USH429H - Low temperature synthesis of metal sulfides - Google Patents

Low temperature synthesis of metal sulfides Download PDF

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Publication number
USH429H
USH429H US07/042,089 US4208987A USH429H US H429 H USH429 H US H429H US 4208987 A US4208987 A US 4208987A US H429 H USH429 H US H429H
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United States
Prior art keywords
solution
organic solvent
reaction
toluene
organometallic compound
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Abandoned
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US07/042,089
Inventor
Daniel C. Harris
Robert W. Schwartz
Curtis E. Johnson
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US Department of Navy
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US Department of Navy
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Priority to US07/042,089 priority Critical patent/USH429H/en
Assigned to UNITED STATES OF AMERICA, THE, AS REPRESENTED BY THE SECRETARY OF THE NAVY reassignment UNITED STATES OF AMERICA, THE, AS REPRESENTED BY THE SECRETARY OF THE NAVY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: HARRIS, DANIEL C., JOHNSON, CURTIS E., SCHWARTZ, ROBERT W.
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G9/00—Compounds of zinc
    • C01G9/08—Sulfides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B17/00—Sulfur; Compounds thereof
    • C01B17/20—Methods for preparing sulfides or polysulfides, in general
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/30—Particle morphology extending in three dimensions
    • C01P2004/32—Spheres
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/80—Compositional purity

Definitions

  • This invention is related to metal sulfide powders useful as precursors for optical ceramics and catalysts. More particularly, this invention is related to a low temperature synthesis of metal sulfide powders by reaction between an organometallic compound and hydrogen sulfide.
  • Metal sulfide powders are useful as precursors for optical ceramics used in sensor windows and domes on aircraft, satellites, and missiles. Precursors having high purity and small. uniform particles are necessary to provide optical ceramics having excellent thermal, mechanical and optical properties. Additionally, metal sulfide powders are useful as catalysts because they contain small, uniform particles having a large surface area.
  • Organometallic compounds are known to be useful in the preparation of some metal chalcogenides.
  • organometallic compound such as diethyl zinc with hydrogen sulfide, hydrogen selenide or dimethyltellurium has.been reported.
  • the reaction is run at temperatures of 750° C. or greater and has been used to prepare the sulfides, selenides and tellurides of zinc and cadmium.
  • Aocording to the present invention finely divided metal sulfide powders of uniform size are produced by adding a solution of an organometallic compound at a predetermined rate to an organic solvent saturated with H 2 S.
  • the reaction can be performed at temperatures in the range of -78° C. to 100° C.
  • the reaction solution is kept saturated with H 2 S by adding H 2 S at a rate greater than that for the organometallic compound.
  • the present invention provides a synthesis of metal sulfide powders by reaction of an organometallic compound in solution with hydrogen sulfide (H 2 S) at temperatures from about -78° C. to about 100° C.
  • Organometallio reagents are particularly suitable for the low temperature preparation of metal sulfide powders which are desired as precursors to 8-12 micrometer infrared-transmitting ceramics.
  • Organometallic reagents in the low temperature synthesis of ceramic powders offers many advantages over conventional preparations.
  • Organometallic reagents can be obtained in high purity and can be mixed at a molecular level while in solution.
  • Bimetallic complexes may also be useful for making ternary materials.
  • the low temperatures possible with organometallic oompounds in solution are a factor in promoting small and uniformly sized particles which are suitable for processing under mild conditions into fine-grained ceramics.
  • Metal sulfide powders have been prepared by reacting H 2 S with dimethylzinc, di(tertiary-butyl)zinc, triethylaluminum, trimethylaluminum, diethylmagnesium, and bis(trimethylsilylmethyl)cadmium.
  • Other reagents besides metal alkyl compounds may be useful, such as metal alkoxides, thioalkoxides and hydrides.
  • Residual hydrocarbon usually results from incomplete reaction of the organometallic reagent or from residual organic solvent.
  • the amount of residual hydrocarbon due to unreacted zinc-alkyl groups parallels the order of stability of the zinc-alkyl compounds.
  • dimethylzinc is more stable than diethylzinc, which in turn, is more stable than di(t-butyl)zinc.
  • Zinc sulfide powders made from dimethyl zinc contain more unreacted metal alkyl reagent and, consequently, more residual hydrocarbon than powders made from diethylzinc or di(t-butyl)zinc.
  • a H 2 S purge of an organometallic compound in solution results in significantly higher levels of residual hydrocarbon than procedures involving the addition of an organometallic reagent in solution to an organic solvent that is saturated with H 2 S.
  • the H 2 S purge of a diethylzinc/heptane solution at 25° C. resulted in a residual zinc-ethyl group level of 30,000 ethane/mole zinc) as measured by acid hydrolysis in which the liberated hydrocarbon is measured using gas chromatography.
  • adding a diethylzinc/toluene solution to toluene saturated with H 2 S at -20° C. resulted in a residual zinc-ethyl group level of about 10 ppm.

