Phonon scattering in quasicrystalline i-Al72Pd19.5Mn8.5: A study of the low-temperature thermal conductivity

Abstract

We measured the thermal conductivity of an icosahedral quasicrystal i-Al 72 Pd 19.5 Mn 8.5 in the temperature range between 0.4 K and 300 K. The analysis of the low-temperature results was based on a Debye-type model. The results of the analysis for the two temperature regions of 0.4 K < T < 40 K and 0.4 K < T < 1 K, are not consistent in the sense that a tunnelling-states contribution to phonon scattering is verified only for 0.4 K < T < 1 K. The same fitting procedure indicates that structural defects of the stacking-fault type are an important source of phonon scattering. Their physical presence was clearly identified by a transmission electron microscopy experiment.

Thermal conductivity of the Al-based quasicrystals and approximants

“…Before closing discussion, we also comment on the variable range hopping conduction of phonons (VRH-P) predicted by Janot [9]. This mechanism is sometimes employed to account for the unusual increase of thermal conductivity at high temperature for the icosahedral quasicrystals [8,15,16]. One may, therefore, wonder that it could be a possible origin for the unusual increase of thermal conductivity observed for our present samples.…”

“…One may, therefore, wonder that it could be a possible origin for the unusual increase of thermal conductivity observed for our present samples. The analysis in the context of VRH-P may reproduce the thermal conductivity of our present samples partly because it uses a parameter fitting with which the increasing tendency is somehow accounted for and partly because the data is limited in a narrow temperature range below 400 K. However the fitting solely with VRH-P is rather poor both for the present materials and those in the literature [15,16], and the scenario solely with VRH-P cannot account for the characteristic composition dependence of j 00 ðTÞ experimentally obtained in our study. Therefore we conclude that VRH-P is not the dominant mechanism leading to the unusual behavior in thermal conductivity of the present samples.…”

Heat Transport in Aluminum‐Based Quasicrystals i‐AlPdMn, i‐AlCuFe, and d‐AlCoNi

“…Transport properties (electrical resistivity, thermopower, and thermal conductivity) and transmission electron microscopy (TEM) experiments of isocahedral Al 72 Pd 19.5 Mn 8.5 were reported recently 10. 11…”

“…The second important scattering process should be responsible for maximum/plateau appearance at ${T \approx 20 - 30{\rm{K}}}$ . It is the umklapp ‐type process with the phenomenological form of the scattering rate pertinent to quasicrystals,11, 24, 25 ${\tau _{{\rm{qu}}}^{ - {\rm{1}}} \; \propto \;x^\alpha T^\beta }$ . The corresponding frequency and temperature dependence of the quasi‐umklapp scattering rate is …”

Porous Nano-SiC as Thermal Insulator: Wisdom on Balancing Thermal Stability, High Strength and Low Thermal Conductivity

“…In addition, thermal conductivity is inversely proportional to the density of stacking faults ρ sf due to the relationship between phonon-scattering rate τ −1 sf and ρ sf (τ −1 sf = Aω 2 ρ sf ). [34] In Figure 3(b), we plot the normalized deviation of thermal conductivity κ at different density of stacking faults. κ is calculated by:…”