Comparative analysis of energy-level splitting of Pr^(3+) doped in LiYF_4 and LiBiF_4 crystals:a complete energy matrix calculation

Based on the combination of Racah＇s group-theoretical consideration with Slater＇s wavefunction, a 91 ×91 complete energy matrix is established in tetragonal ligand field D2d for Pr3＋ ion. Thus, the Stark energy-levels of Pr3＋ ions doped separately in LiYF4 and LiBiF4 crystals are calculated, and our calculations imply that the complete energy matrix method can be used as an effective tool to calculate the energy-levels of the systems doped by rare earth ions. Besides, the influence of Pr3＋ on energy-level splitting is investigated, and the similarities and the differences between the two doped crystals are demonstrated in detail by comparing their several pairs of curves and crystal field strength quantities. We see that the energy splitting patterns are similar and the crystal field interaction of LiYF4：Pr3＋ is stronger than that of LiBiF4：Pr3＋.

Interfacial thermodynamics-inspired electrolyte strategy to regulate output voltage and energy density of battery chemistry

The electrochemical behaviors of battery chemistry,especially the operating voltage,are greatly affected by the complex electrode/electrolyte interface,but the corresponding basis understanding is still largely unclear.Herein,the concept of regulating electrode potential by interface thermodynamics is proposed,which guides the improvement of the energy density of Zn-MnO_(2) battery.A cationic electrolyte strategy is adopted to adjust the charge density of electrical double layer,as well as entropy change caused by desolvation,thus,achieving an output voltage of 1.6 V(vs.Zn^(2+)/Zn)and a capacity of 400 mAh g^(-1).The detailed energy storage behaviors are also analyzed in terms of crystal field and energy level splitting.Furthermore,the electrolyte optimization benefits the efficient operation of Zn-MnO_(2) battery by enabling a high energy density of 532 Wh kg^(-1) based on the mass of cathode and a long cyclic life of more than 500 cycles.This work provides a path for designing high-energy-density aqueous battery via electrolyte strategy,which is expected to be extended to other battery systems.

A strategy for preparing broadband polymer based optical waveguide amplifiers:doping low crystal field symmetric nanocrystals in polymer matrix as gain media

Optical waveguide amplifiers are essential devices in integrated optical systems,with their gain bandwidths directly influencing the operating wavelengths of optical circuits.Previous Er^(3+)-doped polymer optical waveguide amplifiers have been limited to amplifying signals within the C-band.To achieve broadband polymer optical waveguide amplification,we propose the use of nanocrystals with low crystal field symmetry to extend the working bandwidth.Our approach utilizes LiYF_(4):Yb,Er nanoparticles embedded in poly(methyl methacrylate)as the gain medium,enabling signal amplification from most of the S-band to the whole(C+L)band.The low crystal field symmetry of the LiYF_(4)host significantly splits the^(4)I_(13/2)and^(4)I_(15/2)levels of Er^(3+)ions owing to the crystal field effect,facilitating broadband down-conversion luminescence under 980-nm excitation.Furthermore,a fluorescence kinetic analysis confirms that the broadband luminescence of Er^(3+)arises from significant energy-level splitting caused by the crystal field effect.Under 980-nm excitation,the amplifiers exhibited relative gains of approximately 12.6 dB at 1535 nm,7.4 dB at 1480 nm,and 3.7 dB at 1610 nm.The Er^(3+)-doped broadband polymer optical waveguide amplifier was successfully prepared.