US3932592A
Expired / Lapsed
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Process for preparing cathodochromic sodalite
Assignee: Massachusetts Institute of Technology
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Filing: 1974-04-01
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Granted: 1976-01-13
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Expires: 1994-04-01
Abstract
Abstract A process for preparing cathodochromic materials whereby coloration properties of the materials are enhanced by a low-temperature re-crystallization process. Crystalline powders formed using either hydrothermal or sintering growth techniques are hydrothermally re-crystallized at a temperature sufficiently high and for a time sufficiently long to effect re-crystallization. The temperature range for hydrothermal re-crystallization is 60°C to 300°C and the re-crystallization growth time is at least the order of 12 hours and, more typically, the order of three days. There is shown a cathode ray tube employing said materials.
Inventors
- 👤 Lee T. Todd, Jr.
- 👤 Eugene F. Farrell
- 👤 Arthur Linz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 06:51
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/20; C01B33/26; C01B33/28; C01B33/2807; C01B33/2892; Y; Y10; Y10S; Y10S423/00; Y10S423/32
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
254 words
A process for preparing cathodochromic sodalite consisting essentially of sodalite of the formula Na 6 Al 6 Si 6 O 24 . 2(1-z) NaX, wherein z is the fraction of NaX vacancies and X is taken from the group consisting of chlorine, bromine, iodine, OH and mixtures thereof, that comprises: mixing essentially stoichiometric quantities of sodium hydroxide, sodium halide, aluminum oxide and silicon dioxide to form a charge; placing the charge in a hydrothermal pressure vessel having a lower or dissolving zone and an upper or growth zone; adding to the charge water and further sodium hydroxide to provide an excess of sodium hydroxide in the charge; applying heat to the vessel and maintaining the temperature of the charge therein between 300°C and 500°C, the lower or dissolving zone of the vessel being at least 10°C higher in temperature than the upper or growth zone of the vessel, the 300°C to 500°C temperature being maintained for at least the order to 20 hours; cooling the vessel to room temperature and removing from the vessel the material which is in a crystallized powder form in a concentrated sodium hydroxide solution and contains a sodalite phase and unwanted phases; hydrothermally re-crystallizing the powder in a hydrothermal vessel at a temperature of at least 80°C for the order of 3 days to convert the unwanted phases to the sodalite phase and provide a resulting powder that is high in sodalite; and annealing the resulting powder in hydrogen between 550°C and 950°C for 15 minutes to an hour.
Claim 2
Dependent Claim
254 words
A process for preparing cathodochromic sodalite consisting essentially of sodalite of the formula Na 6 Al 6 Si 6 O 24 . 2(1-z) NaX, wherein z is the fraction of NaX vacancies and X is taken from the group consisting of chlorine, bromine, iodine, OH and mixtures thereof, that comprises: mixing essentially stoichiometric quantities of sodium hydroxide, sodium halide, aluminum oxide and silicon dioxide to form a charge; placing the charge in a hydrothermal pressure vessel having a lower or dissolving zone and an upper or growth zone; adding to the charge water and further sodium hydroxide to provide an excess of sodium hydroxide in the charge; applying heat to the vessel and maintaining the temperature of the charge therein between 300°C and 500°C, the lower or dissolving zone of the vessel being at least 10°C higher in temperature than the upper or growth zone of the vessel, the 300°C to 500°C temperature being maintained for at least the order to 20 hours; cooling the vessel to room temperature and removing from the vessel the material which is in a crystallized powder form in a concentrated sodium hydroxide solution and contains a sodalite phase and unwanted phases; hydrothermally re-crystallizing the powder in a hydrothermal vessel at a temperature of at least 80°C for the order of 3 days to convert the unwanted phases to the sodalite phase and provide a resulting powder that is high in sodalite; and annealing the resulting powder in hydrogen between 550°C and 950°C for 15 minutes to an hour.
