Crystal Structure and Site Preference of Ba‐Doped α‐Tricalcium Phosphate (Ca1‐xBax)3(PO4)2 Through High‐Resolution Synchrotron Powder Diffraction (x = 0.05 to 0.15).

Yashima, Masatomo; Kawaike, Yoichi

doi:10.1002/chin.200742003

Cited by 8 publications

(8 citation statements)

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“…Ca-17 sites of a-TCP [33]. In this regard, the present calculations cannot attain complete agreement with the experiment.…”

Section: Defect Formation Energies In the Solid-solid Equilibriumcontrasting

confidence: 73%

First-principles calculations of divalent substitution of Ca2+ in tricalcium phosphates

et al. 2015

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“…Ca-17 sites of a-TCP [33]. In this regard, the present calculations cannot attain complete agreement with the experiment.…”

Section: Defect Formation Energies In the Solid-solid Equilibriumcontrasting

confidence: 73%

First-principles calculations of divalent substitution of Ca2+ in tricalcium phosphates

et al. 2015

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“…The Ba-doped Ca 3 (PO 4 ) 2 phase was obtained over the range of (Ca 0.95‑ y Ba y ) 3 (PO 4 ) 2 :0.05Eu 2+ (0 ≤ y ≤ 0.132), where Ba doping stabilizes the high-temperature α form to room temperature. Also, crystal structure analysis of (Ca 1– x Ba x ) 3 (PO 4 ) 2 ( x = 0.05–0.15) through synchrotron diffraction has been performed, showing that the cell parameters a , b , c , and β increase with more Ba doping. However, a higher Ba/Ca ratio would induce new phases formation (such as Ba 3 Ca 3 (PO 4 ) 4 and Ba 2 Ca(PO 4 ) 2 ) with other crystal structures.…”

Section: Results and Discussionmentioning

confidence: 99%

Discovery of New Solid Solution Phosphors via Cation Substitution-Dependent Phase Transition in M₃(PO₄)₂:Eu²⁺ (M = Ca/Sr/Ba) Quasi-Binary Sets

et al. 2015

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The cation substitution-dependent phase transition was used as a strategy to discover new solid solution phosphors and to efficiently tune the luminescence property of divalent europium (Eu2+) in the M3(PO4)2:Eu2+ (M = Ca/Sr/Ba) quasi-binary sets. Several new phosphors including the greenish-white SrCa2(PO4)2:Eu2+, the yellow Sr2Ca(PO4)2:Eu2+, and the cyan Ba2Ca(PO4)2:Eu2+ were reported, and the drastic red shift of the emission toward the phase transition point was discussed. Different behavior of luminescence evolution in response to structural variation was verified among the three M3(PO4)2:Eu2+ joins. Sr3(PO4)2 and Ba3(PO4)2 form a continuous isostructural solid solution set in which Eu2+ exhibits a similar symmetric narrow-band blue emission centered at 416 nm, whereas Sr2+ substituting Ca2+ in Ca3(PO4)2 induces a composition-dependent phase transition and the peaking emission gets red shifted to 527 nm approaching the phase transition point. In the Ca3–x Ba x (PO4)2:Eu2+ set, the validity of crystallochemical design of phosphor between the phase transition boundary was further verified. This cation substitution strategy may assist in developing new phosphors with controllably tuned optical properties based on the phase transition.

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“…94 At temperatures exceeding 1430 °C, α-TCP transforms to α′-TCP, the third and the final TCP polymorph, which, unlike α-TCP, cannot be quenched down to room temperature as a metastable phase. 95 All three of these TCP polymorphs exhibit comparatively similar, but distinguishable XRD patterns. 96 At 800 °C, β-TCP became a dominant phase in the system, regardless of whether the precursor was ACP or HAp, but so did α-TCP, the phase that usually forms at much higher temperatures than 800 °C (Figures 3 and 4).…”

Section: Crystal Growth and Designmentioning

confidence: 95%

Disordering the Disorder as the Route to a Higher Order: Incoherent Crystallization of Calcium Phosphate through Amorphous Precursors

