Rapid, accurate phase quantification of multiphase calcium phosphate materials using Rietveld refinement

Rietveld refinement has been employed to estimate the crystalline phase compositions of multiphase calcium phosphate mixtures containing calcium hydroxyapatite [Ca5(PO4)3OH], and alpha and beta tricalcium phosphate [Ca3(PO4)2]. Two methods were employed using fixed structural models for all three phases and refining the zero offset, scale factors, lattice parameters and one peak breadth parameter using either a constant background (method A) or a background with two refined parameters (method B). Analysis of a matrix of quantitative standards across a broad spectrum of phase compositions indicates that method A results in small systematic deviations of the Rietveld phase compositions (< 1 wt%) from the nominal values, but the systematic deviations are eliminated by refining the background (method B). The methods require approximately 10 min to complete, and are suitable for quality control of calcium phosphate production (and potentially other multiphase systems) when accuracy, precision and time are all significant considerations.

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Interlaboratory study on the quantification of calcium phosphate phases by Rietveld refinement

Powder Diffraction ◽

10.1017/s088571561500038x ◽

2015 ◽

Vol 30 (3) ◽

pp. 231-241 ◽

Cited By ~ 6

Author(s):

Nicola Döbelin

Keyword(s):

Standard Deviation ◽

Calcium Phosphate ◽

Rietveld Refinement ◽

Xrd Analysis ◽

Interlaboratory Study ◽

Accuracy And Precision ◽

Crystallite Sizes ◽

Phase Quantification ◽

Repeatability Standard Deviation ◽

Instrument Configuration

An interlaboratory study (ILS, round robin) was conducted to assess the accuracy and precision of the phase quantification of calcium phosphate (CaP) bioceramics by X-ray diffraction (XRD) and Rietveld refinement. For that purpose, a mixture of hydroxyapatite and β-tricalcium phosphate, two CaP phases commonly used in synthetic bone graft substitutes, was prepared and sent to 12 laboratories for XRD analysis. Results from 26 different instruments were received and evaluated statistically according to ASTM E691 – 13. The statistical analysis revealed that the reproducibility standard deviation of phase quantities was approximately two times greater than the repeatability standard deviation, which is obtained by repeating the analysis on a single instrument configuration multiple times. The 95% reproducibility limit for phase quantities was R = ±1.67 wt%. The study also demonstrated that several participants overinterpreted their data in an attempt to refine crystallite sizes of the minor phase.

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Production and Characterization of a 316L Stainless Steel/β-TCP Biocomposite Using the Functionally Graded Materials (FGMs) Technique for Dental and Orthopedic Applications

Metals ◽

10.3390/met11121923 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1923

Author(s):

Bruna Horta Bastos Kuffner ◽

Patricia Capellato ◽

Larissa Mayra Silva Ribeiro ◽

Daniela Sachs ◽

Gilbert Silva

Keyword(s):

