Creep of Fe2SiO4 and Co2SiO4 single crystals in controlled thermodynamic environments

D. L. Ricoult; D. L. Kohlstedt; D. L. Ricoult

doi:10.1080/01418618508245271

Creep of Fe₂SiO₄ and Co₂SiO₄ single crystals in controlled thermodynamic environments

D. L. Ricoult, D. L. Kohlstedt, D. L. Ricoult

Earth and Environmental Sciences-Twin Cities

Research output: Contribution to journal › Article › peer-review

23 Scopus citations

Abstract

Creep experiments have been carried out on single crystals of Fe₂SiO₄ and Co₂SiO₄. The crystals were internally buffered by oxide precipitates against FeO and SiO₂, respectively. The following flow laws were obtained: for internally buffered fayalite, ϵ = 1·7 × 10²²σ^6±1 pg^O_Oexp(-923±220kJmoL⁻¹RT), and for internally buffered cobalt olivine. (formula presented) where ϵ is in units of s⁻¹ and σ and p_o2 are in units of MPa. In Fe₂SiO₄, he observed p_o2 dependence of the strain rate can be explained by a model in which creep is controlled by the motion of positively charged jogs along edge dislocation lines, with the diffusion of oxygen by a vacancy mechanism as the rate-limiting step. In Co₂SiO₄, on the contrary, the p_o2 dependence suggests that creep may be glide controlled, that is, rate limited by migration of ionized kinks along the dislocations. However, defect associations, which cannot be totally ruled out, were not considered in this work.

Original language	English (US)
Pages (from-to)	79-93
Number of pages	15
Journal	Philosophical Magazine A: Physics of Condensed Matter, Structure, Defects and Mechanical Properties
Volume	51
Issue number	1
DOIs	https://doi.org/10.1080/01418618508245271
State	Published - Jan 1985

Bibliographical note

Funding Information:
The authors wish to thank Professor H. Takei (Tohuku University, Sendai, Japan), the Smithsonian Institution (Washington, D.C.) and Dr. C. B. Finch (Oak Ridge Laboratory, Tenn.) for kindly donating the crystals of synthetic Co,SiO,, natural and synthetic Fe,SiO,, respectively. This work was supported by the National Science Foundation through the Materials Science Center at Cornell University.

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title = "Creep of Fe2SiO4 and Co2SiO4 single crystals in controlled thermodynamic environments",

abstract = "Creep experiments have been carried out on single crystals of Fe2SiO4 and Co2SiO4. The crystals were internally buffered by oxide precipitates against FeO and SiO2, respectively. The following flow laws were obtained: for internally buffered fayalite, ϵ = 1·7 × 1022σ6±1 pgOOexp(-923±220kJmoL−1RT), and for internally buffered cobalt olivine. (formula presented) where ϵ is in units of s−1 and σ and po2 are in units of MPa. In Fe2SiO4, he observed po2 dependence of the strain rate can be explained by a model in which creep is controlled by the motion of positively charged jogs along edge dislocation lines, with the diffusion of oxygen by a vacancy mechanism as the rate-limiting step. In Co2SiO4, on the contrary, the po2 dependence suggests that creep may be glide controlled, that is, rate limited by migration of ionized kinks along the dislocations. However, defect associations, which cannot be totally ruled out, were not considered in this work.",

author = "Ricoult, {D. L.} and Kohlstedt, {D. L.} and Ricoult, {D. L.}",

note = "Funding Information: The authors wish to thank Professor H. Takei (Tohuku University, Sendai, Japan), the Smithsonian Institution (Washington, D.C.) and Dr. C. B. Finch (Oak Ridge Laboratory, Tenn.) for kindly donating the crystals of synthetic Co,SiO,, natural and synthetic Fe,SiO,, respectively. This work was supported by the National Science Foundation through the Materials Science Center at Cornell University.",

year = "1985",

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T1 - Creep of Fe2SiO4 and Co2SiO4 single crystals in controlled thermodynamic environments

AU - Ricoult, D. L.

AU - Kohlstedt, D. L.

AU - Ricoult, D. L.

N1 - Funding Information: The authors wish to thank Professor H. Takei (Tohuku University, Sendai, Japan), the Smithsonian Institution (Washington, D.C.) and Dr. C. B. Finch (Oak Ridge Laboratory, Tenn.) for kindly donating the crystals of synthetic Co,SiO,, natural and synthetic Fe,SiO,, respectively. This work was supported by the National Science Foundation through the Materials Science Center at Cornell University.

PY - 1985/1

Y1 - 1985/1

N2 - Creep experiments have been carried out on single crystals of Fe2SiO4 and Co2SiO4. The crystals were internally buffered by oxide precipitates against FeO and SiO2, respectively. The following flow laws were obtained: for internally buffered fayalite, ϵ = 1·7 × 1022σ6±1 pgOOexp(-923±220kJmoL−1RT), and for internally buffered cobalt olivine. (formula presented) where ϵ is in units of s−1 and σ and po2 are in units of MPa. In Fe2SiO4, he observed po2 dependence of the strain rate can be explained by a model in which creep is controlled by the motion of positively charged jogs along edge dislocation lines, with the diffusion of oxygen by a vacancy mechanism as the rate-limiting step. In Co2SiO4, on the contrary, the po2 dependence suggests that creep may be glide controlled, that is, rate limited by migration of ionized kinks along the dislocations. However, defect associations, which cannot be totally ruled out, were not considered in this work.

AB - Creep experiments have been carried out on single crystals of Fe2SiO4 and Co2SiO4. The crystals were internally buffered by oxide precipitates against FeO and SiO2, respectively. The following flow laws were obtained: for internally buffered fayalite, ϵ = 1·7 × 1022σ6±1 pgOOexp(-923±220kJmoL−1RT), and for internally buffered cobalt olivine. (formula presented) where ϵ is in units of s−1 and σ and po2 are in units of MPa. In Fe2SiO4, he observed po2 dependence of the strain rate can be explained by a model in which creep is controlled by the motion of positively charged jogs along edge dislocation lines, with the diffusion of oxygen by a vacancy mechanism as the rate-limiting step. In Co2SiO4, on the contrary, the po2 dependence suggests that creep may be glide controlled, that is, rate limited by migration of ionized kinks along the dislocations. However, defect associations, which cannot be totally ruled out, were not considered in this work.

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