Structural Analysis of Glassy Lead Borate Containing MoO3 In Relation to Its Optical Properties

Abstract

Glasses with the base un-doped composition 80%PbO.20%B2O3 andthat containing MoO3 with 1% and 5% were studied using X-ray diffraction(XRD) technique. The scattered X-ray intensity was Fourier transformed andthe Radial Distribution Function (RDF) analysis was applied to extract thestructural information's of these samples. The first nearest neighbor is observedat 1.315Å, 1.456Å and 1.499Å respectively for the un-doped and dopedsamples. This first nearest neighbor seems to be due to B-O correlations in theform of triangles. The second nearest neighbor is centered at about 2.12Å forthe base sample and is shifted to 1.92Å for the doped ones; this peak isattributed to O-O correlations having a coordination number of about two. TheB-B pairs were located at 2.36Å for the investigated samples with a reducedcoordination number, ~2.0. The coordinated Pb-O pairs were observed at2.60Å with a form of PbO3 in the sample having 1% MoO3, and an appreciablechange in both Pb-O bond length and coordination number was noted in theother two samples. The Pb-O pairs in the two samples(0.0 and 5% MoO3) werestretched (at 2.80Å) and arranged in the tetrahedral form(PbO4). The peaklocated at 3.55Å for the base sample and that contains 1% MoO3 is mainly dueB-O pairs arranged in BO4 and BO3 forms. In the third sample (having 5%MO3) both of Non-Bridging Oxygen(NBO) and Bridging ones(BO) in theconnected B-O pairs are evolved; at 3.24Å and 3.64Å with an arranged BO3form. The Pb-Pb metallic correlations were observed at ~4.0Å with acoordination number about 4.0 for all samples. The structure of these glassynetworks was modeled and the different bond angles were concerned. The XRDexperimental findings were supported by IR, Raman and ESR measurements ofthe studied samples.