Structural and Dynamical Effects of the CaO/SrO Substitution in Bioactive Glasses

Silicate glasses containing silicon, sodium, phosphorous, and calcium have the ability to promote bone regeneration and biodegrade as new tissue is generated. Recently, it has been suggested that adding SrO can benefit tissue growth and silicate glass dissolution. Motivated by these recent developme...

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Main Authors: Margit Fabian, Matthew Krzystyniak, Atul Khanna, Zsolt Kovacs
Format: Article
Language:English
Published: MDPI AG 2024-10-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/29/19/4720
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author Margit Fabian
Matthew Krzystyniak
Atul Khanna
Zsolt Kovacs
author_facet Margit Fabian
Matthew Krzystyniak
Atul Khanna
Zsolt Kovacs
author_sort Margit Fabian
collection DOAJ
description Silicate glasses containing silicon, sodium, phosphorous, and calcium have the ability to promote bone regeneration and biodegrade as new tissue is generated. Recently, it has been suggested that adding SrO can benefit tissue growth and silicate glass dissolution. Motivated by these recent developments, the effect of SrO/CaO–CaO/SrO substitution on the local structure and dynamics of Si-Na-P-Ca-O oxide glasses has been studied in this work. Differential thermal analysis has been performed to determine the thermal stability of the glasses after the addition of strontium. The local structure has been studied by neutron diffraction augmented by Reverse Monte Carlo simulation, and the local dynamics by neutron Compton scattering and Raman spectroscopy. Differential thermal analysis has shown that SrO-containing glasses have lower glass transition, melting, and crystallisation temperatures. Moreover, the addition of the Sr<sup>2+</sup> ions decreased the thermal stability of the glass structure. The total neutron diffraction augmented by the RMC simulation revealed that Sr played a similar role as Ca in the glass structure when substituted on a molar basis. The bond length and the coordination number distributions of the network modifiers and network formers did not change when SrO (x = 0.125, 0.25) was substituted for CaO (25-x). However, the network connectivity increased in glass with 12.5 mol% CaO due to the increased length of the Si-O-Si interconnected chain. The analysis of Raman spectra revealed that substituting CaO with SrO in the glass structure dramatically enhances the intensity of the high-frequency band of 1110–2000 cm<sup>−1</sup>. For all glasses under investigation, the changes in the relative intensities of Raman bands and the distributions of the bond lengths and coordination numbers upon the SrO substitution were correlated with the values of the widths of nuclear momentum distributions of Si, Na, P, Ca, O, and Sr. The widths of nuclear momentum distributions were observed to soften compared to the values observed and simulated in their parent metal-oxide crystals. The widths of nuclear momentum distributions, obtained from fitting the experimental data to neutron Compton spectra, were related to the amount of disorder of effective force constants acting on individual atomic species in the glasses.
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spelling doaj-art-e9edbdca3579401a97cbc0ade29bdcf02025-08-20T02:16:55ZengMDPI AGMolecules1420-30492024-10-012919472010.3390/molecules29194720Structural and Dynamical Effects of the CaO/SrO Substitution in Bioactive GlassesMargit Fabian0Matthew Krzystyniak1Atul Khanna2Zsolt Kovacs3HUN-REN Centre for Energy Research, Konkoly Thege Miklos st. 29-33, 1121 Budapest, HungaryISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UKDepartment of Physics, Guru Nanak Dev University, Amritsar 143005, IndiaDepartment of Materials Physics, Institute of Physics, Eötvös Loránd University, Pázmány Péter st. 1/a, H-1117 Budapest, HungarySilicate glasses containing silicon, sodium, phosphorous, and calcium have the ability to promote bone regeneration and biodegrade as new tissue is generated. Recently, it has been suggested that adding SrO can benefit tissue growth and silicate glass dissolution. Motivated by these recent developments, the effect of SrO/CaO–CaO/SrO substitution on the local structure and dynamics of Si-Na-P-Ca-O oxide glasses has been studied in this work. Differential thermal analysis has been performed to determine the thermal stability of the glasses after the addition of strontium. The local structure has been studied by neutron diffraction augmented by Reverse Monte Carlo simulation, and the local dynamics by neutron Compton scattering and Raman spectroscopy. Differential thermal analysis has shown that SrO-containing glasses have lower glass transition, melting, and crystallisation temperatures. Moreover, the addition of the Sr<sup>2+</sup> ions decreased the thermal stability of the glass structure. The total neutron diffraction augmented by the RMC simulation revealed that Sr played a similar role as Ca in the glass structure when substituted on a molar basis. The bond length and the coordination number distributions of the network modifiers and network formers did not change when SrO (x = 0.125, 0.25) was substituted for CaO (25-x). However, the network connectivity increased in glass with 12.5 mol% CaO due to the increased length of the Si-O-Si interconnected chain. The analysis of Raman spectra revealed that substituting CaO with SrO in the glass structure dramatically enhances the intensity of the high-frequency band of 1110–2000 cm<sup>−1</sup>. For all glasses under investigation, the changes in the relative intensities of Raman bands and the distributions of the bond lengths and coordination numbers upon the SrO substitution were correlated with the values of the widths of nuclear momentum distributions of Si, Na, P, Ca, O, and Sr. The widths of nuclear momentum distributions were observed to soften compared to the values observed and simulated in their parent metal-oxide crystals. The widths of nuclear momentum distributions, obtained from fitting the experimental data to neutron Compton spectra, were related to the amount of disorder of effective force constants acting on individual atomic species in the glasses.https://www.mdpi.com/1420-3049/29/19/4720bioactive glassesisotopic disorderforce-constant disordernuclear momentum distributionneutron diffractionneutron Compton scattering
spellingShingle Margit Fabian
Matthew Krzystyniak
Atul Khanna
Zsolt Kovacs
Structural and Dynamical Effects of the CaO/SrO Substitution in Bioactive Glasses
Molecules
bioactive glasses
isotopic disorder
force-constant disorder
nuclear momentum distribution
neutron diffraction
neutron Compton scattering
title Structural and Dynamical Effects of the CaO/SrO Substitution in Bioactive Glasses
title_full Structural and Dynamical Effects of the CaO/SrO Substitution in Bioactive Glasses
title_fullStr Structural and Dynamical Effects of the CaO/SrO Substitution in Bioactive Glasses
title_full_unstemmed Structural and Dynamical Effects of the CaO/SrO Substitution in Bioactive Glasses
title_short Structural and Dynamical Effects of the CaO/SrO Substitution in Bioactive Glasses
title_sort structural and dynamical effects of the cao sro substitution in bioactive glasses
topic bioactive glasses
isotopic disorder
force-constant disorder
nuclear momentum distribution
neutron diffraction
neutron Compton scattering
url https://www.mdpi.com/1420-3049/29/19/4720
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AT matthewkrzystyniak structuralanddynamicaleffectsofthecaosrosubstitutioninbioactiveglasses
AT atulkhanna structuralanddynamicaleffectsofthecaosrosubstitutioninbioactiveglasses
AT zsoltkovacs structuralanddynamicaleffectsofthecaosrosubstitutioninbioactiveglasses