Mechanical Properties ◽

Stainless Steel ◽

Calcium Phosphate ◽

Functionally Graded Materials ◽

Tricalcium Phosphate ◽

316L Stainless Steel ◽

Functionally Graded ◽

Graded Materials ◽

Beta Tricalcium Phosphate ◽

Orthopedic Applications

Metallic biomaterials are widely used for implants and dental and orthopedic applications due to their good mechanical properties. Among all these materials, 316L stainless steel has gained special attention, because of its good characteristics as an implantable biomaterial. However, the Young’s modulus of this metal is much higher than that of human bone (~193 GPa compared to 5–30 GPa). Thus, a stress shielding effect can occur, leading the implant to fail. In addition, due to this difference, the bond between implant and surrounding tissue is weak. Already, calcium phosphate ceramics, such as beta-tricalcium phosphate, have shown excellent osteoconductive and osteoinductive properties. However, they present low mechanical strength. For this reason, this study aimed to combine 316L stainless steel with the beta-tricalcium phosphate ceramic (β-TCP), with the objective of improving the steel’s biological performance and the ceramic’s mechanical strength. The 316L stainless steel/β-TCP biocomposites were produced using powder metallurgy and functionally graded materials (FGMs) techniques. Initially, β-TCP was obtained by solid-state reaction using powders of calcium carbonate and calcium phosphate. The forerunner materials were analyzed microstructurally. Pure 316L stainless steel and β-TCP were individually submitted to temperature tests (1000 and 1100 °C) to determine the best condition. Blended compositions used to obtain the FGMs were defined as 20% to 20%. They were homogenized in a high-energy ball mill, uniaxially pressed, sintered and analyzed microstructurally and mechanically. The results indicated that 1100 °C/2 h was the best sintering condition, for both 316L stainless steel and β-TCP. For all individual compositions and the FGM composite, the parameters used for pressing and sintering were appropriate to produce samples with good microstructural and mechanical properties. Wettability and hemocompatibility were also achieved efficiently, with no presence of contaminants. All results indicated that the production of 316L stainless steel/β-TCP FGMs through PM is viable for dental and orthopedic purposes.

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Intracellular mineralization of Bacterionema matruchotii

Canadian Journal of Microbiology ◽

10.1139/m81-042 ◽

1981 ◽

Vol 27 (3) ◽

pp. 267-270 ◽

Cited By ~ 4

Author(s):

S. W. Ooi ◽

A. C. Smillie ◽

T. B. Kardos ◽

M. G. Shepherd

Keyword(s):

Crystal Growth ◽

Calcium Phosphate ◽

Intracellular Calcium ◽

Electron Micrographs ◽

Solid Phase ◽

Calcium Hydroxyapatite ◽

Mineral Formation ◽

Phosphate Mineral ◽

Calcium And Phosphorus ◽

Phosphorus Levels

Intracellular calcium phosphate mineral formation in Bacterionema matruchotii has been examined relative to two established points: the product of calcium and phosphorus levels at which spontaneous precipitation occurs (Ca × P), 50 (mg %)2, and the product at which calcium hydroxyapatite itself induces crystal growth, 35 (mg %)2. The extent of intracellular mineralization in the defined calcifying medium was determined analytically after washing the cells. Electron micrographs of B. matruchotii cells revealed needlelike crystals of mineral, typical of calcium hydroxyapatite. Bacterionema matruchotii was found to be an efficient nucleator and can bring about the formation of solid phase at a Ca × P product as low as 35 (mg %)2.

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Resorbable Synthetic Bone Grafts Formed From a Silicon Stabilized Calcium Phosphate Bioceramic

MRS Proceedings ◽

10.1557/proc-550-313 ◽

1998 ◽

Vol 550 ◽

Cited By ~ 2

Author(s):

S. Langstaff ◽

M. Sayer ◽

T. Smith ◽

S. Pugh

Keyword(s):

Calcium Phosphate ◽

Chemical Reactivity ◽

Calcium Hydroxyapatite ◽

Bone Grafts ◽

Ceramic Coatings ◽

Substitution Reactions ◽

Synthetic Bone ◽

Characteristic Features ◽

Synthetic Bone Grafts

AbstractSynthetic bone grafts resistant to random dissolution at physiological pH, yet capable of being gradually resorbed in vitro by osteoclasts have been created. Bulk ceramics and ceramic coatings formed from an additive stabilized colloidal sol possess two characteristic features: a phase mixture of calcium hydroxyapatite (HA) and a silicon stabilized tricalcium phosphate, and a microporous morphology based on inter-connected particles (0.2-1.0 μm). The characteristic phase composition arises during sintering through substitution reactions where silicon enters the calcium phosphate lattice under conditions of high chemical reactivity. Evidence for in vitro resorption lacunae on bulk ceramics is presented.

