BO4 Structural Units Research Articles

Unraveling the hidden Urbach edge and Cr6+ optical transitions in borate glasses

Two alkaline-borate glass systems of composition x Li2O · 0.2 Cr2O3 · (99.8–x) B2O3 (x = 20, 30 and 40 mol%) and y K2O · (20-y) Li2O · 0.2 Cr2O3 · 79.8 B2O3 (y = 5, 10, 15 and 20 mol%) were prepared by traditional melt-quenching technique. The tunability of their optical spectra, offered by different alkaline contents, allowed disentangling the absorption edge from the characteristic Cr6+ optical transitions. Specifically, the optical band gap is barely affected (3.55 ± 0.15 eV), whilst Cr6+/Cr3+ optical transitions undergo subtle intensity variation with the alkaline content. With increasing the alkaline content, or type, the crystal field strength (10 Dq) is increased, Racah parameters are decreased, and the ligand environment facilitates the crossover from weak into strong ligand field regimes. Electron spin resonance spectroscopy confirmed the existence and quantified the percentage of both Cr6+ (through charge transfer into Cr5+ O−) and Cr3+ oxidation states. Finally, the number of non-bridging oxygen, obtained from Infrared spectroscopy, is increased noticeably for both type and percentage of alkaline, while BO4 structural units increase with Li content and are barely affected for K-doped system.

Comprehensive study on the effect of Gd2O3 NPs on elastic properties of zinc borotellurite glass system using non-destructive ultrasonic technique

Quaternary Gd2O3 NPs doped zinc borotellurite (TeO2-B2O3-ZnO-Gd2O3 NPs) glass system were fabricated using conventional melt-quenching method with composition {[(TeO2)70(B2O3)30]70(ZnO)30}1-x(Gd2O3 NPs)x (x = 1.0, 2.0, 3.0, 4.0 and 5.0 mol%). The physical, structural and elastic properties of the glass samples were investigated. X-ray diffraction (XRD) were used to confirm the amorphousity of the samples. Fourier Transform Infrared (FTIR) spectroscopy indicated the presence of TeO3, TeO4, BO3 and BO4 structural units within the glass matrix. The presence of Gd2O3 NPs was proven from Transmission Electron Microscopy (TEM). The density and molar volume showed anomalous behavior. The elastic properties of the glass system were characterized by using pulse-echo technique. The longitudinal and shear ultrasonic velocities vary from 3883 to 4042 m/s and 2265 to 2282 m/s, respectively. The observed change in the ultrasonic velocities imply that there are substantial change in the structure of the vitreous network. The experimental elastic moduli (longitudinal modulus (L), shear modulus (G), bulk modulus (K) and Young's modulus (E)) increases from 68.77 to 79.45 GPa, 23.40 to 26.68 GPa, 37.56 to 48.25 GPa and 58.13 to 66.55 GPa, respectively. The increase in elastic moduli of the glass system indicates that the strength and rigidity of the glass increase. The experimental elastic moduli were correlated and compared with the theoretically calculated elastic moduli using Makishima-Mackenzie and Bond Compression model.

EPR, optical, physical and structural studies of strontium alumino-borate glasses containing Cu2+ ions

Glass composition (30 − x) SrO–xAl2O3–69.5B2O3–0.5CuO (0 ≤ x ≤ 15 mol%) captioned as SABC was prepared by the conventional melt quenching technique. Peak-free X-ray diffractograms and homogeneous plain SEM image confirm the glassy nature of the prepared samples. EPR and optical absorption spectral studies were carried out to understand the effect of modifier oxide (SrO) and transition metal (TM) ion Cu2+ in the glass network. From the EPR spectra, spin-Hamiltonian parameters were evaluated. It was observed that $$g_{\parallel } > g_{ \bot } > g_{e} \,{\text{and}}\,A_{\parallel } > A_{ \bot }$$ suggest that the ground state of Cu2+ is $$d_{{x^{2} - y^{2} }}$$ (2B1g state) and the site symmetry around Cu2+ is tetragonally distorted octahedral. The optical absorption spectra revealed a broad absorption for all the glass samples. This band is assigned to 2B1g → 2B2g transition. From optical absorption spectra, optical band gap and Urbach energy values were calculated. The FTIR and Raman spectral studies showed that the glass network consists of BO3 and BO4 structural units.

