Study of the lattice sites of Ti and Ni impurities in LiNbO<sub>3</sub>single crystals, by means of X-ray absorption spectroscopy

Zaldo, C.; Prieto, C.; De×pert, H.; Fessler, P.

doi:10.1088/0953-8984/3/23/002

Cited by 44 publications

(22 citation statements)

References 30 publications

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“…1) The uncertainty reached in the R a values measured through EXAFS is higher than 1 pm [7][8][9]. For instance, in the case of LiNbO 3 doped with Mn 2+ [7] and Ti 4+ [9] the metal-ligand distances involve uncertainties of + 5 pm.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Impurity-ligand distances derived from magnetic resonance and optical parameters

1992

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Non empirical methods for obtaining information from EPR, ENDOR and optical data on the true impurity-ligand distance, R, as weU as on the true va¡ AR, induced by chemical and hydrostatic pressures, phase transiUons in the host material and temperature changes are discussed through this work. Special attention is addressed to spectroscopic parameters of d-impurities whose dependence on R can reasonably be calculated theoretically for the superhyperfine (shf) tensor or the lowest optical transitions but not for fine structure temas. In the case of Ÿ with unpalred o-electrons it is shown that the isotropic shf constant, A~, is specially sensitive to R changes.The microscopic origJn of this fact is discussed in detail. Determination of true R values from experimental A s has been carried out for impurities like Mn 2+ or Ni + with encouraging results. In the case of Mn 2+ in fluorides, results obtained by this method coincide with those reached through EXAFS and the analysis of the experimental 10 Dq. FinaUy, for some selected complexes, a view is offered on the dependence of several EPR and optical parameters upon metal-ligand distances. The ma_in conclusion is that AR values of the order of 0.1 pro can be detected using EPR and optical parameters thus irnproving by an order of magnitude the sensitivity reached through EXAFS. In particular the use of ENDOR allows one to measure AR values close to 0.01 pm.

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Section: Introductionmentioning

confidence: 99%

“…For instance, in the case of LiNbO 3 doped with Mn 2+ [7] and Ti 4+ [9] the metal-ligand distances involve uncertainties of + 5 pm. Therefore, ARK changes produced by applied hydrostatic pressures lower than about 5 GPa, structural phase transitions in the host lattice or thermal expansion effects cannot be detected at all using EXAFS.…”

Section: Introductionmentioning

confidence: 99%

Impurity-ligand distances derived from magnetic resonance and optical parameters

1992

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“…This brief introduction highlights the importance of having a good understanding of the lattice distortions induced by substitutional impurities in ionic crystals. Moreover, their experimental measurement is a difficult task, [2][3][4] and so theoretical calculations become an ideal complement to the experimental studies.…”

Section: Introductionmentioning

confidence: 99%

Ga + , In+, and Tl+ impurities in alkali halide crystals: Distortion trends

Aguado

2000

The Journal of Chemical Physics

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A computational study of the doping of alkali halide crystals (AX: A = Na, K; X = Cl, Br) by ns 2 cations (Ga + , In + and Tl + ) is presented. Active clusters of increasing size (from 33 to 177 ions) are considered in order to deal with the large scale distortions induced by the substitutional impurities. Those clusters are embedded in accurate quantum environments representing the surrounding crystalline lattice. The convergence of the distortion results with the size of the active cluster is analyced for some selected impurity systems. The most important conclusion from this study is that distortions along the (100) and (110) crystallographic directions are not independent. Once a reliable cluster model is found, distortion trends as a function of impurity, alkali cation and halide anion are identified and discussed. These trends may be useful when analycing other cation impurities in similar host lattices.

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“…The electronic spectra of doped ionic crystals are known to be strongly coupled with the crystal field, and thus are quite sensitive to the lattice distortions around the impurity. Employment of extended X-ray-absorption fine structure (EXAFS) technique would allow in principle the experimental measurement of these distortions, but in practice this is difficult in many cases: for example, when the impurity concentration is low [2][3][4], or when two or more impurity charge states coexist [5]. This is the main reason why reliable ab initio calculations of the local structure around defects are both timely and desirable.…”

Section: Introductionmentioning

confidence: 99%

Quantum Mechanical Study of the Lattice Distortions Induced by Aliovalent Pb2+ Impurities in Alkali Halides

Aguado

2002

phys. stat. sol. (b)

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An embedded cluster analysis of the lattice distortions induced by a Pb 2þ substitutional impurity in NaI, RbI and CsF crystals is presented. Active clusters containing more than 100 atoms and embedded in a quantum representation of the crystalline environment are used. Charge compensation is achieved by introducing a cation vacancy in the host lattice. Both nearest-neighbor (NN) and next-nearest-neighbor (NNN) vacancy positions are explicitly considered, as well as the case where vacancy and impurity are well separated from each other. Only in the first two cases, the impurity adopts an off-center equilibrium position. Distortion trends as a function of the host lattice are identified and discussed. These trends are then employed to advance the expected distortions in similar crystals. The examples of Pb 2þ -doped RbF and KBr are found to behave according to the expectations. Finally, the relative stability of the NN and NNN configurations is discussed.

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Study of the lattice sites of Ti and Ni impurities in LiNbO₃single crystals, by means of X-ray absorption spectroscopy

Cited by 44 publications

References 30 publications

Impurity-ligand distances derived from magnetic resonance and optical parameters

Impurity-ligand distances derived from magnetic resonance and optical parameters

Ga + , In+, and Tl+ impurities in alkali halide crystals: Distortion trends

Quantum Mechanical Study of the Lattice Distortions Induced by Aliovalent Pb2+ Impurities in Alkali Halides

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Study of the lattice sites of Ti and Ni impurities in LiNbO3single crystals, by means of X-ray absorption spectroscopy

Cited by 44 publications

References 30 publications

Impurity-ligand distances derived from magnetic resonance and optical parameters

Impurity-ligand distances derived from magnetic resonance and optical parameters

Ga + , In+, and Tl+ impurities in alkali halide crystals: Distortion trends

Quantum Mechanical Study of the Lattice Distortions Induced by Aliovalent Pb2+ Impurities in Alkali Halides

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Product

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Study of the lattice sites of Ti and Ni impurities in LiNbO₃single crystals, by means of X-ray absorption spectroscopy