Structural phase transition of the ordered fluoride CoZrF<sub>6</sub>

Rodriguez, Vincent; Couzi, M.; Tressaud, A.; Grannec, J.; Chaminade, J.P.; Soubeyroux, J.L.; Écolivet, C.

doi:10.1080/00150199008211387

Cited by 6 publications

(18 citation statements)

References 7 publications

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“…3, the experimental results are in good agreement with (7) within the temperature interval 1.5 K < To -T < 33 K. The possibility to describe the temperature dependences of the thermodynamic properties and the order parameter [7] of CoZrF, within the framework of the mean field theory can be explained from our point of view in the following way. The nature of the PT Fm3m + R3 is ferroelastic and therefore there exists a strong coupling between the main order parameter and the acoustic degrees of freedom thanks to which the critical fluctuations of rj are suppressed.…”

Section: *supporting

confidence: 74%

“…0.5%. The transition temperature To = (272.4 f 0.3) K corresponding to the maximum of the anomalous C, curve is in good agreement with the value of To obtained by Rodriguez et al [7]. The lattice and anomalous contributions have been separated by graphic extrapolation of the heat capacity curve in the cubic range to the low-temperature region (dashed line in Fig.…”

Section: Resultssupporting

confidence: 58%

“…V . GOREV et al [7]. The straight line is the predicted behaviour given by (6) For PT Fm3m + Rg the rhombohedra1 solutions are given by (2) The relationships between the elastic strains and the order parameter are found from the conditions aQ,,/t3Xi = 0, a@/aXj = 0, …”

Section: *mentioning

confidence: 99%

“…In our case it is interesting to know why the entropy change in CoZrF, (AS = 0.7R) is so large. denotes the temperatu_re interxal in which the (AC,/T)-' behaviour foilows (7); z = (To -T)/To, N = -[(B)2/3A,C7J"2 is the degree of proximity of the PT to the tricritical point [15] CoZrF, Cs,NaNdCI, [2] AS/ R 0.7 f 0. Following the notation of Aleksandrov and Misyul [13], the tilt system for CoZrF, in the rhombohedra1 phase is (qqq), which means a superposition of equal tilts around three fourfold axes.…”

Section: *mentioning

confidence: 99%

“…The temperature dependence of the order parameter of CoZrF, was measured by Rodriguez et al [7]. Its behaviour was explained within the framework of the Landau theory.…”

Section: *mentioning

confidence: 99%

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Thermodynamic Investigations of the Phase Transition in Ferroelastic CoZrF₆

Горев

Flerov

Tressaud

et al. 1992

Physica Status Solidi (b)

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Section: *supporting

confidence: 74%

Section: Resultssupporting

confidence: 58%

Section: *mentioning

confidence: 99%

Section: *mentioning

confidence: 99%

“…The temperature dependence of the order parameter of CoZrF, was measured by Rodriguez et al [7]. Its behaviour was explained within the framework of the Landau theory.…”

Section: *mentioning

confidence: 99%

See 3 more Smart Citations

Thermodynamic Investigations of the Phase Transition in Ferroelastic CoZrF₆

Горев

Flerov

Tressaud

et al. 1992

Physica Status Solidi (b)

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Transition metal impurities in fluorides: Role of electronic structure of fluorine on spectroscopic properties

Trueba¹,

García‐Fernández²,

Garcı́a-Lastra³

et al. 2011

Journal of Fluorine Chemistry

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Ground State and Optical Excitations in Compounds with Tetragonal CuF₆^4– Units: Insight into KAlCuF₆ and CuFAsF₆

Aramburu

Moreno

2019

Inorg. Chem.

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It has been argued that AAlCuF 6 (A = K, Cs) and CuFAsF 6 are the only known crystals that exhibit compressed CuF 6 4− units due to the Jahn−Teller effect. However, no grounds for this singular behavior have yet been reported. By means of first-principles calculations on such compounds and the isomorphous compounds involving Zn 2+ ions instead of Cu 2+ , we prove that neither the ground state nor the equilibrium geometry of CuF 6 4− complexes in KAlCuF 6 and CuFAsF 6 is the result of a Jahn−Teller effect. In contrast, it is shown that the internal electric field, E R (r), created by the rest of the lattice ions upon the localized electrons in the complex, plays an important role in understanding this matter as well as the d−d transitions of these two compounds. The energy of an optical transition is shown to involve two contributions: the intrinsic contribution derived for the isolated CuF 64− unit at equilibrium and the extrinsic contribution coming from the E R (r) field. Aside from reproduction of the experimental d−d transitions observed for KAlCuF 6 , it is found that in CuFAsF 6 the b 1g (x 2 − y 2 ) → a 1g (3z 2 − r 2 ) transition is not the lowest one due to the stronger effects from the internal field. Interestingly, the intrinsic contribution corresponding to that transition can simply be written as β(R eq − R ax ) where R eq and R ax are the equatorial and axial Cu 2+ −F − distances and β = 2.7 eV/Å is the same for all systems involving tetragonal CuF 6 4− units and an average metal− ligand distance close to 2.03 Å. This shows the existence of a common point shared by the Jahn−Teller system KZnF 3 :Cu 2+ and other non-Jahn−Teller systems such as KAlCuF 6 , CuFAsF 6 , K 2 ZnF 4 :Cu 2+ , and Ba 2 ZnF 6 :Cu 2+ . Although most Jahn−Teller systems display an elongated geometry, there are however many Cu 2+ compounds with a compressed geometry but hidden by an additional orthorhombic instability. The lack of that instability in KAlCuF 6 and CuFAsF 6 is also discussed.

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Structural phase transition of the ordered fluoride CoZrF₆

Cited by 6 publications

References 7 publications

Thermodynamic Investigations of the Phase Transition in Ferroelastic CoZrF₆

Thermodynamic Investigations of the Phase Transition in Ferroelastic CoZrF₆

Transition metal impurities in fluorides: Role of electronic structure of fluorine on spectroscopic properties

Ground State and Optical Excitations in Compounds with Tetragonal CuF₆^4– Units: Insight into KAlCuF₆ and CuFAsF₆

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Structural phase transition of the ordered fluoride CoZrF6

Cited by 6 publications

References 7 publications

Thermodynamic Investigations of the Phase Transition in Ferroelastic CoZrF6

Thermodynamic Investigations of the Phase Transition in Ferroelastic CoZrF6

Transition metal impurities in fluorides: Role of electronic structure of fluorine on spectroscopic properties

Ground State and Optical Excitations in Compounds with Tetragonal CuF64– Units: Insight into KAlCuF6 and CuFAsF6

Contact Info

Product

Resources

About

Structural phase transition of the ordered fluoride CoZrF₆

Thermodynamic Investigations of the Phase Transition in Ferroelastic CoZrF₆

Thermodynamic Investigations of the Phase Transition in Ferroelastic CoZrF₆

Ground State and Optical Excitations in Compounds with Tetragonal CuF₆^4– Units: Insight into KAlCuF₆ and CuFAsF₆