Cleavage Plane Research Articles

Unravelling the cleavage-rate relationship from both the experimental and theoretical standpoint: The instance of fluorite dissolution.

The phenomenon of solid dissolution into a solution constitutes a fundamental aspect in both natural and industrial contexts. Nevertheless, its intricate nature at the microscale poses a significant challenge for precise quantitative characterization at a foundational level. In this work, the influence across three specific cleavage planes, namely (100), (111), and (110) on the dissolution kinetics of fluorite in aqueous environments was examined from both experimental and theoretical standpoints. For the very first time, the surface potential of fluorite planes during dissolution was measured by means of a fluorite single-crystal electrode. Experimental results indicate that the dissolution of fluorite leads to a marked increase in surface roughness as well as an augmentation in the surface area of all analyzed surfaces. The most significant alteration in roughness is observed on the (111) plane, whereas the most substantial increase in surface area occurs on the (110) plane. In comparison to the (100) crystallographic plane, which demonstrates the slowest dissolution kinetics, the (111) and (110) planes display dissolution at a comparatively expedited rate. Theoretical simulations corroborate this trend, concurrently facilitating an effective examination of the system's free-energy landscape to analyze the dynamics and rates associated with the attachment and detachment of ions to the fluorite surface. Notably, the presence of interfacial defects has the potential to influence the free energy landscape, thereby altering the transition of ions into the bulk solution. Ultimately, the interplay of correlations and discrepancies between experimental findings and theoretical predictions is critically examined.

Precipitation and TRIP enhanced spallation resistance of additive manufactured M350 steel

This work investigates the spall damage and microstructural deformation behaviors of a heat-treated, hierarchical structured 18 wt% Ni-350 maraging steel (M350) produced by laser powder bed fusion (LPBF) under shock loading. The samples were shock-loaded along different orientations with peak shock stresses ranging from 7.0 GPa to 10.5 GPa. Experimental results demonstrate that the M350 exhibits ultra-high spall strength of 5.01–5.89 GPa and 4.53–4.99 GPa when loading perpendicularly and parallel to the building direction, respectively. Spall damage is characterized as a typical transgranular brittle fracture with {100} cleavage planes within the block. The observed superior mechanical performance is attributed to the precipitation strengthening and the transformation-induced plasticity (TRIP) effect. Dislocation slip cuts through the Ni3Ti precipitates, causing them to fracture, simultaneously, high density precipitates impede dislocation movement according to the Orowan mechanism, preventing the formation of microcracks. The residual austenite undergoes martensitic transformation with the formation of new secondary laths with widths of 20–60 nm to accommodate localized plastic deformations, which creates a large number of grain boundaries and leads to grain refinement.

Microscopic investigation of chemical and physical alteration behaviors in sandstone minerals induced by CO2-H2O-rock interactions during CO2 saline aquifer storage.

CO2 saline aquifer storage represents a promising strategy for mitigating the environmental impact of greenhouse gas emissions. However, the long-term effects of CO2 dissolved in formation water on rock minerals remain insufficiently understood. This study utilizes cast thin section analysis, scanning electron microscopy, and energy dispersive spectrometry techniques to perform a comprehensive microscopic investigation on this issue. Experimental results from sandstone core samples drilled from the Ordos pilot field reveal that feldspar minerals predominantly undergo geochemical dissolution, while quartz and clay minerals primarily exhibit physical alterations. Feldspar minerals, including albite, potassium feldspar, and anorthite, exhibit significant geochemical dissolution, characterized by cleavage plane dissolution, swelling, selective dissolution, and in-situ accumulation of dissolution products. This process leads to the formation of secondary minerals such as quartz, kaolinite, and illite, along with various microscopic structures like vugs, pits, and filamentous remnants. Alterations in quartz include the formation of stress-induced microfractures, the attachment of mineral clasts, the precipitation of geochemical reaction products, and pore blockage. In clay minerals, the formation, closure, interconnection, and reconfiguration of microfractures are evident characteristics, particularly at the nanoscale. The products of CO2-H2O-rock interactions typically comprise a complex mixture of physical and chemical products, marked by intricate elemental compositions and diverse structural forms, including blocky, granular, powdery, filamentous, and floc-like structures. This work reveals the distinctive chemical dissolution mechanisms of sandstone with complex mineral compositions, clarifies the CO2-induced physical alteration behavior of multiple minerals and identifies the multi-scale migration mechanisms of products generated by CO2-H2O-rock interactions. Moreover, these interactions have a dual impact: they enhance the porosity and permeability, while also potentially compromising the structural integrity of the rock and formation. This research provides a foundation for assessing the impact of CO2 storage on fluid flow and evaluating environmental safety concerns, such as CO2 leakage and geological subsidence.

