Nano calcium phosphates doped with titanium and fluoride ions: sinterability and stability of phases

Güngör Geridönmez, Serap
The purpose of this study was to synthesize calcium phosphates doped with titanium and fluoride ions in different combinations. Pure and doped calcium phosphates were synthesized by a precipitation method. The synthesized materials were sintered at 1100ºC and 1300ºC for 1h. The ceramics were characterized by density measurements to determine the effect of sintering temperature. Presence of phases and bonds were characterized by XRD diffraction and FTIR spectroscopy. Grain sizes of the samples were obtained by SEM. Microhardness test was applied on the samples to determine the mechanical properties of the samples. It was observed that Ti4+ addition decreased the density of samples significantly at 1100°C, whereas increasing the sintering temperature to 1300°C caused an increase. Increasing the F- ion amount increased the densification at 1100°C when molar ratios were 1.0, 1.25, 1.50 and decreased the density at 1300°C when Ca /P molar ratios were 1.0, 1.25, 1.67 and 2.0. Ti4+ and F- co-doped samples showed variety in their density behaviour after the sintering at 1100ºC and 1300ºC. The XRD analyses demonstrated that for Ca to P ratio 1 at 1100°C, β-CPP phase, when sintering temperature was raised to 1300°C, as a second phase of β-CPP and α-TCP observed. Increasing the molar ratio to 1.25 and 1.50 demonstrated β-TCP and/or β-CPP and β-TCP/ HA at 1100°C and β-TCP and/or β-CPP, α-TCP, TiO2 and HA, α-TCP, TiO2 phases at 1300°C, respectively. In higher Ca/P molar ratios of 1.67 and 2.0, HA, β-TCP, α-TCP, CaO, TiO2, CaTiO3 and HA, CaO, α-TCP, CaTiO3 phases were determined. Increasing the sintering temperature to 1300°C resulted in transformation to α-TCP. In FTIR spectroscopy analysis, when the samples with molar ratio of 1, 1.25, 1.50, 1.67 and 2.0, sintered at 1100°C, the characteristic bands of β-CPP, OCP/β-TCP, β-TCP/HA, HA and HA were observed, respectively. With increasing the sintering temperature to 1300°C, samples with molar ratio of 1.0 and 1.25 revealed additional secondary characteristic peaks of HA and β-TCP. SEM images revealed that sintering temperature and ion amounts of dopants had significant effect on grain sizes of the samples. The grain sizes were generally increased when sintering temperature rose from 1100°C to 1300°C. The μ-hardness test demonstrated that Ti4+ and F- ions in large amounts had positive effect on the mechanical properties at the sintering temperatures of 1100°C and 1300°C.


Microstructural, biological and mechanical investigations of hydroxyapatite-β-tricalcium phosphate composites doped with strontium and fluoride
Pourreza, Elmira; Evis, Zafer; Department of Engineering Sciences (2016)
The aim of this study was to investigate the microstructure, mechanical and biological properties of biphasic hydroxyapatite--Tricalcium phosphate (HT) and HT substituted with constant fluoride (F−) and varying strontium (Sr2+) amounts. All the samples were synthesized via precipitation method and sintered at 1100°C for 1 h. It was observed that the relative density of the sintered strontium and fluoride doped HT slightly increased. For microstructural analysis, X-ray diffraction (XRD), scanning electron m...
Polybenzimidazole based nanocomposite membranes with enhanced proton conductivity for high temperature PEM fuel cells
Ozdemir, Yagmur; Uregen, Nurhan; DEVRİM, YILSER (2017-01-26)
In this study, phosphoric acid doped PBI nanocomposite membranes were prepared by dispersion of various amounts of inorganic nanoparticles in PBI polymer followed by phosphoric acid (H3PO4) doping for high temperature proton exchange membrane fuel cells (HT-PEMFC). All of the PBI composite membranes were cast from the same FBI polymer with the same molecular weight. Titanium dioxide (TiO2), silicon dioxide (SiO2) and inorganic proton conductor zirconium phosphate (ZrP) were used as inorganic fillers. The PB...
Collagen/PEO/gold nanofibrous matrices for skin tissue engineering
Akturk, Omer; Keskin, Dilek (The Scientific and Technological Research Council of Turkey, 2016-01-01)
As a novel approach in skin tissue engineering, gold nanoparticles (AuNPs) were synthesized and incorporated at different concentrations into collagen/PEO nanofibrous matrices in this study. The group containing 14.27 ppm AuNPs (CM-Au) had the best nanofibrous morphology. CM-Au was cross-linked with glutaraldehyde vapor (CM-AuX). All groups were disrupted in collagenase in 2 h, but cross-linked groups and Matriderm (R) resisted hydrolytic degradation for 7 and 14 days, respectively. Due to its small pores a...
Controlled assemble and microfabrication of zeolite particles on SiO2 substrates for potential biosensor applications
Öztürk, Semra; Turan, Raşit; Akata Kurç, Burcu (2008-12-04)
Zeolite nanoparticles were organized into functional entities on SiO2 substrates and microfabrication technique was tested to form patterns of zeolite nanoparticles on SiO2 using the electron beam lithography (EBL). The effect of different techniques for efficient zeolite assembly on the SiO2 substrates was investigated. For this purpose, three different assembly techniques were tested. The first two methods are spin-coating (SC) and ultrasound aided strong agitation (US) methods, which were tested using ba...
Catalytic oxidation of nitrogen containing compounds for nitrogen determination
Karakaş, Gürkan (2019-02-15)
The high temperature catalytic oxidation (HTCO) performance of Al2O3 supported Pt, Cu, Cu-Ce and Fe catalysts were systematically studied with a perspective of selective oxidation of nitrogenous compounds to nitric oxide for quantitative determination of bound nitrogen. The catalyst samples were prepared via impregnation and characterized by XRD and BET. In addition, temperature programmed reaction experiments with acetonitrile and oxygen were conducted to evaluate the catalytic activity and selectivity tow...
Citation Formats
S. Güngör Geridönmez, “Nano calcium phosphates doped with titanium and fluoride ions: sinterability and stability of phases,” Ph.D. - Doctoral Program, Middle East Technical University, 2012.