CoChat
Sign Up
Cited by 4Electron Spin Resonance StudiesSolid-state spectroscopy and crystallographyRare-earth and actinide compounds

The DOI matches its Crossref record; 12 of the 12 references it cites were found in a registry or an index; 1 of the 13 sources its claims cite were checked for support.

Effect of strain on the crystal field of tetragonal Gd3+in CaF2

Open access
Devine, S D·1977·Journal of Physics C: Solid State Physics
DOI 10.1088/0022-3719/10/18/021
Open this paper in CoChat — free accountOpen PDF

Abstract

The EPR longitudinal and shear strain parameters for tetragonal Gd 3+ in CaF 2 have been measured using the ultrasonic strain modulation technique (UMER). A comparison has been made with the results for the cubic Gd 3+ site using the superposition model as a guide, but as the local elastic constants for the tetragonal defect are unknown, the conclusions are tentative.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

This paper uses ultrasonically modulated EPR to measure longitudinal and shear strain/stress parameters for tetragonal Gd³⁺ in CaF₂, then compares them with the cubic Gd³⁺ site using the superposition model. The comparison is only tentative because the local elastic constants around the tetragonal defect are unknown.

Key findings

  • Stress coefficients for tetragonal Gd³⁺ in CaF₂ were determined for longitudinal and shear strains, including second-order, fourth-order, and estimates of sixth-order parameters.
  • The tetragonal parameters often differ from cubic-site values: magnitudes are of similar order, but many signs are opposite, which the paper attributes largely to the interstitial fluorine ion.
  • The fourth-order ratio for tetragonal Gd³⁺ is within 25% of the value expected for a cubic site, while the fourth-order magnitudes are lower than the pure cubic crystal by about a factor of two; the paper notes a possible 9% change in ligand equilibrium positions and cites a mean distortion of 5% from Edgar and Newman.
  • Using cubic elastic constants as an approximation, the intrinsic parameter t₂ from C₂(δ) is estimated as 3.7, compared with −0.51 for fluorine ions in cubic lattice positions; for fourth order, t₄ = 7.2 versus 7.4 for the cubic case, while another calculation gives t₄ = 21.8.

Methods

  • Design: EPR strain-modulation measurements using the ultrasonic modulation of EPR (UMER) technique on sandwich samples of tetragonal Gd³⁺ in CaF₂.
  • Data/sample: Room-temperature X-band EPR spectra were measured with 40 kHz strain modulation; stress was applied along (110) and (001) directions, with the magnetic field perpendicular to these directions. The stress modulation amplitude was 1.7 × 10⁷ dyn cm⁻², and 80 measured lines were fitted.
  • Analysis: Perturbation theory was used to relate resonant-field shifts to stress spin-lattice coefficients; fits used elastic constants from Ho and Ruoff, with strain-shift accuracy depending on strain accuracy of about 2% and magnetic-field modulation accuracy of about 4%.

Limitations

  • Stated: the local elastic constants around the tetragonal defect are unknown, so true strain coefficients cannot be evaluated and the conclusions are tentative.
  • Stated: the sixth-order parameters were not well determined, so little could be concluded about them.
  • Evident: the provided text omits Table 2 and the figure, so many fitted parameter values and equation details cannot be checked; OCR corruption also affects parts of the equations and notation.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1088/0022-3719/10/18/021

Cites

12 of 12 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

1 of 13 cited sources checked · 1 supported · 0 flagged

  • Premisecitation

    Edgar and Newman (1975) have accounted for these fourth-order parameters using a mean distortion of 5%.

    “In fact Edgar and Newman (1975) have accounted for these parameters using a mean distortion of 5 %.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Edgar and Newman (1975) source
  • Findingnone given

    The ratio b4^0 : b4^4 for tetragonal Gd3+ is within 25% of that expected on the assumption that the site is cubic.

