Theory of lanthanide crystal fields

Newman, D J

doi:10.1080/00018737100101241

Cited by 679 publications

(230 citation statements)

References 82 publications

Supporting

Mentioning

214

Contrasting

Unclassified

Order By: Relevance

“…Note that the local symmetry group does not impose an identical position for the two-with the exception of the 21 constraint to lie in m. The Eu ion is indeed slightly off the Ba position as was shown for the mixed compound by an X-ray diffraction study [14]. The Newman superposition model [15] was applied to the local coordination cluster of this ion. As the second 21 order crystal field terms are dominating, only these ones cm ) and excitation spectrum (detected at 23 900 cm ).…”

Section: Ka-bandmentioning

confidence: 99%

Europium doped BaMgF4, an EPR and optical investigation

Rey¹,

Bill²,

Lovy³

et al. 1998

Journal of Alloys and Compounds

View full text Add to dashboard Cite

21Eu was introduced into pure and oxygen codoped BaMgF single crystals. A detailed EPR study of this ion (S57 / 2) was realized on 4 both types of systems. The result is that only one spectrum was observed involving a strong crystal field. The associated site symmetry of the impurity is C . It occupies very closely a Barium lattice site as was established by correlating the EPR results with those of a refined Eu EPR spectrum (the only one). Optical emission and excitation experiments were performed between 13 000 and 53 000 cm . The 21 7 6 1 results due to the Eu impurity are given and discussed qualitatively within the 4f ⇔4f 5d scheme.

show abstract

Section: Ka-bandmentioning

confidence: 99%

Europium doped BaMgF4, an EPR and optical investigation

Rey¹,

Bill²,

Lovy³

et al. 1998

Journal of Alloys and Compounds

View full text Add to dashboard Cite

show abstract

“…For Fe3+ the sign of 62° is also still un known in many cases. Almost completely unknown is the dependence of the intrinsic zero field splitting parameter b2 [7] on the type of ligand, since the available data are restricted to a few ligands only.As part of a systematic study, EPR data for MnBr42~ in single crystals of four compounds were evaluated. The results for two of these were subReprint requests to Dr. G. Lehmann, Institut für Physi kalische Chemie, Westf.…”

mentioning

confidence: 99%

Correlation of Zero Field Splittings and Site Distortions III. MnBr₄ ^2- and Crystal Structure Refinements for Rb₃ZnBr₅ and Cs₂ZnBr₄

Heming

Lehmann

Henkel

et al. 1981

Zeitschrift Für Naturforschung A

View full text Add to dashboard Cite

C o r r e la tio n o f Z e ro F ield S p littin g s a n d S ite D is to r tio n s III . M n B r42~ a n d C r y s ta l S tr u c tu r e R e fin e m e n ts f o r R b 3Z n B r 5 a n d C s g Z n BM. Heming and G. Lehmann Institut für Physikalische Chemie, Westfälische Wilhems-Universität, Münster and G. Henkel and B. Krebs Institut für Anorganische Chemie, Westfälische Wilhelms-Universität, Münster Z. Naturforsch. 36a, 286-293 (1981); received January 31, 1980 EPR data for Mn2+ in Cs2ZnBr4, Rb3ZnBr5, Cs3CdBr5 and [(CH3)4Nl2ZnBr4 single crystals were determined and the crystal structures of Rb3ZnBrs and Cs2ZnBr4 were refined. Superposition analysis of the fine structure data for the latter two compounds resulted in an intrinsic zero field splitting parameter 62 for MnBr42_ of + 0.44 cm-1 suggesting a sizeable positive contribution of covalency. Cs3CdBrs was prepared in single crystals for the first time. It crystallizes in a primitive tetragonal space group. From the fine structure parameter 62° and the above value of 62 an elongation of the CdBr42~ tetrahedra along the c-axis with a bond angle of 105.7° was deter mined. This result is in agreement with the anisotropy of the 55Mn hyperfine splitting constant with A\\ = -68.6 and A±= -70.6 • 10~4 cm~i. IntroductionThe zero field splittings of S-state ions are -at least for their largest part -determined by the distortions of their first coordination spheres. Growing though not yet generally accepted evidence for this statement stems from quantitative correla tions of sign and size of the second order axial split ting parameter 62° with deviations of bond angles [1] and bond lengths [2] from cubic symmetry, from evaluation of uniaxial strain data for Mn2+ and Fe3+ in MgO and CaO [3] and from various applications [4][5][6] of the superposition model of Newman [7]. With a very large body of available EPR data such correlations are in most cases limit ed by the accuracy of the necessary crystal struc ture data (if complete parameter sets are at all available). For Fe3+ the sign of 62° is also still un known in many cases. Almost completely unknown is the dependence of the intrinsic zero field splitting parameter b2 [7] on the type of ligand, since the available data are restricted to a few ligands only.As part of a systematic study, EPR data for MnBr42~ in single crystals of four compounds were evaluated. The results for two of these were subReprint requests to Dr. G. Lehmann, Institut für Physi kalische Chemie, Westf. Wilhelms-Universität, Schloss platz 4, D-4400 Münster.jected to a superposition analysis using the results of simultaneous crystal structure refinements for these compounds. The resulting value of b2 allowed for the determination of the distortion angle of the CdBr42_ groups with Ü2d site symmetry in the third compound from the EPR results for Mn2+ in this compound alone. ExperimentalSingle crystals of manganese-doped Cs2ZnBr4, RbßZnBrs and [(CH3)4N]2ZnBr4 were grown by slow evaporation of acidified aqueous solutions of the components at 333 K. In all th...

