Crystal Growth and Optical Spectroscopy of Ytterbium-Doped Lutetium Orthophosphate

The flux growrh method is employed to grow the Yb:LuPO4 crystal using lead pyrophosphate Pb2P2O7 as the high-timperature solvent. The infrared spectroscopy(IR) was tested to determine the purity of the obtained crystal. The absorption spectra of the 5% Yb-doped Yb:LuPO4 crystal was measured at room temperature. Three absorption peaks that located on 985nm, 976nm and 953nm were found, and the absorption cross sections on the absorption peaks were calculated respectively. The results shows that Yb:LuPO4 crystal has potential to be applied as laser material.

Synthesis of Lead Pyrophosphate, Pb2P2O7, in Water

Polyphosphates are used in drinking water to prevent the precipitation of cations such as calcium and iron. The possible negative impact of using polyphosphates is the undesirable complexation of lead that could result in elevated lead levels in consumers' tap water. Although the water industry has focused on complexation, lead polyphosphate solids such as lead pyrophosphate, Pb2P2O7, have been considered in other fields and not been shown to form in water. The ability to form lead pyrophosphate in water could have a potential impact on the strategies used to reduce lead levels in drinking water distribution systems. The objective of this work was to determine whether lead pyrophosphate could form under simulated potable drinking water conditions. Lead pyrophosphate was synthesized in water (pH 8.2, 10 mg C/L, 2.7 mg Cl2/L) after 13 days of aging. The formation of lead pyrophosphate was confirmed by X-ray diffraction and microscopy analysis. Synthesis did not require elevated temperatures or microwave assisted approaches used by past researchers. The findings suggest that lead (and possibly other metal) pyrophosphates could conceivably form in real drinking water systems, although much more work is necessary to determine the chemistry and kinetic boundaries.

The Structure of Lead-Indium Phosphate Glass

ABSTRACTLead-indium phosphate glasses exhibit a number of useful properties such as a high index-of-refraction, low preparation temperature and melt viscosity, and good chemical durability. The structure of such a glass (composition in wt. %: 65 PbO, 29 P2O5, 6 In2O3) has been investigated by total neutron scattering using the GLAD diffractometer at Argonne's spallation neutron source IPNS. Peaks corresponding to the P-O, Pb-O/In-O, and 0-0 pairs were observed in the radial distribution function. The short-range structure in the glass, in terms of average coordination numbers and bond distances, is compared with those of a pure P2O5 glass and with the crystal structure of lead pyrophosphate, Pb2P2O7. Unlike silicate glasses in which the SiO4 tetrahedra form a 3-dimensional network, the PO4 tetrahedra in phosphate glasses form a chain-like structure. The structural modification by the lead cations in phosphate glasses appears to occur mainly in the medium range affecting the lengths and connectivity of the chain-like structure.