Study of nanoscale deformation mechanisms in bulk hexagonal hydroxyapatite under uniaxial loading using molecular dynamics

Snyder, Alexander; Salehinia, I.

doi:10.1016/j.jmbbm.2020.103894

Cited by 15 publications

(23 citation statements)

References 40 publications

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“…The PCFF-interface force eld was used to conduct the simulations 42 . Earlier studies have reported that the 'Interface Force eld' provides reasonable accuracy in determining bulk modulus 32,33 . The tensile loading simulations were performed using a model of 1188 atoms.…”

Section: In Silico Tensile Response Analysismentioning

confidence: 99%

“…The periodic boundary conditions were applied in all 3 directions. The cutoff distance for Lennard-Jones and Coulombic pair potentials was set to 9.5 Å, similar to the study by Snyder et al 33 . Ewald summation was used in all simulations, to ensure the acceptable convergence of the system 43 .…”

Section: In Silico Tensile Response Analysismentioning

confidence: 99%

“…Also, a few published papers reported the compression failure of undoped HA single crystals, using MD simulations and therefore, the present in silico study is expected to add new results on HA system. 33 In each case, the system was rst equilibrated at the respective temperature for 100 picoseconds before the load application. A strain rate of 1×10 10 /s was applied in each case, to study the stress response of the structure.…”

Section: In Silico Tensile Response Analysismentioning

confidence: 99%

“…The temperature was not found to signi cantly in uence the mechanical behavior of the HA crystal. In a different study, Synder et al studied nanoscale mechanical deformations in hexagonal hydroxyapatite using MD simulations 33 . While using a consistent valence force eld (CVFF), they too found that the fracture strength under tension was weakest along Z axis and strongest under compression.…”

Section: Introductionmentioning

confidence: 99%

“…It employs Newton's equations of motion to predict the trajectory of various atoms in a system, and allows one to determine the interactions, that atoms have with each other in a given system 30 . MD simulations have been conducted to study the mechanical properties of HA crystals in a few studies [31][32][33] . For example, Qin et al found that HA crystals with sizes up to 2 nm in a collagen bril matrix can increase mechanical strength 31 .…”

Section: Introductionmentioning

confidence: 99%

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In silico study on probing atomistic insight into structural stability and tensile properties of Fe-doped hydroxyapatite single crystals

Basu

Nag

Kottan

et al. 2022

Preprint

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Hydroxyapatite (HA, Ca10PO4(OH)2) is a widely explored material in the experimental domain of biomaterials science, because of its resemblance with natural bone minerals. Specifically, in the bioceramic community, HA doped with multivalent cations (e.g., Mg2+, Fe2+, Sr2+, etc.) has been extensively investigated in the last few decades. Experimental research largely established the critical role of dopant content on the changes in mechanical and biocompatibility properties. The plethora of experimental measurements of mechanical response on doped HA is based on compression or indentation testing of polycrystalline materials. Such measurements, as well as computational predictions of mechanical properties on single crystalline (doped) HA are scarce. On that premise, the present study aims to build atomistic models of Fe2+-doped HA, a model system, with varying Fe content (10, 20, 30, and 40 mol%) and to explore their uniaxial tensile response by means of molecular dynamics (MD) simulation, together with the calculation of IR spectrum. In the equilibrated unit cell structures, Ca(1) sites were found to be energetically favourable for Fe2+ substitution. The local distribution of Fe2+ ions significantly affects the atomic partial charge distribution and chemical symmetry surrounding the functional groups. These signatures are reflected in the significant decrease in the intensity of IR peaks found in the Fe-doped HA, together with peak splitting because of the symmetry change in the crystal structure. Another important objective of this work is to computationally predict the mechanical response of doped HA in their single crystal format. An interesting observation is that the elastic anisotropy of undoped HA was not compromised with Fe-doping. Tensile strength (TS) is systematically reduced in doped HA with Fe2+ dopant content and a decrease in TS with temperature can be attributed to the increased thermal agitation of atoms at elevated temperatures. The physics of the tensile response was rationalized in terms of the strain dependent changes in covalent/ionic framework (Ca-P distance, P-O bond strain, O-P-O angular strain, O-H bond distance). Further, the dynamic changes in covalent bond network were energetically analyzed by calculating the changes in O-H and P-O bond vibrational energy. Summarizing, the current work develops our foundational understanding of the atomistic phenomena involved in the phase stability and tensile response of Fe-doped HA single crystals.

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Section: In Silico Tensile Response Analysismentioning

confidence: 99%

Section: In Silico Tensile Response Analysismentioning

confidence: 99%

Section: In Silico Tensile Response Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%