ChemInform Abstract: OPTICAL ABSORPTION CHARACTERISTICS OF NICKEL(2+) IN MIXED‐ALKALI BORATE GLASSES

Ahmed, A. A.; Abbas, Amir

doi:10.1002/chin.198338372

Cited by 3 publications

(3 citation statements)

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“…4 T 1g ðGÞ: The band positions reported for the different mixed alkali NaKB glasses corresponding to 6 A 1g ðSÞ ! 4 T 1g ðGÞ transition are also presented in Table 4 [36]. However, they did not report the band positions but concluded that the effect is small.…”

Section: Optical Absorption Studiesmentioning

confidence: 99%

Mixed alkali effect in borate glasses—EPR and optical absorption studies in xNa2O–(30−x)K2O–70B2O3 glasses doped with Mn2+

Chakradhar

Ramesh

Rao

et al. 2003

Journal of Physics and Chemistry of Solids

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The mixed alkali borate xNa 2 O-(30 2 x )K 2 O-70B 2 O 3 (5 # x # 25) glasses doped with 1 mol% of manganese ions were investigated using EPR and optical absorption techniques as a function of alkali content to look for 'mixed alkali effect' (MAE) on the spectral properties of the glasses. The EPR spectra of all the investigated samples exhibit resonance signals which are characteristic of the Mn 2þ ions. The resonance signal at g ø 2.02 exhibits a six line hyperfine structure. In addition to this, a prominent peak with g ø 4.64, with a shoulder around g ø 4.05 and 2.98, was also observed. From the observed EPR spectrum, the spin-Hamiltonian parameters g and A have been evaluated. It is interesting to note that some of the EPR parameters do show MAE. It is found that the ionic character increases with x and reaches a maximum around x ¼ 20 and thereafter it decreases showing the MAE. The number of spins participating in resonance (N ) at g ø 2.02 decreases with x and reaches a minimum around x ¼ 20 and thereafter it increases showing the MAE. It is also observed that the zero-field splitting parameter (D ) increases with x, reaches a maximum around x ¼ 15 and thereafter decreases showing the MAE. The optical absorption spectrum exhibits a broad band around ,20,000 cm 21 which has been assigned to the transition 6 A 1g (S) ! 4 T 1g (G). From ultraviolet absorption edges, the optical bandgap energies and Urbach energies were evaluated. It is interesting to note that the Urbach energies for these glasses decrease with x and reach a minimum around x ¼ 15. The optical band gaps obtained in the present work lie in the range 3.28-3.40 eV for both the direct and indirect transitions. The physical parameters of all the glasses were also evaluated with respect to the composition.

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Section: Optical Absorption Studiesmentioning

confidence: 99%

Mixed alkali effect in borate glasses—EPR and optical absorption studies in xNa2O–(30−x)K2O–70B2O3 glasses doped with Mn2+

Chakradhar

Ramesh

Rao

et al. 2003

Journal of Physics and Chemistry of Solids

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“…A single absorption band in near-infrared region is observed in all samples, which are attributed to d-d transition band due to Cu 2+ ions [17]. Cu 2+ undergoes a Jahn-Teller distortion, which leads to the splitting of energy levels in terms of ligand field theory [18]. It is observed that the elongated structures are usually more energetically favoured than the compressed ones [19].…”

Section: Resultsmentioning

confidence: 85%

IR, EPR and Optical Absorption Studies of xCuO-(1-x)Bi2O3 Glasses

Sharma¹,

Ilamathi²

2018

Asian J. Chem.

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CuO-containing glasses draw special attention because of their different electrical conductivity [1] and structureproperty behaviour [2,3] compared to the glasses containing V2O5 [4] and MoO3 [5]. In the case of CuO, during the reduction process by citric acid for gel formation [6], Cu + (3d 10) ions are formed. The Cu 2+ (3d 9) ion is an interesting paramagnetic site to study the nature of bonding and site symmetry [7] by electron paramagnetic resonance (EPR) spectroscopy. Electron paramagnetic resonance investigations of Cu 2+ ions in glasses are interesting and have received a considerable attention due to the sensitivity of parameters to local symmetry and have been studied in wide variety of glasses [8]. Furthermore, in the case of Bi2O3-containing glasses, the structural complications involving the different units in the network, makes it interesting to study the structural-property relations in such systems. Unconventional glasses containing Bi2O3 as glass former are of great interest because of their potential applications in industry and many allied areas [9]. By correlating the electron paramagnetic resonance and optical absorption spectra, we obtain information regarding the bond parameters that determine the metal-ligand bond nature in the glasses. In this paper we study the changes in IR, electron paramagnetic resonance and optical absorption parameters as a result of the variation in glass composition.

