Variations of structure and composition in magnesium incorporated hydroxyapatite/β-tricalcium phosphate

2006 ◽  
Vol 21 (2) ◽  
pp. 428-436 ◽  
Author(s):  
Hyun-Seung Ryu ◽  
Kug Sun Hong ◽  
Jung-Kun Lee ◽  
Deug Joong Kim
Keyword(s):  
Phase Transition ◽  
Tricalcium Phosphate ◽  
Phase Evolution ◽  
Processing Parameters ◽  
Solubility Limit ◽  
Mode Analysis ◽  
X Ray Diffraction ◽  
Mg Addition ◽  
Tcp Phase ◽  
Mg Content

The phase evolution of magnesium incorporated hydroxyapatite/β-tricalcium phosphate (HA/β-TCP) ceramics of high purity prepared by solid-state reaction was investigated with the aid of x-ray diffraction and infrared spectroscopy (IR) in transmittance mode analysis. The dependence of the microstructure on the phase evolution of biphasic ceramics during natural sintering was also investigated as a function of Mg content. When sintered at 1100 °C, Mg is preferentially incorporated into the β-TCP phase rather than the HA phase. This Mg incorporation into the β-TCP effectively suppresses the phase transition from β- to α-TCP. With increasing sintering temperature, the solubility limit of the Mg in the β-TCP decreases and Mg starts to be either incorporated into the HA phase or segregated as free MgO. The decreased Mg content in the β-TCP facilitates the phase transition from β- into α-TCP, at 1300 °C or higher. Different processing methods on Mg addition show that the retarded phase transition from β- to α-TCP is the inherent property of Mg-doped HA/TCP. The variations in processing parameters mainly affect the microstructure instead of the phase evolution, leading to highly densified HA/β-TCP ceramics.

Influence of Zn and Mg Doping on the Sintering Behavior and Phase Transformation of Tricalcium Phosphate Based Ceramics

2014 ◽  
Vol 805 ◽  
pp. 706-711 ◽  
Author(s):  
Karen C. Kai ◽  
Carlos A.V.A. Machado ◽  
Luis Antonio Genova ◽  
Juliana Marchi
Keyword(s):  
Phase Transformation ◽  
Tricalcium Phosphate ◽  
Sintering Behavior ◽  
Drying Process ◽  
Zn Doping ◽  
Wet Chemical Synthesis ◽  
Mg Addition ◽  
Tcp Phase ◽  
Wet Chemical ◽  
Dilatometric Studies

β-tricalcium phosphate based ceramics (β-TCP) are resorbable biomaterials used as bone substitutive materials. Several ions can substitute specific Ca positions in the crystalline structure of TCP, so that general Me-TCP can be obtained. Particularly, magnesium can increase the temperature of β-α-TCP transformation while zinc stimulates the bone formation. In this work, the influence of magnesium or zinc ions on the sintering behavior of Me-TCP was investigated. The powders were produced through wet chemical synthesis with a freeze drying process. The powders were calcined and subsequently uniaxially pressed into pellets. The pellets were sintered up to 1300°C/1h. The influence of Mg or Zn doping was investigated by dilatometric studies, thermal analysis and XRD. The microstructure was evaluated through SEM. The results suggest that Mg increased temperature of β-α-TCP phase transformation. The Me-doped TCP samples can be considered as promising biomaterials, having stimulatory effect of Zn or suitable densification due to Mg addition.

