AFM study of the epitaxial growth of brushite (CaHPO4� 2H2O) on gypsum cleavage surfaces
The epitaxial overgrowth of brushite (CaHPO4·2H 2O) by the interaction of phosphate-bearing, slightly acidic, aqueous solutions with gypsum (CaSO4·2H2O) was investigated in situ using atomic force microscopy (AFM). Brushite growth nuclei were not observed to form on the {010} gypsum cleavage surface...
| Main Authors: | , , , , , |
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| Format: | Journal Article |
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Mineralogical Society of America
2010
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| Online Access: | http://hdl.handle.net/20.500.11937/39210 |
| _version_ | 1848755529701130240 |
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| author | Pinto, A. Ruiz-Agudo, E. Putnis, Christine Putnis, Andrew Jiménez, A. Prieto, M. |
| author_facet | Pinto, A. Ruiz-Agudo, E. Putnis, Christine Putnis, Andrew Jiménez, A. Prieto, M. |
| author_sort | Pinto, A. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | The epitaxial overgrowth of brushite (CaHPO4·2H 2O) by the interaction of phosphate-bearing, slightly acidic, aqueous solutions with gypsum (CaSO4·2H2O) was investigated in situ using atomic force microscopy (AFM). Brushite growth nuclei were not observed to form on the {010} gypsum cleavage surface, but instead formed in areas of high dissolution, laterally attached to gypsum [101] step edges. During the brushite overgrowth the structural relationships between brushite (Aa) and gypsum (A2/a) result in several phenomena, including the development of induced twofold twining, habit polarity, and topographic effects due to coalescence of like-oriented crystals. The observed brushite growth is markedly anisotropic, with the growth rate along the main periodic bond chains (PBCs) in the brushite structure increasing in the order [101] > [101] > [010], leading to tabular forms elongated on [101]. Such a growth habit may result from the stabilization of the polar [101] direction of brushite due to changes in hydration of calcium ions induced by the presence of sulfate in solution, which is consistent with the stabilization of the gypsum [101] steps during dissolution in the presence of HPO2-4 ions. The coupling between growth and dissolution was found to result in growth rate fluctuations controlled by the changes in the solution composition. |
| first_indexed | 2025-11-14T08:57:45Z |
| format | Journal Article |
| id | curtin-20.500.11937-39210 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T08:57:45Z |
| publishDate | 2010 |
| publisher | Mineralogical Society of America |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-392102023-08-02T06:39:08Z AFM study of the epitaxial growth of brushite (CaHPO4� 2H2O) on gypsum cleavage surfaces Pinto, A. Ruiz-Agudo, E. Putnis, Christine Putnis, Andrew Jiménez, A. Prieto, M. The epitaxial overgrowth of brushite (CaHPO4·2H 2O) by the interaction of phosphate-bearing, slightly acidic, aqueous solutions with gypsum (CaSO4·2H2O) was investigated in situ using atomic force microscopy (AFM). Brushite growth nuclei were not observed to form on the {010} gypsum cleavage surface, but instead formed in areas of high dissolution, laterally attached to gypsum [101] step edges. During the brushite overgrowth the structural relationships between brushite (Aa) and gypsum (A2/a) result in several phenomena, including the development of induced twofold twining, habit polarity, and topographic effects due to coalescence of like-oriented crystals. The observed brushite growth is markedly anisotropic, with the growth rate along the main periodic bond chains (PBCs) in the brushite structure increasing in the order [101] > [101] > [010], leading to tabular forms elongated on [101]. Such a growth habit may result from the stabilization of the polar [101] direction of brushite due to changes in hydration of calcium ions induced by the presence of sulfate in solution, which is consistent with the stabilization of the gypsum [101] steps during dissolution in the presence of HPO2-4 ions. The coupling between growth and dissolution was found to result in growth rate fluctuations controlled by the changes in the solution composition. 2010 Journal Article http://hdl.handle.net/20.500.11937/39210 10.2138/am.2010.3557 Mineralogical Society of America restricted |
| spellingShingle | Pinto, A. Ruiz-Agudo, E. Putnis, Christine Putnis, Andrew Jiménez, A. Prieto, M. AFM study of the epitaxial growth of brushite (CaHPO4� 2H2O) on gypsum cleavage surfaces |
| title | AFM study of the epitaxial growth of brushite (CaHPO4� 2H2O) on gypsum cleavage surfaces |
| title_full | AFM study of the epitaxial growth of brushite (CaHPO4� 2H2O) on gypsum cleavage surfaces |
| title_fullStr | AFM study of the epitaxial growth of brushite (CaHPO4� 2H2O) on gypsum cleavage surfaces |
| title_full_unstemmed | AFM study of the epitaxial growth of brushite (CaHPO4� 2H2O) on gypsum cleavage surfaces |
| title_short | AFM study of the epitaxial growth of brushite (CaHPO4� 2H2O) on gypsum cleavage surfaces |
| title_sort | afm study of the epitaxial growth of brushite (cahpo4� 2h2o) on gypsum cleavage surfaces |
| url | http://hdl.handle.net/20.500.11937/39210 |