Tetsuo Araki

Oxyfluoride tellurite glasses doped by erbium: thermal analysis, structural organization and spectral properties

Abstract The effects of fluorine substitution in zinc tellurite glass system doped with rare earths on the spectral properties of the Er 3+ ions are investigated. Differential thermal analysis, vibrational spectroscopies studies and in situ high-temperature X-ray diffraction measurements have been considered in term of fluorine influence. As a function of composition, we have principally measured optical absorption, spontaneous emission, and lifetime measurements. Judd–Ofelt intensity parameters of Er 3+ in these host glasses were determined and used to calculate radiative transition rates and lifetimes. The bulk composition variation and addition of fluoride compounds in tellurite glasses result among others, in broad emission spectra, improved emission lifetime and difference in relative band intensities compared to pure oxide glass.

Spectral properties of Er3+ doped oxyfluoride tellurite glasses

The glass forming capability, glass structural organization and optical properties have been examined in rare-earth doped oxyfluoride zinc tellurite glass system. As a function of composition, differential thermal analysis, vibrational spectra, optical absorption, spontaneous emission and lifetime measurements have been analyzed in term of fluorine influence. The bulk composition variation and addition of fluoride compounds in tellurite glasses result among others, broad emission spectra compared to silicate glasses, in improved emission lifetime and slight difference in relative band intensities compared to pure oxide glass.

Investigation of glass formation and color properties in the P2O5–TeO2–ZnO system

Abstract The compositional dependence of glass-forming tendency and thermal properties was investigated for the P2O5–TeO2–ZnO system with the aid of an automatic sample preparation system including a batch-preparing apparatus and a multi-sample casting machine. The samples exhibited a variety of colors, such as transparent, yellow, wine red and brown depending on composition. Analyses with scanning electron microscopy and X-ray photoelectron spectroscopy revealed that the reddish coloration results from a colloidal suspension of nanometer-sized elemental Te particles.

The apparatus for automatic batch melting in the crucibles

Abstract The automatic melting apparatus has been developed as a combinatorial methodology in the field of glass science and technology. The apparatus can manage 10 pieces of crucibles, where the 10 crucibles are automatically taken out from the furnace, followed by the automatic casting onto the metal plate. This procedure is perfectly reproducing the researcher’s manual operation. Therefore we could certainly do 10 times as much as the work that we used to do in manual operation. Besides we could make a good performance on this apparatus for efficiency, accuracy, and reproducibility. In this paper, the concrete structure and mechanism of the apparatus is described.

Combinatorial methodologies for determination of glass-forming region

Abstract The combinatorial methodologies have been studied to automate the process for the determination of glass-forming region. The glass batches were prepared automatically and were melted simultaneously by applying various heating techniques, followed by cooling to room temperature to get the melt-quench samples. In this study, the combinatorial methods for the preparation of batches and the melting in the crucibles have been developed. The apparatus for the preparation of glass batches (automatic batch preparation apparatus) has been developed firstly in the world. The apparatus can prepare 24 different glass batches at one time in a 4-component system. The furnace designed for melting some glass batches simultaneously (automatic batch-melting apparatus) has been developed. The automatic batch-melting apparatus can work on the melting of 10 glass batches and the casting of the 10 melts onto the metal plates. The other possible methods for the determination of glass-forming regions have been discussed to develop the further advancements of the combinatorial methodologies.

Optimization of host glass composition to make soda borosilicate glasses doped with reduced rare earth ions

Soda borosilicate glasses with various compositions containing 1 mol% of Sm 3+ were prepared in a reductive atmosphere to reduce Sm 3+ ions. For the glass preparation, a multi-sample glass-formation tester was adopted. This apparatus is capable of handling 24 samples at once. The existence of thermally reduced Sm 2+ was confirmed by their fluorescent emission spectrum. By using compositional combinatorial approach, the glass-forming region and the optimal region for reducing Sm 3+ ions were determined in a ternary compositional diagram of soda borosilicate system. It was found that both regions overlapped each other and located near B 2 O 3 -rich side of the diagram.