Resumen
Germanium crystal The present invention provides α -germanium crystals of laminar morphology wherein said crystal comprises one or more germanium nanollamines stacked together, as well as two methods of obtaining said crystals. The invention also provides the powder comprising the a-germanium crystals of the invention, dispersions comprising the a-germanium crystal of the invention or the powder of the invention, as well as the ink comprising said dispersions. (Machine-translation by Google Translate, not legally binding)
Reivindicaciones
1. An α-germanium crystal with lamellar morphology, wherein said crystal comprises one or more α-germanium nanosheets stacked on top of one another, and wherein said crystal exhibits a thickness comprised between 0.56 nm and 100 nm and lateral dimensions comprised between 0.1 µm x 0.1 µm and 10 µm x 10 µm. 2. The α-germanium crystal according to claim 1, exhibiting lateral dimensions comprised between 0.1 µm x 0.1 µm and 5 µm x 5 µm. 3. The α-germanium crystal according to any of claims 1 or 2, wherein said crystal comprises 2 to 150 nanosheets of α-germanium stacked on top of one another. 4. The α-germanium crystal according to any of claims 1 to 3, wherein the thickness of the crystal is comprised between 2 and 20 nm. 5. Method of preparing the α-germanium crystal as defined in any of claims 1 to 4, wherein said method comprises grinding polycrystalline α-germanium at a rotating speed comprised between 1000 and 3000 rpm, in the presence of: - at least one alcohol, wherein said alcohol is a linear, branched, or cyclic chain alcohol and has a number of carbons comprised between 3 and 5 atoms; or - a mixture comprising at least one alcohol and water, wherein said alcohol of the mixture is a linear, branched, or cyclic chain alcohol and has a number of carbons comprised between 3 and 5 atoms, and wherein the content of said alcohol in said mixture is comprised between 60% and 99% by volume. 6. Method according to claim 5, which further comprises dispersing the obtained α-germanium crystal in water, organic solvents, or in a mixture of water and organic solvents, and centrifuging said dispersion. 7. Method of preparing the α-germanium crystal as defined in any of claims 1 to 4, which method comprises: a) preparing a dispersion of polycrystalline α-germanium in: - at least one alcohol, wherein said alcohol is a linear, branched, or cyclic chain alcohol and has a number of carbons comprised between 3 and 5 atoms; or - a mixture comprising at least one alcohol and water, wherein said alcohol of the mixture is a linear, branched, or cyclic chain alcohol and has a number of carbons comprised between 3 and 5 atoms, and wherein the content of said alcohol in said mixture is comprised between 60% and 99% by volume, b) sonicating and centrifuging the dispersion obtained in a), wherein the centrifugation speed is comprised between 500 rpm and 3000 rpm, and c) separating the supernatant to obtain the α-germanium crystal as defined in claims 1 to 4. 8. Method according to any of claims 5 to 7, which method further comprises a step of vacuum-drying the obtained α-germanium crystal. 9. Method according to any of claims 5 to 8, wherein the alcohol is selected from isopropyl, 2-propanol, n-butanol, n-pentanol alcohol and mixtures thereof. 10. Method according to any of claims 5 to 9, wherein the alcohol content in the mixture of alcohol and water is 80% by volume. 11. Powder comprising the α-germanium crystal as defined in any of claims 1 to 4. 12. Electronic device comprising the α-germanium crystal as defined in any of claims 1 to 4 or the powder according to claim 11. 13. Dispersion comprising the α-germanium crystal as defined in any of claims 1 to 4 or the powder as defined in claim 11 dispersed in water, organic solvents, or in a mixture of water and organic solvents. 14. Ink comprising the dispersion as defined in claim 13. 15. Method of application of the dispersion as defined in claim 13 or of the ink as defined in claim 14, comprising the application of the dispersion or of the ink by means of screen-printing, drop-casting, spraying, or spin-coating.
