The velocities of longitudinal and shear ultrasonic waves propagated in the
(Pr2O3)x(P2O5)1-x
glass system, where x is the mole fraction of
Pr2O3 and (1 -
x) is the mole fraction of
P2O5, have been measured as
functions of temperature and hydrostatic pressure. The temperature
dependencies of the second order elastic stiffness tensor components (SOEC)
CS
IJ , which have been determined
from the velocitydata between 10 and 300 K, show no evidence of phonon mode
softening throughout the whole temperature range. The elastic stiffnesses
increased monotonically, the usual behaviour associated with the effect of the
phonon anharmonicityof atomic vibration. At low temperatures, strong phonon
interactions with two-level systems have been observed. The ultrasonic wave
attenuation of longitudinal and shear waves is dominated bya broad acoustic
loss peak whose height and peak position are frequencydependent. This
behaviour is consistent with the presence of thermally activated structural
relaxation of the two-level systems in these glasses. The fractal bond
connectivity of these glasses, obtained from the elastic stiffnesses
determined from ultrasonic wave velocities, has a value between 2.32 to 2.55,
indicating that their connectivitytends towards having a threedimensional
character. The hydrostatic pressure dependencies of longitudinal ultrasonic
waves show a slight increase with pressure. As a consequence, the hydrostatic
pressure derivatives (
CS11/
P)P=0 of the elastic
stiffness
CS11/
and
(BS/P)P=0
of the bulk modulus BS of
(Pr2O3)x(P2O5)1-x
glasses are positive. The bulk modulus increases with pressure, and thus these
glasses stiffen under pressure, which is associated with the normal elastic
behaviour. The GrÜneisen parameter approach has been used to quantifythe
vibrational anharmonicityof the long-wavelength acoustic phonons in these
glasses.
Effect of the Interfacial Transition Zone on ultrasonic wave attenuation and velocity in concrete