Glass sheet and glass sheet photoelectric converter device
The present invention provides a glass sheet formed on molten tin, that exhibits a high transmittance that is originally inherent to its composition. In this glass sheet, the difference between a visible light reflectance of a surface formed in contact with the molten tin and a visible light reflectance of a surface on the opposite side thereof is not greater than 0.25%. And when the glass sheet's thickness is 4 mm, a light transmittance at 540 nm wavelength is at least 91.5%, and a light transmittance at 450 nm wavelength is at least 91.0%, and after irradiating UV light for 6 hours as specified in the radiation-proofing test according to JIS R3212, a light transmittance at 540 nm wavelength is at least 91.0% and a light transmittance at 450 nm wavelength is at least 90.5%.
1. A glass sheet formed on molten tin,
wherein a difference between a visible light reflectance of a surface formed in contact with the molten tin and a visible light reflectance of a surface on the opposite side thereof is not greater than 0.25%;
wherein, when the glass sheet's thickness is 4 mm, a light transmittance at 540 nm wavelength is at least 91.5%, and a light transmittance of at 450 nm wavelength is at least 91.0%, and wherein after irradiating UV light for 6 hours as specified in the radiation-proofing test according to Japanese Industrial Standard (JIS) R3212, a light transmittance at 540 nm wavelength is at least 91.0% and a light transmittance at 450 nm wavelength is at least 90.5%;
wherein a maximum value of tin oxide concentration in terms of SnO 2 , in the glass sheet at a depth of up to 10 μm from the surface formed in contact with the molten tin, measured by a wavelength dispersive X-ray detector (WDX) mounted to an electron probe micro-analyzer (EPMA), is not greater than 1 mass %; and
wherein a maximum value of iron oxide concentration in terms of Fe 2 O 3 , in the glass sheet at a depth of up to 5 μm from the surface formed in contact with the molten tin, measured by a wavelength dispersive X-ray detector (WDX) mounted to an electron probe micro-analyzer (EPMA), is not greater than 0.2 mass %.
2. The glass sheet according to claim 1 , wherein said difference of the visible light reflectance is not greater than 0.15%.
3. The glass sheet according to claim 1 , wherein both the visible light reflectance of a surface formed in contact with the molten tin and the visible light reflectance of a surface on the opposite side thereof is not greater than 4.5%.
4. The glass sheet according to claim 3 , wherein both the visible light reflectance of a surface formed in contact with the molten tin and the visible light reflectance of a surface on the opposite side thereof is not greater than 4.25%.
5. The glass sheet according to claim 1 , wherein, in a rest without a portion up to a depth of 10 pm from the surface formed in contact with the molten tin, the glass sheet has a composition with an amount of iron oxide total in terms of Fe 2 O 3 that is not greater than 0.04 mass %.
6. The glass sheet according to claim 5 , wherein the composition is substantially free from cerium oxide.
7. The glass sheet according to claim 5 , wherein the composition includes, in mass %:
65 to 80% SiO 2 ,
0 to 5% Al 2 O 3 ,
0 to 10% MgO,
5 to 15% CaO,
10 to 18% Na 2 O,
0 to 5% K 2 O,
5 to 15% MgO+CaO,
10 to 20% Na 2 O+K 2 O,
0.05 to 0.3% SO 3 , and
0 to 5% B 2 O 3 .
8. A glass sheet for a photoelectric conversion device comprising the glass sheet according to claim 1 and a conductive film deposited on that glass sheet.
9. The glass sheet for a photoelectric conversion device according to claim 8 , wherein the conductive film is deposited on the surface opposite from the surface formed in contact with the molten tin.
10. The glass sheet for a photoelectric conversion device according to claim 8 , further comprising an undercoating film disposed between the glass sheet and the conductive film.
11. The glass sheet according to claim 1 , wherein the glass sheet is formed on the molten tin in a float bath in an atmosphere such that formation of the tin oxide in the molten tin is suppressed by maintaining a ratio of hydrogen gas to nitrogen gas in the atmosphere of the float bath at a level in which no tin oxide is found in the molten tin.
12. The glass sheet according to claim 1 , wherein the iron concentration in the molten tin is less than 100 ppm.
13. The glass sheet according to claim 12 , wherein the iron concentration in the molten tin is less than 95 ppm.
14. The glass sheet according to claim 12 , wherein the iron concentration in the molten tin is less than 90 ppm.