Animal and vegetal materials of mouse oocytes segregate at first zygotic cleavage: a simple mechanism that makes the two-cell blastomeres differ reciprocally from the start.

Recent advances in embryology have shown that the sister blastomeres of two-cell mouse and human embryos differ reciprocally in potency. An open question is whether the blastomeres became different as opposed to originating as different. Here we wanted to test two relevant but conflicting models: one proposing that each blastomere contains both animal and vegetal materials in balanced proportions because the plane of first cleavage runs close to the animal-vegetal axis of the fertilized oocyte (meridional cleavage); and the other model proposing that each blastomere contains variable proportions of animal and vegetal materials because the plane of the first cleavage can vary - up to an equatorial orientation - depending on the topology of fertilization. Therefore, we imposed the fertilization site in three distinct regions of mouse oocytes (animal pole, vegetal pole, equator) via ICSI. After the first zygotic cleavage, the sister blastomeres were dissociated and subjected to single-cell transcriptome analysis, keeping track of the original pair associations. Non-supervised hierarchical clustering revealed that the frequency of correct pair matches varied with the fertilization site (vegetal pole > animal pole > equator), thereby, challenging the first model of balanced partitioning. However, the inter-blastomere differences had similar signatures of gene ontology across the three groups, thereby, also challenging the competing model of variable partitioning. These conflicting observations could be reconciled if animal and vegetal materials were partitioned at the first cleavage: an event considered improbable and possibly deleterious in mammals. We tested this occurrence by keeping the fertilized oocytes immobilized from the time of ICSI until the first cleavage. Image analysis revealed that cleavage took place preferentially along the short (i.e. equatorial) diameter of the oocyte, thereby partitioning the animal and vegetal materials into the two-cell blastomeres. Our results point to a simple mechanism by which the two sister blastomeres start out as different, rather than becoming different.

The Orbitomalar Ligament: A Cleavage Plane in Oculofacial Trauma.

We describe an oculofacial injury phenotype manifesting as a cleavage plane following the orbitomalar ligament in 5 cases. Across these cases, curvilinear wounds followed the course of the orbitomalar ligament, running clean planes through orbicularis oculi down to the infraorbital rim and arcus marginalis. One case involved bilateral orbitomalar ligaments, and 1 case involved the inferior canaliculus. Associated craniofacial injuries included orbital floor fracture, orbital hemorrhage, and zygomaticomaxillary complex fractures. Moderate-to-severe globe injuries were encountered, including hyphema, commotio retinae, retinal hemorrhages, cyclodialysis cleft, lens dislocation, and globe rupture. Wound closure included deep polyglactin sutures to recreate mid-facial support from the disrupted orbitomalar ligament; 1 case that did not receive deep, layered closure was associated with lower eyelid ectropion. These cases illustrate how orbitofacial ligaments may influence trauma phenotypes and inform subsequent repair.

Late Cretaceous turbidite systems of southern Belgrade outskirts: Constraints on the Santonian convergence onset, evidence from the Sava Suture Zone (Guberevac-Babe, northern Šumadija, Serbia)

As ancient depositional systems associated with active continental margins, turbidites may provide crucial information on orogenic evolution. This paper offers new stratigraphic and structural data on one of the late Alpine turbidite systems of the Late Cretaceous age (Guberevac-Babe-Ropočevo area; Serbia). The two opposite yet juxtaposed tectonic systems were initially deposited within the Sava Suture Zone and East Vardar Zone, whereby the former experienced Upper Cretaceous contractional- and extensional-type deformations. The new biostratigraphic dating constrains the age of mapped compressional structures, which indicates their Santonian age. This deformed segment of the newly dated Santonian clastic-carbonate turbidite sequence near the Guberevac site exposes new important compressional structures. The folds, reverse faults, and tectonic stylolites are allocated several kilometers from the primary deformation (Bela Reka thrust fault), positioned within the crustal footwall of the overriding East Vardar Zone. The complexity of the geological processes in the Guberevac-Babe-Ropočevo area is further revealed by the previously mapped layering of Upper Cretaceous strata, exposed within the wider investigated area. Our combined field study provides a new statistical analysis of structural elements such as faults, folds, and bedding planes, adding to the depth of the understanding of the Sava Suture Zone. The observed contractional structures, mesoscopic folds, thrust faults, two-generation cleavage planes, as well as the produced statistical structures, are mostly imprinted into the out-of-deformation front or within the mixed clastic-carbonate turbidites of the Sava Suture Zone (Guberevac-Babe area). The composite study shows that the investigated footwall segment, represented by the deformed Sava Suture Zone turbidites, underwent tectonic shortening during Santonian (convergence onset). After the main crustal thickening event ceased, the Guberevac-Babe-Ropočevo suture segment was reactivated several times (post-orogenic extension). The investigated segment of the Neotethyan Vardar paleosuture experienced a total of four deformation stages spanning Late Cretaceous to Miocene times. These include the Late Oligocene reactivation and emplacement of the Glavčina-Parlozi Late Oligocene subvolcanic body and the slightly younger Stenička bara Miocene igneous system.

