Anomalous stress effects on the fluorescence of SrTiO3:Cr3+

Burke, William J.; Pressley, R. J.

doi:10.1016/0038-1098(69)90173-2

Cited by 38 publications

(10 citation statements)

References 6 publications

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“…47,48 The compression of the crystal in the ͓111͔ direction ͑equivalent of the tensile stress in the ͑111͒ plane͒ leads to a transformation into the nonpolar trigonal phase. 49 According to the single-crystal phase diagram, 50 T a is increased up to ϳ125 K under an applied uniaxial ͓111͔ stress of 0.7 GPa (67 kg/mm 2 ) corresponding to our results. However, the appearance of the in-plane polarization in the film should indicate its symmetry reduction to monoclinic at least.…”

Section: ͑2͒supporting

confidence: 84%

Origin of soft-mode stiffening and reduced dielectric response inSrTiO3thin films

et al. 2002

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The problem of the reduced dielectric response in thin films of high-permittivity materials is analyzed by studying the soft-mode response in several SrTiO 3 thin films by means of Fourier transform far infrared, monochromatic submillimeter, and micro-Raman spectroscopies. A 300-nm-thick metalorganic chemical vapor deposition film, quasiepitaxially grown on a ͑0001͒ sapphire substrate with a perfect ͗111͘ orientation, displays a ferroelectric transition near 125 K induced by a tensile residual stress, appearing apparently simultaneously with the antiferrodistortive transition. On the other hand, polycrystalline chemical solution deposition films grown on ͑0001͒ sapphire, and also tensile stressed, show a harder soft mode response without the appearance of macroscopic ferroelectricity. This effect, which increases with the film thickness, is explained by a strong depolarizing field induced by the percolated porosity and cracks ͑in the 10-nm scale͒ along the boundaries of columnar grains ͑normal to the probe field direction͒. Brick-wall model calculations showed that 0.2 vol. % of such a porosity type reduces the permittivity from 30000 to less than 1000. The activation of the forbidden IR modes in the Raman spectra in the whole 80-300-K temperature range studied is explained by the effect of polar grain boundaries, in analogy with the bulk ceramics.

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Section: ͑2͒supporting

confidence: 84%

Origin of soft-mode stiffening and reduced dielectric response inSrTiO3thin films

et al. 2002

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“…From 110 K to 300 K, the thermal expansion of SrTiO 3 is almost linear with a measured linear coefficient of expansion 9.4 × 10 −6 K −1 , [9] which is close to the linear coefficient of expansion of MgO (Its value is 9.35 × 10 −6 K −1 at 252 K; when T < 252 K, it decreases; and when T > 252 K, it increases [8] ). Because the difference between the pressure-induced R-line shifts of SrTiO 3 :Cr 3+ and MgO:Cr 3+ is not large, [2,8,10] we may approximately estimate the contribution from thermal expansion to R-line TS of SrTiO 3 :Cr 3+ by the one of MgO:Cr 3+ . From 76.8 K to 265.6 K, it is only 4.9 cm −1 , [8] and the total R-line TS of SrTiO 3 :Cr 3+ is 61 cm −1 .…”

Section: Various Contributions To Ts From Epimentioning

confidence: 99%

Estimation of the saturation energy density in a 2.92-μmQ-switched single-frequency Cr³⁺:Yb³⁺:Ho³⁺:YSGG laser

2003

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By taking into account all the irreducible representations and their components in the electron-phonon interaction (EPI) as well as all the levels and the admixtures of basic wavefunctions within d 3 electronic configuration, the values of the parameters in the expressions of thermal shift (TS) from EPI for the ground level, R level and R line of SrTiO3:Mn 4+ have been evaluated; the R-line TS and various contributions to it have been calculated in the low-temperature region. It is found that all the three terms of R-line TS from EPI relevant to the lattice vibration are red shifts. The Raman term is the largest, the neighbor-level term is the second, and the optical-branch term is very small over the range of T ≤ 80 K. The contribution to R-line TS from thermal expansion has been approximately neglected in this work. The very strong EPI relevant to its lattice vibration for SrTiO3:Mn 4+ causes its R-line TS to be an unusually large red-shift. Only by taking into account the strong softening of the low-frequency acoustic modes of the lattice vibration at low temperatures, can we successfully explain the variation of R-line TS of SrTiO3:Mn 4+ with temperature.