Physical, structural, optical and photons attenuation attributes of lithium-magnesium-borate glasses: Role of Tm2O3 doping

Room temperature visible photoluminescence from rare earth ions doped in glasses became prospective for eye safe laser and sensor applications. Driven by this idea, glass system with nominal composition of 20Li2O–(70-x)B2O3–10MgO–xTm2O3 (where 0 ≤ x ≤ 1) were synthesized via a melt-quenching technique. As-quenched samples were analyzed using various analytical tools at room temperature. XRD patterns of as-quenched samples confirmed their amorphous nature and FTIR spectra revealed the existence of BO3 and BO4 structural units. Achieved glasses were transparent and thermally stable (verified by DTA curves). UV–vis-NIR spectra of glasses disclosed four significant absorption bands at round 791, 683, 466 and 355 nm which were assigned to the transitions from ground level of 3H6 to respective 3H4, 3F3, 1G4 and 1D2 excited levels of Tm3+ ions. Photoluminescence emission spectra (at an excitation wavelength of 473 nm) of prepared glasses displayed three characteristic peaks positioned at 476, 650 and 783 nm corresponding to 1G4→3H6, 1G4→3F4 and 3H4→3H6 transitions from Tm3+ ions. Also, the photon shielding properties for the LMB glasses with different Tm2O3 content were studies using the well known program (XCOM). The mass attenuation coefficients showed an increase behavior as the Tm2O3 concentration rise. Overall, the properties of LMB glasses were discerned to be sensitive to the Tm2O3 concentration variation. It was concluded that the proposed glass compositions may be useful for solid state lasers and telecommunications applications.

Structural Characteristics of a Family of Bioactive Glasses Formed by Replacing Varying Amounts of SiO 2 in 45S5 Glass with B 2O 3

Bioactive glasses with controllable reactivity and bioactive potential have been created by replacing varying amounts of SiO2in silicate 45S5 glass with B2O3. While these borate and borosilicate glasses formed from 45S5 glass are receiving growing interest for hard and soft tissue repair, their structural characteristics have received little attention. In this study, the structural characteristics of a family of bioactive glasses formed by replacing varying amounts of SiO2 in 45S5 glass with B2O3 were evaluated using multiple spectroscopic techniques. A benefit of this work is the use of multiple spectroscopic techniques and one set of compositional variation for a widely used family of bioactive glasses. The results showed that when compared to 45S5 glass, SiO2 remained the primary network in a borosilicate glass designated 45S5-1B, formed by replacing 33.3 mol. % of the SiO2 in 45S5 with B2O3. The glass network in both glasses was composed mainly of SiO4 tetrahedral units with 2 nonbridging oxygen atoms. In comparison, B2O3 was the primary network former in borosilicate 45S5-2B and borate 45S5-3B glasses, formed by substituting 66.7 mol. % and 100 mol. %, respectively, of SiO2 in 45S5 glass with B2O3. The network in these two glasses was composed mainly of trigonal BO3 structural units (orthoborate or pyroborate groups) and a smaller fraction ∼30%) of tetrahedral BO4 units. The observed structural characteristics are used to rationalize data from a previous study for the reactivity and bioactive potential of this family of bioactive glasses.

Borotellurite Glasses for Gamma-Ray Shielding: An Exploration of Photon Attenuation Coefficients and Structural and Thermal Properties

Gamma-ray attenuation characteristics and vibrational and thermal features have been studied for singly doped erbium (Er), dysprosium (Dy), and Er/Dy-codoped sodium lithium zinc lead borotellurite glasses. For all glasses, the amorphous nature was confirmed from the x-ray diffraction profiles, and BO3, BO4, TeO4, TeO3 +1, and TeO3 structural units were identified by both Fourier transform infrared spectroscopy and Raman spectroscopy. Glass transition (Tg), onset crystallization (Tx), peak crystallization (Tc), and melting (Tm) temperatures including thermal stabilities (ΔT) were evaluated following the glass differential scanning calorimetry profiles. An enhancement in Tg (359→399°C) and ΔT variation at 131–169°C with Er2O3, Dy2O3, and Er2O3/Dy2O3 incorporation suggested that the prepared glasses possess good thermal stability. The radiation shielding properties within the 0.356–1.33-MeV photon energy range were assessed for all the glasses. The mass attenuation coefficient (μ/ρ) values have been calculated using Monte Carlo simulation code. Further, photon interaction parameters like effective atomic number (Zeff), half-value layer (HVL), and mean free path (MFP) were also computed. The host and 1.0 Er/1.0 Dy (mol.%)-codoped glasses possess the lowest and highest Zeff values and their magnitudes are varied within the range 11.40–15.99 and 12.14–17.26, respectively. For the host glass, exposure buildup factor values were calculated by the geometric progression (GP) fitting method within the 0.015–15-MeV energy range and up to a penetration depth of 40 MFP. The removal cross sections ΣR (cm−1) for fast neutrons were calculated to evaluate the attenuation of neutrons through the prepared glasses.

