# US 11,078,415 B2 · Lanthanum based upconverting microrods and application thereof

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- Number: US 11,078,415 B2
- Document ID: US11078415B2
- Status: Granted
- Kind: B2
- Application number: 16/072,104
- Filed: 2017-01-20
- Published: 2019-02-07
- Granted: 2021-08-03
- Earliest claimed: 2016-01-22
- Assignees: Council of Scientific and Industrial Research
- Applicants: Council of Scientific and Industrial Research
- Inventors: Jayaraj Nithyanandhan; Kadhiravan Shanmuganathan; Alagumalai Ananthan
- Web page: https://patentgrep.com/patent/US11078415B2

## CPC

- C09K 11/7773: {with alkali or alkaline earth metal}
- C01F 17/36: halogen being the only anion, e.g. NaYF4
- C09K 11/025: {non-luminescent particle coatings or suspension media}
- B82Y 15/00: Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
- B82Y 20/00: Nanooptics, e.g. quantum optics or photonic crystals
- B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites
- B82Y 40/00: Manufacture or treatment of nanostructures
- C01P 2002/72: by d-values or two theta-values, e.g. as X-ray diagram
- C01P 2004/04: obtained by TEM, STEM, STM or AFM
- C01P 2004/16: Nanowires or nanorods, i.e. solid nanofibres with two nearly equal dimensions between 1-100 nanometer
- C01P 2004/54: Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension
- C01P 2004/62: Submicrometer sized, i.e. from 0.1-1 micrometer
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C01F: COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; sulfides or polysulfides of magnesium, calcium, strontium, or barium C01B17/42; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds other than ammonia or cyanogen containing nitrogen and non-metals and optionally metals C01B21/082; amides or imides of silicon C01B21/087}; metal {imides or} amides C01B21/092, {C01B21/0923}; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanic acid C01C3/14; salts of cyanamide C01C3/16; thiocyanates C01C3/20; {double sulfates of magnesium with sodium or potassium C01D5/12; with other alkali metals C01D15/00, C01D17/00})
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## Abstract

The present invention provides a monodispersed lanthanum based upconverting microrods comprising β-NaYF4:Yb3+, Er3+ and β-NaYF4:Yb3+, Tm3+, capped with oleic acid. The upconverting microrods, embedded in polymer matrices is used for making security tags and for sensing application. The process of preparation of the oleic acid capped upconverting microrods is also disclosed.

## Claims

### Claim 1

A monodispersed lanthanum based upconverting microrods selected from β-NaYF4:Yb3+, Er3+ and β-NaYF4:Yb3+, Tm3+, capped with an organic ligand consisting of oleic acid, for making security tags and for sensing applications,
wherein the β-NaYF4:Yb3+, Er3+ comprises β-NaYF4:Yb3+ and Er3+ but not Gd3+ and has an aspect ratio in the range of 6 to 12, or wherein the β-NaYF4:Yb3+, Tm′ comprises β-NaYF4:Yb3+ and Tm3+ but not Gd3+ and has an aspect ratio in the range of 3 to 7, and
wherein the microrods selected from β-NaYF4:Yb3+, Er3+ and β-NaYF4:Yb3+, Tm3+ have a length of 120.257 nm and 418.1457 nm respectively, and a width of 12.5412 nm and 83.9962 nm respectively.

### Claim 2

A process for the preparation of monodispersed lanthanum based upconverting microrods selected from β-NaYF4:Yb3+, Er3+ and β-NaYF4:Yb3+, Tm3+, capped with an organic ligand consisting of oleic acid, for making security tags and for sensing applications, where the β-NaYF4:Yb3+, Er3+ comprises β-NaYF4:Yb3+ and Er3+ but not Gd3+ and has an aspect ratio in the range of 6 to 12, or wherein the β-NaYF4:Yb3+, Tm3+ comprises β-NaYF4:Yb3+ and Tm3+ but not Gd3+ and has an aspect ratio in the range of 3 to 7 the process comprising the steps of:
a. mixing oleic acid, sodium hydroxide, absolute ethanol and water;
b. adding a solution containing a mixture of lanthanum compounds and sodium fluoride to a reaction mixture of step (a);
c. refluxing the reaction mixture of step (b) for a period in the range of 4 to 6 hrs at a temperature in the range of 160 to 180° C. and allowed to cool at room temperature; and
d. heating the reaction mixture of step (c) for a period in the range of 50 to 60 hrs at a temperature in the range of 180 to 195° C., under nitrogen atmosphere, followed by drying to afford the oleate-capped lanthanum based upconverting microrods.

### Claim 3 (depends on 2)

The process as claimed in claim 2, wherein the mixture of the lanthanum compounds of step (b) contains Yttrium(III) chloride hexahydrate (YCl3.6H2O), Ytterbium(III) Chloride Hexahydrate (YbCl3.6H2O) and Erbium(III) chloride hexahydrate (ErCl3.6H2O).

### Claim 4 (depends on 2)

The process as claimed in claim 2, wherein the oleate-capped lanthanum based upconverting microrods are embedded in polymer matrices for making security tags that respond to different wavelengths and for sensing applications.

### Claim 5 (depends on 4)

The process as claimed in claim 4, wherein the polymer matrices are selected from polydimethylsiloxane (PDMS), Ethylene propylene diene monomer (EPDM), Polyethylene oxide (PEO), Polystyrene (PS) and a natural silk scaffold.