US3775066A - Method for producing crystal plate of gadolinium molybdate - Google Patents

Method for producing crystal plate of gadolinium molybdate Download PDF

Info

Publication number
US3775066A
US3775066A US00183864A US3775066DA US3775066A US 3775066 A US3775066 A US 3775066A US 00183864 A US00183864 A US 00183864A US 3775066D A US3775066D A US 3775066DA US 3775066 A US3775066 A US 3775066A
Authority
US
United States
Prior art keywords
crystal plate
single crystal
melt
temperature
producing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00183864A
Other languages
English (en)
Inventor
H Yumoto
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Application granted granted Critical
Publication of US3775066A publication Critical patent/US3775066A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • C30B19/00—Liquid-phase epitaxial-layer growth
    • 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
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
    • 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
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
    • C30B11/003—Heating or cooling of the melt or the crystallised material
    • 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
    • C30B29/32—Titanates; Germanates; Molybdates; Tungstates

Definitions

  • ABSTRACT A method for producing single crystal plate of gadolinium molybdate which comprises forming a crystal plate of a specified orientation of gadolinium molybdate at the surface of a melt of gadolinium molybdate while giving to the melt a temperature gradient of inner portion of the melt being at a high temperature and of the melt surface being at a lower temperature than that of the inner portion and thereafter cooling the whole melt from [200C to 1100C at a cooling rate of 30-l70C/min to obtain single crystal of a specified orientation of gadolinium molybdate.
  • FIG. 2 OLING SD IIEC M LR AO TFN S I Y M RHR CA n EB LY GLE NOR QMP RATE POLYCRYSTALLINE MOLYBDATE FORMED AT SLOWER COOLING RATE FIG. 2
  • the present invention relates to a method for growing single crystal plate .of gadolinium molybdate.
  • Said MOGsingle crystal to which electric field (coercive electric field) or stress(coercive stress) at least equal to the threshold value specific to said crystal is applied exhibits physical properties which are the same as thoseof the crystal whose a.axis and b axis are replaced. Said properties keep a kind of memory state which remains as it is, after the cause (i.e. external electric field or external stress) has been removed. Therefore, many practical-uses of said MOG single crystal are expected with reference to optical characteristic of the crystal and mechanical properties. Therefore, it is necessary to utilize'the crystal plate having a specified orientation in order to offer the MOG for practical use.
  • MOG crystal The growth rate of MOG crystal is highest at direction l next at l and extremely low at 001 as compared with the first two cases.
  • the melt of MOG can well wet the surface of platinum vessel and has a great sticking force to the platinum surface when it is solidified. Therefore, anattempt to homogeneously single-crystallize the melt of MOG in a platinum vessel has not turned out asuccess'The following is one example thereof.
  • a melt of 25 g of MOG was poured into a platinum boat of 10 mm in width, 80 mm in length and 8 mm in depth to form ahomogeneous polycrystal. Then, when a melting zone of about 10mm in width was transferred from one end to another end of the melt at a velocity of l0-l00'mm/hr, the whole of the melt was not converted into single crystal and only polycrystal containing several crystal grains which stick to platinum wall could be obtained.
  • a platinum vessel of 10 mm in width, 15 cm in length and 5 cm in depth was filled with polycrystalline powders of MOG. Then, the polycrystalline powders' were molten and thereafter cooled at various temperature gradients to obtain no single crystal. Especially, the whole surface of crystal did not become horizontal plane and meniscus due to surface tension was apt to increase.
  • An object of the present invention is to provide a method for producing single crystal, which is not effected by the defect that a melt of MOG will wet a platinum vessel and has a high sticking force to the surface of platinum when it solidifies.
