Olivine Research Articles

Progress in the Application of LiMnPO4 Nanomaterials in Lithium-ion Battery Cathode

Lithium-ion batteries (LIBs) have become vital in today's energy storage systems, especially for electric cars and portable gadgets. High energy density, extended cycle life, and quick charging times are features of lithium batteries. Compared to conventional batteries, they are lightweight, ecologically benign, and have a low self-discharge rate. LiMnPO4 nanomaterials have garnered significant interest among various cathode materials due to their superior thermal stability, safety, and high operating voltage. The main topics of this paper are the structural characteristics, production techniques, and performance improvements of LiMnPO4 nanoparticles as LIBs cathodes. The basic operating principles of LIBs were covered in this article, with particular attention paid to the redox reactions occurring at the electrodes, the unique olivine structure of LiMnPO4, and how these factors affect electrochemical performance. The efficiency of many synthesis methods, such as spray pyrolysis, sol-gel, solid-state, hydrothermal, and solvothermal processes, in yielding superior LiMnPO4 nanoparticles is assessed. Additionally, surface modifications through ion doping and carbon coating are reviewed to highlight their roles in enhancing conductivity and stability. This article aims to provide ideas for developing high-performance LiMnPO4 cathode materials to affect LIBs' development positively. This article aims to provide ideas for developing high-performance LiMnPO4 cathode materials to influence LIBs' development positively.

Laboratory experiments of carbon mineralization potential of the main terrestrial basalt reservoirs in China

Against the background of realizing the goal of “carbon peaking and carbon neutrality”, using basaltic rocks for carbon mineralization is one of the most promising approaches to reduce the rise in atmospheric CO2 concentrations. This study conducted a series of experiments to assess carbon mineralization in nine basalt samples from the main terrestrial basalt reservoirs in China within CO2-H2O/brine-rock systems at low temperatures (≤35 °C). The results indicate that the secondary carbonates formed in the CO2-H2O/brine-basalt system are predominantly calcite rather than Mg-carbonate minerals at low temperatures (≤35 °C). Hence, at low temperatures (≤35 °C), basalt rich in Ca-bearing minerals promotes the formation of stable carbonate minerals more effectively than basalt containing Mg-bearing minerals. Furthermore, under conditions of low temperatures (≤35 °C) and pressures of approximately 3 MPa, the results suggest that alkaline olivine basalt, with a higher content of Ca-minerals and typical alkaline minerals (nepheline and Na-sanidine), exhibits the highest pH value and the highest amount of calcite. Hence, the alkaline minerals, nepheline and Na-sanidine, serve as pH buffers to increase the pH and promote the precipitation of calcite within CO2-H2O– basalt systems at low temperatures (≤35 °C). Among the nine evaluated basalts, basalt from the Shandong Linqu-Changle volcanic basin exhibits the highest rate of carbon mineralization at low temperatures (≤35 °C). Hence, Cenozoic alkaline olivine basalt from Shandong Linqu-Changle volcanic basin is one of the most promising basalt reservoirs in China for future in- situ carbonation. As for ex- situ carbonation, compared with olivine, diopside or Ca-plagioclase may be more appropriate for increasing ocean negative emissions.

Raman Spectroscopy Investigations of Ribbeck Meteorite.

On 21 January 2024, asteroid 2024BX1, discovered the three hours before, fell to Earth south of Ribbeck in the Havelland region of Germany. In this study, fragments of the Ribbeck meteorite, characterized by white and gray colors lithology, were examined for their chemical and phase compositions. The white lithology fragment exhibited a homogeneous chemical and phase structure typical of orthopyroxene, which crystallizes in the orthorhombic system. The gray lithology fragment showed a greater diversity in chemical and phase compositions. Raman spectra analysis revealed that, in addition to the pyroxenes found in the white lithology fragment, minerals from the olivine group (fayalite and forsterite) were also present, along with plagioclase and sulfur in pure crystalline form.

Crystal Structure and Li-Fe Order in Synthetic Mg(2-2x)LixFe3+x(SiO4) Olivine Structure.

