A complete structural study has been carried out on sodium borophosphate glass containing increasing amounts of either niobium or tantalum. A combination of high energy x-ray diffraction, neutron diffraction, extended x-ray absorption fine structure, nuclear magnetic resonance, and infrared and Raman spectroscopy has been used to discern the local atomic structure of each component and the changes with M content, where M is either niobium or tantalum. The glasses are found to consist of tetrahedral borate and phosphate with octahedral MO(6). As expected, B and P play the roles of tetrahedral network formers. At low M content there are isolated MO(6) units with P center dot center dot center dot M and B center dot center dot center dot M linkages that contribute to the glass network. As the M content increases, the number of M center dot center dot center dot M links increases, and at the highest M content each MO(6) unit is connected to several others. The octahedra become significantly distorted as the niobium content increases, an effect that is not seen for tantalum.

The atomic structure of niobium and tantalum containing borophosphate glasses

BETTINELLI, Marco Giovanni;SPEGHINI, Adolfo;
2009-01-01

Abstract

A complete structural study has been carried out on sodium borophosphate glass containing increasing amounts of either niobium or tantalum. A combination of high energy x-ray diffraction, neutron diffraction, extended x-ray absorption fine structure, nuclear magnetic resonance, and infrared and Raman spectroscopy has been used to discern the local atomic structure of each component and the changes with M content, where M is either niobium or tantalum. The glasses are found to consist of tetrahedral borate and phosphate with octahedral MO(6). As expected, B and P play the roles of tetrahedral network formers. At low M content there are isolated MO(6) units with P center dot center dot center dot M and B center dot center dot center dot M linkages that contribute to the glass network. As the M content increases, the number of M center dot center dot center dot M links increases, and at the highest M content each MO(6) unit is connected to several others. The octahedra become significantly distorted as the niobium content increases, an effect that is not seen for tantalum.
2009
niobium; tantalum; borophosphate glasses
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11562/337163
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