Solar Wind Ion Sputtering from Airless Planetary Bodies: New Insights into the Surface Binding Energies for Elements in Plagioclase Feldspars

Our understanding of the ion-sputtering contribution to the formation of exospheres on airless bodies has been hindered by the lack of accurate surface binding energies (SBEs) of the elements in the various mineral and amorphous compounds expected to be on the surfaces of these bodies. The SBE for a given element controls the predicted sputtering yield and energy distribution of the ejecta. Here, we use molecular dynamics computations to provide SBE data for the range of elements sputtered from plagioclase feldspar crystalline end members, albite and anorthite, which are expected to be important mineral components on the surfaces of the Moon and Mercury. Results show that the SBE is dependent on the crystal orientation and the element’s coordination, meaning multiple SBEs are possible for a given element. Variation in the SBEs among the different surface positions has a significant effect on the predicted yield and energy distribution of the ejecta. We then consider sputtering by H, He, and a solar wind mixture of 96% H and 4% He. For each of these cases, we derive best-fit elemental SBE values to predict the ejecta energy distribution from each of the (001), (010), and (011) cleavage planes. We demonstrate that the He contribution to the sputtering yield cannot be accounted for by multiplying the 100% H results by some factor. Lastly, we average our results over all three possible lattice orientations and provide best-fit elemental SBE values that can be easily incorporated into sputtering yield models.

Step-by-step hysteroscopic treatment of International Federation of Gynaecology and Obstetrics type 3 myoma with the cold loop technique.

To demonstrate the "cold loop technique" for the hysteroscopic treatment of International Federation of Gynaecology and Obstetrics (FIGO) type 3 myomas. Step-by-step demonstration of the technique using educative video. A 45-year-old patient with infertility with repeated oocyte donor invitro fertilization failures affected by a FIGO type 3 myoma. FIGO type 3 myomas exhibit complete myometrial development while encroaching on the endometrium. This hybrid nature, combining features of both submucous and intramural myomas, may have a detrimental "double hit" effect for patients seeking pregnancy. Currently, there is a dearth of robust evidence regarding the ideal surgical approach for FIGO type 3 myomas. Despite the preference for the hysteroscopic approach due to their closer proximity to the uterine cavity compared with the serosa, the primary limitations of the conventional hysteroscopic approach include the risks of damaging healthy myometrium and the significant risk of adhesions. We showcase the hysteroscopic treatment of a 29-mm FIGO type 3 myoma on the anterior uterine wall using the "cold loop technique." The video emphasizes key procedural phases: opening the "endometrial-myometrial window" with minimal sacrifice of myometrium; identifying the correct cleavage plane through blunt dissection of fibroconnective bridges anchoring the myoma to the pseudocapsule using cold loops; and slicing the detached intramural component of the fibroid, displaced into the uterine cavity, with an electrical loop. Integrity of the uterine cavity and the healthy myometrium surrounding the myoma and avoiding postsurgical intrauterine adhesions. The myoma was completely removed in a single surgical step, and at the end of the procedure, the myoma's "notch" and its intact pseudocapsule were clearly visible. The patient was discharged in good health the day after the surgery. At the 3-month follow-up, the diagnostic office hysteroscopy revealed a fully recovered uterine cavity. The "cold loop technique" holds the potential to facilitate the safe removal of FIGO type 3 myomas, minimizing the risk of damage to the adjacent healthy myometrium and resulting in a lower likelihood of postoperative adhesions. This is especially critical for women contemplating conception.

