US2777255A - Method for producing improved monocrystalline refractive material - Google Patents

Method for producing improved monocrystalline refractive material Download PDF

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US2777255A
US2777255A US334709A US33470953A US2777255A US 2777255 A US2777255 A US 2777255A US 334709 A US334709 A US 334709A US 33470953 A US33470953 A US 33470953A US 2777255 A US2777255 A US 2777255A
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strontium titanate
crystal
monocrystalline
temperature
refractive material
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US334709A
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Merker Leon
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NL Industries Inc
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Nat Lead Co
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/51—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on compounds of actinides
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/46—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/48—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on zirconium or hafnium oxides, zirconates, zircon or hafnates
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/50—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on rare-earth compounds
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/16—Oxides
    • C30B29/22—Complex oxides
    • C30B29/26—Complex oxides with formula BMe2O4, wherein B is Mg, Ni, Co, Al, Zn, or Cd and Me is Fe, Ga, Sc, Cr, Co, or Al
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S117/00—Single-crystal, oriented-crystal, and epitaxy growth processes; non-coating apparatus therefor
    • Y10S117/918—Single-crystal waveguide

Definitions

  • optical materials having high refractive indices and high'disp'e'rsion are utilized in the manufacture of lenses and prism's.
  • materials having a high index of refraction are utilized in the construction of optical systems such as telescopic or high magnification microscopic objectives.
  • Highly refractive single crystal material is also useful for the preparation'of ornamental objects such 40 as gem stones. Synthetic gems of various types and colors are in great demand for both personal adornment and industrial uses.
  • An object of this invention therefore is to provide a method for producing a monocrystalline material which possesses exceedingly high index of refraction with a high dispersion or relatively low 1! value.
  • a further object is I and other objectswill become apparent from the follow titanate in an oxidizing atmosphere at a high temperature annealed crystal to an oxidizing atmosphere at temperature of about 200 C. to about 500 C. to improve the color. It has been found that the internal strains in the single crystal strontium titanate may be relieved by an- 5 nealing the crystal in an oxidizing atmosphere at temperature from about 1000 C. to about 1700 C. for 12 to 180 hours. The color of the annealed crystal may be improved by subsequently treating the crystal in an oxidizing atmosphere at temperature from about 200 C. to about 7 500 C. for 6 hours to hours.
  • strontium titanate is intended to embrace fussing particles of strontium titanate, it is necessary to employ high temperatures.
  • Strontium titanate melts in the neighborhood of about 2050 C. and it is therefore preferred to use an oxygen-hydrogenfiame in order to obtain the necessary temperatures without the possible introduction of impurities.
  • strontium titanate powdered ra'terial which is substantially free from objectionable or incompatible impurities which detrlmentally would affect the crystal structure.
  • Starting material should be finely divided and fairly uniform in size.
  • Such a material may "be conveniently prepared by first reacting titanium oxalate with strontium chloride to precipitate strontium titanium oxalate. After thoroughly washing the strontium titanium oxalate, it is heated at a temperature of at least 500 C. to remove the oxalate portion thus forming strontium titanate. Preferably this strontium titanate material is then crushed and ground to obtain finely divided material from which the strontium titanate single crystal is subsequently formed.
  • the black boule was subjected to the oxidation treatment contemplated in the instant in vention.
  • the black boule was treated at temperature of 1500 C. for 25 hours and was then cooled slowly to 300 C. temperature and held at 300 C. temperature for 48 hours.
  • the boule after treatment possessed a subdouble oxidation treatment.
  • the single crystal material should be subjected first to a very high temperature oxidation treatment, i. e. from 3 temperatures of about 1000 C. to about l700 C. These high temperature treatments should be maintained between 12 and 180 hours. At this stage the monocrystalline strontium titanate possesses a purplish or pinkish appearance instead of the former black color.
  • the monocrystalline material is then subjected to the second oxidation treatment which should be carried out at temperature from about 200 C. to about 500 C. for 6 hours to This low temperature treatment is necessary in order to obtain a substantially White boule.
  • the two oxidation treatments can be carried out in separate fun naces or in the same furnace by merely lowering the temperature after the first treatment to that required for the second.
  • the strains in the crystal are relieved and boules which are properly annealed are obtained.
  • These monocrystalline titanate are substantially white in masses of strontium color and are properly annealed and may be shaped into many bodies useful for optical purposes such as, e. g.
  • lens blanks suitable for preparation of lenses, prisms, and other optical products and also may be cut into various shapes and sizes to produce many articles such as ornamental objects and novelty gems, Which depend for their attractiveness and usefulness on the high refractive index of the material of which they are composed.
  • the index of refraction of the strontium titanate crystal is extremely high, i. e. about 2.4, and the reciprocal dispersion is about 13. These valves will vary slightly as various types of starting materials and processing conditions are employed.
  • the strontium titanate crystal when cut into a lens has a high magnifying power and a short focal length.
  • Such material is particularly useful for telescopic and microscopic objectives and the like, achromatic lenses and prisms and for other optical purposes which advantageously utilize wide fields, high apertures and short focal lengths.
  • the index of refraction and reciprocal disperson are very different from any type of known glass.
  • This monocrystalline mass of strontium titanate after A proper annealing according to this invention will not tend to chip, splinter or crack as easily as those crystals which are not properly annealed.
  • Method for producing an improved single crystal of strontium titanate prepared by co-fusion of finely divided strontium titanate particles which comprises annealing the single crystal of strontium titanate in an oxidizing atmosphere at temperatures from about 1000 C. to about 1700 C. for 12 to 180 hours to relieve the strains in said crystal and subsequently heating the crystal in an oxidizing atmosphere at temperatures from about 200 C. to about 500 C. for 6 to 80 hours to improve the color.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Composite Materials (AREA)
  • Inorganic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Metallurgy (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Compositions Of Oxide Ceramics (AREA)