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Foamed β-Tricalcium Phosphate Scaffolds

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.361-363.323 ◽

2007 ◽

Vol 361-363 ◽

pp. 323-326 ◽

Cited By ~ 5

Author(s):

Edgar Benjamin Montufar ◽

C. Gil ◽

Tania Traykova ◽

M.P. Ginebra ◽

Josep A. Planell

Keyword(s):

Calcium Phosphate ◽

Bone Regeneration ◽

Tricalcium Phosphate ◽

Initial Material ◽

Sintering Process ◽

Bioactive Material ◽

Bioactive Scaffolds ◽

Calcium Phosphate Cements ◽

Beta Tricalcium Phosphate ◽

Nanometric Range

The design and processing of 3D macroporous bioactive scaffolds is one of the milestones for the progress of bone tissue engineering and bone regeneration. Calcium phosphate based ceramics are among the most suitable materials, due to their similarity to the bone mineral. Specifically, beta-tricalcium phosphate (β-TCP) is known to be a resorbable and bioactive material, with well established applications as bone regeneration material. The aim of this work is to explore a new route to obtain β-TCP macroporous scaffolds starting from calcium phosphate cements. To this end foamed calcium phosphate cement, composed of alpha tricalcium phosphate as starting powder was used as initial material. The set foamed structures, made of calcium deficient hydroxyapatite (CDHA) were sintered to obtain the final β-TCP macroporous architecture. The interconnected macroporosity was maintained, whereas the porosity in the nanometric range was strongly reduced by the sintering process. The sintering produced also an increase in the mechanical properties of the scaffold.

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Bimodal Porous Bi-Phasic Calcium Phosphate Ceramics and Its Dissolution in SBF Solution

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.330-332.91 ◽

2007 ◽

Vol 330-332 ◽

pp. 91-94 ◽

Cited By ~ 2

Author(s):

Y. Zhang ◽

Yoshiyuki Yokogawa ◽

Tetsuya Kameyama

Keyword(s):

Calcium Phosphate ◽

Tricalcium Phosphate ◽

Biphasic Calcium Phosphate ◽

Reaction Rate ◽

Ceramic Materials ◽

Calcium Phosphate Ceramics ◽

Fine Powders ◽

Beta Tricalcium Phosphate ◽

Sbf Solution ◽

New Phase

Biphasic calcium phosphate (BCP) ceramics, a mixture of hydroxyapatite (HAp) and beta-tricalcium phosphate (β-TCP), of varying HAp/β-TCP ratios were prepared from fine powders. Porous BCP ceramic materials with HAp/β-TCP weight rations of 20/80, 40/60, and 80/20 were prepared. In this study, the bioactivity is reduced at a larger HAp content rate, which is likely related to the high driving pore for the formation of a new phase, and the reaction rate was proportional to the β-TCP. The porous BCP ceramics having a bigger porosity rate can easily under up dissolution. The powder having a larger β-TCP content rate can easily generate a new phase. The dissolution results confirmed that the biodegradation of calcium phosphate ceramics could be controlled by simply adjusting the amount of HAp or β-TCP in the ceramics and porosity rate.

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Innovative Preparation Calcium Hydroxyapatite from Duck Eggshell via Pyrolysis

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.851.8 ◽

2016 ◽

Vol 851 ◽

pp. 8-13

Author(s):

Nuchnapa Tangboriboon ◽

Jularpar Suttiprapar

Keyword(s):

