Polyamorphic transitions in yttria–alumina liquids

Wilding, Martin C.; McMillan, Paul F.

doi:10.1016/s0022-3093(01)00686-x

Cited by 67 publications

(112 citation statements)

References 40 publications

Supporting

Mentioning

103

Contrasting

Order By: Relevance

“…As mentioned above, a first-order liquid-to-liquid transition has been reported for TPP slightly above T g at atmospheric pressure (40)(41)(42). A first-order transition between two liquid states with the same composition has also been reported for 20-32 mol % Y 2 O 3 in Y 2 O 3 -Al 2 O 3 melts at Ϸ1500 K (49,50). In this case, the low-temperature phase is the low-density phase (51,52).…”

Section: Indications Of a First-order Phase Transition Experiments Lmentioning

confidence: 53%

Physical vapor deposition as a route to hidden amorphous states

Dawson

Kearns

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

106

View full text Add to dashboard Cite

Stable glasses of indomethacin (IMC) were prepared by using physical vapor deposition. Wide-angle X-ray scattering measurements were performed to characterize the average local structure. IMC glasses prepared at a substrate temperature of 0.84 Tg (where Tg is the glass transition temperature) and a deposition rate of 0.2 nm/s show a broad, high-intensity peak at low q values that is not present in the supercooled liquid or melt-quenched glasses. When annealed slightly above Tg, the new WAXS pattern transforms into the melt-quenched glass pattern, but only after very long annealing times. For a series of samples prepared at the lowest deposition rate, the new local packing arrangement is present only for deposition temperatures below Tg ؊20 K, suggesting an underlying first-order liquid-to-liquid phase transition.entropy ͉ glass ͉ liquid-liquid transition ͉ supercooled ͉ X-ray scattering I f a liquid is cooled to just below its melting point, one of two outcomes will be observed. If the liquid readily forms crystal nuclei, then crystals will form and grow. Otherwise, the system will remain in the now metastable liquid state. In the absence of crystallization, further cooling of this supercooled liquid will result in slower dynamics, and eventually, the dynamics will become so slow that the supercooled liquid cannot maintain its equilibrium state (1). At this glass transition temperature (T g ), the system properties deviate from the properties of the supercooled liquid, and a glass is formed.Whereas the liquid-to-crystal transition is a first-order phase transition, the supercooled liquid-to-glass transition is a kinetic event based on relaxation times growing rapidly as the temperature is decreased. A great deal of recent work has been concentrated on understanding the nature of slow dynamics in supercooled liquids (2-11). As a liquid is cooled at lower rates, more time is given for the system to find equilibrium, and thus, T g decreases. For many organic liquids, T g decreases 3-4 K for every order-of-magnitude decrease in the cooling rate. Because there is a practical limit as to how slowly a sample can be cooled, a glass always forms upon cooling (if crystallization does not occur).What if one could cool a supercooled liquid extremely slowly such that equilibrium was always maintained? There are good reasons to believe that something interesting must occur. In 1948, Kauzmann discussed the consequences of very slow cooling for the entropy of a supercooled liquid, which identified the so-called Kauzmann entropy crisis (12). For some liquids, if the entropy is extrapolated to low temperature, it becomes equal to that of the crystal not too far below the conventional T g ; further extrapolation leads to a negative entropy above absolute zero in violation of the third law of thermodynamics. Because this is impossible, it is generally assumed that the extrapolation that produces this crisis must be incorrect, and thus something interesting must occur when a supercooled liquid is cooled very slowly. Several theories...

show abstract

Section: Indications Of a First-order Phase Transition Experiments Lmentioning

confidence: 53%

Physical vapor deposition as a route to hidden amorphous states

Dawson

Kearns

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

106

View full text Add to dashboard Cite

show abstract

“…structural transitions between high density (HDA) and low-density (LDA) amorphous phases, have been reported in the Y 2 O 3 -Al 2 O 3 system close to yttrium aluminum garnet (YAG: Y 3 Al 5 O 12 ) composition [5,8]. Wilding et al [40] found that the main structural difference between the two amorphous phases is a change in the local coordination environment of yttrium. Substituting yttrium by lanthanum or erbium leads to single-phase glasses, either by making the second liquid (LDA) unstable relative to the first (HDA) or by reducing the phase transition or nucleation temperature for the second liquid well below the glass transition temperature of the first.…”

Section: Vitrification Enthalpiesmentioning

confidence: 99%

Thermochemistry of rare-earth aluminate and aluminosilicate glasses

Zhang

Navrotsky

2004

Journal of Non-Crystalline Solids

View full text Add to dashboard Cite

“…Such transitions have been observed, for example, in liquid phosphorous 2 and sulfur, 3 by X-ray diffraction and neutron diffraction techniques respectively, regarding for static signatures. Other examples of this phenomena include Si, [4][5][6] binary liquids such as Y 2 O 3 -Al 2 O 3 , 7,8 vitreous SiO 2 9,10 and GeAsS chalcogenide glasses. 11 More recently, metallic glasses (MGs) have attracted interest as a new class of amorphous materials due to their potential for structural applications.…”

mentioning

confidence: 99%

Polyamorphic transitions in Ce-based metallic glasses by synchrotron radiation

et al. 2011

View full text Add to dashboard Cite

We report here a polyamorphic phase transition upon application of pressure on a Ce-based metallic glass (MG), Ce70Al10Ni10Cu10, investigated by X-ray diffraction (XRD) and inelastic Xray scattering (IXS). This alloy is found to display a strong hysteresis in the volume per atom upon application and subsequent release of pressure. The observed structural changes are correlated with changes observed by IXS in the elastic constants, acoustic mode frequencies and sound speed. The results reported here point towards three different amorphous phases for this allow existing in the 0 -25 GPa pressure region: a low and a high density states and an intermediate mixed state that displays a hysteresis behavior. Finally, we discuss the impact of Ce concentration on the polyamorphic transition for a series of Ce-based metallic glasses alloys and link it to the phase transformation between γ-Ce and α-Ce under pressure.

show abstract

Polyamorphic transitions in yttria–alumina liquids

Cited by 67 publications

References 40 publications

Physical vapor deposition as a route to hidden amorphous states

Physical vapor deposition as a route to hidden amorphous states

Thermochemistry of rare-earth aluminate and aluminosilicate glasses

Polyamorphic transitions in Ce-based metallic glasses by synchrotron radiation

Contact Info

Product

Resources

About