
%0 Journal Article
%A Hudson, PRW 
%A Bomers, MC 
%A Fyans, RA 
%T How Isotopes Obscure the Anisotropic Phonon Umklapp Scattering in Dielectrics
%J Australian Journal of Physics
%D 1976/04/01
%V 29
%N 2
%P 25-30
%K 
%R https://doi.org/10.1071/PH760025
%U https://www.publish.csiro.au/paper/PH760025 
%X Calculations of the thermal conductivity of h.c.p. 4He, doped with up to 1 % 3He, are presented using a Debye relaxation-time approach. The results are analysed to extract information on the exponents in the anisotropic phonon Umklapp relaxation rate. The results show that even if 1 % of 3He is present the exponents may be measured to within 7 % of their undoped value. Consequently, anisotropic phonon Umklapp parameters may be determined in crystals where natural isotopes exist 