show abstract

“…It is well known 14 that in the PCEM the higher rank Bq k (k > 2) are in general underestimated, suggesting that chemical bonding effects are more important for these parameters, while the Bq 2 parameters are in general considerably overestimated. These tendencies of the PCEM are modified, in the correct sense, by the SOM factors ρj(2βj) k+1 , producing a significant improvement in the theoretical Bq k values.…”

Section: The Simple Overlap Modelmentioning

confidence: 99%

“…The general form of the one-particle ligand field Hamiltonian for a metal ion in a chemical environment is given by 7,8,14 :…”

Section: The Simple Overlap Modelmentioning

confidence: 99%

A description of ligand field effects in the Di-mu-Azido-Bis [{Azido(N,N-Diethylethylenediamine)}Copper(II)] compound by the simple overlap model

Malta¹,

Mauro²,

Mattioli³

et al. 1998

J. Braz. Chem. Soc.

View full text Add to dashboard Cite

Apresentamos uma descrição teórica de efeitos de campo ligante no composto di-µ-azidobis[{azido(N,N-dietiletilenodiamina)}cobre(II)] através do Modelo Simples de Recobrimento. O Hamiltoniano do campo ligante é expresso em termos de operadores tensoriais irredutíveis, assumindo-se um sítio de simetria D3h ocupado pelo íon cobre (II). Os parâmetros de campo ligante, calculados a partir de dados estruturais disponíveis, indicam que o íon cobre(II) encontra-se sob a influência de um campo ligante muito forte.A energia da absorção d-d é bem reproduzida fenomenologicamente pelo modelo.We present a theoretical description of ligand field effects in the di-µ-azido-bis[{azido( N,Ndiethylethylenediamine)} copper(II)] compound by the Simple Overlap Model. The ligand field Hamiltonian is expressed in terms of irreducible tensor operators for an assumed D3h site symmetry occupied by the copper ion. The ligand field parameters, calculated from the available structural data, indicate that the copper ion is under the influence of a very strong ligand field. The energy of the d-d absorption band is well reproduced phenomenologically by the model.

show abstract

Theory of lanthanide crystal fields

Cited by 679 publications

References 82 publications

Europium doped BaMgF4, an EPR and optical investigation

Europium doped BaMgF4, an EPR and optical investigation

Correlation of Zero Field Splittings and Site Distortions III. MnBr₄ ^2- and Crystal Structure Refinements for Rb₃ZnBr₅ and Cs₂ZnBr₄

A description of ligand field effects in the Di-mu-Azido-Bis [{Azido(N,N-Diethylethylenediamine)}Copper(II)] compound by the simple overlap model

Contact Info

Product

Resources

About

Theory of lanthanide crystal fields

Cited by 679 publications

References 82 publications

Europium doped BaMgF4, an EPR and optical investigation

Europium doped BaMgF4, an EPR and optical investigation

Correlation of Zero Field Splittings and Site Distortions III. MnBr4 2- and Crystal Structure Refinements for Rb3ZnBr5 and Cs2ZnBr4

A description of ligand field effects in the Di-mu-Azido-Bis [{Azido(N,N-Diethylethylenediamine)}Copper(II)] compound by the simple overlap model

Contact Info

Product

Resources

About

Correlation of Zero Field Splittings and Site Distortions III. MnBr₄ ^2- and Crystal Structure Refinements for Rb₃ZnBr₅ and Cs₂ZnBr₄