| 摘要 |
The rod-shaped apatite crystals of the formula Ca<SUB>5</SUB>(PO<SUB>4</SUB>)<SUB>3</SUB>(OH)<SUB>x</SUB>F<SUB>y </SUB>have the following features a) the length-to-breadth ratio of the crystals is at least >=5 and b) x+y=1, where if x or y<>0 the total amount of the crystals is present as a mixture of individual hydroxyapatite crystals and fluoroapatite crystals and/or as mixed crystals, such that, based on the total amount of the crystals, (1-x).100% of the hydroxide ions present if y=0 are replaced by fluoride ions. The invention furthermore describes dispersions which contain such rod-shaped apatite crystals, and a process for the preparation of the dispersions or of the apatite crystals. |
