Ferroelectric polarization of hydroxyapatite from density functional theory

Hu, Shunbo; Jia, Fanhao; Marinescu, Cornelia; Cimpoesu, Fanica; Qi, Yuting; Tao, Yongxue; Stroppa, Alessandro; Ren, Wei

doi:10.1039/c7ra01900a

Cited by 43 publications

(27 citation statements)

References 38 publications

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“…The results obtained with the hybrid functional are almost the same as those obtained in a previous work, with small differences due to the different tolerances here employed. The lattice results obtained in the PW/PBEsol framework are also in line with those reported by Hu and coworkers, using the same basis set and DFT functional …”

Section: Resultssupporting

confidence: 89%

Second‐order elastic constants of hexagonal hydroxylapatite (P6₃) fromab initioquantum mechanics: Comparison between DFT functionals and basis sets

Ulian

Valdrè

2017

Int J of Quantum Chemistry

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Three very popular Hamiltonians in the density functional theory framework, PBE, PBEsol, and B3LYP, and different basis sets (Gaussian‐type orbitals and plane waves) were employed to simulate the hydroxylapatite unit cell and its second‐order elastic constants. Dispersive interactions were included in the quantum‐mechanical treatment via the DFT‐D2 and Tkatchenko‐Scheffler schemes. The calculated bulk, shear, and Young's moduli were in the range of 82‐117 GPa, 42‐51 GPa, and 107‐134 GPa, respectively. The axial moduli, Ka and Kb, were instead in the range of 277‐322 GPa and 506‐509 GPa. The theoretical data, especially those from plan waves simulations, are in good agreement with available results in literature and further extend the knowledge of the mechanical and vibrational properties of hydroxylapatite.

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Section: Resultssupporting

confidence: 89%

Second‐order elastic constants of hexagonal hydroxylapatite (P6₃) fromab initioquantum mechanics: Comparison between DFT functionals and basis sets

Ulian

Valdrè

2017

Int J of Quantum Chemistry

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“…Hexagonal OHAp is known to be a piezoelectric material, a property related to the ordered hydroxyl group alignment in the calcium channel. According to recent studies in literature, OHAp exhibits also a ferroelectric behavior. Being a piezoelectric compound, a detailed knowledge on the mechanical properties of hydroxylapatite could be important.…”

Section: Introductionmentioning

confidence: 90%

Equation of state of hexagonal hydroxylapatite (P6₃) as obtained from density functional theory simulations

Ulian

Valdrè

2017

Int J of Quantum Chemistry

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Hydroxylapatite is an important calcium phosphate phase whose knowledge is useful in different fields, for instance in bone biology, development of biomaterials and even cultural heritage. In this work, the equation of state of this mineral was calculated by using the quasi-harmonic approximation, also including for the first time the temperature effect. In athermal conditions (0 K), we found that the pressure dependence of the hydroxylapatite unit cell volume is well described by a third-order Birch-Murnaghan formulation, with parameters K 0 5 115.9(1), K' 5 4.47(6), and V 0 5 524.323 (27). The inclusion of temperature led to a lower bulk modulus, for example, KT 0 5 109.55 GPa at 300 K. The thermal expansion coefficient between 0 and 1000 K was also reported. The results are in good agreement with the few available experimental data reported in literature and further extend the knowledge of the mechanical and thermal behavior of this important mineral. K E Y W O R D S DFT/B3LYP-D*, equation of state, hydroxylapatite, quasi-harmonic approximation, thermal expansion coefficient | I N TR ODU C TI ONThe growing interest in biomaterials and biominerals led, in recent years, to several researches aimed to unravel the mechanical properties of calcium phosphates among which hydroxylapatite (OHAp, space group P6 3 /m, Figure 1) is one of the most investigated because of its similarities to the mineral phase of bone and dental tissues. For instance, specific and peculiar experimental Raman piezo-spectroscopy were employed to better understand the microscopic processes governing the behavior of natural bone tissues (sane and osteoporotic) as well as the mechanochemical framework describing how the microstructure of synthetic biomaterials affects the failure of artificial joints. [1,2] This method can analyse the mechanical stress as stored in the apatite crystals belonging to both natural bone (sane and osteoporotic) and synthetic biomaterials by the Raman shift of the apatite (compared to unstressed apatite). Another example regards the mechanical stability and failure of hydroxylapatite/collagen fibrils nano-composite, which was simulated by molecular mechanics methods in several works of Dubey and Tomar. [3][4][5] Finally, the effects of carbonate ion on the OHAp unit cell was studied from both the structural [6][7][8][9][10] and vibrational [11][12][13][14] points of view, to better understand the differences between stoichiometric hydroxylapatite and biological apatite (which contains several CO 22 3 and other ionic substitutions). Hexagonal OHAp is known to be a piezoelectric material, a property related to the ordered hydroxyl group alignment in the calcium channel.According to recent studies in literature, [15][16][17][18] OHAp exhibits also a ferroelectric behavior. Being a piezoelectric compound, a detailed knowledge on the mechanical properties of hydroxylapatite could be important.Hydroxylapatite is also a valued material for cultural heritage purposes. Recently, it was found that this mineral could be used to...

