In situ HAFM study of the thermal dehydration on gypsum (010) surfaces
-
Guntram Jordan
and
José Manuel Astilleros
Abstract
Hydrothermal AFM has been used to study the thermal dehydration reaction on gypsum (010) surfaces in solutions at different saturation states, and in the absence of a bulk liquid phase. Experiments were carried out at temperatures ranging from 25 to 130 °C. Whereas supersaturated solutions (β = 1.8.5) caused gypsum growth in the entire temperature range, solutions close to equilibrium (β = 1.02) caused various responses of the gypsum surface. The most prominent was a sharp transition from fast growth to very fast dissolution at ~120 °C suggesting a sudden nucleation of a phase more stable than gypsum. No structural relation could be found between the parental gypsum (010) surface and the crystallizing phase. In the absence of a bulk liquid phase, dehydration takes place via the nucleation and spreading of etch-pit like pattern. Laterally, the thermal etch pits spread in an unrestricted way. In the vertical direction, pit growth was limited to a few micrometers. Dehydration by monolayer pits and nucleation of the dehydration process at monolayer steps on the (010) surface were never observed. Thus, unlike growth or dissolution, surface energy related to kink sites or individual point defects seems to be insufficient to trigger dehydration. The temperature-dependent lateral pit growth yields an activation energy of 119 ± 11 kJ/mol. The product phase disintegrates at the parental surface into nano-size particles without any morphologically noticeable transition zone.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- Structural model for the biogenic Mn oxide produced by Pseudomonas putida
- Electron-beam (5–10 keV) damage in triplite-group phosphates: Consequences for electron-microprobe analysis of fluorine
- Vacancy defects in MgO at high pressure
- Plastic flow of pyrope at mantle pressure and temperature
- Parvo-mangano-edenite, parvo-manganotremolite, and the solid solution between Ca and Mn2+ at the M4 site in amphiboles
- Reinvestigation of the MgSiO3 perovskite structure at high pressure
- The mechanism and kinetics of α-NiS oxidation in the temperature range 670–700°C
- Influence of charge location on 29Si NMR chemical shift of 2:1 phyllosilicates
- The size distribution of exsolution lamellae in iron-free clinopyroxene
- The high-pressure phase transformation and breakdown of MgFe2O4
- Elastic behavior, phase transition, and pressure induced structural evolution of analcime
- A new chemical etching technique for peridotites using molten anhydrous borax
- Poppiite, the V3+ end-member of the pumpellyite group: Description and crystal structure
- Cation redistribution in the octahedral sheet during diagenesis of illite-smectites from Jurassic and Cambrian oil source rock shales
- A shock-induced polymorph of anatase and rutile from the Chesapeake Bay impact structure, Virginia, U.S.A.
- Water in the interlayer region of birnessite: Importance in cation exchange and structural stability
- In situ HAFM study of the thermal dehydration on gypsum (010) surfaces
- Influence of dehydration kinetics on T-O-T bridge breaking in zeolites with framework type STI: The case of stellerite
- Estimation of volume fractions of liquid and vapor phases in fluid inclusions, and definition of inclusion shapes
- Thermodynamics of uranyl minerals: Enthalpies of formation of uranyl oxide hydrates
- SIMS investigation of electron-beam damage to hydrous, rhyolitic glasses: Implications for melt inclusion analysis
- Synthetic Ag-rich tourmaline: Structure and chemistry
- Genesis and compositional heterogeneity of smectites. Part III: Alteration of basic pyroclastic rocksA case study from the Troodos Ophiolite Complex, Cyprus
- Ganterite, the barium mica Ba0.5K0.5Al2(Al1.5Si2.5)O10(OH)2, from Oreana, Nevada
- Letter. Transformation of pentlandite to violarite under mild hydrothermal conditions
Articles in the same Issue
- Structural model for the biogenic Mn oxide produced by Pseudomonas putida
- Electron-beam (5–10 keV) damage in triplite-group phosphates: Consequences for electron-microprobe analysis of fluorine
- Vacancy defects in MgO at high pressure
- Plastic flow of pyrope at mantle pressure and temperature
- Parvo-mangano-edenite, parvo-manganotremolite, and the solid solution between Ca and Mn2+ at the M4 site in amphiboles
- Reinvestigation of the MgSiO3 perovskite structure at high pressure
- The mechanism and kinetics of α-NiS oxidation in the temperature range 670–700°C
- Influence of charge location on 29Si NMR chemical shift of 2:1 phyllosilicates
- The size distribution of exsolution lamellae in iron-free clinopyroxene
- The high-pressure phase transformation and breakdown of MgFe2O4
- Elastic behavior, phase transition, and pressure induced structural evolution of analcime
- A new chemical etching technique for peridotites using molten anhydrous borax
- Poppiite, the V3+ end-member of the pumpellyite group: Description and crystal structure
- Cation redistribution in the octahedral sheet during diagenesis of illite-smectites from Jurassic and Cambrian oil source rock shales
- A shock-induced polymorph of anatase and rutile from the Chesapeake Bay impact structure, Virginia, U.S.A.
- Water in the interlayer region of birnessite: Importance in cation exchange and structural stability
- In situ HAFM study of the thermal dehydration on gypsum (010) surfaces
- Influence of dehydration kinetics on T-O-T bridge breaking in zeolites with framework type STI: The case of stellerite
- Estimation of volume fractions of liquid and vapor phases in fluid inclusions, and definition of inclusion shapes
- Thermodynamics of uranyl minerals: Enthalpies of formation of uranyl oxide hydrates
- SIMS investigation of electron-beam damage to hydrous, rhyolitic glasses: Implications for melt inclusion analysis
- Synthetic Ag-rich tourmaline: Structure and chemistry
- Genesis and compositional heterogeneity of smectites. Part III: Alteration of basic pyroclastic rocksA case study from the Troodos Ophiolite Complex, Cyprus
- Ganterite, the barium mica Ba0.5K0.5Al2(Al1.5Si2.5)O10(OH)2, from Oreana, Nevada
- Letter. Transformation of pentlandite to violarite under mild hydrothermal conditions