Olivines are naturally occurring silicates consisting of isolated (SiO4)4- tetrahedra linked through M1O6 and M2O6 octahedra. In this study, we report the structural and crystal-chemical characterization of synthetic olivine crystals containing up to 25% Li-Fe3+ synthesized using the flux growth technique. Based on site scattering, <M1-O> and <M2-O> mean bond lengths, and charge neutrality of the chemical formula, we found a perfect ordering of Li and Fe3+ at the two distinct M1 and M2 sites. Unrestrained linear extrapolation to a hypothetical isostructural LiFe3+(SiO4) composition aligns well with the tabulated ionic radii of Li and Fe3+. Comparison made with the isostructural LiSc(SiO4) reveals that the Li-centered M2O6 octahedron has a significant capacity to distort in order to accommodate structural stresses, due to the relatively weak Li-O bond, while still achieving a bond valence sum that closely matches the formal charge of Li+. This behavior suggests the potential feasibility of an extended Li + Fe3+ for 2 Mg coupled substitution within the olivine structure. The reported structure of the LiFe3+(SiO4) endmember in the literature, despite its apparent matching of cell dimensions and space group with olivine, exhibits extremely unconventional crystal chemical features, raising questions about its validity. Given the importance of the suitability of Li-insertion in LiFeSiO4 as electrodes in rechargeable Li-ion batteries, further studies are needed to investigate its crystal structure and crystal chemistry.

Influences of the Stagnant Pacific Slab Beyond Its Westernmost Edge: Insights From the Cenozoic Alkaline Basalts in the Dariganga Volcanic Field, SE Mongolia

AbstractIt remains uncertain whether a stagnant slab in the mantle transition zone can affect the asthenospheric mantle beyond its leading edge. To address this question, we investigated Cenozoic alkaline basalts from the Dariganga volcanic field (DVF) in southeastern Mongolia. The DVF is located west of North–South Gravity Lineament (NSGL) in Eastern China, which is spatially coincident with the seismically detected stagnant Pacific slab front. Basalts from the DVF consist of nephelinite, basanite and alkali olivine basalt. These rocks have relatively high Nb/U (average = 58) and Nb/La (&gt;1) ratios and radiogenic Nd–Hf isotopic compositions. They also have high Ca/Al (0.60–1.13), Zn/FeT (13.5–16.5), and FeO/MnO (77–112) ratios as well as low δ26Mg (−0.42‰ to −0.26‰) values, reflecting an asthenospheric mantle source modified by carbonated eclogite‐derived melts. Pb–Nd–Hf isotope characteristics indicate that the carbonated eclogite‐derived melts likely originated from the stagnant Pacific slab. Although Cenozoic basalts from both the east of the NSGL (ENSGL) and DVF domains exhibit light δ26Mg values, basalts from the ENSGL nevertheless have lower δ26Mg values than those in the DVF domain. This suggests a gradual westward decline in the amount of carbonated melts/fluids derived from the stagnant Pacific slab. This variation trend, combined with a more fertile and oxidized asthenospheric mantle toward the ENSGL, indicates that the stagnant slab has affected the mantle and created a compositional aureole beyond its leading edge, which substantially contributed to the formation of the alkaline basalts in the DVF.

Energy transfer mechanism in infrared-emitting NaYGeO4:Tm3+, Ho3+ phosphors

Two series of NaY0.85Tm0.15-xHoxGeO4 (x = 0.005–0.03) and NaY0.85-xTm0.15HoxGeO4 (x = 0.0–0.055) phosphors have been prepared by the citrate technique. According to XRPD study, all the germanates crystallize in olivine structure and have an orthorhombic lattice, space group Pnma, Z = 4. The diffuse reflectance spectra have been measured and the optical band gap has been estimated. Under 808 nm laser diode excitation, the NaYGeO4:Tm3+, Ho3+ samples exhibit luminescence in the range of 1640–2240 nm, which is caused by 3F4 → 3H6 transition in Tm3+ and 5I7 → 5I8 transition in Ho3+ ions. The highest intensity of holmium lines, while maintaining relatively high intensity of thulium lines, was observed for NaY0.82Tm0.15Ho0.03GeO4, NaY0.815Tm0.15Ho0.035GeO4 samples with the Tm3+/Ho3+ ratio close to 5/1. The luminescence decay kinetics has been studied and the rate of energy transfer from Tm3+ to Ho3+ ions has been calculated. The obtained results indicate an effective energy transfer accelerated by migration due to dipole-dipole interaction. The mechanism of excitation and infrared luminescence in NaYGeO4:Tm3+, Ho3+ phosphors has been proposed.

