film composed of a single layer of sp 2 hybrid carbon atoms, which has the potential ability of fast photoresponse .…”