Indian Patents. 237904:A PROCESS FOR THE SYNTHESIS OF IN SITU CAPPED NANOCRYSTALLINE γ-FE2O3

Title of Invention	A PROCESS FOR THE SYNTHESIS OF IN SITU CAPPED NANOCRYSTALLINE γ-FE2O3
Abstract	A process for the preparation of capped nanocrystalline γ-Fe2O3, comprising preparing a solution of a salt of iron in an organic diol, raising the temperature to 130 to 220°C to remove vapours, followed by refluxing and cooling to precipitate the γ-Fe2O3.

Full Text	FIELD OF THE INVENTION This invention relates to a process for the synthesis of capped nanocry stalling ?-Fe2O3. This invention further relates to a one-stop synthesis of in-situ capped n an ocrystalline ?-Fe2O3. BACKGROUND OF THE INVENTION Nanocrystalline ?-Fe2O3 ts a very in pernant commercial material due to its application, both in technology and biological fields The acicular shaped ?-Fe2O3 nanoparticles are used in magnetic storage devices such as, audiotapes, magnetic tickets and floppy disks, etc.. The encapsulation of these magnetic materials in biological or synthetic polymer matrices makes it useful as bioprocessors. The capping of the nano materials makes it soluble in organic solvents and suitable for use in ferrofluids. The commercial method of preparation of ?-Fe2O3 is a multistep process, which starts with the precritation of FeOOH particles from the aqueous Fee+ solution. This is followed by dehydration to form a- Fe-O3, which is then reduced at clevated temperatures to Fe3O4 Finally, the ?-Fe2O3 nano particles are formed by controlled oxidation of Fe3O4. The particle size distribution of the commercially synthesized nano ?-Fe2O3 is very large and due to the absence of any capping agent, these particles always have a tendency to agglomerate and reduce the surface energy. In recent past, some methods have been developed to form capped nanocrystalline ?-Fe2O3 with narrow particle size distribution. One of the methods is decomposition of iron cunferron complex by injecting it into a surfactant solution at high temperature temperature, In. another method, first Fe(CO)5 is decomposed in a surfactant solution to form Fe nano particles, followed by oxidation by a mild oxidizing agent to form ?-Fe2O3. OBJECTS OF THE INVENTION It is therefore an object of this invention to propose a process for the synthesis of capped nanocrystalline ?-Fe2O3 which is a one-pot process. It is a further object of this invention to propose a process for the synthesis of capped nanocrystallin. ?-Fe2O3 which does not require sophisticated reaction conditions Another object of this invention to respose a process for the synthesis of capped nano crystalline ?-Fe2O3 inch bads to Fe2O3with a narrow particle size distribution. These and other objects of the invention will be apparent from the ensuing description. At the outset of the description which follows, it is to be understood that the ensuing description only illustrates a particular form of this invention. However, such a particular form is only an exemplary embodiment and the teachings of the invention is not intended to be taken restrictive!}'. BRIEF DESCRIPTION OF THE INVENTION Thus according to this invention is provided a process for the synthesis of capped nanocrystalline ?-Fe2O3 In accordance with this invention is provided a process for the synthesis of capped nanocrystalline ?-Fe2O3 comprising preparing a solution of a salt of iron in an organic diol and slowly raising the temperature to 130-220°C followed by removal of all nitrous fumes and water vapour The solution is then refluxed for a predetermined period of time followed by cooling to room temperature and precipitation of the nanocrystalline ?-Fe2O3 by an alcohol. The organic diol used may be selected from 1,4 butanediol and 1,5- pentanediol. The invention will now be explained in greater detail with the help of the following non -limiting example. EXAMPLE To prepare nanocrystalline ?-Fe2O3, Fe(No2)3 9H2O was dissolved in of 1,4 butane diol and temperature was slowly raised to 130 °C. For the complete removal of nitrous fumes and water vapor, the solution was kept for 1 hr at this temperature Earn the solution was refluxed for Thr and cooled to room temperature followed by methanol addition and separation oi the precrutate Similar preparation methods were carried out with other diols va ying the temperature from 130 °C to 220 °C. The ?-Fe2O3 so formed is characterised and the results of characterisation of the in-situ cappebel ?-Fe2O3 are shown in the figures of the accompanying drawings Fig.la shows an XRD analysis of prepared iron oxide; Fig. 1b shows a TEM image of the ?-Fe2O3 particles; Fig Ic shows the particle size distribution; Fig. Id shows the TG curve of the as prepared sample; and Fig. Le shows the FT1R spectra of the as prepared sample (a) and the sintered samples This is a one-pot synthetic process does not require controlled atmosphere and can be performed under ambient atmosphere The ?- Fe2O3 so formed is in-situ capped with the dioi moiety and no other surfactant is needed for capping, the ?-Fe2O3 has a narrow particle size distribution. WE CLAIM: 1. A process for the preparation of capped nanocrystalline ?-Fe2O3, comprising preparing a solution of a salt of iron in an organic diol, raising the temperature to 130 to 220°C to remove vapours, followed by refluxing and cooling to precipitate the ?-Fe2O3. 2. The process as claimed in claim 1, wherein said ?-Fe2O3 is precipitated by cooling the solution and adding alcohol. 3. The process as claimed in claim 1, wherein said organic diol used is 1,4-butanediol or 1,5-pentanediol. 4. Nanocrystalline ?-Fe2O3 capped with a diol, selected from 1,4-butanediol or 1,5-pentanediol. A process for the preparation of capped nanocrystalline γ-Fe2O3, comprising preparing a solution of a salt of iron in an organic diol, raising the temperature to 130 to 220°C to remove vapours, followed by refluxing and cooling to precipitate the γ-Fe2O3.