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“…Ahmed et al [15] have found only a small deviation from the linearity in the optical absorption spectral characteristics of Cu 2+ in a couple of mixed alkali borates, with the composition of the alkali elements. However, a systematic study of the spectral characteristics in mixed alkali borate glasses is necessary to evolve a consistent understanding of the mixed alkali effect in borate glasses, as borate glasses undergo interesting structural changes with alkali content.…”

Section: Introductionmentioning

confidence: 97%

The effect of mixed alkali on EPR and optical absorption spectra in mixed alkali borate xNa2O–(30−x)K2O–70B2O3 glasses doped with iron ions

Chakradhar

Ramesh

Rao

et al. 2005

Journal of Non-Crystalline Solids

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Electron paramagnetic resonance (EPR) and optical absorption studies of iron doped mixed alkali borate glasses, xNa 2 O-(30 À x)K 2 O-70B 2 O 3 (5 6 x 6 25) have been investigated as a function of alkali content to look for the Ômixed alkali effectÕ on the spectral properties of the glasses. The EPR spectra of all the investigated samples exhibit resonance signals which are characteristic of the Fe 3+ ions. The EPR spectrum exhibits an intense resonance signal at g = 4.02 ± 0.1, a moderately intense signal at g = 2.02 ± 0.1 and a shoulder in the region of g = 7.20 ± 0.5. The existence of the resonances at g = 4.02 and g = 7.20 have been attributed to Fe 3+ ions in rhombic and axial symmetry sites respectively. The g = 2.02 resonance is due to Fe 3+ ions coupled by exchange interactions. The number of spins (N) participating in resonance and its paramagnetic susceptibility (v) have been evaluated. It is observed that N and v decrease with x up to x = 10 and then increase up to x = 15 exhibiting a minimum at x = 10 and a maximum at x = 15 and thereafter it gradually decreases. The optical absorption spectrum exhibits three bands assigned to 6 A 1g (S) ! 4 A 1g (G), 4 E g (G); 6 A 1g (S) ! 4 T 2g (G) of Fe 3+ and the other band is assigned to Fe 2+ -Fe 3+ inter-valence charge transfer band. From ultraviolet absorption edges, the optical bandgap and Urbach energies have been evaluated. The optical band gap energy obtained in the present work varies 2.74-3.77 eV for both the direct and indirect transitions. The physical parameters of all the glasses have been evaluated with respect to x.

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ChemInform Abstract: OPTICAL ABSORPTION CHARACTERISTICS OF NICKEL(2+) IN MIXED‐ALKALI BORATE GLASSES

Abstract: Die Ligandenfeldstärke, der Racah‐Parameter und der Koordinationszustand des Ni" in Ni‐haltigen gemischtalkalischen Boratgläsem (Li,O‐K,O‐B2O3 und Na2O‐ K,O‐B,O3) werden anhand ihrer spektralen Absorption im Sichtbaren und nahen lR bestimmt.

Cited by 3 publications

References 1 publication

Mixed alkali effect in borate glasses—EPR and optical absorption studies in xNa2O–(30−x)K2O–70B2O3 glasses doped with Mn2+

Mixed alkali effect in borate glasses—EPR and optical absorption studies in xNa2O–(30−x)K2O–70B2O3 glasses doped with Mn2+

IR, EPR and Optical Absorption Studies of xCuO-(1-x)Bi2O3 Glasses

The effect of mixed alkali on EPR and optical absorption spectra in mixed alkali borate xNa2O–(30−x)K2O–70B2O3 glasses doped with iron ions

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