Thermal-shock resistant green glasses for light filters

Averchenko, O. E.; Богомолова, Л.Д.; Pushkareva, G. I.

doi:10.1007/bf00698346

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“…With all these additives the glasses have a blue color of different intensity with the exception of 0.5% Si additive, for which the glass becomes dark gray. Figure 6 shows that optical absorption spectrum of brown P-50 -Mo glass (1). Strong absorption is seen in the short wavelength part of the spectrum, dropping linearly from 300 to 1000 nm, on which quite narrow bands at 380 and 460 nm and a weak inflection from 650 to 730 nm, rapidly decreasing in the direction of long wavelengths, are clearly manifested.…”

Section: Development Of Green Light Filtersmentioning

confidence: 98%

“…Glasses to be used for such applications have been developed and used in different organizations, including with the participation of the present authors (for example, [1,2]). Such glass must be practicable, have a low linear thermal expansion coefficient (CLTE) in the range (35 -50)´10 -7 K -1 , high heat-resistance (no lower than 300°C) and light transmission at least 20% near maximum transmission at 500 nm (bluish-green color).…”

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confidence: 99%

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Development of green light filters based on high-resistance oxide glasses colored by transition elements

Богомолова

Zhachkin

Pavlushkina³

2012

Glass Ceram

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Glasses in the system Al 2 O 3 -P 2 O 5 -SiO 2 , which are suitable for the green light filters in traffic signal lights, were investigated. The glasses were required to satisfy the following requirements: transmission band maximum at l max = 500 nm high heat-resistance, and low CLTE -(41 -49)´10 -7 K -1 . Transition elements served as colorants; they were introduced into the batch as the oxides TiO 2 , V 2 O 5 , CuO, and MoO 3 in amounts 1 wt.%, as well as their pairs in different combinations. The EPR and optical spectra were investigated. It was shown that glass with the composition (wt.%) 55 P 2 O 5 , 17.1 Al 2 O 3 , 20 SiO 2 , 1.5 La 2 O 3 , 2 ZrO 2 , 2.5 B 2 O 3 , 1.5 MoO 3 , and 0.5 CuO can be recommended for use as heat-resistant green light filters.Colored light filters are used for signal lights in aviation, railroad, and sea transport. The glasses used for light filters must possess definite characteristics (color, thermal, mechanical, and others) for reliable recognition of the signal color at a considerable distance under different operating conditions (elevated temperature, velocity of the object, atmospheric precipitation, and others).Glasses which can be used to manufacture green signal light filters were studied in the present work. Glasses to be used for such applications have been developed and used in different organizations, including with the participation of the present authors (for example, [1,2]). Such glass must be practicable, have a low linear thermal expansion coefficient (CLTE) in the range (35 -50)´10 -7 K -1 , high heat-resistance (no lower than 300°C) and light transmission at least 20% near maximum transmission at 500 nm (bluish-green color).The glasses are usually colored by transition elements (TE). Theoretically and experimentally, the electronic absorption spectra of TE due to transitions between sublevels of the d-shells (d -d transitions), which are characterized by small extinction coefficients, lie in the visible, near-UV, and IR frequencies of electromagnetic radiation. The transitions are forbidden by selection rules with respect to the orbital quantum number. In the absence of a center of symmetry (octahedral environment of the TE) the d shells can mix with the p shell as a result of thermal vibrations, making the transitions allowed though weak. In tetrahedral coordination, when a center of symmetry exists, the absorption bands become stronger.The valence and coordination state of TE and the position and shift of the electronic absorption bands depend on the optical basicity of the glass, which essentially characterizes the capability of oxygen to impart negative charge to a transition element. The basicity of the glasses depends on their properties and is highest in alkali-containing glass. For example, the optical basicity L, which can be calculated using the relations presented in [3], equals 0.65 in glass with molar content 40 Na 2 O and 60 SiO 2 , L = 0.46 with 30 Al 2 O 3 and 70 P 2 O 5 , and L = 0.43 with 33 SiO 2 and 67 P 2 O 5 .In the present work we studied ...

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Section: Development Of Green Light Filtersmentioning

confidence: 98%

mentioning

confidence: 99%