Spectroscopic properties and ab initio calculations on the structure of erbium–zinc-borate glasses and glass ceramics

Rada, S.; Păşcuţă, Petru; Rus, L.; Rada, M.; Culea, E.

doi:10.1016/j.jnoncrysol.2011.08.017

Cited by 25 publications

(4 citation statements)

References 33 publications

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“…The Zn–O distance appears at significantly higher value at 1.97 Å for all three investigated samples. This value is in good agreement with the results obtained for other glasses with ZnO ( r Zn‐O = 1.93–1.95 Å, 1.83–1.91 Å, 1.94–1.97 Å, 1.96 Å). The O–O correlation functions consist of double peak with characteristic distances at 2.35 Å and at 2.85–2.98 Å, the actual value of the second subpeak depends on MoO 3 /B 2 O 3 fraction.…”

Section: Reverse Monte Carlo Modelingsupporting

confidence: 92%

“…The basic network former units in MoO 3 ‐based glasses are MoO 4 tetrahedral, however, for systems with high concentration (>80 mol%) both MoO 4 and MoO 6 units are present . Several studies deal with ZnO containing glassy systems, concerning the role of Zn 2+ cations, which may act as modifier if its fraction is low or network former in case of relatively high content of ZnO …”

Section: Introductionmentioning

confidence: 99%

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Formation of Mixed Bond‐Angle Linkages in Zinc Boromolybdate Glasses

Fábián

Sváb

2016

J. Am. Ceram. Soc.

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The short and medium range structure of glassy MoO3-ZnO-B2O3 has been studied by neutron diffraction and reverse Monte Carlo simulation. The partial atomic pair correlation functions and coordination numbers are presented, not yet reported for this system. We have established that the first neighbor distances do not depend on concentration within limit of error, the actual values are rB-O=1.38 Å, rMo-O=1.72 Å and rZn-O=1.97 Å. It is found that ZnO takes part in the glassy structure as network former, as ZnO4 tetrahedral are linked both to MoO4 and to BO3 and BO4 groups. It is revealed that BO4/BO3 increases with increasing B2O3 content. We have found that only small amount of boroxol ring is present, BO3 and BO4 groups are organized into superstructure units, and a small part is in isolated BO3 triangles. The BO3 and BO4 units are linked to MoO4 or ZnO4 forming mixed [4] Mo-O- [3] B, [4] Mo-O- [4] B, [4] Mo-O- [4] Zn, [3] B-O- [4] Zn, [4] B-O- [4] Zn bond-linkages. IntroductionZinc boromolybdate materials are known as low melting dielectric materials and they have high potential in several applications, due to their stable and unique structure with favourable optical properties [1 and references therein]. The glass formation tendency of MoO3-ZnO-B2O3 and of several other similar compositions has been explored and the optical spectroscopic features have been analyzed by Dimitriev et al. [1][2][3][4][5][6][7][8]. The structure characterization is challenging, as far as this system contains the conditional network former MoO3 and the traditional network former B2O3. For B2O3-based glasses it is widely accepted that the network consists of BO3 and BO4 groups [9][10][11][12][13][14][15][16][17], however, the question often arises concerning the relative amount of the trigonal and tetrahedral units. The basic network former units in MoO3-based glasses are MoO4 tetrahedral, however, for systems with high concentration (> 80 mol %) both MoO4 and MoO6 units are present [3,[18][19][20]. Several studies deal with ZnO containing glassy systems, concerning the role of Zn 2+ cations, which may act as modifier if its fraction is low or network former in case of relatively high content of ZnO [1,[21][22][23][24][25]. The glassy xMoO3-50ZnO-(50-x)B2O3 (x=10, 20, 30 mol %) have been prepared and thoroughly investigated using various optical spectroscopic methods and DTA [1]. Concerning the structural characteristics it was found, that the molybdenum-based glasses contain mainly Mo 6+ ions and a small amount of Mo 5+ ions might be present. It was found, that the coordination state of Mo 6+ ions is mainly (MoO4) 2-tetrahedral units, and formation of diborate, triborate and tetraborate groups, which contain BO3 triangles and BO4 tetrahedra was also suggested. In order get deeper insight into the network structure, including the inter-atomic distances and coordination distributions, we have undertaken neutron diffraction study combined with reverse Monte Carlo (RMC) modeling [26] on the same system. Our interest is mainly foc...

