Naslov
Anisotropic thermal conductivity of the Y-Al-Ni-Co decagonal approximant

Autori
Smontara, Ana ; Smiljanić, Igor ; Bilušić, Ante ; Dolinšek, J. ; Gille, P.

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Frontiers in Complex Metallic Alloys, CMA- Zagreb'08, Program and Abstracts / Smontara, Ana - Zagreb : Institut za fiziku, 2008, 62-62

ISBN
978-953-98955-7-8

Skup
Frontiers in Complex Metallic Alloys

Mjesto i datum
Zagreb, Hrvatska, 01.10.2008. - 04.10.2008

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
thermal conductivity; decagonal approximants; Y-Al-Ni-Co

Sažetak
The anisotropic thermal conductivity  of Y-Al- Ni-Co decagonal approximant with composition Al76Co22Ni2.[1] has been measured along three orthogonal directions a*, b and c of the Y-Al- Ni-Co unit cell, where (a, c) monoclinic atomic planes are stacked along the perpendicular b direction. The phononic contribution  ph= - el was estimated by subtracting the electronic contribution  el from the total conductivity using the Wiedemann-Franz (WF) law,  el = Lo σ (T) T and the measured electrical conductivity data σ (T) on the same specimens [2]. Though the use of the WF law is a rough approximation, in this way determined  ph gives an indication of the anisotropy of the phononic spectrum. At room temperature (RT), we get the anisotropy:  a*=12.5 W/mK,  ela*=9.1 W/mK with their ratio ( ela*/ a*)RT=0.73,  b=46.3 W/mK,  elb=29.2 W/mK with ( elb/ b)RT=0.63 and  c=17.4 W/mK,  elc=12.2 W/mK with ( elc/ c)RT=0.70. Electrons are thus majority heat carriers for all three directions. The anisotropic thermal conductivities appear in the order  b> c> a*and similarly  elb> elc> ela*, which is identical to the order in which the anisotropic electrical conductivities appear σ b>σ c>σ a*. The anisotropic  ph's appear in the same order,  phb> phc> pha*, so that the phononic conductivity is the highest along the b direction perpendicular to the (a, c) atomic layers, whereas the two in-plane conductivities are lower and show smaller anisotropy. For all directions,  ph's show a typical phonon umklapp maximum at about 40 K. While it is expected that the anisotropic electronic thermal conductivities  el should appear in the same order as the anisotropic electrical conductivities (both are related to the electronic density of states), it is not a priori obvious that the anisotropic phononic thermal conductivities should also appear in this order, as  ph is related to the vibrational density of states. Striking anisotropy in thermal conductivity of the Y-Al- Ni-Co is due to the anisotropy of the structural symmetry.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

Napomena
This work was supported in part by the 6th Framework EU Network of Excellence 'Complex Metallic Alloys' (Contract No. NMP3-CT-2005- 500140).

POVEZANOST RADA