Claim 3
Dependent Claim
220 words
A process for preparing cathodochromic sodalite consisting essentially of sodalite of the formula Na 6 Al 6 Si 6 O 24 . 2(1-z) NaX, wherein z is the fraction of NaX vacancies and X is taken from the group consisting of chlorine, bromine, iodine, OH and mixtures thereof, that comprises: mixing essentially stoichiometric quantities of sodium hydroxide, sodium halide, aluminum oxide and silicon dioxide to form a charge; adding water and further sodium hydroxide to the charge to form a mixture having an excess of sodium hydroxide; reacting the mixture hydrothermally at a temperature between 300°C and 500°C for at least the order of twelve hours, the lower or dissolving zone of the mixture being at least 10°C higher in temperature than the upper or growth zone of the mixture; cooling to room temperature the product of the reaction which appears as a slurry containing crystalline powder in a concentrated sodium hydroxide solution; removing the sodium hydroxide solution from the product to provide a crystalline powder containing sodalite crystals and other component crystals; hydrothermally transforming the crystalline powder at a temperature sufficiently high and a growth period sufficiently long to effect re-crystallization of at least some of said other component crystals to sodalite crystals; and annealing the resulting powder in hydrogen between 550°C and 950°C for at least 15 minutes.
Claim 4
Dependent Claim
220 words
A process for preparing cathodochromic sodalite consisting essentially of sodalite of the formula Na 6 Al 6 Si 6 O 24 . 2(1-z) NaX, wherein z is the fraction of NaX vacancies and X is taken from the group consisting of chlorine, bromine, iodine, OH and mixtures thereof, that comprises: mixing essentially stoichiometric quantities of sodium hydroxide, sodium halide, aluminum oxide and silicon dioxide to form a charge; adding water and further sodium hydroxide to the charge to form a mixture having an excess of sodium hydroxide; reacting the mixture hydrothermally at a temperature between 300°C and 500°C for at least the order of twelve hours, the lower or dissolving zone of the mixture being at least 10°C higher in temperature than the upper or growth zone of the mixture; cooling to room temperature the product of the reaction which appears as a slurry containing crystalline powder in a concentrated sodium hydroxide solution; removing the sodium hydroxide solution from the product to provide a crystalline powder containing sodalite crystals and other component crystals; hydrothermally transforming the crystalline powder at a temperature sufficiently high and a growth period sufficiently long to effect re-crystallization of at least some of said other component crystals to sodalite crystals; and annealing the resulting powder in hydrogen between 550°C and 950°C for at least 15 minutes.
Claim 5
Dependent Claim
18 words
A process as claimed in claim 2 in which the powder is re-crystallized in concentrated sodium hydroxide solution.
Claim 6
Dependent Claim
23 words
A process as claimed in claim 2 in which the sodium hydroxide concentration in the first-named hydrothermal treatment is at least 10 molar.
Claim 7
Dependent Claim
26 words
A process as claimed in claim 2 in which the temperature to effect hydrothermal re-crystallization is in the range of 60°C to 300°C, more or less.
Claim 8
Dependent Claim
22 words
A process as claimed in claim 5 in which the hydrothermal re-crystallization growth time is at least the order of twelve hours.
Claim 9
Dependent Claim
18 words
A process as claimed in claim 6 in which the hydrothermal re-crystallization growth time is about 3 days.
Claim 10
Dependent Claim
18 words
A process as claimed in claim 5 in which the temperature to effect hydrothermal re-crystallization is about 130°C.
Claim 11
Dependent Claim
151 words
A process for preparing cathodochromic sodalite consisting essentially of sodalite of the formula Na 6 Al 6 Si 6 O 24 . 2(1-z) NaX, wherein z is the fraction of NaX vacancies and X taken from the group consisting of chlorine, bromine, iodine, OH and mixtures thereof, that comprises: mixing quantities of sodium hydroxide, sodium halide, aluminum oxide and silicon dioxide to form a charge; comminuting the charge; sintering the commimuted charge to form a crystalline material containing a sodalite phase and at least one unwanted phase; comminuting the sintered product to form a powder; hydrothermally transforming the powder at a temperature sufficiently high and a growth period sufficiently long to effect re-crystallization of at least some of said at least one unwanted phase to increase the sodalite phase in the powder; and annealing the resulting powder in hydrogen between 550°C and 950°C for at least 15 minutes to an hour.