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Section: Reverse Monte Carlo Modelingsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Formation of Mixed Bond‐Angle Linkages in Zinc Boromolybdate Glasses

Fábián

Sváb

2016

J. Am. Ceram. Soc.

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“…In the glass ceramic materials the residual amorphous glassy phase cements the crystal grains and as a result glass‐ceramics possess much higher electrical breakdown strength over the sintered ceramic counterparts with no significant reduction in the optical transmission. In fact, for several glass‐ceramics, it was reported that even the transparency can be retained to a large extent provided the glass material is ceramicized with appropriate nucleating agent with optimal concentration and annealing conditions; because of these characteristics the glass‐ceramics can also be used as luminescent materials . The transparency of the glass ceramic, however, largely depends on the degree of crystallinity, the size of the crystal grains and refractive index of the residual amorphous phase.…”

Section: Introductionmentioning

confidence: 99%

“…In fact, for several glass-ceramics, it was reported that even the transparency can be retained to a large extent provided the glass material is ceramicized with appropriate nucleating agent with optimal concentration and annealing conditions; because of these characteristics the glass-ceramics can also be used as luminescent materials. [9][10][11][12] The transparency of the glass ceramic, however, largely depends on the degree of crystallinity, the size of the crystal grains and refractive index of the residual amorphous phase.…”

Section: Introductionmentioning

confidence: 99%

Insulating characteristics of zinc niobium borate glass‐ceramics

et al. 2017

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Zinc borate glasses with different concentrations of Nb2O5 were prepared and later were heat treated for prolonged times. Prepared samples were characterized by XRD, SEM, DSC, IR and optical transmission spectroscopy techniques. Later, dielectric properties viz., dielectric constant, loss tangent, electric modulii, electrical impedance and a.c. conductivity over wide ranges of frequency and temperature, were investigated as a function of Nb2O5 concentration. Finally, the dielectric breakdown strength was measured in air medium at ambient temperature. The results of characterization techniques viz., XRD, SEM and DSC indicated that multiple crystal grains (with sizes varying from 0.1 to 1 μm) are dispersed in the residual glass phase. The concentration of crystal grains found to increase with increase in Nb2O5 content. The XRD studies have further revealed that the bulk samples are composed of columbite ZnNb2O6 crystal phases. Using generalized gradient approximation (GGA) quantitative information on these crystal phases viz., the lattice parameters, optical band gap and band structure were evaluated. The analysis of results of IR spectral studies have indicated that there is an increasing degree of polymerization of glass network with increase in Nb2O5 content due to the increased connectivity between various structural groups in the glass network. The optical absorption spectra indicated an increase in optical transmittance of the bulk samples with increase in Nb2O5 content. The dielectric parameters are observed to decrease, whereas the dielectric breakdown strength is observed to increase to a large extent due to the crystallization of the glass with the Nb2O5. The increase is attributed to the formation of ZnNb2O6 crystalline phases that contain intertwined ZnO6 and NbO6 structural units. As a whole, zinc borate glasses exhibited a significant increase in the electrical insulating strength due to the crystallization with Nb2O5 as the crystallizing agent. Further, the value of dielectric constant is also found to be the optimal with no dispersion with frequency up to 450 K. Overall, the studied glass‐ceramics meet the necessary physical conditions to be used as insulating layers in the display panels and hence may be considered for such applications.

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Spectroscopic, electrical, and relaxor‐like properties of cellulose acetate–erbium (III) chloride composite films

Basha

Morsi

2017

J of Applied Polymer Sci

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Cellulose acetate thin films doped with erbium (III) chloride (ErCl3) of different concentrations were prepared by the solution method. The prepared composite films were characterized using scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis. IR spectral analysis, UV–visible absorption, a.c. conductivity, and dielectric properties were investigated. The studied ErCl3‐doped samples showed different properties from those of their pure components. SEM micrographs showed that for small dopant concentrations, samples tend to form conducting nanostructures with negligible particle agglomeration. DSC showed a monotonic development of the glass transition temperature by increasing the concentration of dopant material. Variation in the height, shape, and position of the bands in infrared transmission spectra, as well as the glass transition temperatures, indicated a complex interaction with the polymer molecular chains. Thermal stability and thermodynamic parameters were found to be concentration dependent. The electronic transitions’ band gabs and energy tails were calculated from the optical data. The dielectric studies showed that the correlated barrier hopping model was the dominant mechanism of a.c. conductivity. We found that samples with 10% and 20% ErCl3 exhibited high dielectric constants and have pronounced electrostriction and relaxor‐like properties. Such samples can be used in many applications like electromechanical and thermomechanical transducers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45220.

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Spectroscopic properties and ab initio calculations on the structure of erbium–zinc-borate glasses and glass ceramics

Cited by 25 publications

References 33 publications

Formation of Mixed Bond‐Angle Linkages in Zinc Boromolybdate Glasses

Formation of Mixed Bond‐Angle Linkages in Zinc Boromolybdate Glasses

Insulating characteristics of zinc niobium borate glass‐ceramics

Spectroscopic, electrical, and relaxor‐like properties of cellulose acetate–erbium (III) chloride composite films

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