Transformation of Mackinawite to Interlayered Greigite-Pyrrhotite and Pyrite in the Gaoping Submarine Canyon Sediments off Southwestern Taiwan

Iron monosulfides and neoformed pyrite below the sulfate‒methane transition zone (SMTZ) of rapidly accumulating turbiditic sediments from the Gaoping submarine canyon off southwestern Taiwan were examined by SEM-EDS-EBSD, HRTEM, and HAADF STEM to investigate their microstructural characteristics and processes of formation and transformation. Within a few meters below the SMTZ, mackinawite (Mkw) is largely replaced by interlayered greigite-pyrrhotite (Grg-Po) with {111}Grg//{001}Po and Grg//Po, followed by pyrite neoformation in clusters of disseminated matrix grains consisting of coalescing pyrite microcrystals, arrays of polycrystalline interlayer pyrite grains between the cleavage planes of layer silicates, with each grain’s core having inclusions of interlayered Grg-Po locally containing relict Mkw, and amassed pyrite microcrystals on the surface of porous interlayered Grg-Po micronodules. In the deeper sediments, neoformed pyrite is absent and Mkw is largely preserved, with partial replacement by interlayered Grg-Po having an overall topotactic relationship of ⟨110⟩Grg//⟨110 ⟩Po//⟨100⟩Mkw and {111}Grg//(001)Po//~{011}Mkw and a sharp reaction front without transitional profiles. The mineral grain boundaries and structural discontinuities with Mkw resulting from extensive interlayering between Grg {111} cubic close-packed segments and Po {001} hexagonal close-packed layers could serve as conduits for fluid flow and mass transport to drive the replacement reaction. The conversion of Mkw to metastable interlayered Grg-Po is inferred to occur through interface-coupled dissolution‒reprecipitation processes associated with partial oxidation while the partial replacement of interlayered Grg-Po ± minor relict Mkw by pyrite microcrystals with irregular grain boundaries and orientations probably occurred via a dissolution‒precipitation mechanism. Mkw could be initially formed by sulfate reduction driven by anaerobic oxidation of methane in reactive iron-rich sediments in paleo-SMTZs and subsequently transformed into interlayered Grg-Po followed by pyrite neoformation in the sulfidization front below the SMTZ or recent SMTZs in the Gaoping submarine canyon sediments.

Study on the influence of primary peak temperature on the microstructure and impact properties of heat affected zone of a 1000 MPa grade hydropower steel

ABSTRACT The microstructure of various zones in the heat-affected zone (HAZ) of 1000 MPa grade ultra-high-strength steel were investigated by welding thermal simulation. The results showed that the grain sizes were smallest at 950°C, when it was at the fine grain section in HAZ. The continuous reduction in grain size was due to the recovery and recrystallization. Samples subjected to thermal cycles at lower than 950°C exhibited high impact absorption energy of more than 100 J, with distinct fibrous zones and shear lips on the fracture surfaces, indicative of high impact toughness. However, the impact toughness of samples from the CGHAZ, which underwent thermal cycles at higher than 1100°C, decreased significantly to about 10 J, with the fracture surfaces showing macroscopic brittle fracture features and covered entirely by cleavage planes. Microstructural analysis revealed that coarse grains and brittle martensite were the primary causes of embrittlement in the CGHAZ.

Fabrication of InP Vertical Gate-All-Around Transistors Using Crystal Phase Transition Heterojunction

