Elastic properties of lead-phosphate glasses doped with erbium trioxide

The elastic properties of xEr2O3·(50 – x) PbO·50P2O5 (x = 0.1 to 0.5 mol%) glasses are investigated using ultrasonic pulse-echo measurements and their elastic properties are characterized at room temperature. Results from the studies show that both longitudinal and transverse velocities increase with increase of Er2O3 concentration. The elastic constants C11, C12, C44, and Young’s modulus show increasing trend while Bulk modulus and Poisson’s ratio show an increasing trend up to 0.4 mol% and 0.3 mol% of Er2O3, respectively, then there is sudden decreasing trend observed. But in the case of Debye temperatures the reverse trend has been observed. Another notable observation is that the glass with 0.4 mol% and 0.5 mol% of Er2O3 concentration exhibits high velocities and high elastic moduli. This behavior of the elastic properties is related to the change in the structure of glasses as well as the interatomic bonding.PACS No.: 62.20.DC

Reflection and refraction of thermo-viscoelastic waves at the interface between two micropolar viscoelastic media without energy dissipation

Reflection and refraction of a plane harmonic wave at the interface between two viscoelastic media are studied under generalized thermo-viscoelastic theory. Using potential function, the governing equations reduce to two fourth-order ifferential equations. Coefficient ratios of reflection and refraction of different waves with the angle of incidence are obtained using continuous boundary conditions. By numerical calculations, the variation of coefficient ratios of reflection and refraction with the angle of incidence are illustrated graphically for aluminium–epoxy and magnesium crystal micropolar viscoelastic materials. Also, the effects of viscous and micropolar elastic are illustrated by numerical results in the theory of thermo-viscoelasticity without energy dissipation. PACS No.: 62.20.Dc

Investigation of the elastic properties of UNI2Si2 as a function of temperature, magnetic field, and pressure

It is now well-established that the strong anisotropy in the magnetic properties of the intermetallic compounds UT2Si2, where T stands for a transition metal, is responsible for their rich magnetic phase diagram. However, within that series of compounds, UNi2Si2 is one that shows an unusual sequence of magnetically ordered states. Thus, to better understand its unusual properties, we have investigated the elastic properties of UNi2Si2 as a function of temperature, magnetic field, and pressure. In all three magnetic phases, our measurements indicate that the sound-velocity temperature dependence is dominated by the magnetoelastic coupling. Moreover, the analysis of the temperature dependence for the incommensurate longitudinal spin-density wave phase is consistent with a critical exponent β = 0.38 ± 0.01. We also present the magnetic phase diagram for UNi2Si2 obtained at 0 and 8 kbar. Our investigation reveals that the triple-point coordinates (Tp, Hp) decrease with pressure at a rate of dTp/dP = –0.1 K/kbar and dHp/dP = –0.1 T/kbar, respectively. PACS Nos.: 75.30.kz, 62.20.Dc, 62.50.+p, 75.40.Cx