A THERMOCHROMIC GLASS MATERIAL AND A PRODUCTION METHOD THEREOF

Abstract

The present invention relates a thermochromic glass material comprising heavy metal oxide, alkali oxide, halide and at least one of other compounds supporting glass formation together with tellurium oxide (TeO.sub.2); and a production method thereof comprising the steps of preparing the powder mixture comprising TeO.sub.2 (101), melting the mixture by heating (102), cooling the molten mixture by pouring into a mold and obtaining glass (103), keeping the glass removed from the mold in a drying oven and cooling (104).

Claims

1.-11. (canceled)

12. A thermochromic glass material comprising at least one of heavy metal oxide, alkali oxide, halide components together with tellurium oxide (TeO.sub.2) in order to achieve glass formation; and TeO.sub.2 which is in ratio of 30-95% by mole and which enables transmittance value, absorption edge value and band gap energy and thus the color to continuously and reversibly change in the visible region depending on temperature, and allows electronic passage by behaving like an electrolyte as a result of being vitrified and shows semi-conductive feature.

13. A thermochromic glass material according to claim 12, wherein the material comprises at least one of WO.sub.3, Li.sub.2O, Na.sub.2O, K.sub.2O, ZnO, CdO, B.sub.2O.sub.3, TiO.sub.2, CuO, Fe.sub.2O.sub.3, V.sub.2O.sub.5, PbO, Nb.sub.2O.sub.5, MoO.sub.3, GeO.sub.2, P.sub.2O.sub.5, Ag.sub.2O, Sb.sub.2O.sub.3, PbF.sub.2, LiCl, ZnCl.sub.2 compounds as well as TeO.sub.2.

14. A thermochromic glass material according to claim 13, wherein the material comprises 0-35% WO.sub.3, 0-45% Li.sub.2O, 0-40% Na.sub.2O, 0-30% K.sub.2O, 0-40% ZnO, 0-15% CdO, 0-27.5% B.sub.2O.sub.3, 0-15% TiO.sub.2, 0-50% CuO, 0-20% Fe.sub.2O.sub.3, 0-55% V.sub.2O.sub.5, 0-20% PbO, 0-25% Nb.sub.2O.sub.5, 0-55% MoO.sub.3, 0-30% GeO.sub.2, 0-25% P.sub.2O.sub.5, 0-20% Ag.sub.2O, 0-20% Sb.sub.2O.sub.3, 0-25% PbF.sub.2, 0-30% LiCl, 0-30% ZnCl.sub.2 by mole as well as TeO.sub.2 in ratio of 30-95%.

15. A thermochromic glass material according to claim 14, wherein the material comprises 50% TeO.sub.2, 25% WO.sub.3, 25% Li.sub.2O by mole.

16. A thermochromic glass production method (100) which is conducted to obtain a thermochromic glass material according to claim 12, comprising: preparing powder mixture including at least one of heavy metal oxide, alkali oxide, halide together with TeO.sub.2 (101), melting the mixture by heating (102), cooling the molten mixture by pouring into the mold and obtaining glass (103), keeping the glass removed from the mold in the drying oven and cooling it (104).

17. A thermochromic glass production method (100) according to claim 16, further comprising preparing powder mixture (101) wherein carbonates and hydrates of Li.sub.2O, Na.sub.2O, K.sub.2O, B.sub.2O.sub.3 oxides such as Li.sub.2CO.sub.3, Na.sub.2CO.sub.3, K.sub.2CO.sub.3, H.sub.3BO.sub.3 are used instead of the said oxides.

18. A thermochromic glass production method (100) according to claim 17, further comprising preparing powder mixture (101) wherein the compounds forming the composition are weighed and mixed homogenously.

19. A thermochromic glass production method (100) according to claim 18, further comprising melting the mixture by heating (102) wherein the mixture is placed into a furnace preheated to 750-900 C. within a crucible with lid manufactured from platinum or gold and kept for 30-60 minutes in this temperature range.

20. A thermochromic glass production method (100) according to claim 19, further comprising cooling the molten mixture by pouring into the stainless steel or bronze mold preheated to 200-250 C. in order to prevent it from suddenly cooling and cracking, and obtaining glass (103).

21. A thermochromic glass production method (100) according to claim 20, further comprising keeping the glass removed from the drying oven and cooling (104) wherein the molded glass material is kept for 60-120 minutes in a drying oven heated to 200-300 C. and then cooled to room temperature in a controlled way, therefore the internal stresses are eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0013] The figures of the inventive thermochromic glass material and a production method thereof are as follows:

[0014] FIG. 1The graph showing the change in transmittance values in visible region depending on temperature observed in one embodiment of the inventive glass material.

[0015] FIG. 2The graph showing the absorption edge values changing with the increasing temperature in one embodiment of the inventive glass material.

[0016] FIG. 3The graph showing the repetitive change in transmittance values in visible region depending on temperature observed in one embodiment of the inventive glass material.

[0017] FIG. 4The graph showing the change in optical band gap energy depending on temperature observed in one embodiment of the inventive glass material.

[0018] FIG. 5The graph showing the change in conductivity values depending on temperature observed in one embodiment of the inventive glass material.

[0019] FIG. 6 is the flow chart of the inventive method.