IntroductionCrystal phase transition can stabilize metastable crystal phase as single crystal structure. For example, zinc-blende (ZB) stable crystal phase in InP nanostructures can be easily transformed into wurtzite (WZ) crystal structure [1]. One of the advantages in this phenomenon is band-structure change from indirect gap to direct gap. Another advantage of the crystal phase transition enables us to form a kind of heterojunction in single materials, named crystal phase heterojunction (CPHJ). The CPHJ can form ideal heterojunction regardless of misfit dislocations in conventional heterostructure based on lattice mismatched systems. The InP-based CPHJ have been found to form a Type-II band discontinuity by optical characterization [2]. There was, however, few report on electronics application the InP CPHJ. Here we report on fabrication of vertical-gate-all-around (VGAA) transistors using the InP CPHJ, which was formed by the WZ- InP NWs on ZB InP(111)A substrates by selective-area growth.ExperimentA 20 nm-thick SiO2 layer was deposited on n-InP (111) A substrates by RF-sputtering. Periodical circular-shaped mask openings were formed on SiO2 mask by electron beam lithography and wet chemical etching. The opening patterns were designed with diameter of 50 nm and 70 nm and pitch of 400 - 2000 nm. Vertical InP NWs were formed by selective-area metal organic vapor phase epitaxy (MOVPE). Trimethylindium (TMIn) and tertiarybutylphosphine (TBP) were used as source materials, and diethylzinc (DEZn) and monosilane (SIH4) as p- and n- type dopants. The growth temperature for the InP NWs was 660°C. V/III ratio was 24.We fabricated the VGAA structure by using the InP NWs. First, we deposited 10 nm-thick Hf0.8Al0.2O as gate oxides by atomic layer deposition (ALD) on NWs. Next, 200 nm-thick tungsten (W) was deposited around the NW sidewalls as gate metal by sputtering. Benzocyclobutene (BCB) was deposited by spin-coating as isolation layer between gate and drain layers. The top portion of the NWs was exposed by reactive ion etching (RIE). Then drain (Ti/Pd/Au) and source (Ni/Ge/Au/Ni/Au) metals were evaporated on the top of the NWs and on the substrate. Finally, the devices were annealed at 400°C in N2 for 3 min.Result and DiscussionsPosition controlled vertical InP NWs were uniformly formed on the n-InP (111) A substrates. The NW morphology had hexagonal pillar shaped structure surrounded with vertical side facets, that was rotated with thirty-degree against the {-110} cleavage planes. This means {-211} facets were formed as the vertical sidewalls and the crystal structure grown NW was composed of WZ phase.The photoluminescence (PL) spectra of the grown NWs showed the three peak origins whose peaks were at 1.33 eV, 1.37 eV, and1.43 eV, respectively. The peak at 1.33 eV was originated from the InP ZB bandgap, and 1.43 eV was caused from the optical transition of WZ bandgap. The peak at 1.37 eV was assumed to be a type-II optical transition at the InP CPHJ. The PL also evidenced that the grown NWs had WZ structure.The fabricated VGAA transistor showed drain current was moderately modulated by the gate bias. Interesting point was that the Shottky barrier height at the InP CPHJ was modulated by the gate bias and the tunneling transport across the potential barrier in the CPHJ contributed to the drain current. The subthreshold slope of the transistor was 112 mV/dec. The threshold voltage (VTH) was -0.07 V. Gate leak current was about 10-9 – 10-3 A/μm, which was quite high as compared to the other III-V NW-based VGAA-FETs [3]. This was because that gate-oxide/InP interface was degraded. Further investigation will be required for achieving high-quality gate oxides/InP interface and will be discussed the improvement of the demonstrated devices.[1] Y. Kitauchi et al., Nano Lett., 10, 1699-1703 (2010).[2] A Jash et al., ACS Photonics, 10, 3143-3148 (2023).[3] H Gamo et al., IEEE Electron Device Lett, 41, 1169-1172 (2020).

Cleavage and anisotropy dependence of material removal behavior of monocrystalline β-Ga2O3 in abrasive machining

Beta-phase gallium oxide (β-Ga2O3) is recognized as a promising next-generation semiconductor material with an ultra-wide bandgap and broad application prospects. However, its pronounced cleavage and anisotropy presents great challenges in precision abrasive machining, hindering the advancements in related device manufacturing. In this work, systematic nanoscratching and nanogrinding tests, combined with characterization methods such as SEM, TEM, and Raman spectroscopy, as well as stress field theory were performed to explore the effects of easy-cleavable and anisotropy properties on material removal behaviors, specifically the machining directions parallel and perpendicular to the cleavage planes. The results indicate that when the direction is parallel to the cleavage plane, the scratch morphology is dominated by oriented cracks and bulk fractures, and cleavage cracks and stacking faults extending into the matrix cause more severe subsurface damage; when the direction is perpendicular to the cleavage plane, the scratch morphology is mainly induced by free damaged groove, with the subsurface comprising a mixed phase of nanocrystals and amorphous, and a few stacking faults, resulting in a much shallower damage layer. These results were further validated through nanogrinding tests, which showed that when the direction is parallel to the cleavage plane, the ground surface is dominated by cleavage facets, and both surface roughness and subsurface damage are much worse compared to the direction perpendicular to the cleavage plane. A mechanistic model was established, depicting that cracking on the cleavage plane and slip plane, coupled with crack deflection under stress fields, primarily leads to anisotropy in of material removal during abrasive machining. These results enhanced the understanding of the cleavage and anisotropy dependence in the machining process and provided insights for controlling the surface/subsurface damage in precision abrasive machining of β-Ga2O3.

