Microstructural changes of single-crystal apatite fibres during heat treatment

The apatite fibres were prepared using a homogeneous precipitation route. The as-prepared fibres were composed of carbonate-containing apatite with preferred orientation along the c-axis direction. The fibres were highly strained and were composed of domains that preferentially oriented themselves with the c-axis parallel to the surface of the substrate. When the as-synthesized fibres were heated at 800degreesC to 1200degreesC for 1 h, the domain structure of the fibres disappeared but they remained highly strained. In the cases of the apatite fibres heated at 1000degreesC and 1200degreesC, their microstructures changed during sintering to form some grain boundaries and dislocations. The apatite fibres heated at 1200degreesC for 1 h contained many angular voids formed by releasing the carbonate groups during sintering.