A new sight into the glass forming ability caused by doping on Ba-and Ti-site in BaTi_(2)O_(5) glass

摘要

La-and Nb-doped BaTi_(2)O_(5)(BT2)spherical glasses were prepared by a containerless aerodynamic levitation method and their glass-forming regions were established.It is found that La-doping on the Ba-site(network-modifier)and Nb-doping on the Ti-site(network-former)show distinct difference in the glassforming region:less than 10%La can replace Ba whereas 40%Nb can incorporate into BT2 glass.The distinction in glass-forming ability induced by La-and Nb-doping is discussed mainly from the structural arrangement of the glass.Raman spectroscopy analysis shows that La-doping elongates the short Ti-O bonds in the distorted[TiO_(5)]polyhedra and thus relaxes the network.Nb-doping introduces[NbO_(6)]polyhedra into BT_(2) and there exists a critical doping level(20%),below which incorporation of Nb into BT_(2) relaxes the[TiOn]polyhedra by shortening the long Ti-O bond and above which[NbO_(6)]starts to participate in the network skeleton construction resulting in a dramatic change in the glass structure,which is supported by the dramatic change in the exothermic peak on the DTA curves.This work triggers the speculation that the network-modifiers in BT_(2) glass possess a very important role in the structure of network-former skeleton than those in glasses based on traditional network-former oxides such as SiO_(2),GeO_(2) and B_(2)O_(3),which may provide a useful strategy for modifying the properties of these novel glasses by chemical doping.