Abstract

Finely divided metal sulfide powders of uniform size are produced at low temperatures by a method of adding solutions of organometallic compounds to an organic solvent saturated with H2 S. The solvent is kept saturated with H2 S by adding H2 S at a rate greater than that for the organometallic compound.

Description

BACKGROUND OF THE INVENTlON
1. Field of the Invention
This invention is related to metal sulfide powders useful as precursors for optical ceramics and catalysts. More particularly, this invention is related to a low temperature synthesis of metal sulfide powders by reaction between an organometallic compound and hydrogen sulfide.
2. Description of the Prior Art
Metal sulfide powders are useful as precursors for optical ceramics used in sensor windows and domes on aircraft, satellites, and missiles. Precursors having high purity and small. uniform particles are necessary to provide optical ceramics having excellent thermal, mechanical and optical properties. Additionally, metal sulfide powders are useful as catalysts because they contain small, uniform particles having a large surface area.
Conventional methods of synthesizing metal sulfide powders require high temperatures and inorganic starting materials. High temperatures promote particle growth which detracts from the optical and thermomechanical properties of the ceramic. Inorganic starting materials contain undesirable impurities which can degrade the performance of the optical ceramic or catalyst.
Organometallic compounds are known to be useful in the preparation of some metal chalcogenides. For example, the gas phase reaction between an organometallic compound such as diethyl zinc with hydrogen sulfide, hydrogen selenide or dimethyltellurium has.been reported. The reaction is run at temperatures of 750° C. or greater and has been used to prepare the sulfides, selenides and tellurides of zinc and cadmium.
The liquid phase reaction of diethyl zinc with hydrogen sulfide has been reported. This room temperature reaction has been used to prepare zinc sulfide containing ligands such as 2,2'-bipyridine, 1,10-phenanthroline, and pyridine. The procedure involves an H2 S purge of an anhydrous ethereal solution of diethyl zinc and an organic ligand. The procedure has been adapted to produce zinc sulfide without the ligand. However, the particle size of the resulting zinc sulfide was not reported.
Optical ceramic precursors having small particles are desirable because they often can be processed under mild conditions into fine-grained ceramics. The resulting fine-grained ceramics are generally low in defects and have improved optical and mechanical properties. Moreover, if the grain size is substantially smaller than the wavelength of light, then light scattering between grains in non-cubic materials is minimized. As a result, a wider range of metal sulfides would be available as optical ceramics.
Metal sulfide powders used as optical ceramic and catalyst precursors must have few impurities. The purity of the final product is dependent on the purity of the starting material. Inorganic starting materials used in conventional syntheses contain impurities which can degrade the performance of the ceramic. Organometallic starting materials of very high purity are easily obtained by distillation, sublimation or recrystallization. However, the purity of the final product may be affected by the presence of residual hydrocarbon in the form of incompletely reacted organometallic material or entrained solvent.
SUMMARY OF THE INVENTION
Aocording to the present invention finely divided metal sulfide powders of uniform size are produced by adding a solution of an organometallic compound at a predetermined rate to an organic solvent saturated with H2 S. The reaction can be performed at temperatures in the range of -78° C. to 100° C. The reaction solution is kept saturated with H2 S by adding H2 S at a rate greater than that for the organometallic compound.
An object of this invention is to provide a low temperature synthesis of metal sulfides that may be used as precursors to optical ceramics or catalysts.
Another object of this invention is a method of producing high purity metal sulfide powders containing small, uniform particles having a large surface area.
Other objects, advantages and novel features of the invention will become apparent from the following detailed description.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a synthesis of metal sulfide powders by reaction of an organometallic compound in solution with hydrogen sulfide (H2 S) at temperatures from about -78° C. to about 100° C. Organometallio reagents are particularly suitable for the low temperature preparation of metal sulfide powders which are desired as precursors to 8-12 micrometer infrared-transmitting ceramics.
The use of organometallic reagents in the low temperature synthesis of ceramic powders offers many advantages over conventional preparations. Organometallic reagents can be obtained in high purity and can be mixed at a molecular level while in solution. Bimetallic complexes may also be useful for making ternary materials. Additionally, the low temperatures possible with organometallic oompounds in solution are a factor in promoting small and uniformly sized particles which are suitable for processing under mild conditions into fine-grained ceramics.
Metal sulfide powders have been prepared by reacting H2 S with dimethylzinc, di(tertiary-butyl)zinc, triethylaluminum, trimethylaluminum, diethylmagnesium, and bis(trimethylsilylmethyl)cadmium. Other reagents besides metal alkyl compounds may be useful, such as metal alkoxides, thioalkoxides and hydrides.
