1. A process for the synthesis of a calcium phosphate-based material comprising gadolinium and silicon, the process comprising: providing calcium or a calcium-containing compound, a gadolinium-containing compound, a phosphorus-containing compound and a silicon-containing compound; and forming a precipitate by reacting the compounds in an aqueous phase at an alkali pH; thereby synthesizing a calcium phosphate-based material comprising gadolinium, wherein at least some of the gadolinium is in the form of Gd3+ ions substituted in the calcium phosphate lattice, and wherein the material comprises a compound having the general chemical formula: Ca10−yGdy(PO4)6−x(SiO4)x(OH)2−x+y wherein 0.5
Claim: 2. The process of claim 1, wherein the calcium-containing compound comprises a calcium salt.
Claim: 3. The process of claim 2, wherein the calcium salt is selected from one or more of calcium hydroxide, calcium chloride, calcium nitrate and/or calcium nitrate hydrate.
Claim: 4. The process of claim 1, wherein the gadolinium-containing compound is selected from one or both of gadolinium chloride and/or gadolinium nitrate.
Claim: 5. The process of claim 1, wherein the phosphorus-containing compound is selected from one or both of a phosphate salt and/or a phosphoric acid.
Claim: 6. The process of claim 5, wherein the phosphorus-containing compound is selected from one or both of ammonium phosphate and/or phosphoric acid.
Claim: 7. The process of claim 1, wherein the silicon-containing compound comprises a silicate.
Claim: 8. The process of claim 7, wherein the silicate is selected from one or both of tetraethyl orthosilicate (TEOS) and/or silicon acetate.
Claim: 9. The process of claim 1, wherein the pH is from 8 to 13.
Claim: 10. The process of claim 1, wherein an alkali is added to adjust the pH of the solution to the desired pH.
Claim: 11. The process of claim 10, wherein the alkali is ammonium hydroxide or concentrated ammonia.
Claim: 12. The process of claim 1, wherein after the precipitate has been formed it is dried, heated and/or sintered.
Claim: 13. The process of claim 1, wherein the silicon-containing and the gadolinium-containing compounds are supplied in equimolar quantities with respect to the amount of silicon and the quantity of the gadolinium cation.
Claim: 14. The process of claim 1, wherein the silicon-containing compound is supplied in a greater quantity than the gadolinium compound, with respect to the quantity of silicon and the quantity of the gadolinium cation.
Claim: 15. The process of claim 1, wherein the process further involves diluting the thus formed calcium phosphate-based gadolinium-containing material with a gadolinium-free material.
Claim: 16. The process of claim 1, wherein the phase purity of the material, as measured by X-ray diffraction using the whole pattern method, is at least 95%.
Claim: 17. The process of claim 1, wherein 0.001
Claim: 18. The process of claim 1, wherein 0.1
Claim: 19. The process of claim 1, wherein 0
Claim: 20. The process of claim 1, wherein 0
Claim: 21. The process of claim 1, wherein x≥y.
Current International Class: 61; 61; 01; 61; 61; 61
Accession Number: edspap.20200138981
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