The influence of powder processing and sintering temperature on densification, microstructure and mechanical properties of hydroxyapatite (HAp) ceramics was studied. The as-dried, calcined and processed HAp powders were uniaxially compacted and sintered a

The chemical formula of the samples investigated is Ni1−y Zny Fe2O4, where y=0.1, 0.3, 0.5. 0.7 and 0.9. The specimens were prepared by the usual ceramic technology and sintered at 1250 °C in static air atmosphere. The influence of Zn content on the densification and microstructure characteristics of specimens was studied. X-ray diffraction and IR absorption spectra were used for analysing the compositions. It was found that the samples have spinel cubic structure and sintered to about 97–98% of the corresponding X-ray density. Exaggerated grain growth with fine pores inside the grains were observed with increasing Zn content. The overall results are discussed in light of the existing understanding of these systems.