Uskoković

2019

Crystal Growth & Design

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Understanding the stability and phase transformations of amorphous materials may open the way toward structurally complex, nonequilibrium structures that are the future of materials science. Elucidating the ultrafine specifics of the transition of amorphous calcium phosphate (ACP) to hydroxyapatite (HAp) and other crystalline calcium phosphate (CP) phases may also pave the way for the development of nondrug, acellular, and purely materials-based therapies for a number of osteopathic conditions. Reports on classical and nonclassical mechanisms of nucleation and growth of HAp abound, but here it is shown that these two modes of growth are wedded during the crystallization of HAp from an amorphous precursor. This process combines growth via ionic units, atomic clusters, and spheroid amorphous nanoparticles of variable sizes as well as via internal lattice rearrangements and is typified by a mechanistic multiplicity that agrees well with the pleiotropy and protean nature of this material. Formation and retention of the α-polymorph of tricalcium phosphate (TCP) exclusively in a material formed through amorphous precursors under a specific annealing regimen and the diffractometric pattern matching indicated that ACP structurally resembles α-TCP more than β-TCP or HAp. Crystallographic symmetry comparison between HAp and α-TCP-like ACP was provided in support of this match, primarily focusing on the greater void concentration in α-TCP than in other TCP polymorphs and the similarities in the pseudohexagonal arrangement of ionic columns in HAp and α-TCP. The elimination of structural water correlated with the closing of the amorphous structure in the first stages of phase transformation and was entailed by the red shift of P–O stretches and the blue shift of the O–P–O bending vibration modes as well as by the reduction of the high-index (434) and (264) lattice constants of α-TCP-like ACP. Meanwhile, the environment around Ca–O and OH groups varied less during the early stages of crystallization, suggesting that the rearrangement of heavier and more kosmotropic phosphates governs the structural transition, while more chaotropic calcium and hydroxyl ions act as diffusive fillers of the phosphate network. While the structure suddenly opened in parallel with the formation of first crystalline products at high temperature, its closing accompanied by a nonlinear reduction in crystalline order preceded the transition. The path connecting the initial, amorphous state and the final, crystalline one is, therefore, not coherent, and some structural order established in the amorphous structure during aging at room temperature must first be annihilated under the inflow of thermal energy before a longer-lasting order in the material can emerge. These results imply that there is either none or partial continuity between the recovery process under ambient conditions and the recovery process under high-temperature conditions. Last but not least, the reduction of crystallinity as a step preceding its sudden increase attests to the presence...

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Crystal Structure and Site Preference of Ba‐Doped α‐Tricalcium Phosphate (Ca_1‐xBa_x)₃(PO₄)₂ Through High‐Resolution Synchrotron Powder Diffraction (x = 0.05 to 0.15).

Abstract: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Cited by 8 publications

References 1 publication

First-principles calculations of divalent substitution of Ca2+ in tricalcium phosphates

First-principles calculations of divalent substitution of Ca2+ in tricalcium phosphates

Discovery of New Solid Solution Phosphors via Cation Substitution-Dependent Phase Transition in M₃(PO₄)₂:Eu²⁺ (M = Ca/Sr/Ba) Quasi-Binary Sets

Disordering the Disorder as the Route to a Higher Order: Incoherent Crystallization of Calcium Phosphate through Amorphous Precursors

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Crystal Structure and Site Preference of Ba‐Doped α‐Tricalcium Phosphate (Ca1‐xBax)3(PO4)2 Through High‐Resolution Synchrotron Powder Diffraction (x = 0.05 to 0.15).

Abstract: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Cited by 8 publications

References 1 publication

First-principles calculations of divalent substitution of Ca2+ in tricalcium phosphates

First-principles calculations of divalent substitution of Ca2+ in tricalcium phosphates

Discovery of New Solid Solution Phosphors via Cation Substitution-Dependent Phase Transition in M3(PO4)2:Eu2+ (M = Ca/Sr/Ba) Quasi-Binary Sets

Disordering the Disorder as the Route to a Higher Order: Incoherent Crystallization of Calcium Phosphate through Amorphous Precursors

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Crystal Structure and Site Preference of Ba‐Doped α‐Tricalcium Phosphate (Ca_1‐xBa_x)₃(PO₄)₂ Through High‐Resolution Synchrotron Powder Diffraction (x = 0.05 to 0.15).

Discovery of New Solid Solution Phosphors via Cation Substitution-Dependent Phase Transition in M₃(PO₄)₂:Eu²⁺ (M = Ca/Sr/Ba) Quasi-Binary Sets