130,565 research outputs found
Phase transitions and crystal structure evolution of hydrated borates at non-ambient conditions
No full textHydrated borates are a class of minerals composed of clusters or chains of Bφx groups (where φ represents an oxygen atom, a H2O molecule, or an OH- group) organized either in tetrahedra or planar triangular groups. Hydrated borates are considered a more cost-effective alternative to B4C in radiation-shielding concretes [1], primarily due to the significant cross-section (~3840 barns) for thermal neutrons of the 10B isotope, which represents approximately 20% of natural boron. It is advisable to comprehensively characterize the crystal chemistry, elastic properties, P-T phase stability fields, and structural behaviour of natural borates under varying temperature and pressure conditions to model and understand their role as aggregates in radiation-shielding concretes [2], where the components experience pressure (via static compression) and temperature (via irradiation). Since 2018, my research group has conducted an extensive study of economically valuable hydrated borates, as well as common complementary phases occurring in borates deposits. High-pressure investigations of all studied hydrated borates have revealed one or more phase transitions occurring at pressures below 11 GPa, and the occurrence of these transitions appears to be highly correlated with the H2O content of the minerals (e.g., [3-4]). In response to the phase transitions, the most significant structural change observed in our experiments is the increase in the coordination number of alkali/alkaline-earth cations as well as of part of the boron population, from IIIB to IVB, due to the interaction between IIIB and H2O molecules. This, on the other hand, emphasizes the importance of the hydrogen bond network, usually with complex and pervasive configuration, in preserving the stability of the crystalline edifice of this class of materials.
References
1. Okuno K. (2005). Radiat. Prot. Dosimetry. 115, 258–261.
2. Torrenti J. and Nahas G. (2010) Int. Conf. Concr. under Sev. Cond., Merida, Yucatan. 3–18
3. Comboni D., Pagliaro F., Gatta G. D., et al. (2020) J. Am. Ceram. Soc. 103:5291–5301
4. Comboni D., Poreba T., Pagliaro F., et al. (2021) Acta Crystallogr. B 77:940–945
P-induced crystal fluid interaction: the case of ERI and OFF topology
No full textThe P-induced intrusion of molecules or solvated ions within the nanocavities of open-framework minerals, such as zeolites, has been extensively investigated during last decades (e.g., Gatta et al., 2018, and references within). This peculiar property might be exploited to tailor new multifunctional materials or to enhance industrial catalytic processes involving zeolites (Comboni et al., 2020). In addition, from a geological point
of view, a constraint of this phenomena might shed light on the role played by zeolites as fluid carriers in the upper Earth crust, e.g., during the early subduction of altered basalts or oceanic sediments. The aim of the present study is to characterize the high-pressure behavior, promoting the crystal-fluid interaction, on two different natural zeolites species belonging to the ABC-6 family: erionite (AABAAC) and offretite (AAB)
(ERI and OFF topology, respectively). Similarities of the framework between these two species resulted in quite common intergrowth, at least in natural samples (Passaglia et al., 1998). Samples were compressed in non-penetrating and penetrating P-transmitting fluids (PTFs). Investigations were conducted via in-situ high pressure single-crystal synchrotron X-ray diffraction, using a diamond anvil cell (DAC), at the ID15b beamline of ESRF (Grenoble, France) and P02.2 of PETRA-III (Hamburg, Germany). Different PTFs have been employed during the experiments: non-penetrating i) silicone oil and daphne oil (7575) and potentially penetrating, ii) alcohols: water mixtures, iii) pure H2O, iv) Ne. The obtained unit-cell P-V patterns revealed the adsorption of H2O molecules within the structural cavities; in addition, the structure refinements allowed to describe the deformation mechanisms as well as the location of the adsorbed molecules. Interestingly, the magnitude of the absorption phenomena in natural erionite appeared to be comparable with what observed in synthetic zeolites (i.e., AlPO4-5, Lotti et al., 2016), highlighting the great potential of erionite as a mineralogical carrier of fluids in the upper Earth crust.
