Neutron scattering experiments on liquid droplets using electrostatic levitation

Kordel, Tobias; Holland‐Moritz, D.; Yang, Fan; Peters, J.; Unruh, Tobias; Hansen, Thomas C.; Meyer, Andreas

doi:10.1103/physrevb.83.104205

Cited by 91 publications

(61 citation statements)

References 34 publications

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“…The electrostatic levitation experiments utilize electrostatic force generated by high-voltage amplifiers to levitate samples against gravity under high-vacuum (in the range of B10 À 7 mbar) conditions (ref 57). Heating of the sample is achieved by infrared lasers.…”

Section: Methodsmentioning

confidence: 99%

Liquid–liquid transition in a strong bulk metallic glass-forming liquid

et al. 2013

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Polymorphic phase transitions are common in crystalline solids. Recent studies suggest that phase transitions may also exist between two liquid forms with different entropy and structure. Such a liquid-liquid transition has been investigated in various substances including water, Al 2 O 3 -Y 2 O 3 and network glass formers. However, the nature of liquid-liquid transition is debated due to experimental difficulties in avoiding crystallization and/or measuring at high temperatures/pressures. Here we report the thermodynamic and structural evidence of a temperature-induced weak first-order liquid-liquid transition in a bulk metallic glassforming system Zr 41.2 Ti 13.8 Cu 12.5 Ni 10 Be 22.5 characterized by non-(or weak) directional bonds. Our experimental results suggest that the local structural changes during the transition induce the drastic viscosity changes without a detectable density anomaly. These changes are correlated with a heat capacity maximum in the liquid. Our findings support the hypothesis that the 'strong' kinetics (low fragility) of a liquid may arise from an underlying lambda transition above its glass transition.

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Section: Methodsmentioning

confidence: 99%

Liquid–liquid transition in a strong bulk metallic glass-forming liquid

et al. 2013

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“…To facilitate recharging of the sample during levitation, a focused ultra violet light source with a high energy of several eV (λ = 115-350 nm) is used. In addition to this procedure, the sample is also recharged at elevated temperatures by thermionic emission of electrons [89].…”

Section: Electrostatic Levitationmentioning

confidence: 99%

Non-Equilibrium Solidification of Undercooled Metallic Melts

Herlach

2014

Metals

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Abstract:If a liquid is undercooled below its equilibrium melting temperature an excess Gibbs free energy is created. This gives access to solidification of metastable solids under non-equilibrium conditions. In the present work, techniques of containerless processing are applied. Electromagnetic and electrostatic levitation enable to freely suspend a liquid drop of a few millimeters in diameter. Heterogeneous nucleation on container walls is completely avoided leading to large undercoolings. The freely suspended drop is accessible for direct observation of rapid solidification under conditions far away from equilibrium by applying proper diagnostic means. Nucleation of metastable crystalline phases is monitored by X-ray diffraction using synchrotron radiation during non-equilibrium solidification. While nucleation preselects the crystallographic phase, subsequent crystal growth controls the microstructure evolution. Metastable microstructures are obtained from deeply undercooled melts as supersaturated solid solutions, disordered superlattice structures of intermetallics. Nucleation and crystal growth take place by heat and mass transport. Comparative experiments in reduced gravity allow for investigations on how forced convection can be used to alter the transport processes and design materials by using undercooling and convection as process parameters.

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“…Such non-exponential behavior can arise from heterogeneous states in a liquid that relax exponentially, or from the atoms in the liquid that relax in an intrinsically nonexponential way thus causing a rise in cooperativity in the system 36 . In many metallic glass-forming liquid systems β is found to vary from 0.5 -1.0 for self correlation functions 27,37,38 . Our fitting results show distinct results for β of collective correlation functions at all Qvalues.…”

Section: A Phenomenological Kww Analysismentioning

confidence: 99%

Coincidence of collective relaxation anomaly and specific heat peak in a bulk metallic glass-forming liquid

et al. 2015

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The study of relaxational behavior of multi-component metallic liquids still holds the key to understanding and improving the glass-forming abilities of bulk metallic glasses. Herein, we report measurements of the collective relaxation times in a melted bulk metallic glass (LM601 Zr51Cu36Ni4Al9) in the kinetic regime (Q: 1.5 -4.0Å−1 ) using Quasi-Elastic Neutron Scattering (QENS). The results reveal an unusual slope change in the Angell plots of the collective relaxation time of this metallic liquid around 950• C, beyond the melting point of the material. Specific heat capacity measurement also reveals the presence of a peak around the same temperature. The coincidence is rationalized using Adams-Gibbs theory, and motivates more careful experimental and computational studies of the metallic liquids in the future.

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Neutron scattering experiments on liquid droplets using electrostatic levitation

Cited by 91 publications

References 34 publications

Liquid–liquid transition in a strong bulk metallic glass-forming liquid

Liquid–liquid transition in a strong bulk metallic glass-forming liquid

Non-Equilibrium Solidification of Undercooled Metallic Melts

Coincidence of collective relaxation anomaly and specific heat peak in a bulk metallic glass-forming liquid

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