Limits...
Inelastic response of silicon to shock compression.

Higginbotham A, Stubley PG, Comley AJ, Eggert JH, Foster JM, Kalantar DH, McGonegle D, Patel S, Peacock LJ, Rothman SD, Smith RF, Suggit MJ, Wark JS - Sci Rep (2016)

Bottom Line: We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported 'anomalous' elastic waves.Moreover, this interpretation allows for measurement of the kinetic timescales for transition.This model is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK.

ABSTRACT
The elastic and inelastic response of [001] oriented silicon to laser compression has been a topic of considerable discussion for well over a decade, yet there has been little progress in understanding the basic behaviour of this apparently simple material. We present experimental x-ray diffraction data showing complex elastic strain profiles in laser compressed samples on nanosecond timescales. We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported 'anomalous' elastic waves. Moreover, this interpretation allows for measurement of the kinetic timescales for transition. This model is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature.

No MeSH data available.


Related in: MedlinePlus

Elasticity code determined strain history the sample (a) after onset of the drive within the silicon. Shown inset in (b) are simulated and experimental white light Laue signals for x-ray exposure between 3.5–4.5 ns (as indicated by the dashed lines) in (a). This is consistent with the experimental backligher timing of 5 ns once transit time though the ablator is accounted for. Also shown in (b) are lineouts of these signals.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4829838&req=5

f3: Elasticity code determined strain history the sample (a) after onset of the drive within the silicon. Shown inset in (b) are simulated and experimental white light Laue signals for x-ray exposure between 3.5–4.5 ns (as indicated by the dashed lines) in (a). This is consistent with the experimental backligher timing of 5 ns once transit time though the ablator is accounted for. Also shown in (b) are lineouts of these signals.

Mentions: Since the elasticity code described above explicitly tracks longitudinal and transverse elastic strains, one can generate a simulated diffraction pattern for a given experimental geometry. In Fig. 3 we show the strain history of a simulation which has been optimised to match an experimentally observed response. This shot utilised a drive intensity of 4 × 1011 Wcm−2, with backlighter probing the sample 5 ns after the onset of drive at the ablator’s surface. This data is chosen as it displays the clearest distinction between peaks. Only strains within elastically compressed portions of the sample are considered, permitting comparison with the purely elastically response observed in diffraction. A summation of these strain profiles over a 1 ns window, assuming that the backlighter has spectrally flat response over the (300 eV) range of interest, and no significant energy dependence to sample reflectivity, allows us to create a simulated diffraction signal, as shown in 3b. This simulation clearly shows the formation of both HSE, LSE and tensile responses. Best fit to the experimental data is found for a lag time for phase transition of 1.2 ns. It should be noted that due the assumptions on spectral response discussed above, and the stochastic nature of the lag time between shots, this value should be taken as being representative. However, this significant kinetic lag is consistent with considerable predicted enthalpy barrier (of around 500 meV) between the cd and β-Sn phases31.


Inelastic response of silicon to shock compression.

Higginbotham A, Stubley PG, Comley AJ, Eggert JH, Foster JM, Kalantar DH, McGonegle D, Patel S, Peacock LJ, Rothman SD, Smith RF, Suggit MJ, Wark JS - Sci Rep (2016)

Elasticity code determined strain history the sample (a) after onset of the drive within the silicon. Shown inset in (b) are simulated and experimental white light Laue signals for x-ray exposure between 3.5–4.5 ns (as indicated by the dashed lines) in (a). This is consistent with the experimental backligher timing of 5 ns once transit time though the ablator is accounted for. Also shown in (b) are lineouts of these signals.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4829838&req=5

f3: Elasticity code determined strain history the sample (a) after onset of the drive within the silicon. Shown inset in (b) are simulated and experimental white light Laue signals for x-ray exposure between 3.5–4.5 ns (as indicated by the dashed lines) in (a). This is consistent with the experimental backligher timing of 5 ns once transit time though the ablator is accounted for. Also shown in (b) are lineouts of these signals.
Mentions: Since the elasticity code described above explicitly tracks longitudinal and transverse elastic strains, one can generate a simulated diffraction pattern for a given experimental geometry. In Fig. 3 we show the strain history of a simulation which has been optimised to match an experimentally observed response. This shot utilised a drive intensity of 4 × 1011 Wcm−2, with backlighter probing the sample 5 ns after the onset of drive at the ablator’s surface. This data is chosen as it displays the clearest distinction between peaks. Only strains within elastically compressed portions of the sample are considered, permitting comparison with the purely elastically response observed in diffraction. A summation of these strain profiles over a 1 ns window, assuming that the backlighter has spectrally flat response over the (300 eV) range of interest, and no significant energy dependence to sample reflectivity, allows us to create a simulated diffraction signal, as shown in 3b. This simulation clearly shows the formation of both HSE, LSE and tensile responses. Best fit to the experimental data is found for a lag time for phase transition of 1.2 ns. It should be noted that due the assumptions on spectral response discussed above, and the stochastic nature of the lag time between shots, this value should be taken as being representative. However, this significant kinetic lag is consistent with considerable predicted enthalpy barrier (of around 500 meV) between the cd and β-Sn phases31.

Bottom Line: We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported 'anomalous' elastic waves.Moreover, this interpretation allows for measurement of the kinetic timescales for transition.This model is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK.

ABSTRACT
The elastic and inelastic response of [001] oriented silicon to laser compression has been a topic of considerable discussion for well over a decade, yet there has been little progress in understanding the basic behaviour of this apparently simple material. We present experimental x-ray diffraction data showing complex elastic strain profiles in laser compressed samples on nanosecond timescales. We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported 'anomalous' elastic waves. Moreover, this interpretation allows for measurement of the kinetic timescales for transition. This model is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature.

No MeSH data available.


Related in: MedlinePlus