Comboni D., Pagliaro F., Lotti P., Gatta G.D., Merlini M., Milani S., Migliori M., Giordano G., Catizzone E., Collings I.E. & Hanfland M. (2020) - The elastic behavior of zeolitic frameworks: The case of MFI type zeolite under high-pressure methanol intrusion. Catal. Today, 345, 88-96.
Gatta G.D., Lotti P. & Tabacchi G. (2018) - The effect of pressure on open-framework silicates: elastic behaviour and crystal-fluid interaction. Phys. Chem. Miner., 45, 115-138.
Lotti P., Gatta G.D., Comboni., Merlini M., Pastero L. & Hanfland M. (2016) - AlPO4-5 zeolite at high pressure: Crystalfluid interaction and elastic behavior. Microp. Mesop. Mater., 228, 158-167.
Passaglia E., Artioli G. & Gualtieri A. (1998) - Crystal chemistry of the zeolites erionite and offretite. Am. Mineral., 83, 577-589
The role of temperature on P-induced crystal-fluid interaction : a study on LAU and HEU topologies
No full textNatural zeolites can be found in soil, oceanic basalts as well as sediments and diagenetic environments. Their peculiar reversible hydration property (i.e., the ability to adsorb and release H2O molecules) and the ability to overhydrate under pressure, make them suitable carriers of fluids in the upper Earth crust during the early stage of subduction. Despite the extensive study of high-pressure and high-temperature behavior of natural and synthetic zeolites over the last decades, few studies have yet combined the effects of both conditions. Experiments at combined high pressure and high temperature might provide valuable insights on the crystal-fluid interaction preocesses occurring in nature at the geological conditions of stability of zeolites, especially when these microporous compounds can act as carriers and moderators of the circulating fluids.
In this study, the in situ combined high-pressure and high-temperature behavior of two commonly occurring natural zeolites, heulandite and laumontite, was investigated. The P-induced crystal-fluid interaction of these two zeolites was studied at ambient-T by Comboni et al. [1] for laumontite and Seryotkin [2] for heulandite. These results have been used as benchmarks to evaluate the role of temperature on the crystal-fluid interaction. In-situ, HTHP single-crystal synchrotron X-ray diffraction experiments were conducted using a diamond anvil cell (DAC) surrounded by a resistive heater at the ID15b beamline at the European Synchrotron Radiation Facility in Grenoble (France). The setup allowed to reach temperatures of about 150(2)°C. Pressure was measured using the ruby fluorescence technique while temperature was monitored using a thermocouple located very close to the P-chamber, allowing a precise determination of both these variables. The results obtained were consistent with those calculated using the Au-powder pattern.
The results showed that temperature significantly increased the kinetics of H2O adsorption in laumontite, with respect to the compressional behavior at room conditions, leading to a volume expansion observable already at pressures < 5 kbar. It was previously found that laumontite hydrated at ambient conditions after 24 hours, while the presence of a temperature gradient reduced the time at about 15 minutes. Even for heulandite, the comparison with literature data suggests that a higher H2O adsorption rate was observed when the thermal gradient was applied.
References
[1] Comboni D., Gatta G.D., Lotti P., Merlini M. & Hanfland M. 2018. Crystal-fluid interactions in laumontite. Microporous Mesoporous Mater., 263, 86-95.
[2] Seryotkin, Y.V. 2015. Influence of content of pressure-transmitting medium on structural evolution of heulandite: Single-crystal X-ray diffraction study. Microporous and Mesoporous Mater., 214, 127-135
P-induced crystal fluid interaction: the case of ERI and OFF topologies
No full textThe P-induced intrusion of molecules or solvated ions within the nanocavities of open-framework minerals,
such as zeolites, has been extensively investigated during last decades (e.g., Gatta et al., 2018, and references
within). This peculiar property might be exploited to tailor new multifunctional materials or to enhance
industrial catalytic processes involving zeolites (Comboni et al., 2020). In addition, from a geological point
of view, a constraint of this phenomena might shed light on the role played by zeolites as fluid carriers in the
upper Earth crust, e.g., during the early subduction of altered basalts or oceanic sediments. The aim of the
present study is to characterize the high-pressure behavior, promoting the crystal-fluid interaction, on two
different natural zeolites species belonging to the ABC-6 family: erionite (AABAAC) and offretite (AAB)
(ERI and OFF topology, respectively). Similarities of the framework between these two species resulted in
quite common intergrowth, at least in natural samples (Passaglia et al., 1998). Samples were compressed in
non-penetrating and penetrating P-transmitting fluids (PTFs).