Raman spectroscopic study of liebenbergite and Ni2SiO4 spinel at high pressure and high temperature: nickel effects on the vibration properties of olivine and spinel structures

Raman spectroscopic study of liebenbergite and Ni2SiO4 spinel at high pressure and high temperature: nickel effects on the vibration properties of olivine and spinel structures

Enhancing the Mn Redox Kinetics of LiMn0.5Fe0.5PO4 Cathodes Through a Synergistic Co-Doping with Niobium and Magnesium for Lithium-Ion Batteries.

The concerns on the cost of lithium-ion batteries have created enormous interest on LiFePO4 (LFP) and LiMn1-xFexPO4 (LMFP) cathodes However, the inclusion of Mn into the olivine structure causes a non-uniform atomic distribution of Fe and Mn, resulting in a lowering of reversible capacity and hindering their practical application. Herein, a co-doping of LMFP with Nb and Mg is presented through a co-precipitation reaction, followed by a spray-drying process and calcination. It is found that LiNbO3 formed with the aliovalent Nb doping resides mainly on the surface, while the isovalent Mg2+ doping occurs into the bulk of the particle. Full cells assembled with the co-doped LMFP cathode and graphite anode demonstrate superior cycling stability and specific capacity, while maintaining good tap density, compared to the undoped or mono-doped (only with Nb or Mg). The co-doped sample exhibits a capacity retention of 99% over 300 cycles at a C/2 rate. The superior performance stems from the enhanced ionic/electronic transport facilitated by Nb coating and the enhanced Mn2+/3+ redox kinetics resulting from bulk Mg doping. Altogether, this work reveals the importance of the synergistic effect of different dopants in enhancing the capacity and cycle stability of LMFP.

A TEM Study of Structural Degradation in LiFePO4 Batteries after Hybrid Vehicle Use

Establishing a robust, efficient circular economy for batteries hinges on understanding how they decay over time under various conditions. This understanding is crucial to maximize material use before recycling or disposal. A key aspect of this endeavor is the study of lithium iron phosphate (LiFePO4), a pivotal battery technology whose structural integrity over time remains a subject of inquiry.1 Known aging mechanisms in LiFePO4 (LFP) batteries include electrode degradation, SEI growth, and electrolyte decomposition.1 These processes extend to the cathode, where degradation can manifest as Fe dissolution, Li inventory loss, Fe/Li anti-site defects, and LFP amorphization.1–3 However, these mechanisms are typically studied in lab-aged cells under controlled conditions, leaving a gap in our understanding of their behavior in real-life, commercialized applications.Our research aims to bridge this gap by characterizing the degradation mechanisms of LFP cathode material in various states of health (SOH) after use in a hybrid vehicle. We sourced our cathode samples from 26650 cells extracted from a BAE ESS-A123 hybrid bus battery pack. After selecting cells with drastically different SOHs based on previous analyses,4 we employed transmission electron microscopy (TEM) for detailed characterization.In this talk, we will share insights gained from high-resolution TEM characterization, alongside chemical analysis using energy-filtered TEM and electron energy loss spectroscopy (EELS). Our focus will be on changes in the olivine structure, including lattice parameter alterations, Li and Fe migration, and Fe oxidation. By combining cell-level SOH analyses with TEM characterization, we will highlight how electrochemical test results correlate with material degradation mechanisms, enhancing our understanding of battery health, longevity, and diagnostics. Wang, L. et al. Insights for understanding multiscale degradation of LiFePO4 cathodes. eScience 2, 125–137 (2022). Li, X. et al. First Atomic-Scale Insight into Degradation in Lithium Iron Phosphate Cathodes by Transmission Electron Microscopy. J. Phys. Chem. Lett. 11, 4608–4617 (2020). Xu, P. et al. Efficient Direct Recycling of Lithium-Ion Battery Cathodes by Targeted Healing. Joule 4, 2609–2626 (2020). Ramirez-Meyers, K., Rawn, B. & Whitacre, J. F. A statistical assessment of the state-of-health of LiFePO4 cells harvested from a hybrid-electric vehicle battery pack. J. Energy Storage 59, 106472 (2023).

