E. Rivera

Photoluminescence in ZnO-CdO-SiO2 glasses

Photoluminescence (PL) experiments have been carried out in glasses from the ZnO-CdO-SiO2 system. The glasses exhibit broad bands in the PL spectra centered between 540 and 560 nm for emissions and at about 250 nm for excitations. Decay time curves for the different glass samples appear, within experimental errors, quite similar. The curves are not a simple exponential and have been discomposed as a sum of three exponentials with lifetime components of about 0.025, 0.1, and 0.52 ms. The results seem to indicate that luminescence is dominated by short ordering, nuclei and/or crystalline centers.

Microstructural characterization of an opal glass in the Na2OCdOSiO2 system

Abstract The microstructure of an opal glass formulated in the ternary system Na 2 O-CdO-SiO 2 has been determined by scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis (EDX). This type of glass shows tridymite devitrification with a high level of liquid-liquid immiscibility.

Electron microscopy and EDX-microanalysis of photochromic silver halide glasses of the composition systems Al2O3-B2O3-SiO2 and Na2O-CaO-SiO2

The microstructure and microanalysis study of two glasses containing AgCl precipitated particles have been carried out by transmission electron microscopy (TEM, replica method), scanning electron microscopy (SEM) and SEM/EDX (energy dispersive X-ray spectrometry). The composition of these glasses doped with silver halide and CuO was formulated from the Al2O3-B2O3-SiO2 and Na2O-CaO-SiO2 systems respectively. In both glasses the seeds, nuclei, crystals and matrix were analysed, and the mean size and number of crystals were evaluated from the TEM and SEM observations. The microstructure in both glasses is different because of the different shape of the silver halide particles; the particles of the Al2O3-B2O3-SiO2 glass are rounded while Na2O-CaO-SiO2 shows square precipitated particles. Likewise, the darkening behaviour is basically different; the Al2O3-B2O3-SiO2 glass shows a higher darkening velocity than the Na2O-CaO-SiO2 glass, showing for this glass a very small slope value.

The glass-formation area in a ternary Na2OCdOSiO2 section of the quaternary Na2OCdOAl2O3SiO2 system

Abstract The glass-formation area in a ternary Na 2 OCdOSiO 2 section of the quaternary containing Al 2 O 3 has been determined at 1450°C by quenching 37 compositions formulated in the Na 2 OCdOSiO 2 phase diagram. A wide zone of transparent and opal glasses has been found near the silica corner; otherwise glass-ceramics from this system can be obtained by slow cooling of the melt. The chemical analysis of the final glass and SEM/EDX microanalysis are presented and compared in a glass located in the center of the Na 2 OCdOSiO 2 glassy area.

New black glasses in the CdO-Al2O3-SiO2 system useful for optical devices

Abstract A new family of black glasses with CdOAl 2 O 3 SiO 2 glassy matrices and Cu, CuMn, and CuSe additions have been The spectral transmittance was related to the microstructure observed by TEM and SEM electron microscopies. These microstructural observations and XRD analyses showed that these black glasses contained precipitated CuO and cadmium silicate crystals in a phase-separated glassy matrix. These new black glasses could be useful for various optical devices.

The glass formation area in a ternary ZnOCdOSiO2 and an Al2O3 sections of the quaternary ZnOCdOAl2O3SiO2 system

The glass area of the ZnOCdOSiO2 system and in a ternary section of the quaternary Al2O3 has been examined at 1450°C using 38 compositions. The glass-forming area covers a wide central zone of the ternary with transparent, opal and partly crystallized glasses. Transparent and opal glasses are phase-separated with homogeneously distributed droplets.

SEM/EDX microanalysis of a Na2OCdOSiO2 glass-ceramic containing sulphur

Abstract The formation or separation on cooling of a double cadmium-sodium sulfate CdSO 4 ·3Na 2 SO 4 in a glass from the Na 2 O-Al 2 O 3 -CdO-SiO 2 system has been detected by energy dispersive X-ray microanalysis (EDX) in a scanning electron microscope. The existence of prismatic and holed crystals of sulfate grown from the original glass is discussed.