Alteration and mineralization features of the Akcal Epithermal Gold Deposit, Biga Peninsula, Western Anatolia, Turkey: Evidence for low-sulfidation Au-Ag-Sb mineralization

The Akcal epithermal Au-Ag deposit, located on the Biga Peninsula, southwestern Turkey is estimated to contain 32.5 million tonnes of mineralization at an average grade of 1.03 g/t Au, equivalent to 1.2 million ounces of gold. Epigenetic mineralization is hosted by the lower Miocene Sapci volcanic suite, a calc-alkaline subduction-related volcanic arc consisting mainly of andesitic and basaltic andesitic rocks, while the coeval Soma Formation is composed of sandstone, claystone, conglomerate, marl-limestone, siltstone, and tuffite. Near the base of the volcanic pile, the Karakaya Complex is represented by limestone blocks of various sizes (from a few millimetres to several kilometres) within the Sapci volcanic suite. Short wave infrared (SWIR) and X-ray diffraction (XRD) analyses have shown that kaolinite, illite-smectite, montmorillonite, illite, beidellite, gypsum, vermiculite, quartz, and chlorite are the most common alteration minerals at Akcal. The alteration mineralogy indicates that the temperature of hydrothermal fluids broadly varied from 150° to 230°C, with a mildly acidic pH range of 5.0 to 6.5; these conditions accompanied by a lack of alunite suggest low-sulfidation epithermal conditions for the formation of the Akcal epithermal Au-Ag deposit. Petrographic examination and microanalysis by scanning electron microscopy indicate that mineralization at Akcal consists of pyrite and arsenopyrite with lesser hematite, ilmenite, rutile, and apatite. The occurrence of pyrite and hematite on cleavage planes of hydrothermal biotite is evidence of replacement of an earlier potassic alteration phase. Further petrographic examination of the basal limestone reveals replacement by sulfides displaying complex colloform intergrowths of pyrite and marcasite. The lack of skarn alteration and marble supports a carbonate-replacement origin for sulfides occurring in the basal limestone and is likely related to epithermal mineralization at Akcal. Geochemical results show that an Au-Ag-As-Sb±Pb±Zn signature is dominant across the volcanic-hosted epithermal mineralization and carbonate-replacement occurrences in the basal limestone; the lack of Cu mineralization (< 92 ppm) is typical of low-sulfidation epithermal systems. Strong positive correlations between Au and Ag (r′=0.77), As (0.80), and Sb (0.86) indicate that gold is likely hosted as a sub-microscopic phase within pyrite, arsenian pyrite, and arsenopyrite; visible gold (or free gold) and (or) electrum were not identified at Akcal. A model of fluid mixing involving shallow circulating meteoric waters with deeper magmatic-hydrothermal fluids is proposed for the genesis of gold mineralization at Akcal; a positive Au correlation with Mo (r′=0.74) and Mo concentrations of up to 582 ppm, support the involvement of magmatic-hydrothermal fluids in the epithermal system. Boiling as a mechanism for gold precipitation is unlikely given paleodepths of greater than 250 meters (3.0-5.0 MPa) and model temperatures of 150° to 230 °C. Mineralogical and textural evidence of boiling, such as adularia, bladed calcite, and lattice-texture quartz, have not been observed at Akcal. However, the presence of a silica-rich blanket with chalcedony (at Akcal surface) and having formed near the paleo water table may indicate some involvement of CO 2 – rich steam-heated waters, which could suggest some influence from boiling at depth, although evidence of boiling has not been confirmed in samples from Akcal. Precipitation of gold during the fluid mixing process would have occurred through a shift to higher f O 2 conditions and destabilization Au-thiosulphide complexes. This shift towards higher f O 2 is supported by the occurrence of gypsum and hematite with gold mineralization at depth.

Linear and nonlinear ultrasound parameters attributed to anisotropy in granite

The anisotropic nature of granite, a key factor affecting its mechanical properties, is inherently governed by its mineral alignment and the presence of orthogonal cleavage planes: rift, grain, and hardway. This study examines how these cleavage planes influence anisotropy, particularly in the context of microcracking formation and acoustic properties. A new measurement procedure for the acoustic nonlinearity parameter (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:\\beta\\:$$\\end{document}) is developed to address the well-known limitations of conventional linear ultrasound methods, including wave velocity and attenuation coefficient, in detecting microstructural changes induced by existing cleavage planes. Unlike other parameters, \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:\\beta\\:$$\\end{document} exhibits remarkable changes depending on the plane type, highlighting its high sensitivity to the mineral distribution in each cleavage plane and to the microcracks. A correlation between the linear and nonlinear parameters provides further evidence of the superiority of \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:\\beta\\:$$\\end{document} in detecting inherent microscale defects that develop in each plane and affect the anisotropic characteristics of granite. The findings of this study confirm that nonlinear ultrasound is capable of elucidating the mechanisms underlying the origin of anisotropy in granite due to microcracks, with broader implications for understanding unidentified chemical and mechanical phenomena in geological materials.