  • Another object of the present invention is to provide a method for optionally producing single crystal plate of MOG having a desired specific crystal.
  • the gist of the present invention resides in that while keeping the whole melt of MOG at molten state the, temperature of only the surface layer is rapidly reduced to lower than the melting point to grow single crystal plate in the surface layer. After single crystal layer is formed in the surface of the melt by said method, temperature of the whole melt is lowered to solidify it and it is cooled to room temperature and thereafter said single crystal plate is peeled or single crystal seed of MOG or a platinum rod is introduced into the melt to allow crystal plate to grow and then the crystal plate may be drawn up from the melt.
  • the method of the present invention does not comprise cutting a crystal plate of a desired orientation (especially 001 direction), but comprises previously and directly producing a crystal plate of a desired orientation and is conspicuously excellent as compared with the conventional method with reference to time and mass production.
  • FIG. I is a sectional view of a heating furnace which explains essential parts of the heating furnace used for heating gadolinium molybdate in the present invention.
  • FIG. 2 is a graph which shows the light transmission characteristic of single crystal plate of MOG at various wave lengths.
  • FIG. 3a shows one embodiment of the method for producing single crystal plate of MOG of the present invention.
  • FIG. 3b shows a sectional view of a heating furnace which is used for producing single crystal plate of MOG of the present invention.
  • FIG: 4 is a characteristic-curve which shows correlation between depth. of MOG melt and success rate of .single crystal plate obtained.
  • FIG. 5 is a'characteristic curve which'shows correlaplate obtained.
  • FIG. 6 is a characteristic diagram which shows reduction. rate of furnace temperature in production of single -crystal plate of MOG of the present invention.
  • EXAMPLE I 120 Grams of sintered MOG was placed in a platinum vessel having a diameter of 50 mm and a depth of 30 mm and was heated in a muffle furnace 1 as shown in FIG. I.
  • Said muffle furnace was provided with carbon siliside heater 2 which was a main heater and subheater 3 of a platinum heater which corrects temperature distribution. These two heaters can independently adjust the temperature and the main heater can effect program control.
  • Temperature of the furnace was raised to l200C at a rate of about 300C/hr until it reached l000C and at 100C/hr until it reached l200C. The furnace was kept at l200C for about one hour. Thereafter, while keeping such temperature distribution as the temperature of the bottom of the vessel in FIG.
  • the surface of the single crystal plate had a part containing circular convexes of -50 1.1. in thickness beside smooth part.
  • a smooth crystal plate could be produced by polishing both surfaces of the crystal plate with No. 2000 alumina powders.
  • the light transmission characteristic of thus obtained crystal plate is as shown in FIG. 2.
  • EXAMPLE 2 100 Grams of MOG was introduced into a platinum vessel which had a bottom of 3 cm X 5 cm and a depth of 1 cm and upwardly tapered by V4 and was heated in the same furnace as used in Example 1 except that the subheater was reconstructed in such a manner that the platinum heater was wound in closely two steps, whereby a temperature gradient along the long side of the vessel of 2-l0C/cm at l200C was obtained. Furthermore, a temperature gradient of about C between the bottom (the high temperature part) of the vessel and the upper part (the lower temperature part) was imparted.
  • the temperature of the furnace was elevated to l200C at about 300C/hr until l000C and at 100C/hr from l000C to l200C and kept at 1200C for about one hour.
  • the temperature of said melt was lowered to 1 100C at l00-500C/35 min while keeping said temperature gradient and furthermore lowered to l000C at 50C/hr, to 250C at 200C/hr and to lower than 250C by leaving it as it was.
  • a solid layer of MOG was formed in the platinum vessel and the surface of the melt was grown to single crystal except for the part contacting with the edge of the vessel.
