Role of Crystal Field in Mixed Alkali Metal Effect: Electron Paramagnetic Resonance Study of Mixed Alkali Metal Oxyfluoro Vanadate Glasses

Honnavar, Gajanan V; Ramesh, K.; Bhat, S. V.

doi:10.1021/jp409606q

Cited by 14 publications

(16 citation statements)

References 26 publications

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“…The EPR spectra in Fig. 8 are similar to those reported for vanadium-doped glasses [19,24,43] and are typical of VO 2+ ions in axially distorted sites. The EPR spectra can be described in terms of the spin-Hamiltonian for d [1] ions in axial symmetry,…”

Section: Linear Refractive Indexsupporting

confidence: 79%

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Synthesis and structural characterization of a new SbPO4-GeO2 glass system

Montesso

Manzani

Donoso

et al. 2018

Journal of Non-Crystalline Solids

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This work presents the production and characterization of a new prolific binary glass system based on SbPO 4-GeO 2. The dependence of GeO 2 content on thermal, structural and optical properties were investigated by means of thermal analysis, Raman, UV-Vis-NIR, infrared, M-lines and EPR spectroscopy. Glass transition temperatures remain constant around 410°C when GeO 2 content is increased, indicating that GeO 4 units are not responsible for increasing the connectivity of PO 4 units. Thermal stability linearly increases as a function of GeO 2 content, reaching a value around 400°C for glass containing 90 mol% of GeO 2. Raman spectroscopy was used to evaluate the glass structural changes when GeO 2 is incorporated from 30 to 90 mol% indicating a gradual change from a phosphate to a germanate glass skeleton. The optical window extends from 350 nm at UV region, up to 2.7 μm in the middle-infrared region limited by the multiphonon cutoff due to the strong OH absorption. M-lines technique shows that increasing GeO 2 content decreases the refractive index, mainly because the lower concentration of higher polarizable antimony atoms. EPR spectra of heat treated V 2 O 5 doped glasses, at different temperatures above the glass transition temperature, shows the characteristic eight-line hyperfine splitting spectrum. The spin Hamiltonian parameters obtained from the simulated spectra indicates that the paramagnetic tetravalent vanadium ions in the glasses exist as vanadyl form VO 2+ , located in axially distorted octahedral sites. For glasses treated at higher temperatures a second VO 2+ component appears in the EPR spectra and the analysis of the spin-Hamiltonian parameters suggests that these vanadyl ions are in more tetragonal distorted octahedral sites than those in the glass.

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Section: Linear Refractive Indexsupporting

confidence: 79%

“…The +2 and the +3 states, although paramagnetic, are rarely observable by EPR [22]. The +5 (diamagnetic) and the +4 (paramagnetic) are the most frequent valence states of vanadium in oxide glasses [23,24]. In these glasses, the V 4+ ion appears almost exclusively as a vanadyl form, VO 2+ [25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and structural characterization of a new SbPO4-GeO2 glass system

Montesso

Manzani

Donoso

et al. 2018

Journal of Non-Crystalline Solids

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“…The obtained EPR spectrum is attributed to the presence of V 4+ in the glass samples as this species of vanadium is EPR active due to the presence of a single unpaired electron. 13 51 V in V 4+ has an outer shell electronic configuration of 3p 6 3d 1 . So, in vanadyl ion (VO 2+ ) with electron spin S = 1/2 and nuclear spin I = 7/2, the total number of hyperfine components are (2 I + 1) and its rich hyperfine structure consists of 8 lines.…”

Section: Results and Discussionmentioning

confidence: 99%

“…These techniques are able to estimate the changes in the specific coordination of the network former (V 2 O 5 ) and estimate bond lengths up to a few angstroms. 12 , 13 …”

Section: Introductionmentioning

confidence: 99%

Short-Range Structural Insight into Lithium-Substituted Barium Vanadate Glasses Using Raman and EPR Spectroscopy as Probes

Goel¹,

Honnavar

2021

ACS Omega

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We present a corroborative study of the structural characterization of lithium-substituted barium vanadate glasses using Raman and electron paramagnetic resonance (EPR) spectroscopy. Investigation of the thermal and physical properties of these glasses showed a gradual increase in the concentration of nonbridging oxygen. Raman and EPR analysis gave an insight into the changing structure of the glasses. Both the spectroscopic techniques confirmed that vanadium is present in the glasses as distorted VO 6 octahedra. From the analysis of both spectroscopic techniques, it is proposed that the lithium ion prefers to occupy planar positions of the VO 6 octahedra, thus reducing the tetragonal distortion and making the environment around the network-forming unit in the glass matrix more homogeneous as we increase the lithium content. The concentration of V 4+ showed a non-monotonic variation with an increase in Li 2 O as indicated by Raman studies and confirmed by EPR, which indicates a structural change in the distorted VO 6 octahedra.

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“…However, the influence of MAE is not considerably studied in like Optical absorption, FTIR and Electrical properties. Some research workers studied the MAE in the spectroscopic and electrical properties of glasses [8][9][10][11][12][13][14][15]. The glasses contain alkali ions and substitute transition metal oxides make colored glasses, these are generally acting as optically colorless and ionic conductors.…”

Section: Introductionmentioning

confidence: 99%

Structural, Optical and Electrical Properties of Copper Doped Alkali Borate Glasses

Srinivas

Komaraiah

et al. 2021

Preprint

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The compositional effect on Physical properties, Optical absorption and Electrical properties of glass composition xK2O - (25-x) Li2O-12.5BaO-12.5MgO-49B2O3-1CuO (x =0, 5, 10, 15, 20 and 25mol %) was prepared by the melt-quenching technique. From optical absorption spectra few parameters, like Urbach energy, indirect allowed, reflection loss (R), refractive index (n), molar polarizability(αm) molar refractivity (Rm), and theoretical optical basicity (Λth) values of prepared glass samples were measured. The values of Rm, αm, and Λth were increase with increasing of x mol%. The Eopt, R, and n values were changed very small with x mol%, which may be due to the non-bridging oxygen’s moments in the glass matrix. The FTIR spectrum of prepared borate glasses indicates that the influence of BO3 and BO4 units of boron atoms. The explicit vibrational peaks were exhibited of Li–O, K–O, Mg–O, and Ba–O bonds in glass network, and A.C conductivity study was devised to know the structural information about the glass network. The drastic change in the ionic conductivity as a function of the alkali content in the glass composition was analyzed by considering both the ionic mobility and the glass structure. Some physical, optical, and electrical values varied non-linearly with the K2O content, which may influence of non- bridging oxygens or mixed alkali effect.

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Role of Crystal Field in Mixed Alkali Metal Effect: Electron Paramagnetic Resonance Study of Mixed Alkali Metal Oxyfluoro Vanadate Glasses

Cited by 14 publications

References 26 publications

Synthesis and structural characterization of a new SbPO4-GeO2 glass system

Synthesis and structural characterization of a new SbPO4-GeO2 glass system

Short-Range Structural Insight into Lithium-Substituted Barium Vanadate Glasses Using Raman and EPR Spectroscopy as Probes

Structural, Optical and Electrical Properties of Copper Doped Alkali Borate Glasses

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