Unveiling Reaction Mechanisms of Non-Aqueous Zn-Ion Batteries – Zn/LiFePO4 System

Zinc-ion batteries (ZIBs) are among the most promising energy storage technologies because of their low cost, safety, and environmental friendliness. In this work, we focus on investigating the electrochemical reaction mechanisms of ZIBs with Lithium iron phosphate (LiFePO4) as an active material in the positive electrode, Zn(OTf)2+LiCl dissolving Tetraethylene glycol dimethyl ether (TEGDME) as the electrolyte, as well as metallic Zinc as the negative electrode. After testing the ZIB cells by galvanostatic cycling, the cells with TEGDME exhibit the best electrochemical performance in terms of long-term stability. The initial specific discharge capacity is 118.3 mAh g-1 and the capacity retention is 91.4% after 100 cycles at a current density of 10 mA g-1. We propose the reaction mechanisms during the charge-discharge processes involve extraction/insertion processes of Li+ into/out of the olivine structure of LiFePO4 as evidenced by X-ray near-edge spectroscopy (XANES). According to X-ray diffraction (XRD) analysis of the discharged and charged LiFePO4 electrodes, the crystal structure changes from LiFePO4 to FePO4 when charging and back into LiFePO4 again when discharging. Besides, XRD and scanning electron microscopy (SEM) confirm that the cycled Zn electrode is hardly present with passivation and/or corrosion. Therefore, this new combination of Zn/LiFePO4 and TEGDME has a potential for ZIB applications.

Crustal origin for olivine in the lunar Shioli crater ejecta boulders: Insights from the geological setting of Theophilus crater and Nectaris basin

On the Moon, impact craters and basins expose a wide range of crustal and mantle rocks that provide excellent opportunity for sampling them, understanding their origins and reconstructing spatial and temporal evolution of lunar interior. The previous studies detected olivine-bearing mantle rocks in and around large impact craters and basins. The Japanese SLIM mission landed on the ejecta of a ∼ 280-m-diameter Shioli crater that was emplaced on the ejecta blanket of ∼ 103-km-diameter Theophilus crater, for characterizing potential mantle-derived olivine in the Shioli crater ejecta boulders. To test this hypothesis, we studied the geological setting of Shioli crater, host Theophilus crater and Nectaris multi-ring basin using the orbiter data from Chandrayaan-1 and 2, Lunar Reconnaissance Orbiter, and Kaguya missions and the earth-based Arecibo radar observation. The asymmetrically distributed secondary craters and impact melt ponds around Theophilus crater suggests that a northeast-directed oblique impact produced this crater. Composition of Theophilus crater and surrounding region indicates that the crater excavated a heterogeneous target composed of a thin layer of high-Al olivine basalt (Mare Nectaris) underlain by anorthositic highland rocks possibly intruded by Mg-suite plutons; layers of Cyrillus crater ejecta blanket and Nectaris basin materials (both ejecta and impact melt sheets) were also present beneath the mare basalt flows. Hence, the Theophilus ejecta blanket is a mixture of all these materials. Our dating of Theophilus crater suggests that it is a ∼ 2 Ga Eratosthenian crater. Shioli is a fresh simple crater that was formed at ∼ 1 Ma on the uprange ejecta blanket of Theophilus, where the Arecibo radar data indicated the presence of abundant buried Theophilus ejecta boulders. An ESE-directed hypervelocity oblique impact event produced the elongated Shioli crater and its asymmetrically distributed bright ejecta. Shioli is a primary impact crater indicating the role of impact spallation processes associated with this hyper-velocity impact in producing thousands of ejecta (or spall) boulders around Shioli crater, displaying their asymmetric dispersal pattern and spatial variation of boulder sizes and shapes. The larger and elongated boulders are concentrated near the crater rim, while their size and axial ratio gradually decreases outward from the crater rim. The SLIM mission landed on a thin downrange ejecta of Shioli crater, where fewer large-size boulders are present. Our compositional study suggests that the Shioli ejecta boulders are composed of olivine basalt (Mare Nectaris) mixed with highland anorthositic fragments, including the reworked Cyrillus ejecta and Nectaris basin materials. The Shioli ejecta boulders were produced by complex impact fragmentation of already existing, buried Theophilus ejecta boulders. The regional crustal structure of Nectaris basin and its petrological composition suggest that both Nectaris basin and Theophilus crater did not excavate the lunar mantle. Therefore, the Shioli ejecta boulders are of crustal origin, including the olivine minerals present in them. Our results have important implications for the origin of olivine in the Shioli crater boulders being investigated by the SLIM mission.