Infrared and Raman spectroscopic studies of Mn2+ ions doped in strontium alumino borate glasses: Describes the role of Al2O3.

Strontium alumino borate glasses doped with Mn2+ ions (SABM) have been prepared and characterized by XRD, density, Electron paramagnetic resonance (EPR), FT-IR and Raman to investigate the spectral and physical properties of the present glass samples. The FTIR spectra revealed the presence of BO3 and BO4 structural units in SABM glasses. The IR peak at ~467 and ~679 cm-1 assigned as the vibration of metal cations (Sr2+), MnO bond vibrations and bending vibration of AlO in [AlO4] units. The Raman band ~786 cm-1 establishes the presence of AlO4 units. It has been found that an increasing the Al2O3 content increases the bond length of the AlO bond in AlO4 which leads to increase molar volume and decrease density. Differential scanning calorimetry (DSC) studies indicated that the glass transition temperature (Tg) decreases with increase of Al2O3. Evaluated g and A values from EPR spectra gave the conformation about the ionic bonding between the Mn2+ and its neighbouring oxygen ions.

Enhanced thermal stability of high-bismuth borate glasses by addition of iron

Glasses with nominal molar composition 20B2O3 – (80−x)Bi2O3 – xFe2O3 (where x = 0–40) were successfully prepared by melt-quenching. These glasses were characterised by multiple techniques including density, X-ray diffraction (XRD), X-Ray fluorescence (XRF), Raman, FT-IR and Mössbauer spectroscopies, dilatometry and differential thermal analysis (DTA). Partial replacement of Bi2O3 by Fe2O3 leads to decreasing density and molar volume and a substantial increase in thermal stability, as measured by several parameters, with maximum improvements achieved when x = 10–20. These improvements are accompanied by modest increases in dilatometric softening point. FT-IR and Raman spectra confirm the presence of BO3 and BiO6 structural units in all glasses, with glass structure apparently little affected by Fe2O3. Mössbauer spectroscopy confirms that iron is present partly as 4-fold coordinated Fe3+ in all glasses, with some 5- and/or 6- coordinated Fe3+ sites also present.

Synthesis Conditions on the Nature of GdBO3 Phase Formed

AbstractPresent study has been carried out to develop a facile synthetic methodology for preparing single phase monoclinic and triclinic forms of GdBO3, a potential phosphor material. This is achieved by varying annealing temperatures and annealing steps. Detailed structural studies, using X‐ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopic techniques confirmed that, Gd3+‐boric acid complexes formed initially at low temperatures (300 °C or less) get converted to monoclinic and triclinic forms of GdBO3 depending upon annealing temperatures, annealing steps and heating rates. Multiple steps with slow heating rates (∼3 °C/min) lead to the formation of single phase triclinic form of GdBO3. Two step heating with relatively faster heating rates (5 °C/min and above) results in single phase monoclinic GdBO3. FTIR and Raman studies also confirmed that boron exists only as BO4 structural units (in the form of B3O93− rings) in monoclinic GdBO3 and as BO3 structural units in triclinic GdBO3. Luminescence studies carried out with Eu3+ as a probe species confirmed more covalent nature around Eu3+/Gd3+ ions with improved red colour emission from triclinic form of GdBO3 compared to the monoclinic form.