[0020] The inventive thermochromic glass material essentially comprises at least one of heavy metal oxide, alkali oxide, halide components together with tellurium oxide (TeO.sub.2) in order to achieve glass formation.

[0021] In the preferred embodiment of the invention, the glass material comprises at least one of WO.sub.3, Li.sub.2O, Na.sub.2O, K.sub.2O, ZnO, CdO, B.sub.2O.sub.3, TiO.sub.2, CuO, Fe.sub.2O.sub.3, V.sub.2O.sub.5, PbO, Nb.sub.2O.sub.5, MoO.sub.3, GeO.sub.2, P.sub.2O.sub.5, Ag.sub.2O, Sb.sub.2O.sub.3, PbF.sub.2, LiCl, ZnCl.sub.2 compounds as well as TeO.sub.2 in ratio of 30-95% by mole, the ratios of the said compounds in the composition are 0-35%, 0-45%, 0-40%, 0-30%, 0-40%, 0-15%, 0-27.5%, 0-15%, 0-50%, 0-20%, 0-55%, 0-20%, 0-25%, 0-55%, 0-30%, 0-25%, 0-20%, 0-20%, 0-25%, 0-30%, 0-30% by mole, respectively.

[0022] The inventive glass material allows electronic passages by behaving like a conductive electrolyte. The transmittance and absorption edge values of the material in the visible region change with the temperature (FIG. 1 and FIG. 2). Therefore, the inventive glass material can continuously change its color depending on its band gap energy change with the increased temperature. Furthermore, as the applied temperature decreases, the transmittance and absorption edge values of the visible region return to the previous values and thus show reversible features. In FIG. 3 that the thermochromic property of the inventive material is reversible is shown with the graph showing the change in transmittance values as a result of heating and cooling. The thermochromic glass used in the graph given in FIG. 3 comprises 80% TeO.sub.2, 10% WO.sub.3, 10% Li.sub.2O by mole.

[0023] In one embodiment of the invention, the ratios of the compounds inside the thermochromic glass are 50% TeO.sub.2, 25% WO.sub.3, 25% Li.sub.2O by mole. According to this embodiment of the invention, the changes in transmittance and absorption edge values with temperature are given in FIG. 1 and FIG. 2, and the changes in optical band gap energy and observed conductivity values with temperature are given in FIG. 4 and FIG. 5.

[0024] A thermochromic glass material production method (100) developed to fulfill the objective of the present invention comprises the steps of [0025] preparing powder mixture comprising at least one of heavy metal oxide, alkali oxide, halide together with TeO.sub.2 (101), [0026] melting the mixture by heating (102), [0027] cooling the molten mixture by pouring into the mold and obtaining glass (103), [0028] keeping the glass removed from the mold in the drying oven and cooling it (104).

[0029] In the inventive method (100), first the content of the powder mixture to be mixed is determined, and each component to be in the mixture are weighed and mixed with each other homogenously (101).

[0030] While preparing the powder mixture (101), in order to obtain Li.sub.2O, Na.sub.2O, K.sub.2O and B.sub.2O.sub.3 components in the final product, Li.sub.2CO.sub.3, Na.sub.2CO.sub.3, K.sub.2CO.sub.3 and H.sub.3BO.sub.3 are used as starting materials. The carbonates and hydrates which are used are degraded during melting and they transform into oxide.

[0031] In the preferred embodiment of the invention, the mixture is placed into a furnace preheated to 750-900 C. within a crucible with lid manufactured from platinum or gold in order to heat and melt. It is enabled to be molten by waiting for 30-60 minutes in the determined temperature range (102).

[0032] Cooling and shaping the mixture after melting can be performed in various ways. In one embodiment of the invention, in order to prevent the molten glass mixture from suddenly cooling and cracking during pouring into a mold, first the mixture is poured into a stainless steel or bronze mold preheated to 200-250 C. (103).

[0033] The glass material poured into a mold is kept for 60-120 minutes in a drying oven heated to 200-300 C., and then it is cooled to room temperature in a controlled way (104). With controlled and slow cooling performed in this way, internal stresses are eliminated.

[0034] The change in optical features of the obtained glass samples in thickness of 1-3 mm in the visible region was measured with a UV-Vis spectrophotometer having an in-situ heating unit. Measurements were performed for temperatures selected between the room temperature and glass transition temperature. The changes in the visible region spectra obtained depending on temperature are determined in %, transmittance or absorption; the optical band gap energy values of the glasses were measured depending on the temperature with calculations made on the said changes.

[0035] In another analysis made on the inventive thermochromic glass materials, the glass surfaces were made conductive with silver dye, and their electrical conductivity was measured depending on the temperature. The analyses which were performed have shown that the conductivity values of the inventive telluride glasses increase with the increased temperature, their conductivity changes reversibly with temperature, and they have semi-conductive feature. The thermochromic property shown by the telluride glasses is originated from their semi-conductive behavior.

[0036] As a result of the analyses which were made, the material comprising TeO.sub.2WO.sub.3A.sub.2O (A: Li, Na, K) has given the best result in terms of transmittance, absorption edge, conductivity change, thermochromic property and reversible thermochromic behavior depending on temperature.

[0037] The inventive telluride glasses showing thermochromic property can be used in permeable filters used in optical and spectroscopic analysis devices and color measurement devices, calibration apparatuses, microelectronic applications, temperature sensors and data storage devices.