The reaction of organometallic compounds in solution with hydrogen sulfide produces a fine precipitate immediately upon mixing. The major impurity in the resulting metal sulfide powder is residual hydrocarbon which reduces the transparency of optical ceramic materials upon densification.
Residual hydrocarbon usually results from incomplete reaction of the organometallic reagent or from residual organic solvent. The amount of residual hydrocarbon due to unreacted zinc-alkyl groups parallels the order of stability of the zinc-alkyl compounds. For example, dimethylzinc is more stable than diethylzinc, which in turn, is more stable than di(t-butyl)zinc. Zinc sulfide powders made from dimethyl zinc contain more unreacted metal alkyl reagent and, consequently, more residual hydrocarbon than powders made from diethylzinc or di(t-butyl)zinc.
Additionally, certain solvents such as diethyl ether are difficult to completely separate from the metal sulfide powders and may also significantly increase the amount of residual hydrocarbon. Solvents which are easily separated from the metal sulfide powders include toluene and heptane.
The method of adding reagents significantly affects the purity of the resulting metal sulfide powder. A H2 S purge of an organometallic compound in solution results in significantly higher levels of residual hydrocarbon than procedures involving the addition of an organometallic reagent in solution to an organic solvent that is saturated with H2 S. For example, the H2 S purge of a diethylzinc/heptane solution at 25° C. resulted in a residual zinc-ethyl group level of 30,000 ethane/mole zinc) as measured by acid hydrolysis in which the liberated hydrocarbon is measured using gas chromatography. In contrast, adding a diethylzinc/toluene solution to toluene saturated with H2 S at -20° C. resulted in a residual zinc-ethyl group level of about 10 ppm.
Temperature is also important in preparing small, uniform particles. ln the range of temperatures used for the reaction, low temperatures result in smaller particle sizes. One possible explanation may be a larger number of nucleation sites at lower temperature, due to slower diffusion of reactants. Additionally, low temperatures increase the solubility of H2 S in the organic solvent. As a result, increased amounts of H2 S in the solvent are believed to cause more complete reaction of the organometallic reagents leading to less unreacted organometallic compounds. Zinc sulfide has been formed according to the present invention at temperatures ranging from -78° C. to 100° C. Temperatures from -78° C. to about -100° C. may also be favorable for the reaction. Temperatures in the range from -78° C. to about -20° C. have been found to give the best results. At temperatures near the boiling point of H2 S, a 1 Molar solution of H2 S in the organic solvent is preferred.
The rate at which the organometallic compound in solution is added to the H2 S-saturated solvent affects the level of organic residue in the metal sulfide powder. A dilute solution of the organometallic compound added at a constant rate from about 0.01 moles/hour to about 1 mole hour has been found to be suitable for a reaction on the 0.1 mole scale. The preferred rate of addition is about 0.1 mole/hour for a reaction on the 0.1 mole scale. lt is also important to maintain H2 S saturation of the organic solvent during addition of the organometallic compound. This is accomplished by bubbling H2 S through the organic solvent at a rate slightly greater than the rate which the organometallic compound is added.
The following example is given to illustrate but not limit the invention:
EXAMPLE Synthesis of ZnS
Diethylzinc was distilled and stored in a helium-filled glovebox. Toluene and pentane were distilled from sodium and stored under argon. H2 S was used as received.
Approximately 15.2 g (0.123 mole) of diethyl zinc was added to a dry flask under an argon atmosphere. About 90 ml of toluene was added to a reaction vessel which was then cooled and maintained at a temperature of -20° C. to -25° C. The toluene in the reaction vessel was saturated with H2 S by bubbling the gas through the solvent.
The diethylzinc was diluted to 1 mole per liter with 110 mL of toluene and stirred briefly to ensure homogeneity. With rapid H2 S flow through the H2 S-saturated solvent and rapid stirring with a magnetic stirbar in the reaction vessel, the diethylzinc solution was added to the toluene solution via a 22 gauge cannula over a period of about 1 hour. After the addition of the diethylzinc, the H2 S flow was continued for 1 minute. The reaction vessel was allowed to warm to room temperature and the excess H2 S was allowed to escape.
The zinc sulfide powder was collected by filtration under an argon atmosphere and washed with two 30 mL portions of toluene and three 20 mL portions of pentane. The solid was pumped dry for 20 minutes and then transferred to a glovebox. The solid was dried under a vacuum of less than 0.01 torr at 25° C. for one hour then heated and maintained at 100° C. for 24 hours.
Electron micrographs of the solid show spherical particles with diameters ranging from 20 to 100 nanometers. Acid hydrolysis of the solid shows a level of zinc-ethyl group impurity of approximately 10 ppm.
Modifications and variations of the present invention are possible. lt should be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Claims (10)

