abstract
An in situ aqueous precipitation with the aid of Gd3+ as a stabilizer has been used to attain a series of beta-Ca-3(PO4)(2)/t-ZrO2 composites. Analytical characterization techniques were used to investigate the formation of desired composite during progressive heat treatments. The transformation of calcium deficient apatite to beta-Ca-3(PO4)(2), which usually occurs at approximate to 780 degrees C for pure systems, is delayed to beyond 1100 degrees C, depending upon the concentration of Gd3+/Zr4+ used in the synthesis. Gd3+ prefers to accommodate at the lattice sites of both beta-Ca-3(PO4)(2) and t-ZrO2. Gd3+ ensures limited occupancy at the Ca2+(1), Ca2+(2), and Ca2+(3) of beta-Ca-3(PO4)(2) while t-ZrO2 consumes the excess Gd3+. Phase pure beta-Ca-3(PO4)(2)/t-ZrO2 composite mixtures devoid of any secondary phase alongside enhanced structural stability were accomplished at 1500 degrees C. The micrographs of the composite specimen revealed good sintering behaviour, and the Youngs modulus and hardness data determined from indentation displayed significant variations depending on the phase content of the individual components in the composite system.
keywords
BETA-TRICALCIUM PHOSPHATE; X-RAY-ABSORPTION; PREFERENTIAL OCCUPANCY; ZIRCONIA STABILIZATION; VIBRATIONAL PROPERTIES; PHASE-TRANSITIONS; CONTRAST AGENTS; HYDROXYAPATITE; TEMPERATURE; MECHANISMS
subject category
Chemistry
authors
Kumar, PN; Kannan, S; Ferreira, JMF
our authors
José Maria da Fonte Ferreira
Retired Professoracknowledgements
This work resulted from an international collaboration between the CICECO-Aveiro Institute of Materials, within the scope of the project FCT Ref. UID/CTM/50011/2019, financed by national funds through the FCT/MCTES, and the financial assistance received from Council of Scientific and Industrial Research (CSIR) [Reference: 01(2952)/18/EMR-II dated 01.05.2018] India, which are acknowledged. The facilities available at both research centres, CICECO-Aveiro Institute of Materials and the Central Instrumentation Facility (CIF) of Pondicherry University are acknowledged. Dr. P. Nandhakumar [Ref. No. 09/559(0120)/18-EMR-I] acknowledges CSIR, India for a Research Associate Fellowship.