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“…This exchange correlation functional allows also to describe the properties of electronic excitation and the energy of defect formation. Results of calculating the structure and properties of HAp by other authors are performed in [ 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ].…”

Section: Complex Point Defects Of Hap Toward Induction Of Its Surfmentioning

confidence: 99%

Physical Fundamentals of Biomaterials Surface Electrical Functionalization

et al. 2020

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This article is focusing on electrical functionalization of biomaterial’s surface to enhance its biocompatibility. It is an overview of previously unpublished results from a series of experiments concerning the effects surface electrical functionalization can have on biological systems. Saccharomyces cerevisiae cells were used for biological experiments. The hydroxyapatite (HAp) specimens were used to investigate influence of structural point defects on the surface electrical charge. Threshold photoelectron emission spectroscopy was used to measure the electron work function of HAp and biologic samples. The density functional theory and its different approximations were used for the calculation of HAp structures with defects. It was shown that the electrical charge deposition on the semiconductor or dielectric substrate can be delivered because of production of the point defects in HAp structure. The spatial arrangements of various atoms of the HAp lattice, i.e., PO4 and OH groups, oxygen vacancies, interstitial H atoms, etc., give the instruments to deposit the electrical charge on the substrate. Immobilization of the microorganisms can be achieved on the even surface of the substrate, characterized with a couple of nanometer roughness. This cells attachment can be controlled because of the surface electrical functionalization (deposition of the electrical charge). A protein layer as a shield for the accumulated surface charge was considered, and it was shown that the protein layer having a thickness below 1 µm is not crucial to shield the electrical charge deposited on the substrate surface. Moreover, the influence of surface charge on the attachment of microorganisms, when the surface roughness is excluded, and the influence of controlled surface roughness on the attachment of microorganisms, when surface charge is constant, were also considered.

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Ferroelectric polarization of hydroxyapatite from density functional theory

Cited by 43 publications

References 38 publications

Second‐order elastic constants of hexagonal hydroxylapatite (P6₃) fromab initioquantum mechanics: Comparison between DFT functionals and basis sets

Second‐order elastic constants of hexagonal hydroxylapatite (P6₃) fromab initioquantum mechanics: Comparison between DFT functionals and basis sets

Equation of state of hexagonal hydroxylapatite (P6₃) as obtained from density functional theory simulations

Physical Fundamentals of Biomaterials Surface Electrical Functionalization

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Ferroelectric polarization of hydroxyapatite from density functional theory

Cited by 43 publications

References 38 publications

Second‐order elastic constants of hexagonal hydroxylapatite (P63) fromab initioquantum mechanics: Comparison between DFT functionals and basis sets

Second‐order elastic constants of hexagonal hydroxylapatite (P63) fromab initioquantum mechanics: Comparison between DFT functionals and basis sets

Equation of state of hexagonal hydroxylapatite (P63) as obtained from density functional theory simulations

Physical Fundamentals of Biomaterials Surface Electrical Functionalization

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Second‐order elastic constants of hexagonal hydroxylapatite (P6₃) fromab initioquantum mechanics: Comparison between DFT functionals and basis sets

Second‐order elastic constants of hexagonal hydroxylapatite (P6₃) fromab initioquantum mechanics: Comparison between DFT functionals and basis sets

Equation of state of hexagonal hydroxylapatite (P6₃) as obtained from density functional theory simulations