Thermogravimetric and thermokinetic investigation of the dehydroxylation of a hydroxyapatite powder

Wang, Tao; Dorner-Reisel, Annett; Müller, Eberhard

doi:10.1016/s0955-2219(03)00248-6

Cited by 74 publications

(49 citation statements)

References 30 publications

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“…The second mass loss stage, starting above~600°C in HA and at 900°C in HA10Y, is attributed to progressive dehydroxylation, in agreement with other results reported for different types of HA [1,6,35]. Since the onset temperature of the HA dehydroxylation is shifted by the processing conditions, such as: preparation method of the starting powder, impurities, sintering atmosphere and heating rate, and the Y 2 O 3 addition is just the processing parameter distinguishing the HA10Y compacts from the HA ones, the shift of the dehydroxylation to~900°C is tentatively attributed to the Y 2 O 3 addition.…”

Section: Thermal Analysissupporting

confidence: 92%

“…No meaningful exothermic or endo thermic peaks were observed. The initial mass loss up to ~400°C is attributed to the removal of water adsorbed in the surface and pores (up to 200 °C) [1,35] and the loss of lattice water in the rage 200 400 °C. In the case of HA this mass loss is accompanied by a broad exothermic peak centered at ~350 °C in the DTA curve, which is attributed to burning of the re sidual dispersant present in the green compact.…”

Section: Thermal Analysismentioning

confidence: 99%

“…The thermal stability of hydroxyapatite (HA), Ca 10 (PO 4 ) 6 (OH) 2 , is a major concern for fabricating HA implants and coatings because the thermal decomposition on their processing modifies the prop erties of the HA materials, in particular the biomedical ones [1,2]. The decomposition of HA on heating proceeds in two stages: (1) partial dehydration yielding oxyhydroxyapatite (OHA) and water, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…The decomposition of HA on heating proceeds in two stages: (1) partial dehydration yielding oxyhydroxyapatite (OHA) and water, i.e. Ca 10 (PO 4 ) 6 (OH) 2(1-x) O x □ x +xH 2 O(□ denotes noncharged va cancies), followed by complete dehydroxylation that transforms OHA into oxyapatite (OA), Ca 10 (PO 4 ) 6 O□, which is unstable and quickly rehydrates to OHA in air [1,3], and (2) subsequent irrevers ible decomposition of OHA along with HA in calcium phosphates [1,2,4 6]. The works reported about the thermal behavior of HA are mostly focused on the second stage, because it has a strong effect on the mechanical properties [2,7], chemical activity [8] and stability of HA within living organisms [9].…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, the effect of dehydration on the properties of HA materials is often overlooked [2,4 6]. During the dehydration stage of HA, the progressive loss of hydroxyl groups in OHA can shift the temperature of the subsequent decomposition of OHA+HA into calcium phosphates drastically [1]. The study of decom position mechanisms is thus of key importance to optimize the process ing of HA materials.…”

Section: Introductionmentioning

confidence: 99%

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Effect of highly dispersed yttria addition on thermal stability of hydroxyapatite

Parente

Savoini

Ferrari

et al. 2013

Materials Science and Engineering: C

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Abstract:The capability of the colloidal method to produce yttria (Y 2 O 3 ) dispersed hydroxyapatite (HA) has been in vestigated as an alternative method to the conventional method of mechanical mixing and sintering for de veloping HA based materials that could exhibit controllable and enhanced functional properties. A water based colloidal route to produce HA materials with highly dispersed Y 2 O 3 has been applied, and the effect of 10 wt.% Y 2 O 3 addition to HA investigated by thermal analysis, X ray diffraction and Fourier transform in frared spectroscopy. These measurements evidence a remarkable effect of this Y 2 O 3 addition on decomposi tion mechanisms of synthetic HA. Results show that incorporation of Y 2 O 3 as dispersed second phase is beneficial because it hinders the decomposition mechanisms of HA into calcium phosphates. This retardation will allow the control of the sintering conditions for developing HA implants with improved properties. Be sides, substitution of Ca 2+ with Y 3+ ions appears to promote the formation of OH − vacancies, which could improve the conductive properties of HA favorable to osseointegration.