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“…[21] The measurements for the splittings of the R line and the ground state of SrTiO 3 :Cr 3+ caused by uniaxial stresses were made. [20,22] For the ferroelectricity and antiferroelectricity, things of most importance are the researches on lattice dynamics and electron-phonon interaction, which are closely connected with the thermal shift of R line. Further, the foundations of studies of R-line thermal-shift and EPR spectrum are the energy spectra and wavefunctions of crystals.…”

Section: Introductionmentioning

confidence: 99%

Energy Spectra, g Factors and Their Pressure-Induced and/or Thermal Shifts of SrTiO ₃ :Cr ³⁺ and SrTiO ₃ :Mn ⁴⁺ I: Energy Spectra and g Factors at Normal Pressure

Zhang

2001

Commun. Theor. Phys.

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With the strong-field scheme and cubic bases, the complete d3 energy matrix in a tetragonally distorted cubic-field has been constructed. By diagonalizing this matrix, the energy spectra of SrTiO3:Cr3+ and SrTiO3:Mn4+ at normal pressure and various temperatures have been calculated. Correspondingly, the FORTRAN program calculating the g factor of the ground state has been worked out. By using the program and the wavefunction obtained from diagonalizing the complete energy matrix, the g factors of the ground state of SrTiO3:Cr3+ and SrTiO3:Mn4+ at normal pressure and room temperature have been evaluated. The calculated results are in good agreement with the optical-spectral and EPR experimental data. The comparison and analysis of the results of two crystals have been made. It is demonstrated that the covalency of the bonding between Mn4+ and ligands (O2-) in SrTiO3:Mn4+ is stronger than the one of the bonding between Cr3+ and ligands (O2-) in SrTiO3:Cr3+. It is shown that the obtained wavefunctions and values of parameters are reasonable.

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Anomalous stress effects on the fluorescence of SrTiO3:Cr3+

Cited by 38 publications

References 6 publications

Origin of soft-mode stiffening and reduced dielectric response inSrTiO3thin films

Origin of soft-mode stiffening and reduced dielectric response inSrTiO3thin films

Estimation of the saturation energy density in a 2.92-μmQ-switched single-frequency Cr³⁺:Yb³⁺:Ho³⁺:YSGG laser

Energy Spectra, g Factors and Their Pressure-Induced and/or Thermal Shifts of SrTiO ₃ :Cr ³⁺ and SrTiO ₃ :Mn ⁴⁺ I: Energy Spectra and g Factors at Normal Pressure

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Anomalous stress effects on the fluorescence of SrTiO3:Cr3+

Cited by 38 publications

References 6 publications

Origin of soft-mode stiffening and reduced dielectric response inSrTiO3thin films

Origin of soft-mode stiffening and reduced dielectric response inSrTiO3thin films

Estimation of the saturation energy density in a 2.92-μmQ-switched single-frequency Cr3+:Yb3+:Ho3+:YSGG laser

Energy Spectra, g Factors and Their Pressure-Induced and/or Thermal Shifts of SrTiO 3 :Cr 3+ and SrTiO 3 :Mn 4+ I: Energy Spectra and g Factors at Normal Pressure

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Estimation of the saturation energy density in a 2.92-μmQ-switched single-frequency Cr³⁺:Yb³⁺:Ho³⁺:YSGG laser

Energy Spectra, g Factors and Their Pressure-Induced and/or Thermal Shifts of SrTiO ₃ :Cr ³⁺ and SrTiO ₃ :Mn ⁴⁺ I: Energy Spectra and g Factors at Normal Pressure