Investigations were conducted via in-situ high pressure single-crystal synchrotron X-ray diffraction, using
a diamond anvil cell (DAC), at the ID15b beamline of ESRF (Grenoble, France) and P02.2 of PETRA-III
(Hamburg, Germany). Different PTFs have been employed during the experiments: non-penetrating i) silicone
oil and daphne oil (7575) and potentially penetrating, ii) alcohols: water mixtures, iii) pure H2O, iv) Ne.
The obtained unit-cell P-V patterns revealed the adsorption of H2O molecules within the structural cavities;
in addition, the structure refinements allowed to describe the deformation mechanisms as well as the location of
the adsorbed molecules. Interestingly, the magnitude of the absorption phenomena in natural erionite appeared
to be comparable with what observed in synthetic zeolites (i.e., AlPO4-5, Lotti et al., 2016), highlighting the
great potential of erionite as a mineralogical carrier of fluids in the upper Earth crust.
Comboni D., Pagliaro F., Lotti P., Gatta G.D., Merlini M., Milani S., Migliori M., Giordano G., Catizzon
Phase stability of hydrated borates at high pressure
No full textHydrated borates are a class of minerals made by clusters or chains of Bφx groups (φ represents an oxygen, an H2O molecule or an OH-) organized either in tetrahedra or in planar trigonal groups. Hydrated borates are believed to be a cheaper alternative to B4C for radiation-shielding concretes (Okuno et al., 2005), due to the large cross section (~3840 barns) for thermal neutrons of the isotope 10B, which represents about 20% of
the boron in nature. A comprehensive characterization of the crystal-chemistry, elastic properties, stability and structural behavior of natural borates at varying T and P conditions is advisable for modelling and understanding their role when utilized as aggregates in radiation-shielding concretes (Torrenti et al., 2010), in which the components are subject to pressure (by static compression) and temperature (by irradiation). Interestingly, all hydrated borates studied so far at high-pressure display one (or more) phase transition, and the pressure at which the phase transitions occur seems to be correlated to the H2O content of the minerals (e.g., Comboni et al., 2020, 2021). During the phase transitions, the most dramatic structural change is the increase
of the coordination number of part of the IIIB to IVB, by the interaction between the IIIB and one H2O molecule or OH- group, underlying the importance of the hydrogen bond network in the stability of the crystalline structure.
Comboni D., Pagliaro F., Gatta G.D., Lotti P., Milani S., Merlini M., Battiston T., Glazyrin K. & Liermann H.P. (2020) - High-pressure behavior and phase stability of Na2B4O6(OH)2·3H2O (kernite). J. Am. Ceram. Soc., 103, 5291-5301.
Comboni D., Poreba T., Pagliaro F., Battiston T., Lotti P., Gatta G.D., Garbarino G. & Hanfland M. (2021) - Crystal structure of the high-P polymorph of Ca2B6O6(OH)10·2(H2O) (meyerhofferite). Acta Crystallogr., B77, 940-945.
Okuno K. (2005) - Neutron shielding material based on colemanite and epoxy resin. Radiat. Prot. Dosim., 115, 258-261.
