Modification of the diamond cell for measuring strain and the strength of materials at pressures up to 300 kilobar

Kinsland, Gary L.; Bassett, William A.

doi:10.1063/1.1134460

Cited by 103 publications

(31 citation statements)

References 10 publications

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“…Diffraction lines in A and B show clear waviness which is an indication of stress ( Fig. 3) and is not typical in experiments with axial XRD geometry as only the least stressed crystallites satisfy the Bragg's law 24 . The sinusoidal diffraction lines in A-B patterns indicate that the stress field is not uniaxial and pressure gradients exist along the compression axis near the microanvil edge.…”

Section: Resultsmentioning

confidence: 99%

Pressure, stress, and strain distribution in the double-stage diamond anvil cell

Lobanov

Prakapenka

Prescher

et al. 2015

Journal of Applied Physics

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Double stage diamond anvil cells (DAC) of two designs have been assembled and tested. We used a standard symmetric DAC as a primary stage and CVD microanvils machined by a focused ion beam -as a second. We evaluated pressure, stress, and strain distributions in Au and Fe-Au samples as well as in secondary anvils using synchrotron x-ray diffraction with a micro-focused beam. A maximum pressure of 240 GPa was reached independent of the first stage anvil culet size. We found that the stress field generated by the second stage anvils is typical of conventional DAC experiments. The maximum pressures reached are limited by strains developing in the secondary anvil and by cupping of the first stage diamond anvil in the presented experimental designs. Also, 2 our experiments show that pressures of several megabars may be reached without sacrificing the first stage diamond anvils.

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Section: Resultsmentioning

confidence: 99%

Pressure, stress, and strain distribution in the double-stage diamond anvil cell

Lobanov

Prakapenka

Prescher

et al. 2015

Journal of Applied Physics

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“…The 1 atm relation has previously been shown to agree surprisingly well with experiment 35 though zero point energies and thermal corrections were not considered. These articles [15][16]35 discuss the validity and the physical basis for the calculation of elastic properties as strain derivatives of a static crystal potential.…”

Section: Theory: Relationship Of Bulk Moduli To Vibrational Spectramentioning

confidence: 99%

“…The strong shear stress present at high pressure in such nonhydrostatic experiments can produce overly large lattice parameters and anomalously high determinations of bulk moduli. 15 Moreover, none of the accepted equations of state ͑e.g., the universal EOS or finite strain͒ adequately describes the V( P) data for B2. The best description is a straight line:…”

Section: Range Ofmentioning

confidence: 99%

“…Additional errors in V( P) are incurred through the use of solid-pressure transmitting media, 14 which lead to overestimation of the bulk moduli. 15 Acoustic data 8 only yield compression velocities v p , hence, calculation of K s not only requires assumption of V 0 and K 0 Ј with the resulting K s being highly dependent on the chosen equation of state, 8 but also assumes proportionality of shear velocity to v p . The latter assumption 8 is counterindicated by data on acoustic velocities.…”

Section: Introductionmentioning

confidence: 99%

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IR spectroscopy of alkali halides at very high pressures: Calculation of equations of state and of the response of bulk moduli to theB1−B2phase transition

