title: Transmission electron microscopy of Ca oxide nano- and microcrystals in alpha-tricalcium phosphate prepared by sintering of beta-tricalcium phosphate.
abstract: Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to study the porous and non-porous alpha-tricalcium phosphate (alpha-Ca3(PO4)2, alpha-TCP) prepared through a sintering procedure at 1200-1400 degrees C of beta-tricalcium phosphate (beta-Ca3(PO4)2, beta-TCP). The interpretation of experimental and calculated X-ray and electron diffraction patterns showed that the final product at 1400 degrees C was primarily alpha-TCP but roughly 3.0-8.0 wt.% of the starting beta-TCP phase and up to 8.0 wt.% of CaO were in the final product. TEM images and electron diffraction patterns showed that the CaO phase--formed by decomposition of TCP--exists as micron-sized areas of various oriented nanocrystals embedded into the bulk alpha-TCP material and also as self-standing spherulite particles of a few microns in size. Surprisingly, formation of CaO from TCP decomposition occurred at temperatures below those predicted from the phase diagram of the CaO-P2O5 system.
authors.affiliation: Institute of Crystallography of Russian Academy of Sciences, Leninsky Pr. 59, 119333 Moscow, Russia. Suvorova@ns.crys.ras.ru
authors.forename: Elena I
authors.initials: EI
authors.lastname: Suvorova
authors.forename: Natalya A
authors.initials: NA
authors.lastname: Arkharova
authors.forename: Philippe A
authors.initials: PA
authors.lastname: Buffat
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry; D017610:Calcium Compounds / Q000032:analysis*; D002130:Calcium Phosphates / Q000138:chemical synthesis* / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000032:analysis* / Q000648:ultrastructure*; D010087:Oxides / Q000032:analysis*; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; D017610:Calcium Compounds; D002130:Calcium Phosphates; D010087:Oxides; C485828:alpha-tricalcium phosphate; C485817:beta-tricalcium phosphate; C016538:lime