Torrenti J. & Nahas G. (2010) - Durability and Safety of Concrete Structures in the Nuclear Context. Int. Conf. Concr. under Sev. Cond., Merida, Mexico, 3-18
High-pressure behavior of microporous materials: crystal-fluid interactions and deformation mechanisms at the atomic scale
No full textZeolite are crystalline, hydrated aluminosilicates characterized by a tetrahedral framework of
TO4 units, connected in such a way that sub-nanometric channels and cages occur. These
structural cavities host the so-called extra-framework population, which mainly consists of
alkali and alkaline-earth cations and small molecules, such as H2O
1,2
. In the last decades, the
scientific community showed a rising interest on the behavior of microporous and mesoporous
compounds at high-pressure conditions, and on the crystal-fluid interaction phenomena
occurring at extreme conditions3,4
. High-pressure experiments on synthetic zeolites may pave
the way for new routes of tailoring new functional materials (made by hybrid host-guest
architecture), bearing a potentially relevant technological impact5
. From a geological point of
view, zeolites could act as a carrier for H2O and others small molecules or for monoatomic
species (e.g., CO2, CH4, H2S, He, Ar, Kr, Xe,...), and any change of the P-induced extraframework population (at ambient to low/high T) can have relevant geochemical and
geophysical implications6
. In this experimental thesis, the high-pressure behavior and the
crystal-fluid interaction at the atomic scale of a selected series of natural and synthetic zeolites
(i.e., AlPO4-5, leonhardite, laumontite, phillipsite) and a zeolites-like mineral (i.e.,
armstrongite) have been investigated by means of in-situ single-crystal X-ray diffraction, using
“penetrating” and “non-penetrating” pressure-transmitting fluids in a diamond anvil-cell,
exploring the different crystal-fluid interaction in materials with large or small channels, and
with or without extra-framework population. The experiments were conducted at the Earth
Science Department of Milan (ESD-MI) and at the beamlines ID15b (at ESRF, Grenoble) and
P2.02 (at DESY, Hamburg). The results obtained in the framework of this experimental thesis
showed that several variables govern the sorption phenomena at high pressure, among those: the
“free diameters” of the framework cavities, the chemical nature and the configuration of the
extra-framework population, the partial pressure of the penetrating molecule in the fluid (if
mixed with other non-penetrating molecules), the rate of P-increase, the surface/volume ratio of
the crystallites and the temperature at which the experiment is conducted. P-induced
phenomena at the atomic scale were described on the basis of high-quality structure
refinements. Geological and technological potential implications were discussed, e.g. about the
H2O load carried by laumontite, leonhardite and phillipsite in relevant geologic environments
(e.g., first km of the subducted oceanic crust, oil reservoir, ...), along with the potential of
synthetic and natural zeolites as energy storage materials
The role of temperature in P-induced crystal fluid interaction: the case of LAU and HEU topology
No full textZeolites are a class of open-framework aluminosilicate minerals commonly present in soil, oceanic basalts and sediments and diagenetic environments. Zeolites may act as fluid carriers in the upper Earth crust during the early subduction stage thanks to their unique features: the reversible hydration (i.e., the ability of adsorb and release H2O molecules or other small molecules, e.g., CO2, CH4, SO2) and the ability to overhydrate. During the last decades, the high-pressure (HP) and high-temperature (HT) behavior of natural and synthetic zeolites have been intensively investigated but, at the best of our knowledge, no experiments have ever been conducted combining the effects of both thermodynamic variable. Experiments at these conditions (i.e., simulating the PT gradient), using a H2O-based solution as P-transmitting fluids (PTFs), provide a realistic description of crystal-fluid interaction phenomena. In this study, we have investigated the HPHT behavior of heulandite and laumontite, two of the most common natural zeolites, whose presence have been described in a wide range of natural environments. The characterization of the crystal-fluid interaction induced by P in these two species has already been performed by Comboni et al. (2018) and Seryotkin (2015) for laumontite and heulandite, respectively, and was adopted as reference in order to evaluate the T gradient effect. In-situ HPHT single-crystal synchrotron X-ray diffraction experiments were performed at the ID15b beamline, at the ESRF, Grenoble (France). The set-up, easily
reproducible, consist of a membrane-driven diamond anvil cell (DAC) placed in a resistive heater which allowed to increase the T up to 150(2)°C. Pressure was determined by the ruby florescence method, while temperature was measured using a thermocouple located very close to the P-chamber, allowing a precise determination of both (results were consistent with the values calculated by the Au-powder pattern).