Preparation of Porous Biphasic Tricalcium Phosphate and Its In Vivo Behavior

2005 ◽  
Vol 284-286 ◽  
pp. 281-284 ◽  
Author(s):  
Masanobu Kamitakahara ◽  
Chikara Ohtsuki ◽  
M. Oishi ◽  
Shinichi Ogata ◽  
Toshiki Miyazaki ◽  
...  
Keyword(s):  
Tricalcium Phosphate ◽  
Ceramic Body ◽  
Potato Starch ◽  
Bone Substitutes ◽  
The Body ◽  
In Vivo Experiments ◽  
Tcp Phase ◽  
Biphasic Ceramic ◽  
Mg Content

Biphasic ceramic consisting of tricalcium phosphate with α- and β -phases (αβ-TCP) is a candidate as biodegradable bone substitutes since its biodegradability may be controlled by the ratio of the phases. In the present study, preparation of porous αβ-TCP body with continuous pores of 10-50 µm in diameter was attempted using additives of Mg, and its in vivo behavior was examined. Powder of β-TCP was mixed with Mg and potato starch to form slurry, followed by loading in polyurethane foam. The sample was fired at 1400°C for 12 hours for sintering process. α-TCP content of the sample decreased with increasing the Mg content, while β-TCP increased. Ceramic body consisting of β-TCP phase was obtained when 1.0 mass% of Mg was added. Porosity of the body decreased with increasing the content of Mg. The αβ-TCP body with 80% porosity was obtained when the content of Mg was 0.1 mass%. The in vivo experiments showed that the rate of degradation of the obtained αβ-TCP was almost same as α-TCP, and much higher than β-TCP.

In Situ X-Ray Diffraction Study of Phase Development during Hardening of β-Tricalcium Phosphate Bone Cements with Chitosan

2013 ◽  
Vol 587 ◽  
pp. 109-114 ◽  
Author(s):  
Marina Salvarani Tonoli ◽  
Marisa Masumi Beppu
Keyword(s):  
Phase Transformation ◽  
Tricalcium Phosphate ◽  
Chitosan Solution ◽  
Phase Evolution ◽  
Dicalcium Phosphate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Setting Reaction ◽  
Phase Development ◽  
First Moment

The aim of this work was to study the phase transformation during the setting reaction of beta tricalcium phosphate (β-TCP) and phosphoric acid with chitosan solution added. To follow the kinetics of the phase transformation, two methods were used: x-ray diffraction (XRD) was used to study the phase evolution during the hardening process in real time, and was also used in samples where the reaction was supposedly stopped in different times using acetone, as indicated in literature. The setting reaction occurs so fast that the phase transformation could not be observed, but it was possible to invalidate the second mentioned method for this system, as it induces the final product dicalcium phosphate dihydrate DCPD (brushite) to be converted into his anhydrous form dicalcium phosphate DCP (monetite). The addition of chitosan in order to improve biocompatibility was successfully done, it could be observed that chitosan inhibitsbrushitecrystallization in the first moment of the reaction, but the final product was not affected by it.

X-ray diffraction study of the phase transition of K2Mn2(BeF4)3: a new type of low-temperature structure for langbeinites

2001 ◽  
Vol 57 (3) ◽  
pp. 221-230 ◽  
Author(s):  
A. Guelylah ◽  
G. Madariaga ◽  
V. Petricek ◽  
T. Breczewski ◽  
M. I. Aroyo ◽  
...  
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Mode Analysis ◽  
Cubic Phase ◽  
Temperature Phase ◽  
Temperature Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Type ◽  
Low Temperature Phase

The potassium manganese tetrafluoroberyllate langbeinite compound has been studied in the temperature range 100–300 K. Using DSC measurements, a phase transition has been detected at 213 K. The space group of the low-temperature phase was determined to be P1121 using X-ray diffraction experiments and optical observations of the domain structure. The b axis is doubled with respect to the prototypic P213 cubic phase. Lattice parameters were determined by powder diffraction data [a = 10.0690 (8), b = 20.136 (2), c = 10.0329 (4) Å, γ = 90.01 (1)°]. A precise analysis of the BeF4 tetrahedra in the low-temperature phase shows that two independent tetrahedra rotate in opposite directions along the doubled crystallographic axis. A symmetry mode analysis of the monoclinic distortion is also reported. This is the first report of the existence of such a phase transition in K2Mn2(BeF4)3 and also of a new type of low-temperature structure for langbeinite compounds.

scholarly journals Effects of barium substitution on the sintering behavior, dielectric properties of Ca2Nb2O7 ferroelectric ceramics