    “The ratio of b: : b: for tetragonal Gd3+ is within 25 % of that expected on the assumption that the site is cubic.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The site is cubic for the expected ratio b4^0 : b4^4.
  • Findingcitation

    The actual magnitudes of the fourth-order parameters for tetragonal Gd3+ are lower by a factor of two from the pure cubic crystal.

    “However, the actual magnitudes of the fourth order parameters are lower by a factor of two from the pure cubic crystal”
    Quote in the paperSubstantial claim
  • Findingreasoning

    The sign of the stress coefficient C4(B1) is opposite to the equivalent cubic parameter.

    “However, the sign of the corresponding stress coefficient C:(BJ is opposite to the equivalent cubic parameter C”
    Quote in the paperSubstantial claim
  • Findingown data

    The EPR longitudinal and shear strain parameters for tetragonal Gd3+ in CaF2 have been measured using the ultrasonic strain modulation technique (UMER).

    “The EPR longitudinal and shear strain parameters for tetragonal Gd3' in CaF, have been measured using the ultrasonic strain modulation technique (UMER).”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one. 17
  • Probably not a substantial claim. 10

  • It may state two separate claims as one.

    Findingreasoning

    C2(B1) has the same sign as the corresponding cubic parameter, although it is three times as large.

    “This coefficient has the same sign as the corresponding cubic parameter, although it is three times as large.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingnone given

    Although the magnitudes of the tetragonal and cubic strain parameters are of the same order, in many cases the sign is opposite to what might be expected.

    “Although magnitudes are of the same order, in many cases the sign is opposite to what might be expected.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingnone given

    The main strain parameters for tetragonal Gd3+ obtained by Devine et al. (1974) are lower than those obtained in this work, and their errors are considerably larger.

    “In addition, the results for the main parameters are lower than those obtained here and the errors considerably larger.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Devine et a1 (1974) source

  • It may state two separate claims as one.

    Findingown data

    The ratios connecting C4(e) and C4(B1) are of the right sign but about a factor of four different from the cubic case.

    “The ratios connecting the parameters Cy(e) and C$(B,) are of the right sign but about a factor of four different from the cubic case.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingown data

    The parameters C4(e) and C4(B1) do not bear much resemblance to their corresponding cubic parameters because the signs are inconsistent.

    “The parameters CT(e) and C;(B,) do not bear much resemblance to their corresponding parameters for the cubic case as the signs are inconsistent.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingcitation

    The shear parameter C4(B3) is significant for this defect, in contrast to the cubic case where it was unimportant and could not be determined.

    “The shear parameter Ci(BJ is a significant one for this defect which is to be contrasted with the cubic case where it was unimportant and could not be determined (Devine 1976, Oseroff andCalvo 1972).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Devine 1976 source
    • cites Oseroff andCalvo 1972

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Findingnone given

    The EPR X-band spectrum of tetragonal gadolinium ranged from 0.05 to 1.3 T.

    “The EPR X-band spectrum of the tetragonal gadolinium ranged from 0.05 to 1.3 T.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingreasoning

    Assuming the local elastic constants S11 and S12 are cubic, the power-law intrinsic parameter t4 is 7.2, in good agreement with 7.4 obtained for the cubic case.

    “If the local elastic constants S,, and S12 are assumed to be cubic, which may be a good approximation for the lattice fluorine ions as the force constants between them and the paramagnetic ion is not expected to alter a great deal in tetragonal environment, the power law intrinsic parameter is given by t, = -C~(6)120/b~(Sl, + 2S12). (7) Using the value of C:(s) from table 2 the result is t, = 7.2”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The local elastic constants S11 and S12 for the tetragonal defect are approximately those for the cubic site, or are cubic.
    • Rests on an assumption: The force constants between the lattice fluorine ions and the paramagnetic ion are not expected to alter a great deal in the tetragonal environment.

  • It may state two separate claims as one.

    Findingown data

    The ratio C4(e)/C2(e) is -6.4, compared with -7 for a cubic site.

    “For example, Ci(e)/C:(e) = -6.4compared with -7 for a cubic site.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Interpretationnone given

    In the tetragonal case, the interstitial fluorine gives rise to the b2^0 parameter and the corresponding hydrostatic stress coefficient C2(δ).