Results of the P-V pattern in laumontite clearly indicated that temperature enhances the H2O adsorption, giving rise to a volume expansion at P < 5 kbar. Previous experimental finding highlighted that hydration of laumontite occurs at ambient condition after ~ 24h, while with the presence of a T gradient required no more that 20 min. Concerning heulandite, preliminary data seems to suggest a higher H2O adsorption. if compared
to that governed by the effect of P only.
Comboni D., Gatta G.D., Lotti P., Merlini M. & Hanfland M. (2018) - Crystal-fluid interactions in laumontite. Microp.
Mesop. Mater., 263, 86-95.
Seryotkin Y.V. (2015) - Influence of content of pressure-transmitting medium on structural evolution of heulandite: Single-crystal X-ray diffraction study. Microp. Mesop. Mater., 214, 127-135
Pressure-driven crystal structure and fluids interactions in erionite-group zeolites
No full textThe infiltration of molecules (or solvated ions) into the nano-cavities of microporous materials opens
new routes for enhancing mass transfer from fluids to molecules incorporated in the structure.
Thoroughly exploring this phenomenon, in both synthetic and natural zeolites, could expand their
industrial applications, such as the development of new functional materials and enhancement of
catalytic performance [1,2]. From a geological standpoint, understanding this phenomenon can
unveil the role played by zeolites as fluid carriers during the early stages of subduction of oceanic
sediments and altered basalts.
In this research, we examined the interaction between crystals and fluids, driven by pressure, in
three distinct natural zeolites belonging to the ABC-6 group: erionite (ERI framework type, 6-
membered ring sequence: AABAAC), offretite (OFF, with AAB seq.), and bellbergite (EAB, with
AABCCB seq.). The objectives of the experiments were: 1) to understand the potential role of
erionite as a fluid carrier during subduction, given its presence, as a secondary mineral, in altered
oceanic basalts [3]; and 2) to compare the mechanisms employed by structurally similar frameworks
(characterized by the presence of 6-membered rings) in accommodating bulk compression and
adsorbing new molecules.
The investigation made use of in situ high-pressure synchrotron X-ray diffraction experiments on
natural single crystals of erionite, offretite, and bellbergite, employing both potentially penetrating
fluids (methanol:ethanol:water 16:3:1 mixture, ethanol:water 1:1 mixture, methanol, H2O, liquid Ne)
and non-penetrating P-transmitting fluids (silicone oil and daphne oil 7575). The use of the latters
aimed to establish a benchmark for evaluating crystal-fluid interaction, as the adsorption of new
molecules decreases bulk compressibility due to the "pillar" role played by guest species within the
structural voids [1].
The results revealed that erionite exhibits the highest magnitude of adsorption among the three
zeolites. Additionally, the occurrence and magnitude of the phenomena were found to be governed
by the H2O content of the hydrous P-transmitting fluids. Offretite framework allowed Ne atoms to
penetrate into the 12mRs channel in response to applied pressure, exhibiting weak Van der Waals
interactions with the extra-framework population.
On the other hand, natural bellbergite proved to be nearly inaccessible to guest molecules from Ptransmitting
fluids, emphasizing the pivotal role played by "secondary structural factors", such as the
extra-framework content of the sample, on these phenomena.
