Bivalve shells can provide excellent archives of past environmental change but have not been used to interpret ocean acidification events. We investigated carbon, oxygen and trace element records from different shell layers in the mussels <i>Mytilus galloprovincialis</i> combined with detailed investigations of the shell ultrastructure. Mussels from the harbour of Ischia (Mediterranean, Italy) were transplanted and grown in water with mean pH_T 7.3 and mean pH_T 8.1 near CO₂ vents on the east coast of the island. Most prominently, the shells recorded the shock of transplantation, both in their shell ultrastructure, textural and geochemical record. Shell calcite, precipitated subsequently under acidified seawater responded to the pH gradient by an in part disturbed ultrastructure. Geochemical data from all test sites show a strong metabolic effect that exceeds the influence of the low-pH environment. These field experiments showed that care is needed when interpreting potential ocean acidification signals because various parameters affect shell chemistry and ultrastructure. Besides metabolic processes, seawater pH, factors such as salinity, water temperature, food availability and population density all affect the biogenic carbonate shell archive

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The structure of Li 4 Ti 5 O 12 was investigated by neutron powder diffraction, and the study revealed unprecedented details about lithium migration at high temperatures. A commercial sample of the battery anode material Li 4 Ti 5 O 12 (spinel-type) was measured from room temperature to 1100 °C. Up to 500 °C, linearly increasing values for the unit cell parameter, the isotropic atomic displacement parameters, and the oxygen position are observed. At 700 °C, a change of slope occurs, which is assigned to the beginning migration of lithium. Previous investigations identified the octahedral 16c site in the spinel structure as the migration position of lithium upon heating to high temperatures, and because of that, several phase transitions of Li 4 Ti 5 O 12 at high temperatures have been proposed. Here, we unambiguously identify that the lithium atoms occupy split sites around the 16c positions and orderÀdisorder phase transitions of Li 4 Ti 5 O 12 were not observed. One-particle potential shows that the occupancy of 16c is an unstable configuration and that the split-site structure leads to a more favorable migration position. Occupation of the lithium sites (32e) results in the same long-range diffusion path in all AE110ae directions. The onset of lithium migration can explain the change of the ionic conductivity of Li 4 Ti 5 O 12 at high temperatures, which has been observed by impedance spectroscopic studies. Further heating to 1000 °C resulted in a partial decomposition of Li 4 Ti 5 O 12 into the ramsdellite-type Li 2 Ti 3 O 7 and the cubic γ-Li 2 TiO 3 , and at 1100 °C, the Li 4 Ti 5 O 12 spinel was fully decomposed.

Li 4 Ti 5 O 12 , which is a high performance anode material for rechargeable Li-ion batteries, is crystallized directly via a novel continuous flow hydrothermal method using lithium ethoxide and titanium isopropoxide as reactants. Crystalline nanoparticles are obtained in a single step and in less than one minute, by mixing the reactants with superheated water in a continuous flow reactor at nearand supercritical conditions. The Li 4 Ti 5 O 12 nanoparticles have an average crystallite size of 4.5 nm with a specific surface area of ≥230 m 2 /g. In-situ synchrotron powder X-ray diffraction measurements upon annealing of the nanocrystalline Li 4 Ti 5 O 12 were performed in order to investigate the structural and microstructural changes from room temperature to 727 • C. The as-prepared crystalline nanoparticles show significant crystallographic strain, which is found to relax upon annealing above 500 • C, concurrent with crystallite growth. Electrochemical tests of the as-prepared Li 4 Ti 5 O 12 and a sample annealed at 600 • C reveal that heat-treatment results in a significant improvement of the performance in terms of the specific capacity and the rate capability, and overall the annealed nanoparticles have excellent electrochemical properties. The origin of the crystallographic strain is discussed, and further optimization of this rapid, green and scalable synthesis approach is suggested.

Detailed micromagnetic, rockmagnetic and mineralogical investigations on dacitic pumice from the eruption of Mt. Pinatubo (1991, Phillipines) showing reversed NRM/TRM are presented. Two intergrown hemoilmenite‐phases in chemically zoned particles were detected as being responsible: a rim‐(or covering) phase consisting of a weak‐ferromagnetic (disordered) hemoilmenite phase (low saturation magnetization but magnetically hard like hematite, FeTiO3 content 53–57 mol percent) and a core‐phase consisting of a ferrimagnetic (ordered) hemoilmenite phase (high saturation magnetization but magnetically softer, constant FeTiO3 content ≈ 58 mol percent). Preliminary studies were carried out in order to elucidate the magnetic interactions (possibly exchange coupling) responsible for the self‐reversal of the NRM/TRM. A preliminary and schematic model is presented which summarizes the main points of acquisition of a self‐reversed TRM according to our results.

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SUMMARY39 dacitic pumice and lithic samples from the 1991 eruption of Mount Pinatubo were investigated through both magnetic and mineralogical means. As in a previous study, natural remanent magnetization (NRM) is found to be reversed for most of the samples, with respect to the direction of the actual geomagnetic field direction. A few samples, amongst them ancient lithics transported by pyroclastic flows, show scattered NRM directions. From thermal demagnetization of these particular samples it is concluded that their orientation changed after emplacement. The emplacement temperature is estimated to be more than 460°C from thermal demagnetization of lithic samples.Two magnetic minerals with large grain sizes are observed under the optical microscope: titanomagnetite (TM) and haemo-ilmenite ( hem-ilm). Microprobe analyses yield x#0.10 for TM and y#0.52 and y#0.54 for two hem-ilm phases, in agreement with the observed Curie temperatures (~480°C for TM and~250°C for hem-ilm). The hem-ilm particles display chemical zonation, which seems to be correlated with a change of the domain structure: typically, a ferrimagnetic (FM) phase with slightly higher titanium content is observed in the central part whilst the crystal margin, which is weakly ferromagnetic (WF, due to spin-canted antiferromagnetism) is slightly poorer in titanium. Two different mechanisms for the origin and formation of the two observed phases are discussed: (1) chemical zonation of hem-ilm crystals due to a change in conditions in the magma chamber shortly before eruption; (2) similar to the microstructures observed from synthetic samples, this zonation in the large natural hem-ilm could be the result of migration of the WF phase towards the grain boundary during residence below the order-disorder transition temperature in the magmatic chamber. The room temperature hysteresis loop, which seems to be dominated by TM, provides multidomain (MD)-like parameters: J rs /J s =0.01 and H cr /H c =20. The large coercivity of remanence (15-40 mT), which is attributed to hem-ilm, may be intrinsic or due to interactions between WF and FM phases. The field dependence of the magnitude of the thermoremanent magnetization (TRM) is not linear: it increases first, reaches a maximum (negative) value for an applied field H close to 0.5 mT, then decreases steadily. By extrapolation, it is estimated that the TRM should be zero for a field of about 12 mT and become positive beyond. This total TRM is in fact the sum of several components. AF demagnetization of TRMs acquired in different fields shows the presence of at least three components: a self-reversed (SR) component that contains both hard and moderately hard components and a soft normal component. Independently of the value of H, the median destructive field of the SR component is of the order of 159