    “In the tetragonal case the interstitial fluorine gives rise to the b; parameter and the corresponding hydrostatic stress coefficient C;(6).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.

    Interpretationnone given

    If the cubic fluorine ions dominated C4(B3) and C4(E), then C4(E) would equal 2C4(B1).

    “The latter arising from a shear strain in the xz plane.would be equal to 2C:(B,) arising from a shear strain in the xy plane if the cubic fluorine ions dominated these parameters.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Interpretationreasoning

    The parameter C2(e) arising from a longitudinal stress is dominated by the interstitial ion and is opposite in sign to the cubic parameter.

    “The parameter C;(e) arising from a longitudinal stress is also dominated by the interstitial ion so it is no surprise to see that it is opposite in sign to the cubic parameter.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Interpretationcitation

    The lower fourth-order magnitudes might be accounted for by a 9% change in the equilibrium positions of the surrounding ligands.

    “an observation that might be accounted for by a 9 % change in the equilibrium positions of the surrounding ligands (Devine et al 1974).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Devine et al 1974 source

  • It may state two separate claims as one.

    Interpretationreasoning

    Even if the interstitial ion makes no direct contribution to C4(B3) and C4(E), it is likely to have a marked effect on the elastic constants appropriate to an xz strain, so that comparison between them is not particularly fruitful.

    “However, even if the interstitial ion makes no direct contribution to these coefficients, it is likely to have a marked effect on the elastic constants appropriate to an xz strain, so that such a comparison is not particularly fruitful.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisenone given

    The only previous measurements of the strain parameters of the tetragonal system were those obtained by Devine et al. (1974).

    “The only previous measurements of the strain parameters of the tetragonal system were those obtained by Devine et a1 (1974).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Devine et a1 (1974) source

  • Probably not a substantial claim. The paper may give no reason why it holds.

    Premisenone given

    For a cubic site there is no contribution to the second-order crystal-field parameters unless there is a non-cubic distortion.

    “For a cubic site there is no contribution to the second order parameters unless there is a non-cubic distortion.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Interpretationcitation

    The direct contribution of the interstitial defect to the fourth-order parameters is small, and the main effect is distortion of the lattice fluorine positions.

    “indicating that the direct contribution of the interstitial defect is small and that the main effect is the distortion of the lattice fluorine positions.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Interpretationcitation

    The change in sign of the interstitial fluorine contribution from that of fluorines at the corner of a cube might well be expected as the fluorine-gadolinium distance has increased.

    “but the change in sign of the interstitial fluorine from that of fluorines at the corner of a cube might well be expected as the fluorine gadolinium distance has increased (Stedman and Newman 1974).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Stedman and Newman 1974 source

  • It may state two separate claims as one.

    Interpretationreasoning

    The superposition model predicts a contribution to C4(B1) of the form (1 - t2)B2(R) from the four fluorine ions in the cubic environment; a change in sign of t2 to a positive value greater than unity would give rise to a change in sign of this parameter.

    “On the other hand, the superposition model predicts a contribution to C;(B,) of the form (1 -t2)B2(R) from the four fluorine ions in the cubic environment, a change in sign oft, to a positive value greater than unity would give rise to a change in sign of this parameter.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The intrinsic parameter B_n(R) varies with distance as R^{-t_n}.

  • It may state two separate claims as one.

    Premisecitation

    The crystal field parameters for tetragonal Gd3+ in CaF2 have been evaluated by Vinokurov et al. (1963) for charge compensation by an interstitial fluorine and by Zdansky and Edgar (1971) for compensation by an interstitial hydrogen ion.

    “The crystal field parameters have been evaluated for tetragonal Gd3+ in CaF, by Vinokurov et al(1963) for charge compensation by an interstitial fluorine, and by Zdansky and Edgar (1971) for the case of compensation by an interstitial hydrogen ion.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Vinokurov et al(1963)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Zdansky and Edgar (1971)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Interpretationreasoning

    The interstitial contribution may be more significant for the coefficient of O4^4, as the effect on the unstrained parameter b4^4 is 25%.