Calcium Carbonate ◽

Calcium Phosphate ◽

High Purity ◽

Average Particle Size ◽

Calcium Hydroxyapatite ◽

Environmental Conservation ◽

Raw Material ◽

Carbonate Content ◽

Average Particle ◽

Ceramic Yield

Calcium hydroxyapatite made from duck eggshell react to phosphoric acid with the Ca/P mole ratio 1.67 and calcined at 800º, 900º, and 1000°C for each temperature 2 hr. Duck eggshell is a source of calcium carbonate having high purity content more than 98.101 %w/w and small amount of other metal oxides. Duck eggshell is a bio-material similar to other calcium sources i.e. coral, animal bone, and seashell. There are many advantages of using duck eggshell as a raw material such as abundant, low price, high purity of calcium carbonate content, easy to calcium phosphate formation, biocompatibility, bioactive, non-toxic for human, and the high percentage of ceramic yield 69.73%w/w. In addition, one of the most important advantages is to reduce the amount of duck eggshell waste from household and food industries as environmental conservation. The optimum condition to obtain high purity hydroxyapatite is sintering calcium phosphate at 1000°C for 2 hr. The average particle size, specific surface are, pore diameter, and true density of sample sintered at 1000°C for 2 hr are 39.92 µm, 2.12 m2/g, 98.96 Å, 3.02 g/cm3, respectively, in soft fine white powder. Furthermore, the results obtained by XRF, SEM, and XRD confirmed of sample fired at 1000°C for 2 hr to be calcium hydroxyapatite (HA, Ca10(PO4)6(OH)2) of Ca/P mole ratio 1.67 and small amount of calcium phosphate (β-TCP, Ca3PO4) of Ca/P mole ratio 1.5. Therefore, the duck eggshell is a potentially bio-ceramic material to prepare calcium hydroxyapatite applied for biomedical, bio-dental, and many industries i.e. pharmaceutical, toothpaste, cosmetic, and nutrient food etc.

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Milwaukee Shoulder Syndrome

Case Reports in Rheumatology ◽

10.1155/2014/458708 ◽

2014 ◽

Vol 2014 ◽

pp. 1-4

Author(s):

Channa Vasanth Nadarajah ◽

Immo Weichert

Keyword(s):

Calcium Phosphate ◽

Rotator Cuff ◽

Synovial Fluid ◽

Shoulder Pain ◽

Calcium Hydroxyapatite ◽

Shoulder Syndrome ◽

Radiographic Changes ◽

Hydroxyapatite Crystals

Milwaukee shoulder syndrome (MSS) is a rare destructive, calcium phosphate crystalline arthropathy. It encompasses an effusion that is noninflammatory with numerous aggregates of calcium hydroxyapatite crystals in the synovial fluid, associated with rotator cuff defects. We describe a patient that presented with recurrent shoulder pain and swelling with characteristic radiographic changes and MSS was confirmed on aspiration of the synovial fluid.

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Preparation of Porous HA/Beta-TCP Biphasic Bioceramic Using a Molten Salt Process

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.309-311.1075 ◽

2006 ◽

Vol 309-311 ◽

pp. 1075-1078 ◽

Cited By ~ 5

Author(s):

Ren Jei Chung ◽

M.F. Hsieh ◽

K.C. Huang ◽

Fong In Chou ◽

L.H. Perng

Keyword(s):

Calcium Phosphate ◽

Molten Salt ◽

Subcutaneous Implantation ◽

X Ray Diffraction ◽

Beta Tricalcium Phosphate ◽

A Value ◽

Molten Sodium ◽

Controlled Porosity ◽

Diffraction Patterns ◽

Precursor Powders

Bioceramics based on calcium phosphate is convinced to be well biocompatible after abundant researches. In this study, a biphasic bioceramic block (10 mm by 5 mm) (BBB) composed of hydroxyapatite and beta-tricalcium phosphate (40/60 in wt%) was prepared using a molten salt approach. At 800oC, the molten sodium chloride well helped the sintering of the precursor powders. A second calcination at 1000oC was then used to evaporate the salt so that a pure biphasic bioceramic block was obtained. This approach can provide porous BBB with 60% porosity, and powder x-ray diffraction patterns ensured the phasic compositions. However, the electrom probe microanalysis showed that around 2 at% of sodium was retained in the BBB. Scanning electron microscope revealed well-dispersed connective micro-pores of 3 micron and random macro-pores of >100 micron in the BBB. Because the salt was evaporated during the preparation of the BBB, the spatial voids were created, and, as a result. The compressive strength of the BBB can only reach a value of 3 MPa. Subcutaneous implantation of the BBB in mice showed that both acute and chronic imflammation were mild. In summary, the molten salt approach is feasible to fabricate biphasic calcium phosphate ceramics having controlled porosity.

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