resumo
Composites with varied proportions of beta-Ca-3(PO4)(2) and ZnO were obtained through an in situ aqueous precipitation method under slightly basic (pH approximate to 8) conditions. The formation of beta-Ca-3(PO4)(2) phase starts at an early heat-treatment stage (similar to 800 degrees C) and incorporates Zn2+ ions at both Ca2+(4) and Ca2+(5) sites of the lattice up to its occupancy saturation limit. The incorporation of Zn2+ in the beta-Ca-3(PO4)(2) lattice enhances its thermal stability delaying the allotropic beta-Ca-3(PO4)(2)->alpha-Ca-3(PO4)(2) phase transformation. The excess zinc beyond the occupancy saturation limit precipitates as Zn(OH)2 and undergoes dehydroxylation to form ZnO at elevated temperatures. The presence of ZnO in the beta-Ca-3(PO4)(2) matrix yields denser microstructures and thus improves the mechanical features of sintered composites up to an optimal ZnO concentration beyond which it tends to exert an opposite effect.
palavras-chave
BETA-TRICALCIUM PHOSPHATE; ZINC-OXIDE; TCP-TIO2 BIOCOMPOSITES; VIBRATIONAL PROPERTIES; RIETVELD REFINEMENT; ELASTIC PROPERTIES; ZNO NANOPARTICLES; CRYSTAL-STRUCTURE; PHASE-STABILITY; HYDROXYAPATITE
categoria
Chemistry
autores
Kumar, PN; Ferreira, JMD; Kannan, S
nossos autores
José Maria da Fonte Ferreira
Professor(a) Jubilado(a)agradecimentos
The authors are thankful for the financial support received from the Council of Scientific and Industrial Research, India (CSIR Scheme No. 22(612)/12/EMRII). The Instrumentation facility availed from the Central Instrumentation Facility of Pondicherry Univ. is greatly acknowledged. The support of CICECO-Aveiro Institute of Materials (Ref. No. UID/CTM/50011/2013), funded by FEDER funds through the Operational Programme Competitiveness Factors (COMPETE 2020) and the Portuguese Foundation for Science and Technology is acknowledged.