US3880984A
Expired / Lapsed
US
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Method of producing plate single-crystal of gadolinium molybdate
Assignee: Hitachi Ltd
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Filing: 1972-07-26
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Granted: 1975-04-29
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Expires: 1992-07-26
Abstract
Abstract A method of producing a thick plate single-crystal of gadolinium molybdate having smooth (001) faces by the Czochralski method in which a (110) face of a rotating seed crystal is brought into contact with a melt of crystal material and the crystal is pulled under the following temperature conditions: The temperature gradient at the surface of the melt from the center thereof in the radius direction: +1* to +5*C/mm The temperature gradient from the surface of the melt to 10 mm above the surface of the melt: -5* to -10*C/mm The temperature gradient from 10 mm above the surface of the melt in an upward direction: -1* to -2*C/mm The thickness of the plate crystal is determined by the rotational velocity, i.e., the number of revolutions per minute.
Inventors
- 👤 Seikichi Akiyama
- 👤 Hirotsugu Kozuka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 15:48
CPC Classifications
C; C30; C30B; C30B15/00; C30B15/36; C30B29/00; C30B29/10; C30B29/16; C30B29/22; C30B29/32
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
144 words
A METHOF FOR PRODUCING A PLATE SINGLE-CRYSTAL OF GADOLINIUM MOLYBDATE COMPRISING FORMING A MELT MIXTURE OF 1 MOL. OF GADOLINIUM OXIDE AND 3 MOL. OF MOLYBDENUM OXIDE, HEATING THE MELT SO AS TO ESTABLISH A TEMPERATURE GRADIENT AT THE SURFACE OF THE MELT IN A RADIAL DIRECTION FROM THE CENTER OF THE SURFACE OF A POSITIVE 1* TO 5*C/MM, A TEMPERATURE GRADIENT FROM THE SURFACE OF THE MELT IN AN UPWARDLY DIRECTION UP TO 10 MM FROM THE SURFACE OF A NEGATIVE 5* TO 10*C,/MM AND A TEMPERATURE GRADIENT FROM 10 MM ABOVE THE SURFACE IN AN UPWARD DIRECTION OF A NEGATIVE 1* TO 2*C/MM, AND PULLING A SEED CRYSTAL OF GASOLIMIUM MOLYBDATE ROTATING AT ABOUT 30 TO 180 R.P.M. AND WHOSE (110) FACE IS IN CONTACT WITH THE SURFACE OF THE MELT FROM THE MELT WITHOUT CHANGING THE HEATING CONDITIONS OF THE MELT.
Claim 2
Dependent Claim
144 words
A METHOF FOR PRODUCING A PLATE SINGLE-CRYSTAL OF GADOLINIUM MOLYBDATE COMPRISING FORMING A MELT MIXTURE OF 1 MOL. OF GADOLINIUM OXIDE AND 3 MOL. OF MOLYBDENUM OXIDE, HEATING THE MELT SO AS TO ESTABLISH A TEMPERATURE GRADIENT AT THE SURFACE OF THE MELT IN A RADIAL DIRECTION FROM THE CENTER OF THE SURFACE OF A POSITIVE 1* TO 5*C/MM, A TEMPERATURE GRADIENT FROM THE SURFACE OF THE MELT IN AN UPWARDLY DIRECTION UP TO 10 MM FROM THE SURFACE OF A NEGATIVE 5* TO 10*C,/MM AND A TEMPERATURE GRADIENT FROM 10 MM ABOVE THE SURFACE IN AN UPWARD DIRECTION OF A NEGATIVE 1* TO 2*C/MM, AND PULLING A SEED CRYSTAL OF GASOLIMIUM MOLYBDATE ROTATING AT ABOUT 30 TO 180 R.P.M. AND WHOSE (110) FACE IS IN CONTACT WITH THE SURFACE OF THE MELT FROM THE MELT WITHOUT CHANGING THE HEATING CONDITIONS OF THE MELT.
Claim 3
Dependent Claim
24 words
A method of producing a plate single-crystal of gadolinium molybdate according to claim 1, in which the pulling velocity is 1 to 50 mm/hr.
Claim 4
Dependent Claim
48 words
A method of producing a plate single-crystal of gadolinium molybdate according to claim 1, in which the height of the zone above the melt surface in which the temperature gradient is controlled as specified in claim 1 is at least 1.3 times the length of the grown crystal.
Claim 5
Dependent Claim
27 words
A method of producing a plate single-crystal of gadolinium molybdate according to claim 1, in which the length of the seed crystal is 3 to 15 mm.
Claim 6
Dependent Claim
33 words
A method for producing a plate single-crystal of gadolinium molybdate according to claim 1, wherein said seed crystal is pulled from said melt in a direction perpendicular to the surface of said melt.
Claim 7
Dependent Claim
24 words
A method of producing a plate single-crystal of gadolinium molybdate according to claim 5, wherein the pulling velocity is about 1 to 50 mm/hr.
Claim 8
Dependent Claim
24 words
A method of producing a plate single-crystal of gadolinium molybdate according to claim 6, wherein the pull velocity is about 6 to 10 mm/hr.
