The thermal stability and spectroscopic properties of Er3+-doped Na2O-GeO2-PbO glasses were investigated experimentally. The thermal analysis results show that the thermal stability of the investigated glasses is improved with replacing GeO2 by PbO. Subsequently, Judd-Ofelt (J-O) approach was applied to the room temperature absorption of Er3+ (4f 11) transitions to determine J-O intensity parameters. The reduced values of Ω2 with the substitution of PbO for GeO2 indicate the decrease of covalency of Er O bonding. The stimulated emission cross section of the 4-13-2→4I15-2 transition increases as a consequence of the increase of refractive index of glass hosts and the narrowing of fluorescence bandwidth with the increase of PbO. The abnormal large emission cross section and large bandwidth in the Na2O-0.8GeO2-0.1PbO glass arises from the change of germanium coordination with oxygen.

With the addition of the sintering additives Ni and Cu, highly dense Mo-Ti alloys with various Mo:Ti ratios were obtained byhot-pressing method. Under the same conditions a Mo-Ti green body with continuously graded com position, formed by the particle settling method, was sintered. The longitudinal and transverse ultrasonic velocities of Mo-Ti alloys were tested in order to calculate the residual stresses that develop during cooling of the Mo-Ti functionally graded material (FGM). By using an axisymmetric finite element method, the fabricated thermal stress in a disk-shaped Mo-Ti FGM was calculated. The results show that the residual stress continuously changes with the smooth change of graded composition and the maximum value of residual tensile stress is far lower than that of the bending strength of Mo-Ti alloys.

Upconversion fluorescence properties of a new Er3þ/Yb3þ-codoped lead oxyfluorosilicate glass under 975 nm excitation areinvestigated. The blue, intense green and red emissions centered at 408, 529, 545, and 667nm, corresponding to the 2H9/2→4I15/2, 2H11/2→4I15/2, 4S3/2→4I15/2, and 4F9/2→4I15/2 transitions of Er3+, respectively, were simultaneously observed at room temperature. The important role of Yb2O3 in upconversion intensity is observed, and the influence of Yb2O3 and PbF2 on blue, green and red emissions is compared and discussed. The dependence of upconversion intensities on excitation power and possible upconversion mechanisms are evaluated.