Structural and dielectric properties of (100 − x)B2O3-(x / 2)Bi2O3–(x / 2)Fe2O3 glasses and glass-ceramic containing BiFeO3 phase

Glasses of the compositions (100 − x)B2O3-(x / 2)Bi2O3–(x / 2)Fe2O3 with x = 50, 60 and 70 (in mol%) were prepared. The glassy phase of the samples was established by X-ray diffraction (XRD) and Differential thermal analysis (DTA) studies. The formation of the BiFeO3 phase inside the glass matrix (glass-ceramic) by the heat treatment of the sample at x = 60 was identified by XRD, DTA and Fourier transform infrared (FTIR) studies. FTIR results revealed that the glass samples are composed of BO3, BO4, BiO3, BiO6, FeO4 and FeO6 basic structural units. The trends of the glass transition temperature (Tg), density (ρ), molar volume (Vm), oxygen packing fraction (OPD) and theoretical optical basicity (Ʌth) were discussed in terms of the structural modifications that take place in the glass matrix. The variation of the dielectric constant (ɛr), dielectric loss (tan δ) and the ac conductivity of the glass samples cannot be explained on the basis of the distance between iron ions (Ri) only but on the space charge polarization. The dielectric properties of the glass-ceramic were affected by the presence of BiFeO3 phase inside the glass matrix.

Study on the influence of TiO2 on the characteristics of multi component modifier oxide based B2O3 glass system

A series of borate glasses mixed with different modifiers (viz., PbO, BaO, CaO, MgO and ZnO of 10 mol% each) and doped with different concentrations of TiO2 (1.0 to 3.0 mol% in the steps of 0.5) was prepared by melt quenching technique. The prepared samples were characterized by XRD, SEM and spectroscopic techniques. The XRD studies have confirmed the amorphous nature of the samples while the SEM pictures revealed the presence of minute fraction of crystallites (of the size <0.1 μm) in the samples. IR spectral studies of the glasses exhibited vibrational bands due to BO3, BO4, BOB, PbO4, ZnO4, TiO4 and TiO6 structural units. The optical absorption and EPR spectral studies have revealed probable presence of Ti3+ ions that act as modifiers and induce structural defects such as dangling bonds, non-bridging oxygens (NBO's) in the glass network. The observed decrease in the optical band gap with increase in the concentration of TiO2 is attributed to the gradual reduction of Ti4+ ions (which participate in the glass network forming) in to Ti3+ ions that act as modifiers.

Structural and Luminescent property of Holmium doped Borate Glasses

Holmium doped Lithium Lead Borate glasses of different compositions were prepared by melt quenching technique. Fourier transform infrared investigations on lithium lead borate glasses have been made to study the local order and vibrations of atoms in the glass network and it contains mainly BO3 and BO4 structural units. Photoluminescence techniques were employed to investigate the luminescent property of these glasses excited at 451nm. Blue emission have been observed from the transition 495 (5F3 → 5I8).

Structural insights for the International Simple Glass by combining X-ray absorption spectroscopic analysis and atomistic modelling

Structural investigation of disordered systems rely mainly on atomistic simulations or are inferred from experimental techniques like NMR or X-ray absorption spectroscopy, but there is still a gap when trying to combine them. Based on the structural study of the borosilicate glass ISG, we used a combination of 11B NMR, X-ray and neutron diffraction, XANES, EXAFS and EPSR atomistic modelling to further investigate the local and medium range order of this specific glass. In particular, we present improved EXAFS fits by using local Zr environment extracted from EPSR simulations, which highlight the role of SiO4, BO3 and BO4 structural units, and the charge sharing role of alkalis in the Zr environment. We also show that multiple scattering paths are likely to be present in EXAFS data for this kind of glass, which leads to important conclusions regarding Zr environment.

In vitro investigations on CoO doped CaF2[sbnd]CaO[sbnd]B2O3[sbnd]P2O5−MO bioactive glasses by means of spectroscopic studies

In this investigation we have synthesized CaF2CaOB2O3P2O5: CoO glasses mixed with different therapeutically active ions viz., Ba2+, Sr2+, Mg2+ and Zn2+ (that play a vital role in the normal functioning of human body) and performed in vitro bioactivity studies by immersing them in simulated body fluid (SBF) for a period of about a month and the obtained results were analyzed using spectroscopic studies. Due to immersion in SBF solution, a thin layer of hydroxy apatite (HAp) is developed on the surface of the samples. The results of XRD, SEM and also IR spectra have confirmed that the layer deposited on the surface of the samples is crystalline HAp mixed with cobalt ions. The quantitative analysis of the results in vitro bioactive studies with the help of optical absorption and IR spectral studies have indicated that BaO is an efficient modifier in accelerating the HAp growth. The cobalt ions are found to be in tetrahedral positions and participated in the glass network with BO4 and PO4 structural units in larger quantities in CoZn and CoMg glasses and such occupancy is found to be the reason for the relatively low bioactive efficiency of these glasses when compared with that of CoBa glass.