Achieving thermodynamic stability of single-crystal ultrahigh-nickel cathodes via an alcohol-assisted mechanical fusion

Elevating the operating voltage is an effective approach to improve the reversible capacity of ultra-high nickel layered oxide cathode LiNixCoyMnzO2 (NCM, x ≥ 0.8) and solve the “range anxiety” confusion of electric vehicles. However, the undesirable surface reconstruction induced by the high cut-off voltage has a fatal impact on the thermodynamic stability of the material, inevitably leading to fast capacity degradation. Herein, a mechanical fusion aided by alcohol is suggested to create a stable olivine structure for the single-crystal (SC) ultrahigh-nickel cathode LiNi0.92Co0.04Mn0.04O2. The addition of nanoparticles effectively bridges the void of SC-NCM, builds an ideal particle grading, and significantly raises the cost efficiency, as well as promotes the cycling stability and safety of the full cell. Remarkably, the layered/olivine mixture forms a perfect shield by lowering the surface area between the NCM cathode and electrolyte, hence mitigating side reactions and contributing to an incredibly thin and stable cathode/electrolyte interface. Furthermore, the thermodynamic stability of highly delithiated NCM is improved, as both the particle cracks and structural degradation are simultaneously postponed. Consequently, the maximum temperature of the single-crystal LiNi0.92Co0.04Mn0.04O2@LiFePO4‖graphite pouch full cell is dramatically reduced from 599.4 to 351.4 °C, and the full cell achieves 88.2% capacity retention after 800 cycles, demonstrating excellent thermal stability and cycling stability. This facile strategy provides a feasible technical reference for further exploiting the ultrahigh-capacity, high-safety, and long-life Ni-rich cathode for commercial application of lithium-ion batteries (LIBs).

LiMn0.8Fe0.2PO4 as a promising cathode material in solid-state lithium batteries: Structural and electrical characterization

In this study, the synthesis, structural characterization, and electrical property analysis of LiMn0.8Fe0.2PO4 (LM8F) and its carbon-composite variant (LM8F-10%C) as potential cathode materials for solid-state lithium batteries were reported. Employing high-energy ball milling (HEBM) followed by calcination, LM8F was synthesized using ammonium dihydrogen phosphate, lithium carbonate, manganese(II) acetate tetra-hydrate, and iron(III) phosphate as precursors. The introduction of glucose as a carbon source aimed at the formation of a carbon-coated composite to enhance the electrical conductivity of the material. Structural and morphological characteristics of the synthesized materials were elucidated through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FeSEM). The XRD results confirmed the olivine and orthorhombic structure of the synthesized material, highlighting its suitability for use as a cathode in solid-state lithium batteries. Electrical properties were assessed using an LCR meter to examine the impact of carbon coating on electrochemical performance. The findings demonstrated that the inclusion of carbon significantly improved the electrical conductivity, potentially leading to enhanced battery performance. This work contributes to the development of high-performance cathode materials for solid-state lithium batteries, paving the way for future advancements in energy storage technologies.

Study of the variation in the value of gravity resulting from basalt intrusions in the area of Massallata and its surroundings using Bouguer gravity anomaly maps

In this paper an attempt to locate the sites of basalt intrusion, an analysis and study of Bouguer map was carried out for the area, which lies between two circles of width 32,250 - 32,360 north, and between longitudes 14.30 - 13.49 east. The paper included processing the gravity data and separating the gravity anomaly from each other using the derivatives method Interpretation of gravity data was performed using the modeling program (2D, 3D), which aims to create a geological profile that shows the third dimension of the distribution of different rocks, and rather olivine and phenolitic basalt intrusions in the study area depending on the vertical distribution of density, which is reflected in the values of the gravity anomalies in the contour map of the region. Basalt does not have wide openings in the study area, but it is found in the form of dikes in irregularly sprawling areas, especially those that are considered areas of sculpture by the action of running water in the valleys As for the southeastern region of the study area, olivine basalt rocks were found at a depth of 3 - 5 meters, and they are deaf, which indicates their crystallization under the surface of the earth, especially in the area of the Tarhuna agricultural project. Keywords: Basalt intrusions, Bouguer gravity anomaly, Geological profile, Rock density.

Biomass-Derived Carbon Utilization for Electrochemical Energy Enhancement in Lithium-Ion Batteries.