  • EXAMPLE 3 220 Grams of sintered MOG was introduced into a platinum vessel of 50 mm in diameter and 40 mm in depth. This vessel was placed in a work coil of mm in diameter and of nine turns which was connected with a high frequency oscillator of 400 KC and 8 KW, in such a manner that the bottom and side face of said vessel were kept warm with a heat insulating material. The vessel was heated by high frequency induction heating to melt MOG in the vessel at l200C to obtain a melt.
  • a piece of single crystal of MOG as seed crystal was contacted with the surface of the melt using a crystal drawing up axis of a single crystal drawing up device for about 10 minutes and then high frequency current was abruptly decreased to cause immediate growth of crystal plate from the point contacting with the seed crystal.
  • high frequency current was increased to raise the temperature and simultaneously the seed crystal and the crystal plate grown therefrom were slightly drawn up from the surface of the melt to cause no contact with the surface of the melt. At this state, they were cooled to about l000C at 100C/hr, to 250C at 500C/hr and finally to room temperature by leaving it as it was.
  • the crystal plate grown from the seed crystal contained several single crystals and a single crystal plate having a side of 8-5 mm and a thickness of 200-300 s was taken out. According to observation with a microscope, the crystal included some precipitation and dendritic growth and was inferior to that obtained in Examples l and 2 in its homogeneity.
  • a platinum rod may be used.
  • EXAMPLE 4 l2 Grams of sntered GMO was introduced into a platinum boat having a circular bottom and a length of 4 cm, a width of 1 cm and a depth of 1 cm and said boat 30 was covered with a heat insulating material 30' as shown in FIG. 3a, and fixed in a quartz tube 32 of 4 cm in diameter in tubular furnace as shown in FIG. 3b and then said boat was heated in the said tubular furnace 31.
  • the temperature was elevated to l200C to melt MOG in the boat and then a dehydration-dried air was passed through said quartz tube in such a manner that amount of the air was small at first and gradually increased until 3 I/min.
  • the temperature around the MOG was also raised to 1250C, which was kept by controlling the furnace.
  • the surface of MOG solidified in the platinum boat was partially single crystallized and said partial single crystallized plate was removed from the platinum boat.
  • the said removed single crystal plate was 4 mm in length, l-2 mm in width and 200-400 p. in thickness.
  • normal temperature gradient i.e., high temperature at inner part of melt and lower temperature at surface layer
  • the following procedures are preferable.
  • the thickness of the MOG melt is required to be more than 5 mm, actually more than mm.
  • the relation between the thickness of the melt (depth in mm) and success rate of single crystal plate obtained (expressed by percent) is shown by the characteristic curve 5 in HQ. 4. As is clear from the curve, success rate ofsingle crystal obtained when depth of the melt is more than about 30 mm is high.
  • the shape of the vessel may be circular or square one and diameter in case of circular vessel and side in case of square vessel (i.e. cross section) should be more than mm.
  • the crystal plate should be cooled at a cooling rate of less than 50C/hr during the period of from 300C to
  • success rate used herein means yield of single crystal plate.
  • No. 2000 alumina powders used for polishing crystal plate in Example 1 means alumina powders having a diameter of 3 M.
  • a method for producing a single crystal plate of gadolinium molybdate which comprises heating gadolinium molybdate in a vessel to 1,200C thereby forming a melt, providing a temperature gradient between the upper and lower portions of the melt contained in the vessel, the upper portion being at a lower temperature than the lower portion, cooling the gadolinium molybdate melt at a cooling rate of 30C/min. to 170C/min.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
US00183864A 1970-09-30 1971-09-27 Method for producing crystal plate of gadolinium molybdate Expired - Lifetime US3775066A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP45085068A JPS492280B1 (enrdf_load_stackoverflow) 1970-09-30 1970-09-30