2017 ◽  
Vol 07 (02) ◽  
pp. 1750013 ◽  
Author(s):  
Chunchun Li ◽  
Huaicheng Xiang ◽  
Yuandong Qin ◽  
Liang Fang
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Secondary Phase ◽  
Solubility Limit ◽  
Ferroelectric Ceramics ◽  
Sintering Behavior ◽  
X Ray Diffraction ◽  
Spectroscopy Analysis ◽  
X Ray

Barium-doped Ca2Nb2O7 ceramics were prepared in the form of Ca[Formula: see text]BaxNb2O7 (0 [Formula: see text] 0.6) by solid-state reaction. The solubility limit of barium in Ca2Nb2O7 was found to be [Formula: see text] based on X-ray diffraction and Raman spectroscopy analysis. When [Formula: see text] 0.4, Ca[Formula: see text]BaxNb2O7 solid solutions with a monoclinic perovskites-like layered structure (PLS) were formed, whereas beyond [Formula: see text], a secondary phase CaNb2O6 was detected. The dielectric properties obviously depended on the barium substitution. With increasing barium amount, the dielectric constant increased from 33.5 for pure Ca2Nb2O7 to 38.6 for [Formula: see text] ([Formula: see text][Formula: see text]MHz). The Curie temperature ([Formula: see text] of the [Formula: see text] sample was 1280[Formula: see text][Formula: see text][Formula: see text]5[Formula: see text]C. The phase transition was confirmed to be the second order.

Phase Transition Behaviour of Tricalcium Phosphate (TCP) Doped with MgO and TiO2 as Additives

2006 ◽  
Vol 530-531 ◽  
pp. 581-586 ◽  
Author(s):  
D.M.B. Wolff ◽  
E.G. Ramalho ◽  
Wilson Acchar
Keyword(s):  
Phase Transition ◽  
Relative Density ◽  
Tricalcium Phosphate ◽  
Thermal Process ◽  
X Ray Diffraction ◽  
Phosphate Powder ◽  
X Ray ◽  
Air Atmosphere ◽  
Transition Behaviour ◽  
Scanning Electron

In this study, the tricalcium phosphate [β-Ca3(PO4)2] behaviour using MgO and TiO2, respectively as additives has been investigated. The introduction of these additives is to control the phase transition of TCP during thermal process. The tricalcium phosphate (β,α) phases change when the temperature of sintering increase and/or during cooling down. To investigate the phase transition we examined tricalcium phosphate powder doped using 5 mol % of MgO or TiO2. The β-TCP and additives powders were mixture with acetone and dried using rota-vapour to eliminate all the solvent at 45°C for 3 h. After this procedure the powders were uniaxially pressed at 50 MPa and sintered in air-atmosphere at 1100°C to 1200°C for 5 h. All the sintered compacts were measurements by relative density, porosity, shrinkage, shrinkage rate, and the polished and fracture surfaces were investigated using a scanning electron microscope (SEM). To verify the transition phase the differential thermal analysis (DTA) and X-ray diffraction studies were carried out. The experimental results of relative density showed 92 % (MgO) and 90 % (TiO2) at 1200°C.

Controllable Synthesis of Different Bismuth Ferrites by a PVA Modified Hydrothermal Method and Photocatalytic Characterization

2013 ◽  
Vol 1552 ◽  
pp. 35-41 ◽  
Author(s):  
Tong Tong ◽  
Dengren Jin ◽  
Jinrong Cheng
Keyword(s):  
Hydrothermal Method ◽  
Phase Evolution ◽  
Xrd Analysis ◽  
Processing Parameters ◽  
X Ray Diffraction ◽  
Light Region ◽  
Wide Range ◽  
The Individual ◽  
Degradation Effect ◽  
Modified Hydrothermal Method