References:
[1] Gatta GD et al. (2018) Phys Chem Miner 45:115-138
[2] Comboni D et al. (2020) Catal Today 345:88-96
[3] Vitali F et al. (1995) Clays Clay Miner 43: 92-10
The anomalous high-pressure phase transition of inderite
No full textInderite, ideally [MgB3O3(OH)5∙5H2O], is a hydrated borate discovered in the Inder deposit (Kazakhstan) in 1937 and structurally characterized for the first time by Boldyreva [1]. Inderite is a Na-free hydrated borate and, unlike others common Na-bearing minerals like ulexite (NaCaB5O6(OH)6·5H2O) or borax (Na2B4O5(OH)4·8H2O). Therefore, inderite would not promote any deleterious Alcali-Silica Reactions (ASR, triggered by Na-bearing phases), if used as an aggregate in Portland cements. In the last years, phase transitions occurring at different pressures were discovered in a plethora of hydrous borates, including kurnakovite and meyerhofferrite [2,3] which share the same polyion unit [B3O3(OH)5]2-. The high-pressure stability field of this kind of hydrated borates, having polyions in isolated units, appears to be directly correlated with the total H2O content of the mineral itself. In this light, the high-pressure behaviour of inderite was investigated by an in-situ single-crystal X-ray diffraction (up to 17.4 GPa) under hydrostatic conditions. Results show: 1) inderite undergoes a first order phase transition between ~6.15 and ~6.45 GPa marked by a sudden 7.0 % volume decrease; 2) the structure of the high-pressure polymorph, inderite-II, was solved (Fig. 1); 3) as response to the phase transition, the boron site in planar-triangular coordination bonds to a H2O molecule, forming a tetrahedron; 4) inderite was found to be a highly anisotropic mineral.
[1] Boldyreva A.M. Mem Soc russe Min, 1937, 2, 651–671
[2] Comboni D., Poreba T., Pagliaro F., et al. Acta Crystallographica Section B, 2021, 6, 940-945.
[3] Pagliaro F., Lotti P., Battiston T., et al. Construction and Building Materials, 2021, 121094
The behavior at non-ambient conditions of colemanite: a hydrous Ca-borate
No full textColemanite, CaB3O4(OH)3·H2O, is a common hydrous borate of large economic relevance, as it is one of the major commodities of boron with applications in the fields of glass and ceramic industries. Colemanite-rich layers are usually found in stratigraphic successions related to lacustrine basins in semi-arid to arid environments, associated to a local volcanic activity, which provides the source for boron. Despite the large economic relevance, the behavior of this mineral at non-ambient conditions of temperature and pressure was almost unexplored, which can provide a basis for understanding its stability during diagenetic and metamorphic processes. In this contribution, we report the highpressure behavior of colemanite (Lotti et al., 2017), based on in situ single-crystal synchrotron X-ray diffraction data up to 24 GPa, and its low-T behavior by in situ X-ray and neutron single-crystal diffraction. Colemanite was found to be stable up ~ 14.5 GPa, where a reconstructive phase transition towards a high-pressure polymorph (colemanite-II) with same symmetry (space group P21/a), but a six times larger unit cell volume, occurs. The elastic behavior of colemanite was described by fitting the experimental data with a III-order Birchurnaghan equation of state, yielding the following refined elastic parameters: KV0 = 64(4) GPa and KV' 5.5(7). The colemanite-tocolemanite-II phase transition induces an increase in the average coordination number of both the Ca and B cations. In particular, a fraction of the boron sites increases its coordination from triangular to tetrahedral by making a further bond with a H2O-oxygen atom. Although the phase transition occurs (at ambient temperature) at pressures far from those associated with the usual geologic environments of colemanite, the reported results disclosed flexible deformation mechanisms that borate compounds may adopt to accommodate pressure, thus providing new insights on the behavior of borate minerals at non-ambient conditions. The complex hydrogen-bonding network of olemanite has also been characterized, at ambient and low temperature conditions, by means of in situ single-crystal synchrotron X-ray and neutron diffraction experiments. A positional disorder, related to the presence of two mutually exclusive configurations of the H2O-molecule hydrogen atoms, was found both above and below ~ 0°C, where a displacive phase transition from the P21/a to the P21 space group occurs.
Lotti, P., Gatta, G.D., Comboni, D., Guastella, G, Merlini, M., Guastoni, A., Liermann, H.-P. (2017): High-pressure behavior and Pinduced phase transition of CaB3O4(OH)3*H2O (colemanite), J. Am. Ceram. Soc., in press, DOI: 10.1111/jace.14730
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