Cathodes made of LiFePO4 (LFP) offer numerous benefits including being non-toxic, eco-friendly, and affordable. The distinctive olivine structure of LFP cathodes contributes to their electrochemical stability. Nonetheless, this structure is also the cause of their low ionic and electronic conductivity. To enhance these limitations, an uncomplicated approach has been effectively employed. A straightforward solid-state synthesis technique is used to apply a coating of biomass from potato peels to the LFP cathode, boosting its electrochemical capabilities. Potato peels contain pyridinic and pyrrolic nitrogen, which are conducive to ionic and electronic movement and facilitate pathways for lithium-ion and electron transfer, thus elevating electrochemical performance. When coated with nitrogen-doped carbon derived from potato peel biomass (PPNC@LFP), the LFP cathode demonstrates an improved discharge capacity of 150.39 mAh g-1 at a 0.1 C-rate and 112.83 mAh g-1 at a 1.0 C-rate, in contrast to the uncoated LFP which shows capacities of 141.34 mAh g-1 and 97.72 mAh g-1 at the same rates, respectively.

Surface engineering of Li3V2(PO4)3-based cathode materials with enhanced performance for lithium-ion batteries working in a wide temperature range

Operating at extreme temperatures is the biggest challenge for lithium-ion batteries (LIBs) in practical applications, as both the capacity and cycling stability of LIBs are largely decreased due to the sluggish reaction kinetics of the cathodes. Therefore, developing suitable cathode materials is the key point to tackling this challenge. Lithium vanadium phosphate [Li3V2(PO4)3, LVP] is a promising cathode with good features of a high working voltage, high intrinsic ionic diffusion coefficiency, and stable olivine structure in a wide temperature range, although it is perplexed by the low electronic conductivity. To tackle this issue, a series of nitrogen-doped carbon network (NC) coated LVP composites were synthesized using a hydrothermal-assisted sol-gel method. Among them, the LVP@NC-0.8 sample exhibited a remarkable tolerance at a high charging cutoff voltage of 4.8 V in a wide temperature range. Full cells of LVP@NC-0.8||graphite exhibited superior performance at different current rates. Moreover, the reaction mechanism of the LVP@NC-0.8 electrode was proved by in-situ X-ray diffraction technique, demonstrating that temperature was a critical factor that contributed to the sluggish phase transformation with high voltage hysteresis at low temperature and severe crystal structure distortion at high temperature. Theoretical calculations further demonstrated the superiority of the NC for high electronic conductivity and reduced lithium transportation barriers. The enhanced electrochemical performances of LVP-based cathode materials have provided the possible application of LIBs in a wide temperature range.

Compressibility and thermal expansion of magnesium phosphates

Abstract. The ambient-temperature compressibility and room-pressure thermal expansion of two Mg3(PO4)2 polymorphs (farringtonite = Mg3(PO4)2-I, with 5- and 6-fold coordinated Mg, and chopinite = “Mg-sarcopside” = [6]Mg3(PO4)2-II), three Mg2PO4OH polymorphs (althausite, hydroxylwagnerite and ε-Mg2PO4OH, all with [5]Mg and [6]Mg) and phosphoellenbergerite ([6]Mg) were measured on synthetic powders using a synchrotron-based multi-anvil apparatus to 5.5 GPa and a laboratory high-temperature diffractometer, with whole-pattern fitting procedures. Bulk moduli range from 64.5 GPa for althausite to 88.4 GPa for hydroxylwagnerite, the high-pressure Mg2PO4OH polymorph. Chopinite, based on an olivine structure with ordered octahedral vacancies (K0 = 81.6 GPa), and phosphoellenbergerite, composed of chains of face-sharing octahedra (K0 = 86.4 GPa), are distinctly more compressible than their homeotypical silicate (127 and 133 GPa, respectively). The compressibility anisotropy is the highest for chopinite and the lowest for phosphoellenbergerite. First-order parameters of quadratic thermal expansions range from v1 = 2.19×10-5 K−1 for ε-Mg2PO4OH to v1 = 3.58×10-5 K−1 for althausite. Phosphates have higher thermal-expansion coefficients than the homeotypical silicates. Thermal anisotropy is the highest for farringtonite and the lowest for hydroxylwagnerite and chopinite. These results set the stage for a thermodynamic handling of phase-equilibrium data obtained up to 3 GPa and 1000 °C in the MgO–P2O5–H2O and MgO–Al2O3–P2O5–H2O systems.