The correlation between the structural, optical, and electrical properties in mixed alkali fluoroborate glasses containing vanadium ions

Lithium sodium fluoroborate glasses doped with vanadium ions were prepared by melt annealing technique. The structural investigation shows the formation of probable BO3, BO4, BO2F, and BO3F structural units. Moreover, vanadium ions are mostly presented in such glasses as V4+ state and it may form non-bridging oxygens (NBOs). The decreasing in the optical band gap values as a function in the glass composition or vanadium content approves the formation of NBOs. The refractive index is estimated directly from the optical band gap values by using the Dimitrov-Sakka relation. Density, molar volume, molar refraction, and metallization criterion were studied and explained in terms of the structural changes obtained by the impact of the vanadium ions. Thermal activation energy is explained by the formation of Non-bridging oxygens and the effect of V2O5 dopant.

Tuning the structural and optical properties in cobalt oxide-doped borosilicate glasses

Borosilicate glass systems with composition xSiO2 - (50-x) B2O3 - 30Na2O - 19.5ZnO - 0.5CoO (x = 0, 5, 10 and 20 mol. %) have been successfully prepared following the traditional melt quenching technique. The incorporation of SiO2 into borate glass network was found to tune its properties at different aspects, as probed by a set of complementary experimental techniques. The density of such boraosilicate glasses was decreased by SiO2 addition, thus, rendering the glassy network less tightly packed. In addition, the BO4 structural units were found to increase with SiO2 content as obtained from comparative FTIR spectra. Interestingly, the optical properties of such borosilicate glasses could be tuned through SiO2 addition. In particular, the optical band gaps attain larger values together with noticeable suppression of the band tails associated with defective structures upon SiO2 addition. Further insights into the crystal field interaction and d-levels splitting were obtained by a detailed deconvolution procedure applied to the characteristic absorption bands of Cobalt. The outcome of such a process revealed noticeable reductions in the ligand field strength and the associated d-levels splitting with SiO2 additives. Furthermore, the octahedral symmetry contribution was increased in borosilicate compared to the pure borate glasses as inferred from the oxidation states of Co ions probed by ESR. The present system combines the advantageous of the pure borate and silicate glasses and, therefore, offers an alternative candidate for optical applications.

A novel orange-red emitting Ba2Ca(BO3)2:Sm3+ phosphor to fill the amber gap in LEDs: Synthesis, structural and luminescence characterizations

The present paper reports on the structural and luminescent properties of un-doped and Sm3+ doped Ba2Ca(BO3)2 phosphors synthesized by the conventional solid state method. For structural characterizations, the X-ray diffraction, FTIR spectroscopy and Rietveld refinement method were used. The FTIR spectrum was composed of basic BO3 and BO4 structural units of borates. The Sm3+ doped phosphors under 402 nm (6H5/2 → 4L13/2) excitation, showed an orange red emission corresponding to the 601 nm (4G5/2 → 6H7/2) transition of the Sm3+ ion. An increase in the PL emission intensity was observed up to 2 mol % with the increase in Sm3+ ions concentration. The critical distance between the Sm3+– Sm3+ ions were found to be 24.36 Å. Moreover, the phosphors decaytime and optical bandgap at different concentration of Sm3+ ion also have been discussed in details. All the results show that Ba2Ca(BO3)2:Sm3+ phosphor may be used with a near ultraviolet (n-UV) chip to fill the amber gap in light emitting diodes (LEDs).

Novel borate CsZn2B3O7 single crystal with large efficient second harmonic generation in deep-ultraviolet spectral range

The linear and nonlinear optical susceptibility dispersion of CsZn2B3O7 single crystal are comprehensively investigated for a bulk structure in form of single crystal taking into account the influence of the packing structural units. The calculation highlights that the BO3 structural units packing is the main source for the large birefringence in CsZn2B3O7 due to high anisotropic electron distribution, and, hence, it affects the macroscopic second harmonic generation (SHG) coefficients. The large SHG is due to hyperpolarizablity formed by ZnO4 tetrahedra and co-parallel BO3 triangle groups. The absorption edge of CsZn2B3O7 occurs at λ = 218 nm and the optical band gap is estimated to be 5.68 eV that is in good agreement with the experimental data (5.69 eV). Therefore, CsZn2B3O7 is expected to produce a coherent radiation in deep-ultraviolet (DUV) region with SHG of about 1.5 × KDP (1.5 × 0.39 p.m./V = 0.585 p.m./V) that agrees with the measurements. This work is aimed at the report of reliable SHG value and the details of the NLO tensor for bulk CsZn2B3O7 single crystal.

