Shinichiro Hirota

Effect of cations on the inherent absorption wavelength and the oscillator strength of ultraviolet absorptions in borate glasses

Abstract The dispersions were measured for 10 BaO · 5 M m/n O · 85 B 2 3 O glasses, where M was the cation in the periodic table. The inherent wavelength of the ultraviolet (UV) absorption λ0 and the oscillator strength ƒ 0 were determined using the Drude-Voigt dispersion formula: . Cations could be classified into three groups on the basis of the behavior of λ 0 and ƒ 0 . Glasses containing Li+, Na+, K+, Rb+, Cs+, Mg2+, Ca2+, Sr2+, Ba2+, Y3+ and La3+ were characterized by small λ0 and large ƒ 0 values, and λ 0 and ƒ 0 increased with decreasing cationic field strength Z a 2 . Here, λ 0 and ƒ 0 of these glasses could be correlated with the absorption of the non-bridging oxygen ion. Glasses containing Bi3+, Pb2+ and Tl+ were characterized by extremely large λ0 and small ƒ 0 values, and λ 0 and ƒ 0 increased with decreasing Z a 2 . The λ 0 and ƒ 0 values of these glasses were considered to be correlated with the absorption of the cation itself. Glasses containing Ti4+, Zr4+, Hf4+, Nb5+, Ta5+ and W6+ were characterized by larger λ0 and smaller ƒ 0 values than those of the first group. In these glasses, λ0 increased and ƒ 0 decreased with increasing Z a 2 , which cannot, as yet, be fully understood.

Reflection spectra of various kinds of oxide glasses and fluoride glasses in the vacuum ultraviolet region

Abstract Reflection spectra of silicate, borate, phosphate, fluorophosphate and fluoride glasses are studied in the spectral region of 2–13 eV in order to understand their dispersion behaviors in the visible region from the point of view of atomic structures. The absorption bands due to bridging oxygen ions or fluorine ions are found at 11.6 eV and 10.4–9.5 eV in silicate glasses, at 10.2 and 8.8 eV in borate glasses, at 9.5 eV in phosphate glasses, at 11.2 eV in fluorophosphate glasses and at 11 eV in fluorozirconate glasses. In silicate glasses, the bands due to nonbridging oxygen ions are found in the region 8.8-4.9 eV. They shift to lower energies with increasing ionic radius, in the order of Ca 2+ , Sr 2+ and Ba 2+ , for the glasses containing low valency cations, while they shift to higher energies with increasing ionic radius, in the order of Ti 4+ , Zr 4+ and Th 4+ or in the order of Nb 5+ and Ta 5+ , for the glasses containing high valency cations. In glasses containing large amounts of PbO, strong bands due to PB 2+ ions appear in the lower energy regions of 6.3–5.6 eV and 5.2–4.7 eV.

Fundamental absorption of glasses in the vacuum ultraviolet region

Abstract Reflection spectra of silicate, borate, phosphate, fluophosphate and fluoride glasses were measured in the spectral region 2–13 eV in order to correlate dispersion to the absorption wavelength of glass. The bands due to bridging ions and nonbridging ions were found in the range 11.6−8.8 eV and 8.8−4.9 eV respectively. It was confirmed that the bands due to nonbridging ions shift to lower energy for low valent cations and shift to higher energy for high valent cations with increasing ionic radius.

Dispersion and reflection spectra of fluorine and oxide glasses in the vacuum and extreme ultraviolet region

Abstract Reflection spectra of aluminium fluoride glass, zirconium fluoride galss, silicate galss, borate glass, and phosphate glass were measured in the range of 10 eV to 35 eV using synchrotron radiation. Two main bands at 10 eV and 22 eV were observed for fluoride glasses and oxide glasses. The band at 10 eV shifts to higher energy in the order of borate 1 . The higher abnormal partial dispersion is attributed to the lower oscillator strenght at the infrared reflection band, N 4 f 4 . The reflection spectra of oxide glasses due to bridging ions (λ 1 ) shifts to the higher energies in the order of borate

Reflection spectra of fluoride and oxide glasses in the extreme ultraviolet region

Reflection spectra of aluminum fluoride glass, zirconium fluoride glass, silicate glass, borate glass, and phosphate glass were measured in the range of 10 to 35 eV using synchrotron radiation. Two main bands at 10 and 22 eV were observed for the fluoride glasses and oxide glasses. The band at 10 eV shifts to higher energy in the order of borate

Reflection spectra of silicate glasses in the vacuum ultraviolet region

Abstract Reflection spectra of silicate glasses were measured in the spectral region 2–13 eV. The bands due to bridging oxygen were found at 11.6 and 10.4–9.5 eV. The bands for non-bridging oxygens were found in the region 8.8–4.9 eV. They shift to lower energy with increasing ionic radius for the low valency cations while they shift to higher energy with increasing ionic radius for the high valency cations. The correlation between the measured bands and the absorption wavelength calculated from Drude-Voigt dispersion formula is discussed.