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Herrington, J. R.; Boatner, L. A.; Aton, T.; Estle, T. L.

doi:10.1103/physrevb.10.833

Cited by 24 publications

(7 citation statements)

References 15 publications

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“…In the realm of the E⊗e JT coupling, d 9 impurities have been explored in cubic lattices like alkali and silver halides, fluoroperovskites, and oxides like MgO or SrO [31,34,35,[235][236][237][238][239]. Also some attention has been addressed to d 7 ions in low-spin configuration in alkali and silver halides [31,32,213].…”

Section: Phenomena Related To Thementioning

confidence: 99%

Microscopic insight into properties and electronic instabilities of impurities in cubic and lower symmetry insulators: the influence of pressure

Moreno

Barriuso

Aramburu

et al. 2006

J. Phys.: Condens. Matter

224

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This article reviews the microscopic origin of properties due to transition-metal (TM) impurities, M, in insulator materials. Particular attention is paid to the influence of pressure upon impurity properties. Basic concepts such as the electronic localization in an MX(N) complex, the electrostatic potential, V(R), arising from the rest of the lattice ions or the elastic coupling of the complex to the host lattice are initially exposed. The dependence of optical and magnetic parameters on the impurity-ligand distance, R, in cubic lattices is discussed in a first step. Emphasis is put on the actual origin of the R dependence of 10Dq. Examples revealing that laws for strict cubic symmetry cannot in general be transferred to lower symmetries are later given. This relevant fact is shown to come from allowed hybridizations like nd-(n+1)s as well as the influence of V(R). As a salient feature the different colour in ruby and emerald is stressed to arise from distinct V(R) potentials in Al(2)O(3) and Be(3)Si(6)Al(2)O(18). The last part of this review deals with electronic instabilities. The phenomena associated with the Jahn-Teller (JT) effect in cubic lattices, the origin of the energy barrier among equivalent minima and the existence of coherent tunnelling in systems like MgO:Cu(2+) are discussed. An increase of elastic coupling is pointed out to favour a transition from an elongated to a compressed equilibrium conformation. Interestingly the equilibrium geometry of JT ions in non-cubic lattices is shown to be controlled by mechanisms different to those in cubic systems, V(R) playing again a key role. The relevance of first principles calculations for clarifying the subtle mechanisms behind off-centre instabilities is also pointed out. Examples concern monovalent and divalent TM impurities in lattices with the CaF(2) structure. The instability due to the transition from the ground to an excited state is finally considered. For complexes with significant elastic coupling vibrational frequencies and the Stokes shift are expected to undergo bigger changes through a chemical rather than a hydrostatic pressure. The reduction of Huang-Rhys factors upon increasing the pressure is discussed as well.

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Section: Phenomena Related To Thementioning

confidence: 99%

Microscopic insight into properties and electronic instabilities of impurities in cubic and lower symmetry insulators: the influence of pressure

Moreno

Barriuso

Aramburu

et al. 2006

J. Phys.: Condens. Matter

224

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“…According to Herrington et a1 [4] Ham's weak linear E C 3 E Jahn-Teller cluster model [2] explains the observed ESR spectra well when one assumes that the vibronic groundstate doublet (2Es) and the symmetrical first excited state (a singlet) are separated by an energy difference much larger than the microwave quantum. Then, the use of an effective Hamiltonian within only the doublet is justified in explaining the conventional ESR experiments,…”

Section: The Jahn-teller Modelmentioning

confidence: 99%

“…Examples which exhibit in their ESR spectrum pronounced effects due to random strain are Sc2+ in the alkaline earth fluorides [3], Y2+ [4] and La2+ [3] in SrC12.…”

Section: Introductionmentioning

confidence: 99%

“…These facts prompted us to study the effect of uniaxial stress on the ESR spectrum of an appropriately chosen system. The Y2+ ion in SrC12 is useful because its ESR spectrum is known and has been interpreted successfully [4] with the Ham cluster model. It has the further merit of relative simplicity as we have a 4d1 ion with a nuclear spin I = 4.…”

Section: Introductionmentioning

confidence: 99%

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The effect of trigonal and tetragonal stresses on the model Jahn-Teller system Y²⁺:SrCl₂

Bill¹,

Lovy²

1989

J. Phys.: Condens. Matter

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The effect of externally applied stresses of e, and tZg symmetry on the cubic E, C3 e, Jahn-Teller (IT) system Y2+ in SrC1, is studied. Coupling constants were obtained with the aid of EPR and by relying on a Ham-type clustern Hamiltonian, in conjunction with a random strain distribution. This is established from a critical review of the contributing strain sources (including possible percolation effects due to the isotopic composition of natural SrCIJ. The stress of tzg symmetry shows strong effects. We conclude that the cubic Ham factor q is nearly one and that the experiments allow, as a function of this latter stress, us to pass gradually towards a trigonal JT effect. The optical absorption spectrum assigned to Yz+ is given in addition.

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“…1,2 This expectation is based primarily on the analogy with Ti 31 which has the same electronic configuration (3d 1 ) as Sc 21 . [6][7][8][9] In the early work 7-9 the scandium doping was accomplished by evaporating a film of scandium metal onto a pure CaF 2 crystal surface, and then diffusing it into the bulk at an elevated temperature prior to irradiation. It is broadly tunable in the near infrared.…”

mentioning

confidence: 99%

Method for producing large, stable concentrations of Sc²⁺in optically clear CaF₂ crystals

et al. 1998

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This communication describes a new method for producing stable, high concentrations of Sc 21 in optically clear CaF 2 crystals. We have achieved Sc 21 concentrations as high as 3 3 10 18 cm 23 without degradation of optical quality. We have converted as much as 5% of the scandium dopant to the divalent state. The concentration of divalent scandium is stable during room temperature storage for periods of at least one year.

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Electron-paramagnetic-resonance investigation of the dynamic Jahn-Teller effect forSc2+in BaF2

Cited by 24 publications

References 15 publications

Microscopic insight into properties and electronic instabilities of impurities in cubic and lower symmetry insulators: the influence of pressure

Microscopic insight into properties and electronic instabilities of impurities in cubic and lower symmetry insulators: the influence of pressure

The effect of trigonal and tetragonal stresses on the model Jahn-Teller system Y²⁺:SrCl₂

Method for producing large, stable concentrations of Sc²⁺in optically clear CaF₂ crystals

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Electron-paramagnetic-resonance investigation of the dynamic Jahn-Teller effect forSc2+in BaF2

Cited by 24 publications

References 15 publications

Microscopic insight into properties and electronic instabilities of impurities in cubic and lower symmetry insulators: the influence of pressure

Microscopic insight into properties and electronic instabilities of impurities in cubic and lower symmetry insulators: the influence of pressure

The effect of trigonal and tetragonal stresses on the model Jahn-Teller system Y2+:SrCl2

Method for producing large, stable concentrations of Sc2+in optically clear CaF2 crystals

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Product

Resources

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The effect of trigonal and tetragonal stresses on the model Jahn-Teller system Y²⁺:SrCl₂

Method for producing large, stable concentrations of Sc²⁺in optically clear CaF₂ crystals