Investigation of structural, thermal properties and shielding parameters for multicomponent borate glasses for gamma and neutron radiation shielding applications

Multicomponent borate glasses with the chemical composition (60−x) B2O3–10 Bi2O3–10 Al2O3–10 ZnO–10 Li2O–(x) Dy2O3 or Tb4O7 (x=0.5mol%), and (60−x−y) B2O3–10 Bi2O3–10 Al2O3–10 ZnO–10 Li2O–(x) Dy2O3–(y) Tb4O7 (x=0.25, 0.5, 0.75, 1.0, 1.5, and 2.0mol%, y=0.5mol%) have been fabricated by a conventional melt-quenching technique and were characterized by X-ray diffraction (XRD), Attenuated Total reflectance-Fourier transform Infrared (ATR-FTIR) spectroscopy, Raman spectroscopy, thermo-gravimetric analysis (TGA), and differential scanning calorimetry (DSC). Also, the radiation shielding parameters such as mass attenuation coefficient (μ/ρ), half value layer (HVL), mean free path (MFP) and exposure buildup factor (EBF) values were explored within the energy range 0.015MeV–15MeV using both XCOM and MCNPX code to determine the penetration of gamma and neutron radiations in the prepared glasses. The main BO3, BO4, BiO6, and ZnO4 structural units and AlOAl bonds were confirmed by ATR-FTIR and Raman spectroscopy. Weight loss, and the glass transition (Tg), onset crystallization (Tx), and crystallization (Tc) temperatures were determined from TGA and DSC measurements, respectively. The stability of the glass against crystallization (ΔT) is varied within the temperature range 114–135°C for the studied glasses. In addition, the shielding parameters like the (μ/ρ) values investigated using both MCNPX Monte Carlo and XCOM software are in good agreement with each other. The (μ/ρ) values calculated using XCOM software were used to evaluate the HVL and MFP in the photon energy range 0.015MeV–15MeV. It is found that all the synthesized glasses possess better shielding properties than ordinary concrete, zinc oxide soda lime silica glass and lead zinc phosphate glass indicating the high potentiality of the prepared glasses to be utilized as radiation shielding materials.

B[sbnd]O and Te[sbnd]O speciation in bismuth tellurite and bismuth borotellurite glasses by FTIR, 11B MAS-NMR and Raman spectroscopy

Bismuth tellurite and bismuth borotellurite samples were synthesized and structure-property correlations were carried out by density, X-ray diffraction, dielectric measurements, differential scanning calorimetry, infrared, Raman and 11B Magic Angle Spinning Nuclear Magnetic Resonance studies. Low concentration of Bi2O3 (5-mol%) forms bismuth tellurite glass while higher concentration of Bi2O3 (10 and 20-mol%) produces anti-glasses on splat-quenching the melt. The short-range structure of bismuth borotellurite glasses consists of TeO4, TeO3, BO4 and BO3 structural units. Raman studies show that TeO coordination (NTeO) in bismuth tellurite glass and anti-glass samples decreases from 3.48 to 3.43 with increase in Bi2O3 concentration from 5 to 20-mol%. On incorporating 20-mol% of B2O3 into bismuth tellurite sample, NTeO decreases to 3.33 and the glass forming ability enhances significantly as compared to that of bismuth tellurite system. On increasing B2O3 upto 40-mol%, the BO coordination decreases steadily. The addition of Bi2O3 produces the structural transformation: TeO4→TeO3 in Bi2O3-TeO2 system while B2O3 produces the structural transformation: BO4→BO3 in Bi2O3-B2O3-TeO2 series without significantly modifying NTeO. The glass transition temperature increases from 371°C to 410°C on increasing B2O3 from 20 to 40-mol%, this increase is due to increase in the concentration of stronger BO linkages at the expense of weaker TeO bonds. Decrease in the dielectric constant from 24.1 to 19.3 with B2O3 concentration is due to decrease in density while the polarizability of bismuth borotellurite series remains constant.