# US 9,518,219 B2 · Hydrothermal synthesis of bismuth germanium oxide

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- Number: US 9,518,219 B2
- Document ID: US9518219B2
- Status: Granted
- Kind: B2
- Application number: 14/168,543
- Filed: 2014-01-30
- Published: 2015-07-30
- Granted: 2016-12-13
- Earliest claimed: 2014-01-30
- Assignees: Sandia Corporation
- Applicants: Sandia Corporation
- Inventors: Timothy J. Boyle
- Web page: https://patentgrep.com/patent/US9518219B2

## CPC

- C09K 11/7707: {Germanates}
- C01G 29/00: Compounds of bismuth
- G21K 4/00: Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens (photographic processes using X-ray intensifiers G03C5/17; discharge tubes comprising luminescent screens H01J1/62; cathode ray tubes for X-ray conversion with optical output H01J31/50)
- C01P 2002/54: one element only
- C01P 2002/72: by d-values or two theta-values, e.g. as X-ray diagram
- C01P 2002/77: by unit-cell parameters, atom positions or structure diagrams
- C01P 2002/88: by thermal analysis data, e.g. TGA, DTA, DSC
- C01P 2004/02: obtained by optical microscopy
- C01P 2004/03: obtained by SEM
- C01P 2004/20: extending in two dimensions, e.g. plate-like
- C01P 2004/42: (bi)pyramid-like
- C01P 2004/61: Micrometer sized, i.e. from 1-100 micrometer
- C01P 2006/60: Optical properties, e.g. expressed in CIELAB-values
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C01G: COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts or peroxyacids C01B15/00; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium, or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds containing nitrogen, other non-metals and metal C01B21/082}; metal amides C01B21/092; 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 cyanamide C01C3/16; thiocyanates C01C3/20)
- G21K: HANDLING OF PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## Abstract

A method for the hydrothermal synthesis of bismuth germanium oxide comprises dissolving a bismuth precursor (e.g., bismuth nitrate pentahydrate) and a germanium precursor (e.g., germanium dioxide) in water and heating the aqueous solution to an elevated reaction temperature for a length of time sufficient to produce the eulytite phase of bismuth germanium oxide (E-BGO) with high yield. The E-BGO produced can be used as a scintillator material. For example, the air stability and radioluminescence response suggest that the E-BGO can be employed for medical applications.

## Claims

### Claim 1

A method for the hydrothermal synthesis of bismuth germanium oxide, comprising;
dissolving a bismuth precursor and a germanium precursor in water to provide an aqueous solution, and
heating the aqueous solution in a sealed digestion bomb to a reaction temperature in the range of 150 to 200° C. for a length of time sufficient to produce an eulytite phase of bismuth germanium oxide.

### Claim 2 (depends on 1)

The method of claim 1, wherein the bismuth precursor comprises bismuth nitrate or bismuth acetate.

### Claim 3 (depends on 2)

The method of claim 2, wherein the bismuth nitrate comprises bismuth nitrate pentahydrate.

### Claim 4 (depends on 1)

The method of claim 1, wherein the germanium precursor comprises germanium dioxide.

### Claim 5 (depends on 1)

The method of claim 1, wherein an amount of germanium precursor in excess of the stoichiometric amount is dissolved in the aqueous solution.

### Claim 6 (depends on 5)

The method of claim 5, wherein the excess germanium precursor is removed from the bismuth germanium oxide produced by washing with water or by thermal treatment.

### Claim 7 (depends on 1)

The method of claim 1, wherein the reaction temperature is about 185° C.

### Claim 8 (depends on 7)

The method of claim 7, wherein the aqueous solution is heated to about 185° C. for a length of time greater than 12 hours.

### Claim 9 (depends on 1)

The method of claim 1, wherein the eulytite phase of bismuth germanium oxide is produced with a yield of greater than about 80%.

### Claim 10 (depends on 1)

The method of claim 1, further comprising thermal processing the bismuth germanium oxide produced to a temperature greater than 200° C. to remove trace impurities.

### Claim 11 (depends on 3)

The method of claim 3, wherein the concentration of bismuth nitrate pentahydrate in the aqueous solution is between 0.1 and 0.6 molar.

### Claim 12 (depends on 4)

The method of claim 4, wherein the concentration of germanium dioxide in the aqueous solution is between 0.1 and 0.5 molar.

### Claim 13 (depends on 1)

The method of claim 1, further comprising dissolving a dopant in the aqueous solution to shift the optical emission of the bismuth germanium oxide produced.

### Claim 14 (depends on 13)

The method of claim 13, wherein the dopant comprises a lanthanide dopant.

### Claim 15 (depends on 14)

The method of claim 14, wherein the lanthanide dopant comprises Er3+.