Description

United States Patent METHOD r012. PRGDUC'ING IMPROVED MON- cRYsTALLINE' REFRACTWE MATERIAL 5 Leon Merker, New York, N. Y.,' ass'ignor to National Lead .Compan New York, N. Y., a corporation of New Jersey No' Drawing. Application February 2, 1953,
.Serial No. 334,709 1 Claim. or. 49-s9 refraction and dispersion:
One broad use of optical materials having high refractive indices and high'disp'e'rsion is in the manufacture of lenses and prism's. For example, materials having a high index of refraction are utilized in the construction of optical systems such as telescopic or high magnification microscopic objectives. Furthermore combinations of optical materials which individually possess widely variant and the like. Highly refractive single crystal materialis also useful for the preparation'of ornamental objects such 40 as gem stones. Synthetic gems of various types and colors are in great demand for both personal adornment and industrial uses.
An object of this invention therefore is to provide a method for producing a monocrystalline material which possesses exceedingly high index of refraction with a high dispersion or relatively low 1! value. A further object is I and other objectswill become apparent from the follow titanate in an oxidizing atmosphere at a high temperature annealed crystal to an oxidizing atmosphere at temperature of about 200 C. to about 500 C. to improve the color. It has been found that the internal strains in the single crystal strontium titanate may be relieved by an- 5 nealing the crystal in an oxidizing atmosphere at temperature from about 1000 C. to about 1700 C. for 12 to 180 hours. The color of the annealed crystal may be improved by subsequently treating the crystal in an oxidizing atmosphere at temperature from about 200 C. to about 7 500 C. for 6 hours to hours.
Copending application Serial No. 252,906 filed October 24, 1951, now S. Patent N0. 2,628,156, filed by .Leon
Merker and Langtry E. Lynd describes and claims in annealing the monocrystalline strontium titanate boule to obtain a substantially strain-free white boule. Copending application- Serial No. 252,906 is assigned to the same assignee as the instant invention.
The term strontium titanate is intended to embrace fussing particles of strontium titanate, it is necessary to employ high temperatures. Strontium titanate melts in the neighborhood of about 2050 C. and it is therefore preferred to use an oxygen-hydrogenfiame in order to obtain the necessary temperatures without the possible introduction of impurities.
It is convenient to drop finely divided strontium crystal. Such a procedure allows the crystal to build up upon itself gradually increasing in diameter until a boule or carrot-shaped single crystal of strontium titanate is formed.
It is preferred to employ a strontium titanate powdered ra'terial which is substantially free from objectionable or incompatible impurities which detrlmentally would affect the crystal structure. Starting material should be finely divided and fairly uniform in size. Such a material may "be conveniently prepared by first reacting titanium oxalate with strontium chloride to precipitate strontium titanium oxalate. After thoroughly washing the strontium titanium oxalate, it is heated at a temperature of at least 500 C. to remove the oxalate portion thus forming strontium titanate. Preferably this strontium titanate material is then crushed and ground to obtain finely divided material from which the strontium titanate single crystal is subsequently formed.
Using an oxygen-hydrogen burner and passing the finely divided strontium titanate feed material into the intensely heated zone, a single crystal boule of strontium titanate 1 inch long and /2 inch Wide was prepared in 2 hours.
In order to produce an improved type of strontium titanate single crystal, the black boule was subjected to the oxidation treatment contemplated in the instant in vention. The black boule Was treated at temperature of 1500 C. for 25 hours and was then cooled slowly to 300 C. temperature and held at 300 C. temperature for 48 hours. The boule after treatment possessed a subdouble oxidation treatment.
