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Dielectric Properties of Glasses in the Systems Bi 2 O 3 ‐CdO‐SiO 2 , Bi 2 O 3 ‐CdO‐B 2 O 3 , and Bi 2 O 3 ‐CdO‐GeO 2 and Their Relation to the Structure of Glass

1962; Wiley; Volume: 45; Issue: 11 Linguagem: Inglês

10.1111/j.1151-2916.1962.tb11056.x

1551-2916

Bh. V. JANAKIRAMA RAO,

Mineralogy and Gemology Studies

Areas of glass formation and regions of “neo‐ceramic” glasses in the systems Biz03‐CdO‐Si02, Bi203‐Cd0‐B203, and Bi203‐Cd0‐GeO2 are demarcated. Properties of glasses in the neoceramic regions were determined before and after nucleation and heat treatment. There are no maxima or minima in the dielectric properties versus composition curves. The dielectric constants increase after nucleation and heat treatment. The dissipation factors show a remarkable change toward higher values. Transparent glasses with Bi 2 O 3 . CdO as the predominant constituents have unusual dielectric constants ranging from 30 to 42 and dissipation factors ranging from 3 to 50 × 10 −4 ., Since these glasses contain only from 0.5 to 2.0 wt% SiO 2 or B 2 O 3 or 5 wt% GeO 2 , the conventional concept of glass structure composed of a random spacial network of SiO 4 tetrahedra, whose interstices are filled with network modifiers, cannot be sustained in this case. It is suggested that the dominant cations Bi 3 + and Cd 2+ form the network and that the interstices are occupied by Si4 + cations. The function of the Si 4+ ion apparently is to distort the highly polarizable Bi3 + ion enough to form a random network. It appears to be possible that Bi 3+ and Cd 2+ can form the network in sixfold coordination. The dielectric losses observed are explained in terms of the relative instability of the structure.