THE DEPENDENCE OF THE DEBYE TEMPERATURE ON THE ELASTIC-CONSTANTS

Sophisticated methods have been put forward in the literature to calcu late Debye temperatures from the elastic constants c(ik). As a simple alternative method for cubic crystals, a relation is often used that c orrelates Debye temperature and bulk modulus (c(11) + 2c(12))/3 by a s quare-root law. It is shown that, with exception of the alkali metals, such a law is only poorly fulfilled for other cubic elements and comp ounds. If one takes, however, elastic moduli such as [c(44)(c(11) - c( 12)) (c(11) + c(12) + 2c(44))](1/3) or {C-44[(C-11 - C-12) C-44/2](1/2 ) (C-11 - C-12 + C-44)/3}(1/3) instead of the bulk modulus the square- root law is established for various cubic material classes. This proce dure eventually allows to easily evaluate hitherto unknown Debye tempe ratures from the elastic constants with high precision.