What is claimed is:
1. A low temperature method of producing metal sulfide powders with small, uniform size and a large surface area by reaction between an organometallic compound and hydrogen sulfide comprising the steps of:
saturating an organic solvent with H2 S;
adding a solution of an organometallic compound and organic solvent to said H2 S saturated solution;
maintaining H2 S saturation of said reaction mixture by adding H2 S at a greater rate than the organometallic compound;
recovering a pure, finely divided powder; and
drying said powder by heating while under a vacuum.
2. The method of claim 1 wherein said organometallic compound is selected from the group consisting of triethylaluminum, trimethylaluminum, diethylmagnesium, and bis(trimethlsilylmethyl) cadmium.
3. The method of claim 1 wherein said organic solvent is selected from the group consisting of toluene and heptane.
4. The method of claim 1 wherein said saturated solution of an organic solvent and H2 S is maintained at a temperature within the range from about 100° C. to about -40° C.
5. The method of claim 1 wherein said solution of an organic solvent and H2 S is maintained at a temperature within the range from about -40° C. to about -100° C. and at a H2 S concentration of about 1 mole per liter.
6. The method of claim 1 wherein said organometallic compound is added to said H2 S saturated solution at a rate within the range from about 0.01 moles/hour to about 1 mole/hour for a reaction on the 0.1 mole scale.
7. The method of claim 1 wherein said finely divided powder is recovered by filtration and washing.
8. The method of claim 1 wherein said powder is dried by heating under a vacuum of less than 0.01 torr to 100° C. for about 24 hours.
9. A low temperature method of producing zinc sulfide particles with diameters of about 20 to 100 nanometers and a large surface area by reaction between diethyl zinc and hydrogen sulfide comprising the following steps:
maintaining a solution of toluene and H2 S at a temperature within the range from about 100° C. to about -40° C.;
saturating said solution of toluene with H2 S;
adding a solution of diethyl zinc and toluene to said H2 S saturated toluene solution at a rate within the range from about 0.01 moles/hour to about 1 mole/hour for a reaction on the 0.1 mole scale;
maintaining H2 S saturation of said reaction mixture by adding H2 S at a greater rate than diethyl zinc;
recovering a pure, finely divided powder; and
drying said powder by heating while under a vacuum of less than 0.01 torr.
10. The method of claim 9 wherein said solution of an organic solvent and H2 S is maintained at a temperature within the range from about -40° C. to about -100° C. and at a H2 S concentration of about 1 mole per liter.
US07/042,089 1987-04-13 1987-04-13 Low temperature synthesis of metal sulfides Abandoned USH429H (en)