Full Text

FIELD OF THE INVENTION
This invention relates to a process for the synthesis of capped
nanocry stalling ?-Fe2O3.
This invention further relates to a one-stop synthesis of in-situ capped
n an ocrystalline ?-Fe2O3.
BACKGROUND OF THE INVENTION
Nanocrystalline ?-Fe2O3 ts a very in pernant commercial material due
to its application, both in technology and biological fields The
acicular shaped ?-Fe2O3 nanoparticles are used in magnetic storage
devices such as, audiotapes, magnetic tickets and floppy disks, etc..
The encapsulation of these magnetic materials in biological or
synthetic polymer matrices makes it useful as bioprocessors. The
capping of the nano materials makes it soluble in organic solvents and
suitable for use in ferrofluids.
The commercial method of preparation of ?-Fe2O3 is a multistep
process, which starts with the precritation of FeOOH particles from
the aqueous Fee+ solution. This is followed by dehydration to form a-
Fe-O3, which is then reduced at clevated temperatures to Fe3O4
Finally, the ?-Fe2O3 nano particles are formed by controlled oxidation
of Fe3O4. The particle size distribution of the commercially
synthesized nano ?-Fe2O3 is very large and due to the absence of any
capping agent, these particles always have a tendency to agglomerate
and reduce the surface energy.
In recent past, some methods have been developed to form capped
nanocrystalline ?-Fe2O3 with narrow particle size distribution. One of
the methods is decomposition of iron cunferron complex by injecting
it into a surfactant solution at high temperature temperature, In.
another method, first Fe(CO)5 is decomposed in a surfactant solution
to form Fe nano particles, followed by oxidation by a mild oxidizing
agent to form ?-Fe2O3.
OBJECTS OF THE INVENTION
It is therefore an object of this invention to propose a process for the
synthesis of capped nanocrystalline ?-Fe2O3 which is a one-pot
process.
It is a further object of this invention to propose a process for the
synthesis of capped nanocrystallin. ?-Fe2O3 which does not require
sophisticated reaction conditions
Another object of this invention to respose a process for the synthesis
of capped nano crystalline ?-Fe2O3 inch bads to Fe2O3with a narrow
particle size distribution.
These and other objects of the invention will be apparent from the
ensuing description.
At the outset of the description which follows, it is to be understood
that the ensuing description only illustrates a particular form of this
invention. However, such a particular form is only an exemplary
embodiment and the teachings of the invention is not intended to be
taken restrictive!}'.
BRIEF DESCRIPTION OF THE INVENTION
Thus according to this invention is provided a process for the
synthesis of capped nanocrystalline ?-Fe2O3
In accordance with this invention is provided a process for the
synthesis of capped nanocrystalline ?-Fe2O3 comprising preparing a
solution of a salt of iron in an organic diol and slowly raising the
temperature to 130-220°C followed by removal of all nitrous fumes
and water vapour The solution is then refluxed for a predetermined
period of time followed by cooling to room temperature and
precipitation of the nanocrystalline ?-Fe2O3 by an alcohol.
The organic diol used may be selected from 1,4 butanediol and 1,5-
pentanediol.
The invention will now be explained in greater detail with the help of
the following non -limiting example.
EXAMPLE
To prepare nanocrystalline ?-Fe2O3, Fe(No2)3 9H2O was dissolved in
of 1,4 butane diol and temperature was slowly raised to 130 °C. For
the complete removal of nitrous fumes and water vapor, the solution
was kept for 1 hr at this temperature Earn the solution was refluxed
for Thr and cooled to room temperature followed by methanol
addition and separation oi the precrutate Similar preparation methods
were carried out with other diols va ying the temperature from 130 °C
to 220 °C.
The ?-Fe2O3 so formed is characterised and the results of
characterisation of the in-situ cappebel ?-Fe2O3 are shown in the figures
of the accompanying drawings
Fig.la shows an XRD analysis of prepared iron oxide;
Fig. 1b shows a TEM image of the ?-Fe2O3 particles;
Fig Ic shows the particle size distribution;
Fig. Id shows the TG curve of the as prepared sample; and
Fig. Le shows the FT1R spectra of the as prepared sample (a) and the
sintered samples
This is a one-pot synthetic process does not require controlled
atmosphere and can be performed under ambient atmosphere The ?-
Fe2O3 so formed is in-situ capped with the dioi moiety and no other
surfactant is needed for capping, the ?-Fe2O3 has a narrow particle
size distribution.
WE CLAIM:
1. A process for the preparation of capped nanocrystalline ?-Fe2O3,
comprising preparing a solution of a salt of iron in an organic diol,
raising the temperature to 130 to 220°C to remove vapours, followed
by refluxing and cooling to precipitate the ?-Fe2O3.
2. The process as claimed in claim 1, wherein said ?-Fe2O3 is
precipitated by cooling the solution and adding alcohol.
3. The process as claimed in claim 1, wherein said organic diol used is
1,4-butanediol or 1,5-pentanediol.
4. Nanocrystalline ?-Fe2O3 capped with a diol, selected from 1,4-butanediol or 1,5-pentanediol.