Publications (1)

Publication Number Publication Date
US3775066A true US3775066A (en) 1973-11-27

Family

ID=13848297

Family Applications (1)

Application Number Title Priority Date Filing Date
US00183864A Expired - Lifetime US3775066A (en) 1970-09-30 1971-09-27 Method for producing crystal plate of gadolinium molybdate

Country Status (2)

Country Link
US (1) US3775066A (enrdf_load_stackoverflow)
JP (1) JPS492280B1 (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3880984A (en) * 1971-07-28 1975-04-29 Hitachi Ltd Method of producing plate single-crystal of gadolinium molybdate
US3894846A (en) * 1973-02-07 1975-07-15 Hitachi Ltd Method of producing single crystals of gadolinium molybdate family

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1514972A (en) * 1924-04-01 1924-11-11 Carl M Loeb Process of producing molybdates
US3294701A (en) * 1961-11-16 1966-12-27 Ibm Method of preparing fluorescent rare earth compounds
US3328311A (en) * 1965-05-05 1967-06-27 Du Pont Selected luminescent molybdates and tungstates of sc., la, eu, gd, and lu
US3437432A (en) * 1966-07-21 1969-04-08 Du Pont Single crystals
US3562175A (en) * 1968-09-11 1971-02-09 Gen Electric Gadolinium oxide particle growth in lithium oxide flux

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1514972A (en) * 1924-04-01 1924-11-11 Carl M Loeb Process of producing molybdates
US3294701A (en) * 1961-11-16 1966-12-27 Ibm Method of preparing fluorescent rare earth compounds
US3328311A (en) * 1965-05-05 1967-06-27 Du Pont Selected luminescent molybdates and tungstates of sc., la, eu, gd, and lu
US3437432A (en) * 1966-07-21 1969-04-08 Du Pont Single crystals
US3562175A (en) * 1968-09-11 1971-02-09 Gen Electric Gadolinium oxide particle growth in lithium oxide flux

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Kestigian, J. Amer. Ceram. Soc., 48, pp. 544 545, (1965) *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3880984A (en) * 1971-07-28 1975-04-29 Hitachi Ltd Method of producing plate single-crystal of gadolinium molybdate
US3894846A (en) * 1973-02-07 1975-07-15 Hitachi Ltd Method of producing single crystals of gadolinium molybdate family
US3993534A (en) * 1973-02-07 1976-11-23 Hitachi, Ltd. Method of producing single crystals of gadolinium molybdate family

Also Published As

Publication number Publication date
JPS492280B1 (enrdf_load_stackoverflow) 1974-01-19

Similar Documents

Publication Publication Date Title
JPH10203898A (ja) シリコン単結晶の製造方法および種結晶
JP4165068B2 (ja) シリコン単結晶の製造方法
JPS6046993A (ja) 単結晶引上装置
US4303465A (en) Method of growing monocrystals of corundum from a melt
US4944925A (en) Apparatus for producing single crystals
US3775066A (en) Method for producing crystal plate of gadolinium molybdate
US3261722A (en) Process for preparing semiconductor ingots within a depression
EP0476389A2 (en) Method of growing single crystal of compound semiconductors
EP0266227A2 (en) Method for growing compound semiconductor crystals
FR2347974A1 (fr) Procedes et dispositifs de formation d'un ruban de silicium monocristallin au moyen d'un germe d'orientation cristalline <110> (211)
US5007979A (en) Method of fabricating GaAs single crystal
US5785753A (en) Single crystal manufacturing method
US5454345A (en) Method of growing single crystal of β-barium borate
US2829994A (en) Method for preparing silicon-germanium alloys
JPH11349398A (ja) シリコン単結晶の製造方法
JP2825060B2 (ja) ベータ・バリウムボレイト単結晶加工表面の改質方法
JPH0725533B2 (ja) シリコン多結晶インゴツトの製造方法
US3776703A (en) Method of growing 1-0-0 orientation high perfection single crystal silicon by adjusting a focus coil
JP2535773B2 (ja) 酸化物単結晶の製造方法とその装置
JPH0782088A (ja) 単結晶の育成方法
JPH0316988A (ja) 化合物半導体単結晶製造装置
JPH0692781A (ja) 単結晶の製造方法及び製造装置
JP2773441B2 (ja) ＧａＡｓ単結晶の製造方法
Muhlberg Investigations on the Structural Perfection of Bridgman-Grown PbTe Single Crystals
JPH09227280A (ja) 単結晶育成方法