Formation Mechanisms in beta-Ca-3(PO4)(2)-ZnO Composites: Structural Repercussions of Composition and Heat Treatments

abstract

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.

keywords

BETA-TRICALCIUM PHOSPHATE; ZINC-OXIDE; TCP-TIO2 BIOCOMPOSITES; VIBRATIONAL PROPERTIES; RIETVELD REFINEMENT; ELASTIC PROPERTIES; ZNO NANOPARTICLES; CRYSTAL-STRUCTURE; PHASE-STABILITY; HYDROXYAPATITE

subject category

Chemistry

authors

Kumar, PN; Ferreira, JMD; Kannan, S

our authors

acknowledgements

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.

Share this project:

Related Publications

We use cookies for marketing activities and to offer you a better experience. By clicking “Accept Cookies” you agree with our cookie policy. Read about how we use cookies by clicking "Privacy and Cookie Policy".