Optical Spectra and Energy Levels Analysis of the 4f^NIons Doped into Ba₂YCl₇

Abstract

Absorption emission and excitation spectra are measured and analyzed to achieve assignments of energy levels for 4f(N) ions in Ba(2)YCl(7):RE(3+) (RE = Pr, Nd, Tb, Dy, Ho, Er, and Tm) crystals. The experimental energy levels were analyzed in terms of the usual free-ion parameters and the crystal field (CF) ones, B(kq), in the Wybourne notation. The orthorhombic C(2v) symmetry is shown to be a good approximation of the actual triclinic C(1) site symmetry at the metal center. The starting values of the CF parameters B(kq) used for fittings for the studied crystals were obtained from superposition model analysis. A good agreement between the calculated and experimental energy levels was obtained with rms deviations in the range from 6.8 cm(-1) (for Ho(3+)) to 14.1 cm(-1) (for Pr(3+)). The fitted sets of B(kq) parameters are, in general, consistent across the 4f(N) series. This study has enabled determination and discussion of the trends in variation of the free-ion parameters and CF ones across the 4f(N) series. The CF parameter set and energy level structure obtained for Nd(3+) ion in Ba(2)YCl(7) crystal are consistent with those for Nd(3+) in structurally related RbY(2)Cl(7) crystal. This systematic analysis of CF parameters is one of only few such studies encompassing nearly whole series of RE(3+) ions.

Crystal-field study for the orthorhombic Yb3+ centers in Ca3Sc2Ge3O12 and Lu3Ga5O12 garnets

“…The second important point, systematic behavior of fitted CFPs for Yb 3+ ion in different garnets, is closely related to their reliability and can be conveniently performed by the standardization procedures that were developed and utilized by Rudowicz and coworkers (see more details in the literature [53][54][55][56][57]). According to this idea, we find that all the obtained CFPs in Eqs.…”

Terminological confusions and problems at the interface between the crystal field Hamiltonians and the zero-field splitting Hamiltonians—Survey of the CF=ZFS confusion in recent literature

“…Standardization idea [48] limits the rhombicity ratio to the standard range, i.e. for the conventional ZFSPs λ¼ E/D to (0, 1/3) or equivalently for the ZFSPs (as well as CFPs) in the ESO notation λ 0 B 2 2 =B 0 2 to (0, 1), whereas for the CFPs in the Wybourne notation κ ¼ ReB 22 =B 20 to (0, þ 1/√6 E0.408) [48][49][50][51][52][53][54][55]. This idea [48] stems from the transformation properties of the spin operators involved in the respective Hamiltonians [29,30].…”

“…Standardization has profound implications for compatibility of orthorhombic, monoclinic, and triclinic CF (LF) parameter sets or ZFS ones [48][49][50][51][52][53][54][55]. Meaningful comparisons of various parameter sets available in the literature require employing the sets referred to the same nominal axis system [50].…”

“…Best approach is to transform the non-standard sets to the standard range, which enables meaningful analysis and comparison of different ZFS parameter sets or CF (LF) ones. Importantly, direct comparisons of non-standard CFP sets with standard ones or non-standard CFP sets corresponding to different regions in the CF parameter space may lead to misleading structural interpretations, incorrect CFP systematics, and unjustified conclusions concerning the CF strength or controversial claims about inaccuracy of fellow researchers' results [48][49][50][51][52][53][54][55].…”

“…However rhombic symmetry actually imposes strong boundaries, namely the principal directions of the various properties. This quote pertains implicitly to the orthorhombic standardization [48][49][50][51][52][53][54][55]. The convention limiting the rhombicity ratio of the conventional ZFSPs λ¼E/D to the range (0, 1/3) is evidently taken for granted by the authors [34].…”