A process for the preparation of capped nanocrystalline γ-Fe2O3, comprising preparing a solution of a salt of iron in an organic diol, raising the temperature to 130 to 220°C to remove vapours, followed by refluxing and cooling to precipitate the γ-Fe2O3.

Documents:

320-kol-2003-abstract.pdf

320-kol-2003-claims.pdf

320-kol-2003-correspondence.pdf

320-kol-2003-description (complete).pdf

320-kol-2003-examination report.pdf

320-kol-2003-form 1.pdf

320-kol-2003-form 13.pdf

320-kol-2003-form 18.pdf

320-kol-2003-form 2.pdf

320-kol-2003-form 3.pdf

320-kol-2003-form 4.pdf

320-kol-2003-form 5.pdf

320-kol-2003-gpa.pdf

320-kol-2003-reply to examination report.pdf

320-kol-2003-specification.pdf

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Patent Number

237904

Indian Patent Application Number

320/KOL/2003

PG Journal Number

03/2010

Publication Date

15-Jan-2010

Grant Date

12-Jan-2010

Date of Filing

05-Jun-2003

Name of Patentee

INDIAN INSTITUTE OF TECHNOLOGY

Applicant Address

KHARAGPUR

Inventors:

#	Inventor's Name	Inventor's Address
1	VARADWAJ K. S.K.	INSTITUTE OF TECHNOLOGY, DEPARTMENT OF CHEMISTRY, KHARAGPUR 721302
2	GHOSE JAYASREE	INSTITUTE OF TECHNOLOGY, DEPARTMENT OF CHEMISTRY, KHARAGPUR 721302

PCT International Classification Number

C30B 28/04

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA