Influence of Synthesis Route on Phase Formation and Sinterability of Hydroxyapatite-Zirconia Composites

2008 ◽  
Vol 591-593 ◽  
pp. 722-727
Author(s):  
Dolores Ribeiro Ricci Lazar ◽  
Sandra Maria Cunha ◽  
Valter Ussui ◽  
E. Fancio ◽  
Nelson Batista de Lima ◽  
...  
Keyword(s):  
Chemical Reactivity ◽  
Ammonium Hydroxide ◽  
Rietveld Analysis ◽  
Yttria Stabilized Zirconia ◽  
Synthesis Process ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Ammonium Hydrogen ◽  
Ammonium Hydrogen Phosphate ◽  
Diffraction Patterns

Reinforcement with yttria stabilized zirconia (YSZ) is an alternative to improve mechanical strength of hydroxyapatite (HAp) ceramic. However, calcium may react with zirconium to form calcium zirconate. In addition, decomposition of HAp to tricalcium phosphate (TCP) occurs with water loss inhibiting ceramic densification. In order to minimize the formation of these compounds, two synthesis routes were compared in this work: coprecipitation of hydrous yttria stabilized zirconia in a calcium phosphate gel medium and powder mixture of individual calcined powders. Composite nominal compositions were fixed at 90 and 95 HAp wt%. Calcium, zirconium and yttrium chlorides and ammonium hydrogen phosphate were the employed precursors. Ammonium hydroxide was the selected precipitation agent. Calcination was performed at 800oC for 1 hour and pellets were sintered in the range of 1150 and 1350oC for 1, 3 and 5 hours. Ceramic samples were characterized by scanning electron microscopy and apparent density measurements. Crystalline phases were quantified by Rietveld analysis of X-ray diffraction patterns. Results indicate that powders prepared by coprecipitation can cause porosity formation due to the higher chemical reactivity during synthesis process.

scholarly journals Chemical conversion of a solid body of the composite gypsum/polyhydroxybutyrate in hydroxyapatite/polyhydroxybutyrate

Cerâmica ◽  
2019 ◽  
Vol 65 (375) ◽  
pp. 335-339
Author(s):  
A. A. Barbosa ◽  
S. A. Júnior ◽  
A. C. S. Dantas ◽  
A. V. Ferraz
Keyword(s):  
Ammonium Hydroxide ◽  
Chemical Conversion ◽  
Ph Control ◽  
Raw Material ◽  
Added Value ◽  
X Ray Diffraction ◽  
Before And After ◽  
Ammonium Hydrogen ◽  
Diffraction Patterns ◽  
Clear Change

Abstract The transformation of the gypsum into hydroxyapatite allows added value to this raw material, because the ceramic obtained has a high commercial value in relation to gypsum, while the polymer adds biocompatibility and bioactivity properties to the biocomposite. Thus, hydroxyapatite/polyhydroxybutyrate composites were prepared from the gypsum/polyhydroxybutyrate, using a 10% mass ratio of the polymer. The material was obtained by means of a chemical conversion carried out in a solution of ammonium hydrogen phosphate (0.5 mol.L-1) and alkaline medium (ammonium hydroxide 6.0 mol.L-1) for pH control. The reaction occurred at 100 °C at different test times. Analyzes of infrared spectroscopy showed functional groups characteristic of hydroxyapatite after 36 h of reaction; in addition, the biomaterial was identified as the major phase in X-ray diffraction patterns. Scanning electron microscopy of the materials before and after conversion showed a clear change in their morphologies, indicating the success of the synthesis.

