We explore the mechanical properties of lithium metal and investigate how specimen size, crystallographic orientation, temperature and strain rate affect its deformation behavior. In single crystals, it is found that anisotropy plays an essential role both for elasticity and plasticity. We demonstrate that Li single crystal nanopillars plastically deform either by dislocation slip or by twinning, depending on orientation, loading mode (tension versus compression) and strain rate. In the cases of slip, deformation is predominantly mediated by dislocations with a Burgers vector of 1/2 < 111 >, which are active on different planes. Conversely, twinning occurs singularly on {112} planes and displays a twinning/anti-twinning anisotropy, resulting in the strong dependence on orientation and loading mode observed. In terms of size dependence, specimens undergoing dislocation slip show a pronounced 'smaller is stronger' trend in their yield strength. However, for specimens deforming exclusively by twinning, size effects are notably less significant. In polycrystalline nanostructures, opposed to the single crystal findings, the yield strength decreases with finer grain size in the spirit of an inverse Hall-Petch relationship, with grain boundaries being the central effect influencing their mechanical behavior.

This work focuses on a very narrow region in the quaternary system Na2O-P2O5-SiO2-ZrO2 to explore the occasionally proposed deficiency in zirconium and oxygen content of Na+ super-ionic conductor (NaSICON) materials. In addition, this region is known for the formation of glass-ceramics, but a systematic study of such materials has not been carried out yet. For this purpose, 2 series of compositions were defined and synthesized: Na3.4Zr2-3x/4Si2.4-x/4P0.6+x/4O12-11x/8 and Na3.4Zr2-3x/4Si2.4+x/4P0.6+1.5x/4O12-x/16. They only differ in the silicate and phosphate content. In the first series the molar content is constant, nSi + nP = 3. The latter series allows an excess of the 2 cations to meet the composition Na3.1Zr1.55Si2.3P0.7O11 or alternatively re-written as Na3.4Zr1.7Si2.52P0.77Ol2, which was formerly regarded as a superior material to the frequently reported composition Na3Zr2Si2POl2.Several characterization techniques were applied to better understand the relationships between phase formation, processing, and properties of the obtained glass ceramics in the context of the quasi-quaternary phase diagram. The investigations gave clear evidence that a glass phase is progressively formed with increasing x. Therefore, compounds with x > 0.2 have to be regarded as glass-ceramic composites. The resulting NaSICON materials revealed a very limited Zr deficiency with charge compensation by Na ions and a non-detectable amount of oxygen vacancies verified by neutron scattering and atomistic simulations.Hence, this work is the first systematic investigation of pretended Zr-deficient NaSICON materials, which clearly show the chemistry of a 2-phase region. The 2 investigated series are directed toward a region that is orthogonal to the series Na3Zr3-ySi2PyO11.5+y/2 reported in the first part of this series of publications.

Polymer-ceramic composites combine the benefits of polymers and ceramics. In particular, the infiltration of the ceramic cathode with a Li-ion-conducting polymer in an all-solid-state Li battery enhances the utilization of the cathode active material (CAM) and enables the application of thicker cathodes with higher storage capacity. This concept has already been validated in our earlier work, in which a porous LiCoO2-Li6.45Al0.05La3Zr1.6Ta0.4O12 (LLZO:Al:Ta) composite cathode was fabricated by spark plasma sintering (SPS) technique. However, its performance stability was low. In the present work, the concept is modified using an LFP-LATP cathode with LiFePO4 as the CAM, Li1.5Al0.5Ti1.5(PO4)(3) as the ion-conducting phase, and tape-casting with free sintering instead of SPS. Both tape-casting and free sintering are more relevant for large-scale production. The sintered LFP-LATP cathode is infiltrated with the MEEP polymer and LiC2NO4F6S2 ion-conducting salt. A full cell with the polymer-infiltrated cathode, LLZO:Al:Ta separator, and Li anode shows nearly full LFP utilization in the 100 mu m thick cathode with an excellent area-specific storage capacity of above 3 mAh cm(-2). However, after a few dozen cycles, a Li dendrite penetrates the separator leading to abrupt capacity fading. The prevention of Li dendrite formation remains a challenge for our future work.

