Material Strength Effect in the Shock Compression of Alumina

Ahrens, Thomas J.; Gust, W.; Royce, E. B.

doi:10.1063/1.1655810

Cited by 125 publications

(48 citation statements)

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“…Table 6). (Data from McQueen and Marsh [ 1966] and Ahrens et al [1968].) Ius value, making it quite comparable to ultrasonic data for polycrystalline Ah03.…”

Section: Anderson Et Al [1968] Usingsupporting

confidence: 53%

“…In the case of Al20 3 this result is not unexpected, since, at low pressures (below 300 kb), Hugoniot data are known to be offset in pressure by -40 to 50 kb above the isothermal X-ray data of PerezAlbuerne and Drickamer [1965]. This offset above the isothermal data in the shock pressure is believed to be the result of residual stress differences in the high-pressure shock state [Ahrens et al, 1968]. This so-called strength effect [1966]; McQueen et al [1967b].…”

mentioning

confidence: 71%

“…The stress offset, calculated from the value of Trn at the Hugoniot elastic limit for Ab03 ceramic and for crystaldensity polycrystalline Al20 3 , is 40 and 52 kb, respectively. When these stress offsets are subtracted (at a given density) from the pressures along the Hugoniot, the resulting adiabats obtained from the 'hydrostatic' Hugoniot almost coincide with Perez-Albuerne and Drickamer's [1965] hydrostatic X-ray data for Al20 3 [Ahrens et al, 1968]. By applying this correction to the Al20 3 data over the entire pressure range and a similar correction of t:..Ph = 15 kb for MgO (based on a minimum value of the HEL of 37 kb [Ahrens, 1966], the set of corrected equations of state parameters given in Table 6 is obtained.…”

mentioning

confidence: 93%

“…The differing constraints on the zero-pressure density of the hpp of W aug's analysis, in which the Birch relation was used to infer the zero-pressure density, and that of Anderson and Ahrens et al [1968]. ' 1'runin et al [1965]. '…”

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confidence: 99%

“…c Values obtained from measured values of (dK0 ./dP)T using formula given by Chung [1967]. "Ahrens et al [1968].…”

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confidence: 99%

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Equations of state and crystal structures of high‐pressure phases of shocked silicates and oxides

Ahrens¹,

Anderson²,

Ringwood³

1969

Reviews of Geophysics

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260

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Abstract. Shock-wave data are now available for a variety of rocks, minerals, and oxides of geophysical interest in the pressure range appropriate for the lower mantle. These data are analyzed to obtain equation-of-state parameters with emphasis on the shock-induced high-pressure phases. Of twenty-four materials for which Hugoniot data are analyzed, all but MgO, AlzO,, and Mn02 undergo at least one shock-induced phase change below 800 kb. Birch-Murnaghan parameters for the raw Hugoniots, metastable Hugoniots, adiabats, and 25°C isotherms are obtained for the high-pressure phases. On correcting the raw Hugoniot data for MgO and ALOa for strength effects, we find that the calculated adiabatic equations of state are in good agreement with recent ultrasonic data. The zero-pressure densities of high-pressure phases are obtained by constraining the adiabats calculated from the Hugoniot data such that the zero~ pressure densities and the zero-pressure slopes of the adiabats satisfy Anderson's seismic equation of state.Probable crystallographic stmcturcs of the high-pressure phases are inferred from the classical laws of crystal chemistry and, in some cases, from static high-pressure recovery experiments on analog compounds. Shock data for Si02 (stishovite) indicate that transformation to the fluorite-type structure (observed in TiO,) does not take place under shock, at least to -2000 kb. Fe203 probably transforms to either the perovskite or B rare earth structure with a zero-pressure density of 5.96 g/cm 3 • MgAl20• (spinel) may transform to the CaFe20< structure with a zero-pressure density of 4.19 g/cm 3 • 1 Contribution 1571, Division of Geological Sciences, California Institute of Technology, Pasadena.2 On leave from Australian National University, Canberra, Australia.Copyright © 1969 by the American Geophysical Union. 668 AHRENS, ANDERSON, AND RINGWOODFeldspars transform to the hollandite structure (density, of -3.85 g/cm 3 ). Olivine-rich rocks containing greater than 10% FeO either disproportionate to the ilmenite and rock salt structure or transform to a new post-spinel polymorph having the Sr.2PbO. structure. Pyroxenes containing greater than 10% FeO probably transform to the ilmenite structure. High-pressure forms of sillimanite and andalusite have calculated densities of 4.00 and 3.95 g/cm", respectively. This probably represents disproportionation reaction products, A10s + Si02 (stishovite), which would give a density of 4.09 g/cm 3 •The Birch-Murnaghan second-order parameter ~ is nearly zero for MgO and AI.Oa. 0.73 for stishovite, and -1 for the high-pressure phases of the olivines and pyroxenes.

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“…Table 6). (Data from McQueen and Marsh [ 1966] and Ahrens et al [1968].) Ius value, making it quite comparable to ultrasonic data for polycrystalline Ah03.…”

Section: Anderson Et Al [1968] Usingsupporting

confidence: 53%

mentioning

confidence: 71%

mentioning

confidence: 93%

mentioning

confidence: 99%

“…c Values obtained from measured values of (dK0 ./dP)T using formula given by Chung [1967]. "Ahrens et al [1968].…”

mentioning

confidence: 99%

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