Characterizations of Synthetic 8mol% YSZ with Comparison to 3mol %YSZ for HT-SOFC

2020 ◽  
Vol 38 (4A) ◽  
pp. 491-500
Author(s):  
Abeer F. Al-Attar ◽  
Saad B. H. Farid ◽  
Fadhil A. Hashim
Keyword(s):  
Ionic Conductivity ◽  
Electrochemical Impedance ◽  
Structural Information ◽  
Impedance Analysis ◽  
High Energy ◽  
Yttria Stabilized Zirconia ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Powder Morphology ◽  
X Ray

In this work, Yttria (Y2O3) was successfully doped into tetragonal 3mol% yttria stabilized Zirconia (3YSZ) by high energy-mechanical milling to synthesize 8mol% yttria stabilized Zirconia (8YSZ) used as an electrolyte for high temperature solid oxide fuel cells (HT-SOFC). This work aims to evaluate the densification and ionic conductivity of the sintered electrolytes at 1650°C. The bulk density was measured according to ASTM C373-17. The powder morphology and the microstructure of the sintered electrolytes were analyzed via Field Emission Scanning Electron Microscopy (FESEM). The chemical analysis was obtained with Energy-dispersive X-ray spectroscopy (EDS). Also, X-ray diffraction (XRD) was used to obtain structural information of the starting materials and the sintered electrolytes. The ionic conductivity was obtained through electrochemical impedance spectroscopy (EIS) in the air as a function of temperatures at a frequency range of 100(mHz)-100(kHz). It is found that the 3YSZ has a higher density than the 8YSZ. The impedance analysis showed that the ionic conductivity of the prepared 8YSZ at 800°C is0.906 (S.cm) and it was 0.214(S.cm) of the 3YSZ. Besides, 8YSZ has a lower activation energy 0.774(eV) than that of the 3YSZ 0.901(eV). Thus, the prepared 8YSZ can be nominated as an electrolyte for the HT-SOFC.

Effect of Yttria-Stabilized Zirconia Concentration in an Electroless Bath on Microstructure and Composition of Ni/Yttria-Stabilized Zirconia Nanocomposite

2021 ◽  
Vol 21 (11) ◽  
pp. 5592-5602
Author(s):  
Samira Almasi ◽  
Ali Mohammad Rashidi
Keyword(s):  
High Performance ◽  
Yttria Stabilized Zirconia ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Nickel Ion ◽  
Nanocomposite Particles ◽  
X Ray ◽  
Ni Content ◽  
Naoh Solution ◽  
Average Size

The effect of the yttria-stabilized zirconia (YSZ) nanoparticle loading in an electro-less bath was considered as one of the vital synthesis variables for control Ni content and microstructure of prepared nanocomposite particles, which are two crucial factors to achieving high-performance SOFC anode. Nanocomposite particles were prepared using a simple electroless method without any expensive pretreatment of sensitizing by Sn2+ ions as well as activating by Pd2+ ions that are usually used to apply nickel coating on the surface of a non-conductive substrate. The process was performed by adding YSZ nanoparticles into NaOH solution, separating them from the solution by the centrifugal method, then providing several water-based nanofluids with different concentrations of activated YSZ nanoparticles, mixing them with NiCI2 solution, followed by adding the hydrazine and then NaOH solution. X-ray diffraction and scanning electron microscopy coupled with energy dispersive X-ray analysis were used to analyze the prepared nanocomposite particles. It is observed that after adding YSZ nanoparticles into the NaOH solution, the pH of the solution varied gradually from a starting pH of 10.2 to 9. Also, by increasing the YSZ nanoparticles loading in the electroless bath from 76 mg/l to 126 mg/l, the grain size of Ni deposits, the Ni content and the average size of the prepared nanocomposite particles decreased. The electrochemical mechanism previously proposed for the nickel ion reduction was modified, and a novel analytical model was proposed for variation of the efficiency of Ni deposition with YSZ nanoparticles loading.

scholarly journals Equimolar Yttria-Stabilized Zirconia and Samaria-Doped Ceria Solid Solutions

Ceramics ◽  
2018 ◽  
Vol 1 (2) ◽  
pp. 343-352 ◽  
Author(s):  
Reginaldo Muccillo ◽  
Daniel de Florio ◽  
Eliana Muccillo
Keyword(s):  
Tetragonal Phase ◽  
Room Temperature ◽  
Single Phase ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Stabilized Zirconia ◽  
X Ray ◽  
Ceria Solid Solutions ◽  
Attrition Milling

