RESUMO Matrizes de hidroxiapatita (HAp) dopadas com os íons lantanídeos Eu3+, Ce3+ e Gd3+, [Ca10-xLnx(PO4)6(OH)2], foram obtidas pelo método da precipitação com o objetivo de estudar suas propriedades fotofísicas. A partir de análises de Microscopia Eletrônica de Varredura observou-se que amostras dopadas com íons lantanídeos (Ln3+) apresentaram similaridade com a morfologia da HAp pura, por outro lado nos difratogramas de Raios X a partir do refinamento Rietveld verificou-se que a matriz aparece como fase majoritária (≈ 70%) enquanto (≈ 30%) de uma fase secundária de tricálcio fosfato (TCP) foi conferida em função das diferentes dopagens. Isotermas de adsorção obtidas pela técnica BET indicaram que todos os materiais sintetizados são classificados como mesoporosos. Os espectros de emissão dos materiais exibem bandas características dos íons Ln3+ incorporados à estrutura da matriz em 573 nm (5D0→F0), 600 nm (5D0→F1), 628 nm (5D0→F2), e 698 nm (5D0→F4) para HAp/Eu, 337-360 nm (5d→4f) para HAp/Ce e em 425 nm para HAp/Gd.

ABSTRACT Hydroxyapatite (HAp) matrices doped with lanthanide ions Eu3+, Ce3+ and Gd3+, [Ca10-xLnx(PO4)6(OH)2] were obtained through the precipitation method so their photophysical properties could be studied. From the Scanning Electron Microscopy analyzes it was observed that samples doped with lanthanide ions (Ln3+) showed similarity with the morphology of pure HAp, whereas Rietveld-refined X-ray diffractograms showed that the matrix appears as the major phase (≈70%) while (≈30%) of a second phase of tricalcium phosphate (TCP) was due to the different doping levels. Adsorption isotherms obtained by the BET technique indicated that all the synthesized materials are classified as mesoporous. The emission spectra of the materials exhibit bands typical of the Ln3+ ions incorporated into the matrix structure at 573 nm (5D0→F0), 600 nm (5D0→F1), 628 nm (5D0→F2), and 698 nm (5D0 → F4) for HAp/Eu, 337-360 nm (5d → 4f) for HAp/Ce and at 425 nm for HAp/Gd.

Prototypes of porous hydroxyapatite (HAp) were produced from Gypsum/PVA composite, using a mass proportion of 15% polymer. The material was obtained by means of chemical conversion in (NH4)2HPO4 0.5 mol.L-1 solution and NH4OH 6.0 mol.L-1 alkaline medium for pH control, maintained between 6.0 and 9.0. The reaction occurred at a temperature of 100ºC at different test times. The obtained HAp was characterized by several techniques, such as FTIR, which identified the SO4(2-) groups characteristic for the Gypsum block, and the PO4(3-) groups that are attributed to the biomaterial HAp, besides XRD and SEM, which made it possible to confirm a successful conversion of the material. Tests for mechanical resistance to compression (σc) were carried out for both materials as well.