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6337062B1 (en) * 1999-02-25 2002-01-08 Idemitsu Petrochemical Co., Ltd. Method for the production of anhydrous alkali metal sulfide and alkali metal sulfide solution
US6692660B2 (en) 2001-04-26 2004-02-17 Nanogram Corporation High luminescence phosphor particles and related particle compositions
US20040115123A1 (en) * 2001-03-07 2004-06-17 Yingyan Zhou Process for producing nanometer grade powders
US20060132020A1 (en) * 1997-10-31 2006-06-22 Nanogram Corporation Phosphors
US7423512B1 (en) 1997-10-31 2008-09-09 Nanogram Corporation Zinc oxide particles
US7507382B2 (en) 1999-03-10 2009-03-24 Nanogram Corporation Multiple reactant nozzles for a flowing reactor
US20100044636A1 (en) * 2006-11-21 2010-02-25 Dorai Ramprasad Semiconductor nanocrystals and compositions and devices including same
US20100044635A1 (en) * 2006-11-21 2010-02-25 Craig Breen Blue emitting semiconductor nanocrystals and compositions and devices including same
US20100051870A1 (en) * 2006-11-21 2010-03-04 Dorai Ramprasad Semiconductor nanocrytals and compositions and devices including same

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Manasevit, H. M.; Simpson, W. I., The Use of Metal-Organic in the Preparation of Semiconductor Materials, Solid State Science, vol. 118, pp. 644-647--Apr. 1971.
Yamamoto, T.; Taniguchi, A. AnS Doped by Electron Donating Organic Ligant =bpy, phen, py) and Control of Semiconducting Properties of ZnS by the Ligand Inorg. Chem. Acta, vol. 97, pp. 111-113-1985.

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060132020A1 (en) * 1997-10-31 2006-06-22 Nanogram Corporation Phosphors
US7132783B1 (en) 1997-10-31 2006-11-07 Nanogram Corporation Phosphor particles having specific distribution of average diameters
US7423512B1 (en) 1997-10-31 2008-09-09 Nanogram Corporation Zinc oxide particles
US6337062B1 (en) * 1999-02-25 2002-01-08 Idemitsu Petrochemical Co., Ltd. Method for the production of anhydrous alkali metal sulfide and alkali metal sulfide solution
US7507382B2 (en) 1999-03-10 2009-03-24 Nanogram Corporation Multiple reactant nozzles for a flowing reactor
US20040115123A1 (en) * 2001-03-07 2004-06-17 Yingyan Zhou Process for producing nanometer grade powders
US7211230B2 (en) * 2001-03-07 2007-05-01 Anshan University Of Science And Technology Process for producing nanometer grade powders
US6692660B2 (en) 2001-04-26 2004-02-17 Nanogram Corporation High luminescence phosphor particles and related particle compositions
US20040173780A1 (en) * 2001-04-26 2004-09-09 Nanogram Corporation High luminescence phosphor particles and methods for producing the particles
US7101520B2 (en) 2001-04-26 2006-09-05 Nanogram Corporation High luminescence phosphor particles and methods for producing the particles
US20100044636A1 (en) * 2006-11-21 2010-02-25 Dorai Ramprasad Semiconductor nanocrystals and compositions and devices including same
US20100044635A1 (en) * 2006-11-21 2010-02-25 Craig Breen Blue emitting semiconductor nanocrystals and compositions and devices including same
US20100051870A1 (en) * 2006-11-21 2010-03-04 Dorai Ramprasad Semiconductor nanocrytals and compositions and devices including same
US8377333B2 (en) 2006-11-21 2013-02-19 Qd Vision, Inc. Semiconductor nanocrystals and compositions and devices including same
US8404154B2 (en) 2006-11-21 2013-03-26 Qd Vision, Inc. Blue emitting semiconductor nanocrystals and compositions and devices including same
US8691114B2 (en) 2006-11-21 2014-04-08 Qd Vision, Inc. Semiconductor nanocrystals and compositions and devices including same
US8906265B2 (en) 2006-11-21 2014-12-09 Qd Vision, Inc. Blue emitting semiconductor nanocrystals and compositions and devices including same
US8980133B2 (en) 2006-11-21 2015-03-17 Qd Vision, Inc. Semiconductor nanocrystals and compositions and devices including same
US9444008B2 (en) 2006-11-21 2016-09-13 Qd Vision, Inc. Semiconductor nanocrystals and compositions and devices including same
US9534172B2 (en) 2006-11-21 2017-01-03 Qd Vision, Inc. Blue emitting semiconductor nanocrystals and compositions and devices including same
US9882083B2 (en) 2006-11-21 2018-01-30 Samsung Electronics Co., Ltd. Semiconductor nanocrystals and compositions and devices including same

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