Claim 9
Dependent Claim
112 words
A method of producing a plate single-crystal of gadolinium molybdate according to claim 1, wherein the pulling velocity is about 8 mm/hr, wherein the rotational velocity of the seed crystal is about 60 rpm, and wherein heating is accomplished so that the temperature gradient at the surface of the melt at about 10 mm from the center of the surface in the radial direction is about 3.5*C/mm, the temperature gradient from the surface of the melt to 10 mm above the surface in a vertical direction is about -10*C/mm, and the temperature gradient in the range from 10 mm above the surface of the melt in a vertical direction is about -1.1*C/mm.
Claim 10
Dependent Claim
46 words
A method of producing a platE single-crystal of gadolinium molybdate according to claim 1, wherein the temperature gradient above the surface of the melt is maintained up to a distance of at least 1.3 times the length of the grown crystal measured from the melt surface.
Claim 11
Dependent Claim
29 words
A method of producing a plate single-crystal of gadolinium molybdate according to claim 2, in which the rotational velocity of the seed crystal is about 50 to 180 rpm.
Claim 12
Independent Claim
178 words
A method for producing a plate single-crystal of gadolinium molybdate comprising pulling a rotating seed crystal of gadolinium molybdate from a melt mixture of one mole of gadolinium oxide and three moles of molybdenum oxide, said seed crystal having its (110) face in contact with the melt, said seed crystal being pulled from the melt in the direction parallel to the <110> crystallographic direction of the seed crystal, said melt having been heated in such a way that the temperature gradient at the surface of the melt in a radial direction from the center of the surface is positive 1* to 5*C/mm, the temperature gradient from the surface of the melt in an upward direction up to 10 mm from the surface of the melt is negative 5* to 10*C/mm and the temperature gradient from 10 mm above the surface of the melt in an upward direction is negative 1* to 2*C/mm, whereby a plate single-crystal is produced having a thickness of at least about 8 mm and a pair of smooth and uniformly spaced apart parallel faces.
Claim 13
Independent Claim
178 words
A method for producing a plate single-crystal of gadolinium molybdate comprising pulling a rotating seed crystal of gadolinium molybdate from a melt mixture of one mole of gadolinium oxide and three moles of molybdenum oxide, said seed crystal having its (110) face in contact with the melt, said seed crystal being pulled from the melt in the direction parallel to the <110> crystallographic direction of the seed crystal, said melt having been heated in such a way that the temperature gradient at the surface of the melt in a radial direction from the center of the surface is positive 1* to 5*C/mm, the temperature gradient from the surface of the melt in an upward direction up to 10 mm from the surface of the melt is negative 5* to 10*C/mm and the temperature gradient from 10 mm above the surface of the melt in an upward direction is negative 1* to 2*C/mm, whereby a plate single-crystal is produced having a thickness of at least about 8 mm and a pair of smooth and uniformly spaced apart parallel faces.
Claim 14
Dependent Claim
37 words
A method of producing a plate single-crystal of gadolinium molybdate according to claim 11, in which the rotational velocity of the seed crystal is 30 to 180 rpm, and the pulling velocity is 1 to 50 mm/hr.
Claim 15
Independent Claim
184 words
A method for producing a plate single-crystal of gadolinium molybdate having a predetermined thickness between about 8 and 21 mm comprising forming a melt mixture of one mol. of gadolinium oxide and 3 mol. of molybdenum oxide, heating the melt so as to establish a temperature gradient at the surface of the melt in a radial direction from the center of the surface of a positive 1* to 5*C/mm, a temperature gradient from the surface of the melt in an upward direction up to 10 mm from the surface of a negative 5* to 10*C/mm and a temperature gradient from 10 mm above the surface in an upward direction of a negative 1* to 2*C/mm, and pulling a seed crystal of gadolinium molybdate rotating at about 30 to 180 rpm and whose (110) face is in contact with the surface of the melt from the melt without changing the heating conditions of the melt, the rotational speed of the seed crystal corresponding to the desired thickness of the gadolinium molybdate single crystal whereby a gadolinium molybdate single crystal having said predetermined thickness is formed.
Claim 16
Independent Claim
184 words
A method for producing a plate single-crystal of gadolinium molybdate having a predetermined thickness between about 8 and 21 mm comprising forming a melt mixture of one mol. of gadolinium oxide and 3 mol. of molybdenum oxide, heating the melt so as to establish a temperature gradient at the surface of the melt in a radial direction from the center of the surface of a positive 1* to 5*C/mm, a temperature gradient from the surface of the melt in an upward direction up to 10 mm from the surface of a negative 5* to 10*C/mm and a temperature gradient from 10 mm above the surface in an upward direction of a negative 1* to 2*C/mm, and pulling a seed crystal of gadolinium molybdate rotating at about 30 to 180 rpm and whose (110) face is in contact with the surface of the melt from the melt without changing the heating conditions of the melt, the rotational speed of the seed crystal corresponding to the desired thickness of the gadolinium molybdate single crystal whereby a gadolinium molybdate single crystal having said predetermined thickness is formed.
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) | 1978-04-28 | 1978-10-28 | 1979-04-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-28 | 1982-10-28 | 1983-04-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-28 | 1986-10-28 | 1987-04-29 | $7700.00 | Window Closed / Lapsed |