Observation of floating surface state in obstructed atomic insulator candidate NiP2

Obstructed atomic insulator is recently proposed as an unconventional material, in which electric charge centers localized at sites away from the atoms. A half-filling surface state would emerge at specific interfaces cutting through these charge centers and avoid intersecting any atoms. In this article, we utilized photoemission spectroscopy and density functional theory calculations to study one of the obstructed atomic insulator candidates, NiP2. A floating surface state with large effective mass that is close to the Fermi level and isolated from all bulk states is resolved on the (100) cleavage plane, implying better catalytic activity in this plane than the previously studied surfaces. Density functional theory calculation results elucidate that this floating surface state is originated from the obstructed Wannier charge centers, albeit underwent surface reconstruction. Our findings not only shed lights on the study of obstructed atomic insulators, but also provide possible route for development of new catalysts.

Trace element partitioning between natural barite and deep anoxic groundwaters: Implications for radionuclide retention in host rocks of nuclear waste repositories

Safety assessments for deep geological repositories involve risk calculations for the release of radionuclides like Ra, U, Pu and trivalent actinides from the storage containers to the groundwater. The retention of radionuclides through water-mineral interaction along the groundwater flow path could be a crucial factor in case of a repository failure. Barite (BaSO4) assumes significance in this context, as it has the potential to (re)crystallize and incorporate significant quantities of radioactive elements under relevant physico-chemical conditions.The assessment of mineral-fluid partition coefficients provides a means to evaluate the uptake potential of elements into the mineral. Usually, partition coefficients are determined under well-defined and controlled experimental conditions in laboratories. However, these results have shown discrepancies to partitioning coefficients determined from natural systems.Furthermore, effects like diagenesis or changes in the chemical fluid parameters might lead to a secondary alteration of the phases and affecting the retention ability.Here we investigate the incorporation of trace elements in natural barite from a borehole at 415 m depth in the Äspö Hard Rock Laboratory (Sweden). High-resolution LA-ICP-MS enables the quantitative determination of field-based partition coefficients through the integrated pixel average of selected zones in element distribution maps, combined with existing fluid concentration data. Similarities between the solid solution systems (Ra,Ba)SO4 and (Sr,Ba)SO4 allowed the combination of Sr partitioning data with density-functional theory simulations for an estimation of the partition coefficient value for Ra in natural barite. Values in the 10−2 range were determined, showing a deviation from those reported in previous experimental studies in the 10° range.Moreover, lanthanum serves as an analogue element for the radioactive trivalent actinides. The partition coefficient values for La in natural barite were determined in the range of 10−2 and 10−1, aligning well with experimental partition coefficients. Although density functional theory simulations cannot directly convert a La partition coefficient into a partition coefficient for trivalent actinides, it is assumed that these elements exhibit comparable behavior. Besides primary growth zonation, La also exhibits strong secondary enrichment, probably resulting from groundwater mixing and late fluid-mediated element transport through connected intracrystalline pore space oriented at cleavage plane systems. Additional SIMS analysis provides insights into the temporal variation of the sulfate source at the sampling site reflecting the influence of different waters during mineral growth.This study demonstrates a discrepancy between natural and synthetic PRa for barite and emphasizes that secondary processes significantly impact radionuclide retention in barite. Including these effects in reactive transport models will improve the reliability and applicability of integrative risk models.

Single‐Crystalline Zn(002) Facet Enables Ultrastable Anode–Electrolyte Interface

Dendrite growth and detrimental parasitic side reactions at the anode–electrolyte interface severely restrain the reversibility and cyclability of aqueous zinc‐ion batteries. Due to the lowest surface energy in Zn metal with a hexagonal close‐packed structure, (002) facet can effectively alleviate these side effects. In contrast to several existing works on (002) texturization, single‐crystalline Zn successfully grown using a Bridgman method in this work offers a fundamental understanding on this issue. The perfect atomic arrangement of the low‐surface‐energy (002) cleavage planes, without any grain boundaries, not only kinetically enables an epitaxial deposition inhibiting dendrite formation but also thermodynamically endows the most stable state restraining the side reactions. As a result, the single‐crystalline Zn(002) anode demonstrates a cycling stability over 4800 h (6.7 month) at 2 mA cm−2 in symmetric batteries. Zn(002)//Cu asymmetric batteries achieve a high average Coulombic efficiency of 99.92% over 500 cycles at 10 mA cm−2, enabling a fundamental demonstration of interface engineering for advancing batteries.

