Sodium Tetraborate Glasses Research Articles

Mechanical Properties, Elastic Moduli, and Gamma Radiation Shielding Properties of Some Zinc Sodium Tetraborate Glasses: A Closer Look at ZnO/CaO Substitution

Mechanical Properties, Elastic Moduli, and Gamma Radiation Shielding Properties of Some Zinc Sodium Tetraborate Glasses: A Closer Look at ZnO/CaO Substitution

Allowed and forbidden hyperfine structure of Mn 2+ ions in sodium tetraborate glasses—an EPR and optical study

Glass systems of composition (100− x) Na 2B 4O 7·10H 2O+ x MnSO 4·H 2O ( x = 0 , 0.1, 0.3, 0.5, 0.75, 1, 1.25, 1.5, 1.75 and 2 mol%) have been studied by using electron paramagnetic resonance (EPR) and optical absorption techniques. The room temperature EPR spectra exhibit resonance signals at g ≈ 2.0 with a sextet hyperfine structure (hfs) besides two weak signals at g ≈ 3.3 and 4.3. The resonance signal at g ≅ 2.0 is due to Mn 2+ ions in an environment close to octahedral symmetry, whereas the resonances at g ≅ 3.3 and 4.3 are attributed to the rhombic surroundings of the Mn 2+ ions. It is observed that for x = 1.25 mol % in sodium tetra borate glasses (NTB) the EPR spectrum exhibits a good resolution of allowed as well as forbidden hfs at g ≈ 2.0 . The Mn 2+ ions in NTB glasses (with A ≈ 95 G ) are quite ionic in nature. The number of spins ( N) participating in resonance at g ≈ 2.0 has been calculated by comparing the area under the absorption curve with that of a standard of known concentration. A linear relationship is observed between log N and 1/ T in accordance with the Boltzmann law. Magnetic susceptibilities ( χ ) were calculated from the EPR spectra at different temperatures. The susceptibility is varying inversely with temperature in accordance with the Curie law, and the Curie constant is evaluated from the 1 / χ versus T graph. The zero-field splitting parameter D has also been calculated from the allowed hyperfine (HF) lines. The D value was found to be dependent on temperature. The optical absorption spectrum exhibits a single broad band centered around 470 nm and was assigned to the 6A lg(S)→ 4T lg(G) transition. From the ultra violet absorption edges the optical bandgap and Urbach energies have been evaluated.

Topotaxial Nucleation and Growth of TiO2 Submicron-Scale Rod Arrays on Titanium Substrates via Sodium Tetraborate Glass Coating

A novel approach to fabricate sub-μm scale arrays is demonstrated with the growth of rutile TiO2 on titanium substrates. The fabrication process is template-free, simply involving coating of the titanium substrate with sodium tetraborate glass, Na2O•2B2O3: when the glass coating was removed by dissolution in distilled water at 80°C for about 5 h, random or well-ordered submicron-scale rod arrays of rutile were left on the substrate. A glass phase topotaxial (GPT) nucleation and growth mechanism is thought to operate in the crystal growth process.

Electrical conductivities and dielectric constants of some sodium tetraborate glasses containing CuO, irradiated with a low-level fast neutron beam

A number of glass samples were prepared from a mixture of Na2B4O7 and CuO. The prepared glasses were irradiated with a low-level fast neutron beam (flux density 108 n cm-2). The alternating current (a.c.)-electrical conductivity and the dielectric constant at a frequency of 1 kHz of these glasses have been studied as a function of temperature in the range 300–600 K. The measurements showed that an amorphous–crystalline phase transition characterized these samples. This phase transition was affected by neutron irradiation. Also a decrease in the activation energy for the irradiated undoped sample and an increase in the activation energy for the irradiated doped samples were found. After irradiation, the maximum peak, which characterized the dielectric constant of the samples before irradiation, disappeared. © 1998 Chapman & Hall

Electrical, IR spectroscopy, and DTA studies of some sodium tetraborate glasses containing vanadium oxide

