Vibrational Spectroscopic Studies of Germanium-High Bismuthate Glasses and Vitroceramics

Abstract

Bi2O3-rich glasses belonging to the system xGd2O3(1−x)[0.857Bi2O3·0.143GeO2] with 0.005≤x≤0.1, have been obtained by rapid cooling of the melts. Polycrystalline samples have been further obtained by applying a heat treatment at 600ºC for 24 h. Both types of samples were structurally characterized by using X-ray diffraction (XRD), and infrared (IR) and Raman spectroscopic techniques. Local structural units for the investigated samples are identified on the basis of vibrational spectroscopic data. The obtained data reveal the presence of GeO4, GeO6, BiO3 and BiO6 groups as basic structural units of the networks. For the vitroceramic samples some changes occur in their network, mainly reflecting the presence of an ordered structure, but much important is that part of the BiO6 structural units from Bi2O3-GeO2 glass network are converting into BiO3 units. The IR and Raman results support the idea that the local structure of the glasses and vitroceramics is less affected by the presence of Gd3+ ions but there is strong long range order influence on developed crystalline phases from vitroceramic samples, as proved by XRD. However, the spectral analyses reveal the formation of a structure with a higher disorder degree for x=0.1 in comparison with the other investigated vitroceramics as a result of the partial replacement of the Bi3+ ions with Gd3+ ions. Starting from the Bi12GeO20 sellenite phase in the samples with low gadolinium content (x≤0.01), the structure is change to Bi24GeO38 phase, via a BiLa type structure, when the Gd2O3 concentration is increasing up to x=0.1.

Processing and Properties of Eu3+‐Doped Barium Bismuth Titanate (BaBi4Ti4O15) Glass–Ceramic Nanocomposites

“…The observed bands for the glass precursor are broad, whereas for the heat‐treated GCs; sharp bands are observed, indicating the presence of the BBiT crystals. Sharp bands at 480 and 680 cm −1 , seen in the GCs, are due to the presence of Bi–O bonds . The presence of absorption peaks due to the stretching vibrations of Bi–O bonds in the strongly distorted BiO 6 octahedral units at about 490 cm −1 in the FT‐IR absorption spectra were reported by Ardelean et al .…”

Photoluminescence of Ag Nanoparticles and Tm3+ Ions in the Bismuth Germanate Glasses for the Blue Light‐Excited W‐LED

“…8 Our previous work also demonstrated the Ag NPs-enhanced up-conversion luminescence and discussed the influence of annealing temperature or AgCl concentration on Er 3+ luminescence. 16,17 These glasses are also attractive to researchers because of their unique structural characteristics, which result from coordination changes of bismuth and germanium atoms. [10][11][12] These Ag species do emit themselves in the visible, they in addition, transfer some part of the excitation energy to the RE ions, which then emit in the near infrared.…”

“…15 Among the glass host matrices for RE, bismuth germanate glasses are attractive materials for their physical properties as they can be used as optical waveguides in the infrared region, as active media for Raman optical fiber amplifiers, scintillation counters, thermal and mechanical sensors, as well as other optical devices, such as optical fibers, optical switching, optical memory, etc. 16,17 These glasses are also attractive to researchers because of their unique structural characteristics, which result from coordination changes of bismuth and germanium atoms. GeO 2 is a typical glass former as this compound alone can build up a glass network composed from tetrahedra and octahedra of germanium coordinated by oxygen.…”