TELLURITE GLASSES - PART 1 - ELASTIC PROPERTIES

Tellurite glasses (purr, binary, ternary and quaternary systems contai ning transition metal or rare earth oxides) are now a new type of nonc rystalline solids with a lot of applications over a wide range of comp ositions, temperatures and frequencies. Elastic properties provide muc h information about the structures of solids and they are directly rel ated to the interatomic potentials. Glasses are isotropic and have onl y two independent elastic constant, C11 and C44. These two parameters have been collected from the longitudinal and shear sound velocities a nd density of the glass. The rest of the elastic constants (bulk, Youn g's modulus, Poisson's ratio) could be deduced. The hydrostatic and un iaxial pressure dependences of ultrasonic waves in these glasses at ro om temperature have been collected. The data proved both second and th ird order elastic constants of the glass and in consequence the shear and the longitudinal acoustic mode Gruneisen parameters have both been collected. The estimated bulk modulus and Poisson's ratio have been c alculated using the bond compression model according to the cation-ani on bond of each oxide present in the glass. Information about the stru cture of the glass can be deduced after calculating the number of netw ork bonds per unit volume, the value of the average stretching force c onstant, the average ring size, the structure sensitivity factor and t he mean cross-link density. Comparisons between the calculated end exp erimental elastic moduli and Poisson's ratio have been carried out. Al so, the role of halogen inside the glass network has been discussed. ( C) 1998 Elsevier Science S.A. All rights reserved.