The single crystal material should be subjected first to a very high temperature oxidation treatment, i. e. from 3 temperatures of about 1000 C. to about l700 C. These high temperature treatments should be maintained between 12 and 180 hours. At this stage the monocrystalline strontium titanate possesses a purplish or pinkish appearance instead of the former black color. The monocrystalline material is then subjected to the second oxidation treatment which should be carried out at temperature from about 200 C. to about 500 C. for 6 hours to This low temperature treatment is necessary in order to obtain a substantially White boule. The two oxidation treatments can be carried out in separate fun naces or in the same furnace by merely lowering the temperature after the first treatment to that required for the second. When the monocrystalline strontium titanate material is processed according to the instant invention the strains in the crystal are relieved and boules which are properly annealed are obtained. These monocrystalline titanate are substantially white in masses of strontium color and are properly annealed and may be shaped into many bodies useful for optical purposes such as, e. g.
cut into lens blanks suitable for preparation of lenses, prisms, and other optical products; and also may be cut into various shapes and sizes to produce many articles such as ornamental objects and novelty gems, Which depend for their attractiveness and usefulness on the high refractive index of the material of which they are composed.
The index of refraction of the strontium titanate crystal is extremely high, i. e. about 2.4, and the reciprocal dispersion is about 13. These valves will vary slightly as various types of starting materials and processing conditions are employed.
It should be noted that the strontium titanate crystal when cut into a lens has a high magnifying power and a short focal length. Such material is particularly useful for telescopic and microscopic objectives and the like, achromatic lenses and prisms and for other optical purposes which advantageously utilize wide fields, high apertures and short focal lengths. It should be noted that the index of refraction and reciprocal disperson are very different from any type of known glass.
This monocrystalline mass of strontium titanate after A proper annealing according to this invention will not tend to chip, splinter or crack as easily as those crystals which are not properly annealed.
While this invention has been described and illustrated by the examples shown, it is not intended to be strictly limited thereto and other modifications and variations may be employed Within the scope of the following claim.
I claim:
Method for producing an improved single crystal of strontium titanate prepared by co-fusion of finely divided strontium titanate particles which comprises annealing the single crystal of strontium titanate in an oxidizing atmosphere at temperatures from about 1000 C. to about 1700 C. for 12 to 180 hours to relieve the strains in said crystal and subsequently heating the crystal in an oxidizing atmosphere at temperatures from about 200 C. to about 500 C. for 6 to 80 hours to improve the color.
References Cited in the file of this patent UNITED STATES PATENTS 988,230 Verneuil Mar. 28, 1911 1,004,505 Verneuil Sept. 26, 1911 1,298,540 Miller Mar. 25, 1919 1,436,164 Goldschmidt Nov. 21, 1922 2,507,253 Howatt May 9, 1950 2,610,129 Eversole et al. Sept. 9, 1952 2,628,156 Merker et al. Feb. 10, 1953 2,634,554 Barnes Apr. 14, 1953 FOREIGN PATENTS 243,251 Great Britain Nov. 26, 1925 252,698 Switzerland Oct. 1, 1948 608,453 Great Britain Sept. 15, 1948 662,782 France Nov. 26, 1927 664,889 Great Britain Ian. 16, 1952 OTHER REFERENCES G. E. C. Journal, August 1944, pages 56-69. Kremers: Synthetic Optical Crystals, Ind. and Eng. Chem, November 1940, vol. 32, pages 14784482.
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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2985520A (en) * 1958-08-11 1961-05-23 Nat Lead Co Method for preparation of monocrystalline material
US2985518A (en) * 1958-10-01 1961-05-23 Nat Lead Co Metal titanate preparation
US3145114A (en) * 1960-10-24 1964-08-18 Prismo Safety Corp Process for increasing the index of refraction of glass and an article made thereby
DE1197862B (en) * 1958-08-11 1965-08-05 Titan Gmbh Method and apparatus for producing calcium titanate single crystals free of twinning
US3245761A (en) * 1962-10-11 1966-04-12 Norton Co Apparatus for making magnesium oxide crystals
US20110204532A1 (en) * 2009-03-09 2011-08-25 Hiroaki Kinoshita Fabrication process for single-crystal optical devices

Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US988230A (en) * 1910-05-10 1911-03-28 Heller & Son L Process of producing synthetic sapphires.
US1004505A (en) * 1911-06-28 1911-09-26 Heller & Son L Synthetic sapphire.
US1298540A (en) * 1917-11-12 1919-03-25 Gen Electric Device for making jewels.
US1436164A (en) * 1917-05-10 1922-11-21 Titan Co As Titanium pigment and process of producing same
GB243251A (en) * 1924-12-16 1925-11-26 Gen Electric Co Ltd Improved process for the preparation of translucent rod-shaped bodies from powdered material
FR662782A (en) * 1927-11-26 1929-08-12 Swiss Jowel Co S A Process for the manufacture of scientific stones and device for implementing this process
CH252698A (en) * 1944-12-13 1948-01-31 Linde Air Prod Co Process for obtaining, from monocrystalline bodies, objects having at least one part of which the surface is smooth and free from scratches, device for applying this process and object obtained according to this process.
GB608453A (en) * 1945-03-17 1948-09-15 Linde Air Prod Co Multi coloured synthetic gems and process for making same
US2507253A (en) * 1948-05-01 1950-05-09 Gulton Mfg Corp Stabilization of sensitivity of metallic titanate piezoelectric elements
GB664889A (en) * 1948-10-14 1952-01-16 Titan Co Inc Boules and methods of making same
US2610129A (en) * 1949-03-22 1952-09-09 Union Carbide & Carbon Corp Synthetic rutile and method of making
US2628156A (en) * 1951-10-24 1953-02-10 Nat Lead Co Optically glass-like material
US2634554A (en) * 1953-04-14 Synthetic gem production

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2634554A (en) * 1953-04-14 Synthetic gem production
US988230A (en) * 1910-05-10 1911-03-28 Heller & Son L Process of producing synthetic sapphires.
US1004505A (en) * 1911-06-28 1911-09-26 Heller & Son L Synthetic sapphire.
US1436164A (en) * 1917-05-10 1922-11-21 Titan Co As Titanium pigment and process of producing same
US1298540A (en) * 1917-11-12 1919-03-25 Gen Electric Device for making jewels.
GB243251A (en) * 1924-12-16 1925-11-26 Gen Electric Co Ltd Improved process for the preparation of translucent rod-shaped bodies from powdered material
FR662782A (en) * 1927-11-26 1929-08-12 Swiss Jowel Co S A Process for the manufacture of scientific stones and device for implementing this process
CH252698A (en) * 1944-12-13 1948-01-31 Linde Air Prod Co Process for obtaining, from monocrystalline bodies, objects having at least one part of which the surface is smooth and free from scratches, device for applying this process and object obtained according to this process.
GB608453A (en) * 1945-03-17 1948-09-15 Linde Air Prod Co Multi coloured synthetic gems and process for making same
US2507253A (en) * 1948-05-01 1950-05-09 Gulton Mfg Corp Stabilization of sensitivity of metallic titanate piezoelectric elements
GB664889A (en) * 1948-10-14 1952-01-16 Titan Co Inc Boules and methods of making same
US2610129A (en) * 1949-03-22 1952-09-09 Union Carbide & Carbon Corp Synthetic rutile and method of making
US2628156A (en) * 1951-10-24 1953-02-10 Nat Lead Co Optically glass-like material

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2985520A (en) * 1958-08-11 1961-05-23 Nat Lead Co Method for preparation of monocrystalline material
DE1197862B (en) * 1958-08-11 1965-08-05 Titan Gmbh Method and apparatus for producing calcium titanate single crystals free of twinning
US2985518A (en) * 1958-10-01 1961-05-23 Nat Lead Co Metal titanate preparation
US3145114A (en) * 1960-10-24 1964-08-18 Prismo Safety Corp Process for increasing the index of refraction of glass and an article made thereby
US3245761A (en) * 1962-10-11 1966-04-12 Norton Co Apparatus for making magnesium oxide crystals
US20110204532A1 (en) * 2009-03-09 2011-08-25 Hiroaki Kinoshita Fabrication process for single-crystal optical devices

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