25 research outputs found
Effect of Dopants on Zirconia StabilizationâAn X-ray Absorption Study: I, Trivalent Dopants
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65562/1/j.1151-2916.1994.tb06964.x.pd
The relationship between glass structure and poling-induced optical second harmonic intensity for ZnOâTeO 2
Relaxation of ultraviolet-radiation-induced structure and long-lasting phosphorescence in Eu2+-doped strontium aluminosilicate glasses
Relaxation of ultraviolet-radiation-induced structure and long-lasting phosphorescence in Eu 2+
Tellurite and fluorotellurite glasses for fiberoptic Raman amplifiers: glass characterization, optical properties, Raman gain, preliminary fiberization, and fiber characterization
In this study we report the physical properties and spontaneous Raman scattering spectra of nine oxide tellurite and fluorotellurite glasses from three glass systemsâsodiumâzincâtellurite (TZN), tungstenâtellurite, and fluorotellurite..
Structure of glasses studied by x-ray and neutron diffraction
The structures of three xGeO(2)-(1- x)P(2)O(5) glasses, where x = 0.98,0.88, and 0.81, have been studied by neutron and x-ray diffraction experiments that yield well resolved P-O and Ge-O bond distances. The Ge-O coordination number (N(GeO)) increased from 4.0 ± 0.2 to 4.5 ± 0.2 with the decrease in x from 0.98 to 0.81. The increase in N(GeO) is consistent with a structural model that assumes that all oxygen form Ge-O-Ge and P-O-Ge linkages between Ge polyhedra and P tetrahedra and that new GeO(5) or GeO(6) polyhedra are formed with isolated PO(4) units when P(2)O(5) is added to GeO(2). The bond valencies in the P-O bonds of the PO(4) tetrahedra are greater than unity and are balanced in P-O-Ge bridges with underbonded Ge-O links in the GeO(5) or GeO(6) polyhedra. Mixed site connections are expected for the GeO(5) (or GeO(6)) and PO(4) units in glasses with relatively low (<20 mol%) P(2)O(5) content due to the overwhelming fraction of GeO(4) tetrahedra. The structural changes are compared with those reported for alkali germanate glasses. Several features indicate different characteristics for the compositional dependence of N(GeO) for the GeO(2)-P(2)O(5) and alkali germanate glasses. However, the distributions of the first-neighbour Ge-O distances are found to be nearly identical for the GeO(2)-P(2)O(5) and K(2)O-GeO(2) glasses of equimolar K(2)O and P(2)O(5) content
Short-range order and dynamics in crystalline α-TeO2
The short-range order and dynamics in crystalline α-TeO2 have been investigated by neutron and X-ray total scattering and by Rietveld refinement of neutron diffraction data. The true lengths of the two bonds in a TeâOâTe bridge are 1.882(1) and 2.117(1) Ă
, and the high valence, 1.293, of the strong, short bond is balanced by the low valence, 0.686, of the weak, long bond. The root-mean-square (rms) thermal variation, 0.083(1) Ă
, in the long bond length is nearly twice the rms thermal variation, 0.048(1) Ă
, in the short bond length because the largest motion of both Te and O atoms is perpendicular to the short bonds. A bond-valence model for the thermal variation in bond lengths, in which both the average and the instantaneous positions of the atoms conform to bond-valence requirements, accounts closely for the observed distribution of TeâO distances in α-TeO2. This has important implications for the interpretation of diffraction experiments on tellurite glasses
Effect of Dopants on Zirconia StabilizationâAn X-ray Absorption Study: II, Tetravalent Dopants
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65957/1/j.1151-2916.1994.tb05403.x.pd