Claim 12
Dependent Claim
151 words
A process for preparing cathodochromic sodalite consisting essentially of sodalite of the formula Na 6 Al 6 Si 6 O 24 . 2(1-z) NaX, wherein z is the fraction of NaX vacancies and X taken from the group consisting of chlorine, bromine, iodine, OH and mixtures thereof, that comprises: mixing quantities of sodium hydroxide, sodium halide, aluminum oxide and silicon dioxide to form a charge; comminuting the charge; sintering the commimuted charge to form a crystalline material containing a sodalite phase and at least one unwanted phase; comminuting the sintered product to form a powder; hydrothermally transforming the powder at a temperature sufficiently high and a growth period sufficiently long to effect re-crystallization of at least some of said at least one unwanted phase to increase the sodalite phase in the powder; and annealing the resulting powder in hydrogen between 550°C and 950°C for at least 15 minutes to an hour.
Claim 13
Dependent Claim
24 words
A process as claimed in claim 9 in which the quantities of sodium hydroxide, sodium halide, aluminum oxide and silicon dioxide are essentially stoichiometric.
Claim 14
Dependent Claim
19 words
A process as claimed in claim 9 in which the powder is re-crystallized in a concentrated sodium hydroxide solution.
Claim 15
Dependent Claim
42 words
A process as claimed in claim 9 in which the sintering temperature is about 750°C and the sintering time is at least 8 hours and which includes the further step of raising the temperature to about 1000°C for at least 1 hour.
Claim 16
Dependent Claim
26 words
A process as claimed in claim 9 in which the temperature to effect hydrothermal re-crystallization is in the range of 60°C to 300°C, more or less.
Claim 17
Dependent Claim
22 words
A process as claimed in claim 13 in which the hydrothermal re-crystallization growth time is at least the order of 12 hours.
Claim 18
Dependent Claim
18 words
A process as claimed in claim 13 in which the hydrothermal re-crystallization growth time is about 3 days.
Claim 19
Dependent Claim
18 words
A process as claimed in claim 13 in which the temperature to effect hydrothermal re-crystallization is about 130°C.
Claim 20
Dependent Claim
109 words
A process for preparing cathodochromic sodalite, that comprises, forming a crystalline powder having a plurality of phases and containing substantial amounts of a sodalite phase consisting essentially of sodalite of the formula, Na 6 Al 6 Si 6 O 24 .2NaX, wherein X is taken from the group consisting of chlorine, bromine, iodine, OH and mixtures thereof, and at least one unwanted phase, hydrothermally transforming the crystalline powder at a temperature sufficiently high and a growth period sufficiently long to effect re-crystallization thereof, whereby at least some of said at least one unwanted phase is re-crystallized to the sodalite phase, and sensitizing the re-crystallized material to render it cathodochromic.
Claim 21
Dependent Claim
109 words
A process for preparing cathodochromic sodalite, that comprises, forming a crystalline powder having a plurality of phases and containing substantial amounts of a sodalite phase consisting essentially of sodalite of the formula, Na 6 Al 6 Si 6 O 24 .2NaX, wherein X is taken from the group consisting of chlorine, bromine, iodine, OH and mixtures thereof, and at least one unwanted phase, hydrothermally transforming the crystalline powder at a temperature sufficiently high and a growth period sufficiently long to effect re-crystallization thereof, whereby at least some of said at least one unwanted phase is re-crystallized to the sodalite phase, and sensitizing the re-crystallized material to render it cathodochromic.
Claim 22
Dependent Claim
30 words
A process as claimed in claim 17 in which said temperature is in the range from about 60°C to 300°C, and in which said period is at least 12 hours.
Claim 23
Dependent Claim
29 words
A process as claimed in claim 18 in which the re-crystallized material is annealed in hydrogen between 550°C and 750°C for at least 15 minutes to sensitize the same.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-01-12 | 1979-07-14 | 1980-01-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-01-12 | 1983-07-14 | 1984-01-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-01-12 | 1987-07-14 | 1988-01-13 | $7700.00 | Window Closed / Lapsed |