Compositions of (ZrO2)0.92(Y2O3)0.08 (zirconia: 8 mol % yttria—8YSZ) and (CeO2)0.8(Sm2O3)0.2 (ceria: 20 mol % samaria—SDC20) ceramic powders were prepared by attrition milling to form an equimolar powder mixture, followed by uniaxial and isostatic pressing. The pellets were quenched to room temperature from 1200 °C, 1300 °C, 1400 °C and 1500 °C to freeze the defects configuration attained at those temperatures. X-ray diffraction analyses, performed in all quenched pellets, show the evolution of the two (8YSZ and SDC20) cubic fluorite structural phases to a single phase at 1500 °C, identified by Rietveld analysis as a tetragonal phase. Impedance spectroscopy analyses were carried out in pellets either quenched or slowly cooled from 1500 °C. Heating the quenched pellets to 1000 °C decreases the electrical resistivity while it increases in the slowly cooled pellets; the decrease is ascribed to annealing of defects created by lattice micro-tensions during quenching while the increase to partial destabilization of the tetragonal phase.

EPITAXIAL GROWTH OF YTTRIA-STABILIZED ZIRCONIA FILMS ON SILICON BY R.F. MAGNETRON SPUTTERING

1991 ◽  
Vol 05 (27) ◽  
pp. 1829-1835 ◽  
Author(s):  
Q.X. SU ◽  
L. LI ◽  
Y.Y. ZHAO ◽  
Y.Z. ZHANG ◽  
P. XU
Keyword(s):  
Magnetron Sputtering ◽  
Yttria Stabilized Zirconia ◽  
Processing Conditions ◽  
Full Width ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
X Ray ◽  
Si Substrates ◽  
Zirconia Films ◽  
Scanning Electron

Yttria-stabilized Zirconia(YSZ) films were deposited on (100)Si substrates by R.F. magnetron sputtering method. X-ray diffraction analysis showed that the best YSZ films were cubic in structure and was grown epitaxially with (100) orientation. The (200) peak of YSZ films was 0.8° of the full width at half of the maximum, X-ray diffraction based on Seemann-Bohlin focusing geometry showed no peaks. The morphology of the YSZ films was observed by scanning electron microscopy. The effects of the processing conditions (such as substrate temperature, oxygen partial pressure, etc.) on the structure of the film were also discussed.

scholarly journals Identification of tetragonal and cubic structures of zirconia using synchrotron x-radiation source

1991 ◽  
Vol 6 (6) ◽  
pp. 1287-1292 ◽  
Author(s):  
Ram Srinivasan ◽  
Robert J. De Angelis ◽  
Gene Ice ◽  
Burtron H. Davis
Keyword(s):  
Particle Size ◽  
Radiation Source ◽  
Sol Gel ◽  
Yttria Stabilized Zirconia ◽  
Tetragonal Structure ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Synchrotron Source ◽  
Three Samples

X-ray diffraction from a synchrotron source was employed in an attempt to identify the crystal structures in zirconia ceramics produced by the sol-gel method. The particles of chemically precipitated zirconia, after calcination below 600 °C, are very fine, and have a diffracting particle size in the range of 7–15 nm. As the tetragonal and cubic structures of zirconia have similar lattice parameters, it is difficult to distinguish between the two. The tetragonal structure can be identified only by the characteristic splittings of the Bragg profiles from the “c” index planes. However, these split Bragg peaks from the tetragonal phase in zirconia overlap with one another due to particle size broadening. In order to distinguish between the tetragonal and cubic structures of zirconia, three samples were studied using synchrotron radiation source. The results indicated that a sample containing 13 mol% yttria-stabilized zirconia possessed the cubic structure with a0 = 0.51420 ± 0.00012 nm. A sample containing 6.5 mol% yttria stabilized zirconia was found to consist of a cubic phase with a0 = 0.51430 ± 0.00008 nm. Finally, a sample which was precipitated from a pH 13.5 solution was observed to have the tetragonal structure with a0 = 0.51441 ± 0.00085 nm and c0 = 0.51902 ± 0.00086.