The ac electrical conductivity and dielectric constant of semiconductive (Na 2 B 4 O 7 ) 100-x (V 2 O 5 ) x glasses with x = 0.25, 0.5, 1, 2, 3, and 5 mol% have been measured at a constant frequency of 1 kHz in the temperature range from 293 to 600 K. IR spectra of these samples have been recorded at room temperature in the range between 400 and 4000 cm -1 . The results showed a broad absorption band with a peak around 3400 cm -1 , indicating the presence of a hydroxyl group and the formation of B-OH within the glass matrix. The addition of V 2 O 5 caused new absorption bands in comparison with the absorption bands obtained for the pure Na2B407 glass between 500 and 1800 cm -1 . The differential thermal analysis (DTA) was performed for all samples in the temperature range from room temperature to 600 °C.

Optical, infrared and DSC studies of sodium tetraborate glasses containing copper oxide

The optical absorption, density, DSC and infrared absorption spectra of a series of sodium tetraborate glasses are measured as a function of copper content up to 5 mol%. It is found that the addition of CuO shifts the fundamental absorption edges towards lower energies in the range from 6.17–3.48 eV. The addition of CuO does not seem to introduce any new absorption band as compared with the spectrum of a pure sodium tetraborate glass. DSC measurements showed endothermal peaks varying from 486–476 °C depending on the CuO content.

Electrical conductivity studies of sodium tetraborate glasses containing copper

Electrical conductivity studies of sodium tetraborate glasses containing copper

Studies of the Effects of CeO2 on the Optical Absorption and DSC Measurement of Sodium Tetraborate Glasses

Studies of the Effects of CeO2 on the Optical Absorption and DSC Measurement of Sodium Tetraborate Glasses

Some optical and differential scanning calorimetry studies of sodium tetraborate glasses containing vanadium oxide

A series of glass samples was prepared from mixtures of Na2B4O7 and V2O5. Measurements were made for infrared absorption and optical absorption spectra as a function of V2O5 content up to 10 mol%. The addition of V2O5 did not introduce any new absorption band as compared with the infrared spectrum of pure sodium tetraborate glass. The addition of V2O5 shifted the optical absorption edges towards lower energies, and introduced a new absorption band as compared with the optical absorption of pure Na2B4O7 glass. Differential scanning calorimetry as a function of V2O5 content was also measured.

Some electrical and differential scanning calorimetry studies of sodium tetraborate glasses containing iron oxide

A series of glass samples has been prepared from mixtures of Na2B4O7, and Fe2O3. Measurements have been made of the d.c. conductivity as a function of temperature and composition. These results have been interpreted in terms of the activation energy, which increased with a small addition of Fe2O3 (0.5 mol.%) in Na2B4O7 glasses but decreased again with further addition of Fe2O3. D.c. conductivity measurements have revealed a mixed conduction phenomenon in which ionic as well as electronic conduction occur in the glass. Differential scanning calorimetry (DSC) as a function of Fe2O3 content is also measured.

Effect of gamma irradiation on some optical properties of sodium tetraborate glasses containing iron

A series of glass samples were prepared from admixtures of Na 2B 4O 7 and Fe 2O 3. The prepared glasses were irradiated for 12 h and 24 h using a gamma-ray dose rate of 206.4 Gy h −1 The optical absorption spectra were recorded for unirradiated and irradiated glass samples. It is found that gamma irradiation shifts the optical absorption edges towards longer wavelengths and introduces a new absorption band at 550 nm for the iron-free Na 2B 4O 7 glass. This induced band disappears on doping with Fe 2O 3 at high concentration. The doping of Na 2B 4O 7 with Fe 2O 3 produces the iron characteristics band at 440 nm which increases in intensity when gamma-irradiated. Thermoluminescence of irradiated Na 2B 4O 7 shows two peaks around 393 K and 550 K and a linear dose-response over the dose range of 100 to 500 Gy which offers a possibility for use as a radiation dosemeter.