Pervasive calcite veins and cleavage dilation in low-grade metamorphic rocks as a marker of lower Jurassic rift-basin margins: A signature of microbial colonization

We report herein for the first time the occurrence of low-grade metamorphic rocks dilated by the growth of calcite veins induced by microbial communities inhabiting the cleavage planes. This process took place at the rock/sea-water interface in a rocky shore environment when the Hercynian basement rocks of the European-Iberian continental margin in Calabria (Italy) experienced stepwise flooding by a shallow tropical sea in the Early Jurassic, a process which was accompanied by synsedimentary extension, resulting in the birth of the Longobucco Basin. The veins exhibit a multiphase filling history, as, in an early phase, microstromatolites lining the walls of cleavage planes document the initial development of microbial biofilms. Subsequently, the growth of bands of radiaxial fibrous calcite enlarged the cavities through force of crystallization, also producing fissures at a high angle with respect to cleavage, which were in turn enlarged by crystal growth. Carbonate clumped isotope analysis indicates crystallization of calcite from sea water, at temperatures (T47) ranging from c. 33 to c. 44 °C. The inferred palaeoenvironment is that of a rocky coastline, locally with tide pools, where the seawater lapped cliffs made of Palaeozoic metasandstone. Microbially induced mineralization was a very rapid process, as clasts of veined metamorphic rocks are found in only slightly younger Early Jurassic deposits, like the sub-reefal carbonate bodies that grew in the Pliensbachian attached to the Palaeozoic bedrock. The occurrence of low-grade metamorphic rocks bearing calcite veins can be mapped in the field for kilometers, following the high-angle unconformity that separates the shallow-water carbonates from the basement. This microbial overprint therefore is a marker of the margins of a rift basin, where the exposure of basement rock along steep submarine surfaces was the result of footwall unroofing.

Bridgman growth and luminescence properties of Na2Mo2O7 crystal

This research presents a Bridgman method for the crystal growth of disodium dimolybdate (Na2Mo2O7, NM2O) crystals and understanding their luminescence mechanism. An NM2O crystal with a size of 23 * 23 * 90 mm3 was grown using the vertical Bridgman method. The cleavage of the NM2O crystal was analyzed by X-ray diffraction and scanning electron microscopy, which showed that the crystal cleaves along the (001) plane and the cleavage planes appear in a step pattern. Its luminescence properties were studied using transmission spectra and laser-stimulated luminescence spectra, which showed that the transmittance of a 5 mm thick sample reaches 85 % in the range of 500–700 nm with the absorption cutoff edge at 360 nm, resulting in the optical band gap of 3.35 eV. Under excitation of a 278 nm laser beam, the sample exhibited dual-peak emission, typically at around 598 nm and 673 nm, consistent with radioactive annihilation of the self-trapped exciton on [MoO6]6− and [MoO4]2− groups respectively. Also the luminescence at low temperatures were measured and discussed. All results can benefit the crystal growth and application to the 0νββ experiments for the functional material.

Reconstruction of calcite (10.4) manifests itself in the tip-assisted diffusion of water

Calcite (calcium carbonate) is the most abundant carbonate in the Earth's crust. Due to its omnipresence it plays a prominent role in fields such as geochemistry, biomineralization and industrial processes. Moreover, the interaction of water with the most stable cleavage plane, calcite (10.4), has been studied intensively, elucidating atomic-scale details of water binding and structure formation on this surface. Interestingly, calcite (10.4) reconstructs under ultrahigh vacuum conditions, exhibiting a (2 × 1) surface unit cell. Although first indications of this reconstruction have been presented more than 20 years ago, a clear confirmation of the existence has been provided only very recently. Here, we study the tip-assisted diffusion of water molecules on calcite (10.4) under ultrahigh vacuum conditions. By recording images series using dynamic atomic force microscopy we follow the movement of water molecules on the surface kept at 140 K. Analyzing the change in consecutive images allows for elucidating details of the molecular movement on the surface. Most notably, the analysis reveals that water molecules occupy one type of adsorption position exclusively, while the other type is not adopted. Our analysis thus demonstrates that the (2 × 1) reconstruction manifests itself in the movement of single water molecules on this surface.