Relativistic effects on the structural phase stability of molybdenum

Boettger, J. C.

doi:10.1088/0953-8984/11/16/005

Cited by 18 publications

(13 citation statements)

References 36 publications

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“…Our results confirmed the previous reports. [4][5][6] Fig. 1(b) shows the static EOS under ultra high pressure.…”

Section: Lattice Instabilitiesmentioning

confidence: 99%

“…2,3 Mo has a body-centered cubic (bcc) structure at ambient conditions, and it transforms to a close-packed face-centered cubic (fcc) phase above 700 GPa. [4][5][6] In our previous work, the phase transition of Ti was clearly revealed by the accurate ab initio determination of the transverse acoustic (TA) phonon softening. 7 The melting of transition metals is of considerable importance in applied physics and geophysics, and has recently become more important with the advent of static, quasi-equilibrium experiments into the ultra high pressure and temperature range.…”

Section: Introductionmentioning

confidence: 99%

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Density functional theory investigation of the phonon instability, thermal equation of state and melting curve of Mo

Zhao-Yi

Chen

et al. 2011

Phys. Chem. Chem. Phys.

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The phonon instability and thermal equation of state of Mo are extensively investigated using density functional theory. The calculated phonon dispersion curves agree well with experiments. Under compression, we captured a large softening in the transverse acoustic (TA) branches of body-centred cubic Mo. When the pressure is raised to 716 GPa, the frequencies along Γ-N in the TA branches soften to imaginary frequencies, indicating structural instability. For face-centred cubic Mo, the phonon calculations predicted the stability by promoting the frequencies from imaginary to real. Within quasi-harmonic approximation, we predicted the thermal equation of state and some other properties including the thermal expansion coefficient α, product αK(T), heat capacity C(V), entropy S, Grüneisen parameter γ and Debye temperature Θ(D). The melting curves of Mo were also obtained successfully.

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“…Our results confirmed the previous reports. [4][5][6] Fig. 1(b) shows the static EOS under ultra high pressure.…”

Section: Lattice Instabilitiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Density functional theory investigation of the phonon instability, thermal equation of state and melting curve of Mo

Zhao-Yi

Chen

et al. 2011

Phys. Chem. Chem. Phys.

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“…The crystal structure is the most fundamental property of a solid material and controls its physical and chemical behavior. The stable phase of Mo at several hundred GPa (several million atmospheres) pressures has been examined in a number of theoretical studies 22,24,[30][31][32][33][34][35][36][37][38][39] . BCC molybdenum is predicted to transform to either a face-centeredcubic (FCC) structure 24,31,32,[37][38][39] or a double hexagonal-close-packed (dHCP) 35,36 structure between 600 and 700 GPa at 0 K (Fig.…”

Section: Introductionmentioning

confidence: 99%

X-ray diffraction of molybdenum under ramp compression to 1 TPa

et al. 2016

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Molybdenum (Mo) is a transition metal with a wide range of technical applications. There has long been strong interest in its high-pressure behavior and it is often used as standard for high-pressure experiments. Combining powder x-ray diffraction and dynamic ramp compression, structural and equation of state data were collected for solid Mo to 1 TPa (10 Mbar). Diffraction results are consistent with Mo remaining in the body-centered cubic structure into the TPa regime. Stress-density data show that Mo under ramp loading is less compressible than the room-temperature isotherm but more compressible than the single-shock Hugoniot.

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“…For bcc Mo energies, the scalar-relativistic LCGTO-FF calculations of Ref. 55 were used, with lattice constants ranging from 4.374 bohrs to 6.10 bohrs. In addition, the pressure was calculated for the highest compression point (xϭ0.74) using numerical differentiation.…”

Section: Fitting the Asjeos To All-electron Calculations For The Bmentioning

confidence: 99%

Energy and pressure versus volume: Equations of state motivated by the stabilized jellium model

et al. 2001

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Explicit functions are widely used to interpolate, extrapolate, and differentiate theoretical or experimental data on the equation of state ͑EOS͒ of a solid. We present two EOS functions which are theoretically motivated. The simplest realistic model for a simple metal, the stabilized jellium ͑SJ͒ or structureless pseudopotential model, is the paradigm for our SJEOS. A simple metal with exponentially overlapped ion cores is the paradigm for an augmented version ͑ASJEOS͒ of the SJEOS. For the three solids tested ͑Al, Li, Mo͒, the ASJEOS matches all-electron calculations better than prior equations of state. Like most of the prior EOS's, the ASJEOS predicts pressure P as a function of compressed volume v from only a few equilibrium inputs: the volume v 0 , the bulk modulus B 0 , and its pressure derivative B 1. Under expansion, the cohesive energy serves as another input. A further advantage of the new equation of state is that these equilibrium properties other than v 0 may be found by linear fitting methods. The SJEOS can be used to correct B 0 and the EOS found from an approximate density functional, if the corresponding error in v 0 is known. We also ͑a͒ estimate the typically small contribution of phonon zero-point vibration to the EOS, ͑b͒ find that the physical hardness Bv does not maximize at equilibrium, and ͑c͒ show that the ''ideal metal'' of Shore and Rose is the zero-valence limit of stabilized jellium.

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Relativistic effects on the structural phase stability of molybdenum

Cited by 18 publications

References 36 publications

Density functional theory investigation of the phonon instability, thermal equation of state and melting curve of Mo

Density functional theory investigation of the phonon instability, thermal equation of state and melting curve of Mo

X-ray diffraction of molybdenum under ramp compression to 1 TPa

Energy and pressure versus volume: Equations of state motivated by the stabilized jellium model

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