Hofmeister

1997

Phys. Rev. B

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New infrared ͑IR͒ data on NaF, NaCl, KCl, KBr, and KI were obtained at pressures of up to 42 GPa. The large (ϳ20%) drops in vibrational frequencies of alkali halides upon transformation of the B1 phase to B2 are due to the decrease in bond strength as ionic separation increases, and strongly suggest that the bulk modulus K T generally decreases during the transition, rather than increases, as commonly accepted. Bulk moduli and equations of state for B1 phases are obtained from one initial volume V 0 and our vibrational frequencies i ( P) using a semiempirical model ͑previous IR data are used for Rb halides͒. For substances with a cation radius that is greater than 0.6 times the anion radius, initial values K 0 are within 0.4 to 5% of ultrasonic determinations: thus, this model is accurate for cases where quantum mechanical calculations falter. The converse holds for relatively small cations. Curvature of K T with pressure matches the previous determinations even if K 0 is not precisely predicted, which allows determination not only of K 0 Ј , but also of K 0 Љ , which is generally poorly constrained. Care must be taken in specifying the equation of state, as values for both K 0 Ј and K 0 Љ are affected by the format chosen. For the B2 phases, V( P) and K T ( P) are constrained through similar calculations which utilize the volume at the transition as the starting point. Our results are unaffected by shear stress, in contrast to previous x-ray determinations for B2. After transformation at 32 GPa, K T of NaCl-B2 is 119Ϯ4 GPa, 16 Ϯ3% below that of B1. K T ( P) of B2 rises steadily ͑KЈ is fairly large, 4.7Ϯ0.3͒ resulting in a curve. Results derived for KCl, KBr, and KI are similar such that K( P) of their B2 phases are better constrained than those of B1 due to larger stability fields. For the Rb halides, K T is roughly constant across the phase change. The compositional dependence of the changes in frequency, K T , and V for alkali halides are compatible with a simple ball-and-spring model. The calculated B2 phase volumes of the Na halide are infinite at 1 atm, consistent with instability below 8 GPa, which suggests that theoretical calculations should avoid use of 1 atm starting points for the high-pressure B2 phases.This study presents far-IR measurements of NaCl to 42 GPa, of KBr and KI to 35 GPa, and of NaF and KCl to 23 GPa. The pressure dependence of the bulk modulus K T ( P) is derived from a modified Blackman/Brout model 17-18 for both B1 and B2 phases. The motivation is ͑1͒ to constrain K 0 Љ , 56 A. M. HOFMEISTER IR SPECTROSCOPY OF ALKALI HALIDES AT VERY . . .

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“…The subsequent development of the diamond-anvil cell 45 increased the pressure range over which experiments could be performed. Early attempts to deform samples at high pressure were conducted using the diamond cell as a deformation device; 23 a technique which is still used a) Electronic mail: simon.hunt@ucl.ac.uk at very high pressures. 31 More recently, hard pistons were added to nominally hydrostatic multi-anvil assemblies 3,17 to exert a differential stress onto a sample and deform it to shear strains ∼1.…”

Section: Introductionmentioning

confidence: 99%

Deformation T-Cup: A new multi-anvil apparatus for controlled strain-rate deformation experiments at pressures above 18 GPa

Hunt

Weidner

McCormack

et al. 2014

Review of Scientific Instruments

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A new multi-anvil deformation apparatus, based on the widely used 6-8 split-cylinder, geometry, has been developed which is capable of deformation experiments at pressures in excess of 18 GPa at room temperature. In 6-8 (Kawai-type) devices eight cubic anvils are used to compress the sample assembly. In our new apparatus two of the eight cubes which sit along the split-cylinder axis have been replaced by hexagonal cross section anvils. Combining these anvils hexagonal-anvils with secondary differential actuators incorporated into the load frame, for the first time, enables the 6-8 multi-anvil apparatus to be used for controlled strain-rate deformation experiments to high strains. Testing of the design, both with and without synchrotron-X-rays, has demonstrated the Deformation T-Cup (DT-Cup) is capable of deforming 1–2 mm long samples to over 55% strain at high temperatures and pressures. To date the apparatus has been calibrated to, and deformed at, 18.8 GPa and deformation experiments performed in conjunction with synchrotron X-rays at confining pressures up to 10 GPa at 800 °C .

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Modification of the diamond cell for measuring strain and the strength of materials at pressures up to 300 kilobar

Cited by 103 publications

References 10 publications

Pressure, stress, and strain distribution in the double-stage diamond anvil cell

Pressure, stress, and strain distribution in the double-stage diamond anvil cell

IR spectroscopy of alkali halides at very high pressures: Calculation of equations of state and of the response of bulk moduli to theB1−B2phase transition

Deformation T-Cup: A new multi-anvil apparatus for controlled strain-rate deformation experiments at pressures above 18 GPa

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