Microstructures of AIPO4 subjected to high shock pressures

Gratz, A. J.; Doukhan, Jean-Claude; Nellis, W. J.

doi:10.1007/bf00203143

Cited by 14 publications

(5 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These authors also found that the high pressure phase (>15 GPa) was not elastically isotropic and instead was an anisotropic glass. Observations of amorphous phase from the samples after non-hydrostatic compression in the ungasketted diamond anvil cell [6] as well as in the recovered samples after shock loading [7] further supported the idea of the high pressure phase being the amorphous phase.…”

Section: Introductionmentioning

confidence: 64%

High pressure phase transformations in α-AlPO₄: an x-ray diffraction investigation

Sharma

Garg

Sikka

2000

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

We have re-investigated the high pressure behaviour of berlinite AlPO4 (α-AlPO4) with x-ray diffraction using a powerful synchrotron x-ray source SPring-8. Our results show that it transforms to a crystalline phase beyond ~13 GPa. Our data seem to be consistent with a CrVO4 type of structure in the Cmcm space group, similar to the high pressure phase observed in some isostructural phosphate compounds. The persistence of the diffraction pattern up to 40 GPa establishes that the previously accepted amorphization of AlPO4 around 12-18 GPa is incorrect. Experimental results suggest that the so-called memory glass effect observed earlier may in fact be the reversibility of the α-phase⇔crystalline phase transformation. Comparisons of our experimental and theoretical results raise serious doubts about the theoretical understanding of the high pressure behaviour of α-AlPO4.

show abstract

Section: Introductionmentioning

confidence: 64%

High pressure phase transformations in α-AlPO₄: an x-ray diffraction investigation

Sharma

Garg

Sikka

2000

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

show abstract

“…And if shock loading and/or non-hydrostatic stress loading of the α-phase leads to a Cmcm phase then our simulations suggest that on recovery one may observe the glassy phase (as experimentally found! [4]) which arises from the Cmcm phase. In the light of results of section 3.2.2, this amorphous phase will not be the same as the high pressure disordered phase.…”

Section: 23mentioning

confidence: 99%

“…Berlinite AlPO 4 exists in the α-quartz structure at ambient conditions and like quartz, it is reported to become amorphous at high pressures [1][2][3][4][5][6][7]. However, in AlPO 4 , this transformation is reversible and the high pressure amorphous phase has been termed as a memory glass [1], as on the release of pressure the amorphous phase transforms back to the single crystal with the same orientations.…”

Section: Introductionmentioning

confidence: 99%

A molecular dynamical investigation of high pressure phase transformations in berlinite (alpha-AlPO₄)

Garg¹,

Sharma²

1999

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

Since 1990, berlinite ( -AlPO4 ) has been believed to have a memory glass property under high pressures. Recent high pressure Raman scattering experiments have raised serious doubts in our understanding of the high pressure behaviour of -AlPO4 . We have now carried out extensive molecular dynamical calculations to understand the nature of structural changes in -AlPO4 under high pressures. Our simulations show that around 15 GPa the oxygen sublattice becomes disordered and the intensities of the Bragg diffraction peaks are reduced. High pressure causes a monotonic increase in the distortion of the AlO4 and PO4 tetrahedra; and, as observed in earlier MD calculations, -AlPO4 undergoes a first order phase transformation at ~30 GPa to a disordered structure. However, even beyond 30 GPa, the calculated diffraction pattern of this phase continues to show sharp diffraction peaks. At higher compression, this diffraction pattern shows a systematic reduction in the intensity and beyond 45 GPa, most of the peaks vanish except (10 = 12) and (10 = 14). These calculations show the persistence of translational order well beyond the generally accepted pressure of amorphization and support the recent Raman scattering results. Further, this disordered phase does not transform to any new crystalline phase on annealing at high pressures. Our simulations employing instantaneous compression confirm the earlier result that, beyond 12 GPa, the Cmcm phase is more stable than the -phase. However, this phase transforms to a four coordinated disordered phase at ambient conditions and can only be stabilized on compression beyond 20 GPa. Our results, presented here, strongly suggest the need for a re-investigation of -AlPO4 by x-ray diffraction under high pressures.

show abstract

“…martensitic transformations and crystal to amorphous phase transitions have also been studied. [11][12][13][14][15][16][17][18][19][20][21] Solid state structural phase transformations from low to high or from high to low density states have been considered to occur via reconstructive or displacive mechanisms. 22 Such displacive phase transformations involve coordinated shifts of atoms comprising of homogeneous strain and shuffle, and hence, are favoured under high pressure, while reconstructive transformations are less likely to occur at high pressures due to the reduced mobility of atoms.…”

Section: Introductionmentioning

confidence: 99%

Shock compression of reactive powder mixtures

Eakins

Thadhani

2009

International Materials Reviews

View full text Add to dashboard Cite

The shock-compression of reactive powder mixtures can yield varied chemical behaviour with occurrence of mechanochemical reactions in the time-scale of the high-pressure state, or thermochemical reactions in the time-scale of temperature equilibration, or simply the creation of densepacked highly reactive state of material. The principal challenge has been to understand the processes that distinguish between mechanochemical (shock-induced) and thermochemical (shock-assisted) reactions, which has broad implications for the synthesis of novel metastable or non-equilibrium materials, or the design of highly configurable next-generation energetic materials. In this paper, the process of shock-compression in reactive powder mixtures and the associated role of various intrinsic and extrinsic characteristics of reactants in the triggering of ultra-fast "shock-induced" chemical reactions are discussed. Experimental techniques employing time-resolved diagnostics, and results, that identify the occurrence of shock-induced reactions are reviewed. Conceptual and numerical models used to describe the heterogeneous nature of such reactions through mesoscopic details of shock-compression are presented. Finally, a discussion of the application of recent results for the design of reactive material systems with controlled reaction initiation and energy release characteristics is provided.

show abstract

Microstructures of AIPO4 subjected to high shock pressures

Cited by 14 publications

References 23 publications

High pressure phase transformations in α-AlPO₄: an x-ray diffraction investigation

High pressure phase transformations in α-AlPO₄: an x-ray diffraction investigation

A molecular dynamical investigation of high pressure phase transformations in berlinite (alpha-AlPO₄)

Shock compression of reactive powder mixtures

Contact Info

Product

Resources

About

Microstructures of AIPO4 subjected to high shock pressures

Cited by 14 publications

References 23 publications

High pressure phase transformations in α-AlPO4: an x-ray diffraction investigation

High pressure phase transformations in α-AlPO4: an x-ray diffraction investigation

A molecular dynamical investigation of high pressure phase transformations in berlinite (alpha-AlPO4)

Shock compression of reactive powder mixtures

Contact Info

Product

Resources

About

High pressure phase transformations in α-AlPO₄: an x-ray diffraction investigation

High pressure phase transformations in α-AlPO₄: an x-ray diffraction investigation

A molecular dynamical investigation of high pressure phase transformations in berlinite (alpha-AlPO₄)