A. A. Kutub

Some studies of the optical properties of copper phosphate glasses containing praseodymium

A range of copper phosphate glasses containing praseodymium was prepared and the optical absorption edges and infrared optical absorption spectra were measured. The optical energy gap of copper phosphate glass doped with praseodymium is slightly higher than the corresponding composition of the base glass. Heat treatment at 400 and 800° C caused some changes in the infrared absorption bands which are related to the characteristics of the Pr6O111 component.

An investigation of the electrical, optical and DSC properties of a copper-phosphate glass composition

The variation of some physical properties of equimolar copper-phosphate glasses has been reported in the literature. The present work studied a 60 mol% P2O5-40 mol % CuO glass system using electrical conductivity, infrared absorption, optical absorption spectroscopy and differential scanning calorimetry. The results revealed an increase in the activation energy and the optical energy gap compared with that for equimolar P2O5-CuO, which could be attributed to the variation of reduced valence states of the copper ion in the process of glass formation. The relation between the a.c. electrical conductivity with frequency was found to be almost temperature-independent. Infrared measurement revealed similar trends to those reported for the same glass composition. DSC measurements showed endothermal peaks at 360, 520, 560 and 580 °C for this glass composition.

Some electrical and optical properties of copper-sodium-phosphate glasses

ABSTRACT Optical absorption and DC conductivity of amorphous (P2O5)50-(CuO)50−x -(Na2O) x , systems are measured as a function of sodium content up to 15mol%. The electrical resistivity and the activation energy increase with the sodium content. The optical absorption data obtained from the glasses suggest that the ratio [Cu+]/[Cu2+] in the glasses increases with increase in soda content. Thus the observed change in conductivity and optical absorption may be attributed to the change in the ratio of concentration of Cu+ and Cu2+ ions in the glasses as a consequence of changing the sodium content.

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.

Effect of annealing on the electrical and optical properties of V2O5-GeO2 glasses

Increases in the electrical conductivities of vanadium germanate glasses on annealing have been reported recently in the literature. The increases were attributed to the formation of microstructure on annealing. In the present work we report a study of the V2O5-GeO2 glass system using electron paramagnetic resonance, optical absorption, differential scanning calorimetry and electron diffraction techniques. The V2O5-GeO2 glass system consists of an equimolar mixture of vanadium pentoxide and germanium dioxide. One sample was unannealed and the other was annealed at 300° C for about 24 h.The results revealed that the increase in the electrical conductivity of the annealed samples could be attributed to the increase of reduced valence states of vanadium ions which accompany the microstructure formation and not solely to the structural change.

Some optical properties of germania glasses containing praseodymium and chlorine

A range of germanate glasses containing praseodymium and chlorine was prepared. The optical absorption edges and infrared absorption spectra were measured. It is found that a small addition of PrCl3 to GeO2 glasses decreases the optical energy gap, but further addition of PrCl3 increases the optical energy gap. The main infrared absorption bands in the GeO2-PrCl3 glasses are related to those characteristic of the GeO2 component.

The control of the electrical conductivity of germanium vanadate glasses by the admixture of chlorine during preparation

The electrical conductivity of germanium vanadate glasses depends on the relative concentrations of V4+ and V5+ ions. It is found that by adding VCl3 to the melt when the glass is formed, the added chlorine which acts as an oxidizing agent alters the ratio of concentration of vanadium ions and thus the conductivity. The optical absorption coefficients and d.c. conductivities of germanium vanadate glasses are measured as functions of VCl3 content. It is found that the activation energy for conductivity increases with chlorine content, the increase of the activation energy corresponding to the change in optical gap energy. It is considered therefore, that the principle of the addition of a strong oxidizing agent to the glass to alter the reduced valency ion ratio may have general application in the control of electrical conductivity in transition metal ion glasses.

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.

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.

Optical and differential scanning calorimetry studies of the (Na2B4O7)-(CUO)-(CeO2) glass system

A series of glass samples was prepared from an admixture of sodium tetraborate, copper and cerium based on the system (Na2B4O7)98-(CuO)2-x-(CeO2)x where x=0.5, 1 and 1.5 mol%, and results of optical absorption, infrared absorption spectra and differential scanning calorimetry are reported as a function of copper and cerium contents. It was found that increasing the CuO content and decreasing the CeO2 content shifted the fundamental absorption edge to longer wavelengths. It was also found that the incorporation of CuO and CeO2 did not affect the limits of the ultraviolet absorption edge of the base glass.