| Determination of charge-compensated C3v (Ⅱ) centers for Er3+ ions in CdF2 and CaF2 crystals |
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| 作者姓名： | 柴瑞鹏 郝丹辉 高当丽 庞庆 |
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| 作者单位： | College of Science;Xi’an University of Architecture and Technology Huaqing College |
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| 基金项目： | Project supported by the National Natural Science Foundation of China(Grant No.1170513);the Natural Science Foundation of Shaanxi Province,China(Grant No.Z20200051);the Foundation of the Education Department of Shaanxi Provincial Government,China(Grant No.16JK1461);the Scientific Research Foundation of Xi’an University of Architecture and Technology,China(Grant No.QN1729). |
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| 摘 要： | A unified theoretical method is established to determine the charge-compensated C3v(Ⅱ)centers of Er3+ions in CdF2 and CaF2 crystals by simulating the electron paramagnetic resonance(EPR)parameters and Stark energy levels.The potential(Er3+–F?–O42?)and(Er3+-F7?-O42?)structures for theC3v(Ⅱ)centers of Er3+ions in CdF2 and CaF2 crystals are checked by diagonalizing 364×364 complete energy matrices in the scheme of superposition model.Our studies indicate that the C3v(Ⅱ)centers of Er3+ions in CdF2 and CaF2 may be ascribed to the local(Er3+-F?-O42?)structure,where the upper ligand ion F?undergoes an off-center displacement by?Z≈0.3?A for CdF2 and?Z≈0.29?A for the CaF2 along the C3 axis.Meanwhile,a local compressed distortion of the(ErFO4)6?cluster is expected to be?R≈0.07?A for CdF2:Er3+and?R≈0.079?A for CaF2:Er3+.The considerable g-factor anisotropy for Er3+ions in each of both crystals is explained reasonably by the obtained local parameters.Furthermore,our studies show that a stronger covalent effect exists in the C3v(Ⅱ)center for Er3+in CaF2 or CaF2,which may be due to the stronger electrostatic interaction and closer distance between the central Er3+ion and ligand O2?with the(Er3+-F?-O42?)structure.
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| 关 键 词： | EPR parameters distorted local structure covalent effect optical properties |
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