ABSTRACTBismuth ferrites crystallites were synthesized by a polyvinyl alcohol (PVA) modified hydrothermal method. X-ray diffraction (XRD) analysis indicated that the pure phase of Bi25FeO40, BiFeO3 and Bi2Fe4O9 were synthesized with initial Bi/Fe ratio of 1:1 at the temperature of 200°C for 24 h, using NaOH concentration of 2, 5 and 10 M, respectively. With addition of PVA, the individual Bi-Fe oxides could be existed in a more wide range of processing parameters. The phase evolution of bismuth ferrites in the process of hydrothermal reactions was discussed. Moreover, photocatalytic properties of the bismuth ferrites crystallites were explored. The results showed that they possessed band gaps of about 2.0 eV and performed good degradation effect at visible light region.

The effect of reaction conditions on formation of wet precipitated calcium phosphates

2015 ◽  
Vol 29 (10n11) ◽  
pp. 1540017
Author(s):  
Chen Huang ◽  
Peng Cao
Keyword(s):  
Calcium Phosphates ◽  
Homogeneous Medium ◽  
Phase Evolution ◽  
Processing Parameters ◽  
Alkaline Solutions ◽  
Precipitation Process ◽  
X Ray Diffraction ◽  
Sample Characterization ◽  
Ph Buffer ◽  
Ph Level

The precipitation process discussed in the present study involves the addition of alkaline solutions to an acidic calcium phosphate suspension. Several parameters (pH, pH buffer reagent, ageing and stirring) were investigated. The synthesized powders were calcined at 1000°C for 1 h in air, in order to study the thermal stability and crystalline phase compositions. X-ray diffraction (XRD) and ESEM analysis were used for sample characterization. It is found that all these processing parameters affect the crystalline phases evolved and resultant microstructures. Phase evolution occurred at an elevated pH level. The pH buffer reagent would affect both the phase composition and microstructure. Ageing was essential for the phase maturation. Stirring accelerated the reaction process by providing a homogeneous medium for precipitation.

Electron Microscope study of commensurate-incommensurate phase transition in BaZnGeO4

1990 ◽  
Vol 48 (4) ◽  
pp. 172-173
Author(s):  
Naoki Yamamoto ◽  
Makoto Kikuchi ◽  
Tooru Atake ◽  
Akihiro Hamano ◽  
Yasutoshi Saito
Keyword(s):  
Phase Transition ◽  
Electron Microscope Study ◽  
Room Temperature ◽  
Hexagonal Lattice ◽  
Ferroelectric Materials ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Periodic Arrays ◽  
Modulation Wave Vector

BaZnGeO4 undergoes many phase transitions from I to V phase. The highest temperature phase I has a BaAl2O4 type structure with a hexagonal lattice. Recent X-ray diffraction study showed that the incommensurate (IC) lattice modulation appears along the c axis in the III and IV phases with a period of about 4c, and a commensurate (C) phase with a modulated period of 4c exists between the III and IV phases in the narrow temperature region (—58°C to —47°C on cooling), called the III' phase. The modulations in the IC phases are considered displacive type, but the detailed structures have not been studied. It is also not clear whether the modulation changes into periodic arrays of discommensurations (DC’s) near the III-III' and IV-V phase transition temperature as found in the ferroelectric materials such as Rb2ZnCl4.At room temperature (III phase) satellite reflections were seen around the fundamental reflections in a diffraction pattern (Fig.1) and they aligned along a certain direction deviated from the c* direction, which indicates that the modulation wave vector q tilts from the c* axis. The tilt angle is about 2 degree at room temperature and depends on temperature.

Formation and phase evolution of calcium phosphates modulated by ion exchange ionomer Nafion

CrystEngComm ◽  
2020 ◽  
Vol 22 (47) ◽  
pp. 8243-8250
Author(s):  
Shuquan Sun ◽  
Qixuan Chen ◽  
Qijun Song
Keyword(s):  
Phase Transition ◽  
Ion Exchange ◽  
Calcium Phosphates ◽  
Phase Evolution

The phase transition of calcium phosphates regulated by Nafion with the inherent acidity and ion exchange features.

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