Influence of microwave power and irradiation time on some properties of hydroxyapatite nanopowders

Microwave (MW) assisted synthesis of hydroxyapatite (HAP) nanopowders (NPs) is an efficient and eco-friendly contemporary technique. This paper discusses the influence of two MW parameters i.e., microwave power (MWP) and irradiation time (MWIT) on structural and physicochemical properties of HAP NPs. MWP and MWIT settings had little effect on phase constitution of NPs as suggested by XRD analysis. HAP was a major phase in all NPs. Rietveld refinement suggested that with the increase in MWP and changes in MWIT settings, bond length, and Ca/P molar ratio increased, whereas, crystal size, crystallinity, and microstrain of NPs decreased. Also, HAP unit cell contracted along a-axis and expanded along c-axis with the increase in MWP and changes in MWIT settings. FTIR corroborated XRD phase analysis and suggested bone-like apatitic formation in all NPs. FESEM indicated agglomerated state of NPs constituted of nano-dimensional elongated particles. TEM suggested the rod shaped particles having aspect ratio varied between 2 and 3. EDX results corroborated with XRD and FTIR results. By analysis of all results, properties of NPs irradiated at 900 and 1200 W were relatively more promising. Hence, this study systematically and minutely examined the overall effect of MW parameters on various properties of HAP NPs. [GRAPHICS] .