Sinterability of 8 mol% Yttria Stabilized Zirconia

2018 ◽  
Vol 280 ◽  
pp. 102-108
Author(s):  
Tinesha Selvaraj ◽  
Johar Banjuraizah ◽  
S.F. Khor ◽  
M.N. Mohd Zainol
Keyword(s):  
Low Cost ◽  
Crystal Structure Analysis ◽  
Yttria Stabilized Zirconia ◽  
Holding Time ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Holding Period ◽  
Particle Size And Morphology ◽  
Size And Morphology ◽  
Sintering Behaviour

The sintering behaviour of low cost 8 mol% yttria stabilized zirconia powders has been studied. The effect of sintering holding time of the sintered granulated and milled 8YSZ were determined using density measurements, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The elemental composition, particle size and morphology of the as-received 8YSZ powder and proceed for milling was investigated. 48 hours of ball milling on granulated 8YSZ resulted rises in specific surface area and sintered at 1550°C with the various period of time (4, 5, 6 and 7 hours). The milled 8YSZ sample with 5h sintering holding period coded as F5, sintering activity improved and the relative density came up to 98.3%. But then, granulated 8YSZ achieved only 62.7% with 5 hours holding time. Crystal structure analysis for milled 8YSZ powder consists of 59.6% of cubic ZrO2 phase, 40.1% of tetragonal ZrO2 and 0.3% of monoclinic ZrO2. Meanwhile, granulated 8YSZ indicated low content in cubic ZrO2 but high amount in monoclinic ZrO2 phase. In brief, low cost 8YSZ reached higher densification of 98% successfully.

scholarly journals Polymorphism of tricalcium silicate in Portland cement: A fast visual identification of structure and superstructure

2003 ◽  
Vol 18 (1) ◽  
pp. 7-15 ◽  
Author(s):  
M. Courtial ◽  
M.-N. de Noirfontaine ◽  
F. Dunstetter ◽  
G. Gasecki ◽  
M. Signes-Frehel
Keyword(s):  
Portland Cement ◽  
Structural Model ◽  
Rietveld Analysis ◽  
Tricalcium Silicate ◽  
Crystallographic Structure ◽  
X Ray Diffraction ◽  
Diffraction Patterns ◽  
Xrd Patterns ◽  
Industrial Compounds ◽  
Open Question

So-called alite is a solid solution of tricalcium silicate Ca3SiO5 with a few percent of impurities. It constitutes the major phase of anhydrous Portland cement. In industrial compounds, alite crystallizes into two monoclinic forms designated M1 and M3. The possibility of correlation between the crystallographic structure of the clinker and its reactivity is still an open question. The answer of such a question involves a proper quantitative analysis of the various phases—including the exact alite polymorph—of the industrial product. The rather similar structure of the two alites makes it difficult to distinguish them from their XRD patterns. This paper shows that five angular windows in the X-ray diffraction patterns can be used with synthetic alites as well as industrial compounds, to identify the nature of the actual polymorph (M1 or M3) present and the structural model to be used (with or without superstructure) in subsequent Rietveld analysis of the data.

Synchrotron radiation study of yttria-stabilized zirconia, Zr0.758Y0.242O1.879

1999 ◽  
Vol 55 (5) ◽  
pp. 726-735 ◽  
Author(s):  
N. Ishizawa ◽  
Y. Matsushima ◽  
M. Hayashi ◽  
M. Ueki
Keyword(s):  
Synchrotron Radiation ◽  
Single Crystal ◽  
Yttria Stabilized Zirconia ◽  
Data Sets ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
X Ray ◽  
Ideal Position ◽  
Fluorite Type ◽  
The Ideal

The fluorite-related cubic structure of yttria-stabilized zirconia, Zr0.75 8Y0.24 2O1.87 9, has been studied by single-crystal X-ray diffraction using synchrotron radiation and by EXAFS. Two diffraction data sets obtained at X-ray energies of 512 and 10 eV below the Y K edge revealed that in the average structure Zr atoms are displaced from the origin of the space group Fm3¯m along 〈111〉 by 0.19 Å, while Y atoms reside at the origin. Approximately 48% of the O atoms occupy the ideal position in the fluorite-type structure, while 43% of O atoms are displaced from the ideal position along 〈001〉 by 0.31 Å. The remaining 9% of O atoms are presumably sited at interstitial positions. Local structures around Zr and Y are investigated by combining the results of single-crystal X-ray diffraction and EXAFS studies.

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