Investigation of elastic and vibrational properties of some crystal with in the varshni potential function

INVESTIGATION OF ELASTIC AND VIBRATIONAL PROPERTIES OFSOME CRYSTAL WITH IN THE VARSHNI POTENTIAL FUNCTION(M.Sc. Thesis)Mehmet Dinçer ŞAHMARANGAZİ UNIVERSITYINSTITUTE OF SCIENCE AND TECHNOLOGYJanuary 2007ABSTRACTIn this thesis, we have studied the lattice dynamics of some fcc and bcc metalsby Varshni potentials (VP). Firstly, the elastic properties, such as the second-order ( c11 , c12 , c44 ), third-order elastic constants ( c111 , c112 , c123 ), thepressure derivates of the bulk modulus  B  for some fcc and bcc metals, the  P potential has been studied by parametrized according to Girifalco-Weizermethods. Secondly, the parameters defining the VP for Ni and Pd have beencomputed following a procedure similar to a method given by Halıcıoğlu andPamuk. The phonon frequencies along the principal symmetry directions of Ni-45%Pd alloys have been calculated using the computed force constants. Finally,the parameters of the VP for some metals have been computed following themethod defined by Milstein. The computed force constants have been used tocalculate the phonon frequencies of Ni. The theoretical results have beencompared to experimental phonon dispersion results.Science Code : 202.1.147Key Words : Elastic properties, phonon frequencies, second and third-orderelastic constantsPage Number : 57Adviser : Asist. Prof. Dr. Gökay UĞUR