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Section: Thermal Analysissupporting

confidence: 92%

Section: Thermal Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Effect of highly dispersed yttria addition on thermal stability of hydroxyapatite

Parente

Savoini

Ferrari

et al. 2013

Materials Science and Engineering: C

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Structure and Surface Study of Hydroxyapatite‐Based Materials

Costentin

Drouet

Salles

et al. 2022

Design and Applications of Hydroxyapatite‐Based Catalysts

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In addition to designing catalytic materials ever more active and selective, the emergence of new classes of greener catalysts remains very challenging. The apatite family system with hydroxyapatite (HA) structure appears as a good candidate for catalysis due to its ecocompatibility properties, its sorption ability toward organic molecules, and its tunable composition resulting into modulation of its surface properties. Depending on their mode of preparation, these inexpensive and environment-friendly apatitic calcium phosphates exhibit properties of relevance to catalysis, such as large surface area and various morphologies.However, most studies focused so far on the catalytic performance of these compounds, while the study of structure-reactivity relationships required for rationalized optimization remains rather limited. This chapter aims at providing tools to help understand the catalytic behavior of apatite compounds, giving details about their structure, surface properties, and reactivity; this will include both stoichiometric and nonstoichiometric compounds, sometimes biomimetic and potentially substituted. A special attention is dedicated to recent advances in the characterization of their structural properties (bulk and surface/interphase) that have a strong impact on their reactivity, through both experimental and computational approaches to study the mechanisms occurring in the structure or at the crystals surface, as well as thermodynamic and dynamical properties. Remaining characterization challenges for apatite-based catalysts will also be discussed. 1.an influence on the charges carried by the cation and on the related strength of the Ca-O interaction [127], which results in different adsorption properties with guest molecules. To go further, quantum calculations coupled with NMR (Nuclear Magnetic Resonance) resultsshowed the impact of the presence of OHions on the migration of Ca 2+ as well as the rotation of PO4 3groups [128]. In the hydroxyapatite structure, phosphate ions PO4 3are the largest components of the structure. As such, they provide a primary backbone via 3D compact-like piling, generating interstitial sites for the other ions of the structure. Metal cations such as Ca 2+ occupy two types of crystallographic sites, denoted Ca1 (4 sites per unit formula) and Ca2 (6 sites per unit formula), see Figure 2. Ca1 sites are localized along the trigonal axis with the coordinates (1/4, 3/4, 1/2) and (3/4, 1/4, 1/2), forming linear columns along the c-axis. Ca2 sites in contrast form equilateral triangles at z = 1/4 and z = 3/4 on the sixfold screw (senary) 63 axes. Adjacent Ca1 and Ca2 sites are linked through shared oxygen atoms from PO4 tetrahedra. Ca1 sites generate (distorted) polyhedra where the metal ion is in ninefold coordination, while in Ca2 sites it is in sevenfold coordination.The Ca2 triangles contribute to delimit so-called "apatitic channels" where ions such as OHare axially located (Figure 3) [116,120]. In calcium hydroxyapatite, the Ca2 triangular sites correspond to the narrow...

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Short Fiber Reinforced Hydroxyapatite‐based Bioceramics

2004

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25 mm. The hot pressed sample showed a threefold higher strength and Young's modulus than the pressureless sintered samples, see Table 1.Conclusions: Studies were described to find an innovative route for fabricating C/SiC composites by using electrophoresis for infiltrating carbon fiber mats with a slurry of a very fine silicon carbide powder mixed with sintering aids (carbon black and boron carbide) and stabilized by polyethylene imine. It was shown that by means of well-dispersed, stable suspensions a high degree of infiltration of all spaces within the fiber rovings were achieved. For this purpose solid contents of > 10 vol% was more effective than lower contents. The formation of multilayer structures by lamination of single infiltrated fiber mats was demonstrated.

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Thermogravimetric and thermokinetic investigation of the dehydroxylation of a hydroxyapatite powder

Cited by 74 publications

References 30 publications

Effect of highly dispersed yttria addition on thermal stability of hydroxyapatite

Effect of highly dispersed yttria addition on thermal stability of hydroxyapatite

Structure and Surface Study of Hydroxyapatite‐Based Materials

Short Fiber Reinforced Hydroxyapatite‐based Bioceramics

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