Time scales of olivine storage and transport as revealed by diffusion chronometry at Waitomokia Volcanic Complex, Auckland Volcanic Field, New Zealand

Detailed knowledge of the pre-eruptive time scales associated with magma storage and transport is vital to improve volcanic hazard forecasting in active volcanic regions. However, quantification of the timescales of volcanic processes at mafic volcanic centres in continental intraplate settings is challenging, despite them being a source of significant hazards for human populations and infrastructure due to their limited predictability in space and time. We conducted a detailed petrological study to investigate the time scales of olivine storage and transfer throughout the eruption sequence of Waitomokia Volcanic Complex, a tuff ring and scoria cone complex in the Auckland Volcanic Field. Olivine crystal textures and compositions were determined from stratigraphically-constrained samples of the volcanic complex, from the initial phreatomagmatic phase to the final magmatic phase. Olivine crystals are typically <300 μm in length and characterised by skeletal morphologies, displaying chemical zoning in forsterite (Fo = 100*Mg/[Mg + Fe]; mol%), CaO, MnO and NiO wt% contents. We classified olivine into three major groups based on their Fo core compositions: (1) normally zoned crystals with high Fo content (Fo > 85), (2) crystals with intermediate Fo contents (84–81), and (3) reversely zoned crystals with lower Fo core content (<80). Olivine chemical zoning (diffusion) profiles were modelled in the context of a specific magmatic environment linked with changes in thermodynamic variables during storage (temperature, pressure, and oxygen fugacity). We propose that the normally zoned olivine crystals grew in one magmatic environment (ME1), which subsequently intruded into a more evolved (lower MgO) environment (ME2), where they interacted and were stored for up to 135 days before their eruption. During magma ascent to the surface, a second magma mixing event occurred between ME2 and magma within a third magmatic environment (ME3), forming reversely-zoned olivine crystals yielding notably shorter ascent times of approximately a few days. The rocks from the opening phreatomagmatic phase of the eruption show a larger range in olivine group types compared to the final magmatic phase, where those from the deeper ME1 are more abundant. The short time scales of magma transport obtained in our study, on the order of days to months, should be informative of the warning times that may be encountered between the onset of volcanic unrest and an eruption in the Auckland Volcanic Field.

Characteristics of pyroclastic deposits and evolution of Maar Bethok Lamongan Volcano Tiris Probolinggo East Java Indonesia

The Lamongan Volcano Complex has a very different character from the Bromo and Argopuro Volcano groups. Lamongan Volcano has 37 volcanic cones and 27 maars (ranu). This volcano is quarter-old and occupies part of East Java Province. Maar Bethok is composed of lava and intercalation between pyroclastic deposits from phreatomagmatic and magmatic falls that still need to be firmly consolidated. These pyroclastic deposits characterize a strombolian eruption with more lava dome or crater wall material ejected. The rocks that make up the Bethok maar include olivine-pyroxene basalt lava and pyroclastic fall deposits with fragments of olivine basalt and basalt composition. The evolution of the Bethok maar eruption started from magma with an alkaline composition and ended with a more acidic composition. The magmatism of Bethok maar has an island arc calc-alkaline affinity.

Electrochemically Driven Transformation of Olivine LiFePO4 to Olivine NaFePO4 in Cells with Sodium Anode and Carbonate Electrolyte

AbstractThe direct electrochemical transformation of commercial LiFePO4 to NaxFePO4 olivine in a Na||LiFePO4 electrochemical cell with sodium electrolyte has been studied. Electrolytes containing 1 M of NaClO4 in ethylene carbonate (EC), dimethyl carbonate (DMC) and fluoroethylene carbonate (FEC) have been probed, and in the solvents with the ratio of EC:DMC:FEC=0.4:0.5:0.1 by volume, maximal values of the specific capacity (113 mAh g−1) with good cycling stability and maximal discharge currents are achieved upon sodiation. To determine the composition of the cathode material and utilization factor of LiFePO4, the dependence of open circuit voltage on specific capacity has been investigated. The general formula of the sodiation product can be written as Na0.88FePO4. Its theoretic specific capacity may be estimated as 135 mAh g−1. The composition of the products obtained is supported by XRD analysis, which suggests that in discharged cathodes, Coulombic influence of LiFePO4 crystallites on neighboring NaxFePO4 crystallites may enlarge the unit cell of the former and reduce its size of the latter. Probably, shrinkage in the presence of LiFePO4 stabilizes the olivine structure of NaxFePO4 and prevents its transformation from electrochemically active olivine to inactive maricite.