    “The interstitial contribution may be more significant for the coefficient of O:, as has been mentioned the effect on the unstrained parameter b: is 25 %.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Interpretationreasoning

    The high value of t4 = 21.8 might arise if the second-order parameters contribute to the fourth-order terms via some quadratic perturbation.

    “Such a high value might also arise if the second order parameters contribute to the fourth order terms via some quadratic perturbation.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    The values of B_n(R) and t_n have been tabulated for the cubic system by Devine (1976).

    “The values of B,(R) and t, have been tabulated for the cubic system by Devine (1976).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Devine (1976) source

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Study design and conductnone given

    The sixth-order parameters have not been well determined, so little can be said about the values obtained.

    “The sixth order parameters have not been well determined SO that little can be said about the values obtained.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Study design and conductnone given

    The accuracy of the strain shift depends on the accuracy of the strain, which is about 2%, and the accuracy of the magnetic field modulation, about 4%.

    “The accuracy of the strain shift depends on the accuracy of the strain which is -2 % and the accuracy of the magnetic field modulation (-4 %).”
    Quote in the paperNot a substantial claim
25 of 25

  • The paper relies on this without support.

    The local elastic constants for the tetragonal defect are unknown.

    “as the local elastic constants for the tetragonal defect are unknown, the conclusions are tentative.”
    “As the locai elastic constants around the defect are unknown, the local strain is unknown for a given stress, and the normal coordinate expression cannot be evaluated in the strain expansion.”

  • The authors state this as an assumption.

    The intrinsic parameter B_n(R) varies with distance as R^{-t_n}.

    “B,(R) is assumed to vary with distance as R-tri.”

  • The authors state this as an assumption.

    The local elastic constants S11 and S12 for the tetragonal defect are approximately those for the cubic site, or are cubic.

    “An estimate can be made by assuming the local elastic constants SI, and s,, are approximately those for the cubic site”
    “If the local elastic constants S,, and S12 are assumed to be cubic”

  • The authors state this as an assumption.

    The site is cubic for the expected ratio b4^0 : b4^4.

    “on the assumption that the site is cubic.”

  • The paper relies on this without support.

    The force constants between the lattice fluorine ions and the paramagnetic ion are not expected to alter a great deal in the tetragonal environment.

    “as the force constants between them and the paramagnetic ion is not expected to alter a great deal in tetragonal environment”
5 of 5

Citations

Cites

Flagged first, then by citations

Research works printed but not linked: 2

  1. Devine S D, 1977, J. Appl. Phys.
  2. Vinokurov V M, 1963, Sov. Phys.-Solid St., 4, 1637

Cited by

Sorted by citations

Related

Metadata

Authors
Devine, S. D.
Corresponding author
Devine, S D
Venue
Journal of Physics C: Solid State Physics
Publisher
IOP Publishing
Published
1977-09-28
Volume
10
Issue
18
Pages
3569-3575
ISSN
0022-3719 (ISSN-L)
DOI
10.1088/0022-3719/10/18/021
OpenAlex
W2032378347
Cited by
4
References
12
FWCI
0.72
Type
journal article
Language
en
Open access
Locations
Journal of Physics C Solid State Physics (publishedVersion)
Topics
  • Physical Sciences › Chemistry › Spectroscopy › Electron Spin Resonance Studies
  • Physical Sciences › Materials Science › Materials Chemistry › Solid-state spectroscopy and crystallography
  • Physical Sciences › Physics and Astronomy › Condensed Matter Physics › Rare-earth and actinide compounds
Keywords
gadolinium ions, calcium fluoride, crystal field, strain, superposition model, point defects

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

A language model drew the claims from the paper on 2026-10-11, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).

A second model labelled each claim on 2026-10-11 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).

Cited sources are checked with a language model’s help (gpt-6-sol).

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review