Wave-Vector Dependence of the Dynamics in Supercooled Metallic Liquids

Abstract

We present a detailed investigation of the wave-vector dependence of collective atomic motion in Au 49 Cu 26.9 Si 16.3 Ag 5.5 Pd 2.3 and Pd 42.5 Cu 27 Ni 9.5 P 21 supercooled liquids close to the glass transition temperature. Using x-ray photon correlation spectroscopy in a previously uncovered spatial range of only a few interatomic distances, we show that the microscopic structural relaxation process mimics the structure and presents a marked slowing down at the main average interparticle distance. This behavior is accompanied by dramatic changes in the shape of the intermediate scattering functions, which suggest the presence of large dynamical heterogeneities at length scales corresponding to a few particle diameters. A ballisticlike mechanism of particle motion seems to govern the structural relaxation of the two systems in the highly viscous phase, likely associated with hopping of caged particles in agreement with theoretical studies.

Q-dependent collective relaxation dynamics of glass-forming liquid Ca0.4K0.6(NO3)1.4 investigated by wide-angle neutron spin-echo

“…Figure 3b shows that at the studied temperatures also varies in phase with S ( Q ), between ≈0.45 and ≈0.75, being largest around the maximum of S ( Q ). Such a behavior has also been observed in metallic supercooled liquids close to T g by X-ray photon correlation spectroscopy 55 , suggesting a universal dynamical property across a large timescale range covering 16 orders of magnitude (from ≈1 ps to >10 3 s). The Q -dependence of was also observed in ortho -terphenyl 32 , isopropanol 56 , hard-sphere system 57 and binary soft-sphere mixture 58 , indicating again the important effect of particle-particle correlations on the collective relaxation dynamics.…”

Intrinsic relaxation in a supercooled ZrTiNiCuBe glass forming liquid

“…larger range of alloy systems and wave vectors q[23].478 V. CONCLUSION 479 To summarize, in this study we emphasize the ability 480 of measuring microscopic, intrinsic relaxation time with 481 XPCS down to sub-second scale, covering a significant 482 portion of the experimental accessible timescale of me-483 chanical spectroscopy. With this, we compared the mi-484 croscopic and macroscopic structural relaxation behavior 485 of a bulk metallic glass forming alloy Zr 46.8 Ti 8.2 Cu 7.5 -Be 27.5 in the supercooled liquid regime.…”

“…BMGs provide a unique possibility for studying the structural relaxation behavior in both the glass and the supercooled liquid, owing to their good thermal stability against crystallization. In addition, compared to molecular or oxide glass formers, MGs are composed of atoms has become feasible only recently with the instrumental developments of the X-ray photon correlation spectroscopy (XPCS) [16, [19][20][21][22][23][24]. XPCS directly probes the evolution of the structural relaxation features via monitoring the fluctuation of the scattered speckle pattern from a coherent X-ray beam.…”

Resolving molecular diffusion and aggregation of antibody proteins with megahertz X-ray free-electron laser pulses

“…3b where the shape of the correlation functions drastically changes from a simple exponential decay at low doses to a highly stretched (α < 1) and almost logarithmic decay at higher dose values. We account for these changing KWW exponents by computing the average relaxation rate [59,60] Γ (q) = Γ(q)α/Γ f (1/α), where Γ f (x) is the Γ-function. Using these average relaxation rates one pair of parameters (D 0 , α) is calculated per dose and dose rate, where D 0 = Γ (q)/q 2 .…”