•Highly dense LATP (99.8%) sheets were prepared by tape casting.•The ionic conductivity and mechanical properties were optimized by sintering addition of SiO2.•Relationship between the mechanical measurement and microstructures of were discussed.

Tibia trabeculae and vertebrae of rats as well as human femur were investigated by high-resolution TEM at the atomic scale in order to reveal snapshots of the morphogenetic processes of local bone ultrastructure formation. By taking into account reflections of hydroxyapatite for Fourier filtering the appearance of individual alpha–chains within the triple–helix clearly shows that bone bears the feature of an intergrowth composite structure extending from the atomic to the nanoscale, thus representing a molecular composite of collagen and apatite. Careful Fourier analysis reveals that the non–collagenous protein osteocalcin is present directly combined with octacalcium phosphate. Besides single spherical specimen of about 2 nm in diameter, osteocalcin is spread between and over collagen fibrils and is often observed as pearl necklace strings. In high-resolution TEM, the three binding sites of the γ-carboxylated glutamic acid groups of the mineralized osteocalcin were successfully imaged, which provide the chemical binding to octacalcium phosphate. Osteocalcin is attached to the collagen structure and interacts with the Ca–sites on the (100) dominated hydroxyapatite platelets with Ca-Ca distances of about 9.5 Å. Thus, osteocalcin takes on the functions of Ca–ion transport and suppression of hydroxyapatite expansion.

The compatibility of the solid electrolyte Li1.5Al0.5Ti1.5(PO4)3 (LATP) with the cathode materials LiCoO2, LiMn2O4, LiCoPO4, LiFePO4, and LiMn0.5Fe0.5PO4 was investigated in a co-sintering study. Mixtures of LATP and the different cathode materials were sintered at various temperatures and subsequently analyzed by thermal analysis, X-ray diffraction, and electron microscopy. Oxide cathode materials display a rapid decomposition reaction with the electrolyte material even at temperatures as low as 500 °C, while olivine cathode materials are much more stable. The oxide cathode materials tend to decompose to lithium-free compounds, leaving lithium to form Li3PO4 and other metal phosphates. In contrast, the olivine cathode materials decompose to mixed phosphates, which can, in part, still be electrochemically active. Among the olivine cathode materials, LiFePO4 demonstrated the most promising results. No secondary phases were detected by X-ray diffraction after sintering a LATP/LiFePO4 mixture at temperatures as high as 700 °C. Electron microscopy revealed a small secondary phase probably consisting of Li2FeTi(PO4)3, which is ionically conductive and should be electrochemically active as well.

Although bone minerals have been widely studied by various techniques in previous studies, crystal structures, morphology of bone minerals and its building pathway remained still controversy. In this work, the ultrastructure of the mineralization front of rabbit femur has been studied by conventional and high-resolution (HR) transmission electron microscopy (TEM). In order to induce a healing and demineralization process the animals were subjected to a standardized osteotomy stabilized with titan screws and sonic pins. After 84 days follow-up time the newly build bone was investigated. The mineralization front of rabbit femur osteotomy contains partly mineralized collagen fibrils with a pronounced striped pattern together with a large number of agglomerated apatite platelets. The striation is caused by mineralization in the hole zones of the collagen fibrils, corresponding to the early stage of mineralization. In the TEM micrographs, the mineralization zone appears denser and compact when compared with fully mineralized bone, although most of the collagen fibrils are completely mineralized in the latter (higher concentration of interfibrillar apatite platelets within the mineralization zone). In bone some partly mineralized collagen fibrils are also observed, revealing the same arrangement, regular shape, and size of apatite platelets as collagen fibrils in the mineralization zone. Apatite platelets with irregular shapes are observed at the vortex-shaped outer boundary of the mineralization zone, i.e. at the interfaces with nonmineralized collagen or osteoblasts. HR TEM micrographs reveal that the platelets are assumably semicrystalline and that within the platelet nanocrystalline domains of apatite are embedded in an amorphous calciumphosphate matrix.