Some effects of the addition of iron oxide and of annealing on the optical and infrared absorption spectra of sodium tetraborate glasses

The optical and infrared absorption spectra of sodium tetraborate glasses containing iron oxide have been studied as a function of iron content. It was found that the addition of iron oxide shifts the optical absorption edges towards lower energies and introduces a new absorption band as compared with the optical absorption spectrum of pure sodium tetraborate glass. The addition of iron does not introduce any new absorption band in the infrared spectrum of pure sodium tetraborate glass. The measurements were made on unannealed samples and samples annealed at different temperatures.

Optical and DSC studies of the Na2B4O7-Pb3O4 glass system

A series of glass samples were prepared from admixtures of Na2B4O7 and Pb3O4 and results are reported for optical absorption, infrared absorption spectra and differential scanning calorimetry (DSC) as a function of lead content up to 40mol%. It is found that the addition of lead oxide decreases the optical energy gap and shifts the optical absorption edges towards lower energies in the range from 4.96 to 3.29 eV. The addition of lead oxide does not seem to introduce any new absorption band as compared with the infrared spectrum of pure sodium tetraborate glass.

A spectroscopic study of some sodium tetraborate glasses containing lead and copper

Optical absorption, infra-red absorption spectra and differential scanning calorimetry of amorphous (Na2B4O7)80-(Pb3O4)20-x-(CuO)x systems were studied as functions of copper content up to 10 mol%. When the Pb3O4 in the glasses is gradually replaced by CuO, a pronounced decrease in the optical energy gap and an increase in the optical absorption at 750 nm due to the CU2+ ions is observed. The change in the optical absorption may be attributed to the concentration variation of the Cu2+ ions in the glasses as a consequence of changing the lead content.

Some effects of the addition of nickel oxide and of annealing on the optical absorption of sodium tetraborate glasses

A range of sodium tetraborate glasses containing nickel oxide was prepared and the optical absorption spectra measured. The differential scanning calorimetry technique was used to study compositional features of the glass formation. It was found that the addition of nickel oxide decreases the optical energy gap and introduces new absorption bands as compared with the optical absorption spectrum of pure sodium tetraborate glass. The results revealed that the decrease in the optical energy gap and the disappearance of some absorption bands of the annealed samples could be attributed to an increase in the concentration of reduced valence states of nickel ions which accompanies the microstructure formation.

The effects of added CuO on the electrical properties of Na2B4O7-Pb3O4glasses

A range of sodium tetraborate glasses containing lead oxide and copper oxide was prepared. Measurements of the DC conductivity as a function of composition and temperature were made. It was found that the replacement of Pb3O4 by CuO decreased the activation energy linearly with the CuO content of the glasses. 1-V measurements showed an ohmic behaviour with some deviation at high electric field in the temperature range 335–555K for Na2B4O7-Pb304 glass sample. Na2B407-Pb3O4-CuO glass samples showed an ohmic behaviour over the same range of measurements.

Spectroscopic and electrical studies of sodium tetraborate glasses containing nickel oxide

The infrared spectra. X-ray diffraction and electrical conductivity of sodium tetraborate glasses containing nickel have been studied as a function of nickel oxide content. It was found that addition of nickel oxide does not seem to introduce any new absorption band as compared with the infrared spectrum of pure sodium tetraborate glass. The electrical conductivity measurements revealed that the activation energy for conductivity increases with nickel oxide content. This could be explained on the basis of the concept of Hubbard bands, and possibly by a block effect of the nickel ion on the overall mobility of the sodium ion. Measurements were made on unannealed samples and some samples annealed at different temperatures. Annealing the samples at temperatures in the range 460 to 480° C causes the appearance of a crystalline phase, resulting in an increase of electronic conductivity.

Radiation-Induced Atomic Silver in Pyrex and Sodium Tetraborate Glasses

Radiation-Induced Atomic Silver in Pyrex and Sodium Tetraborate Glasses