Crystalline Host Research Articles

Rare-Earth-Metal (Nd3+, Ce3+ and Gd3+)-Doped CaF2: Nanoparticles for Multimodal Imaging in Biomedical Applications.

Here, we describe the synthesis of a novel type of rare-earth-doped nanoparticles (NPs) for multimodal imaging, by combining the rare-earth elements Ce, Gd and Nd in a crystalline host lattice consisting of CaF2 (CaF2: Ce, Gd, Nd). CaF2: Ce, Gd, Nd NPs are small (15-20 nm), of uniform shape and size distribution, and show good biocompatibility and low immunogenicity in vitro. In addition, CaF2: Ce, Gd, Nd NPs possess excellent optical properties. CaF2: Ce, Gd, Nd NPs produce downconversion emissions in the second near-infrared window (NIR-II, 1000-1700 nm) under 808 nm excitation, with a strong emission peak at 1056 nm. Excitation in the first near- infrared window (NIR-I, 700-900 nm) has the advantage of deeper tissue penetration power and reduced autofluorescence, compared to visible light. Thus, CaF2: Ce, Gd, Nd NPs are ideally suited for in vivo fluorescence imaging. In addition, the presence of Gd3+ makes the NPs intrinsically monitorable by magnetic resonance imaging (MRI). Moreover, next to fluorescence and MR imaging, our results show that CaF2: Ce, Gd, Nd NPs can be used as imaging probes for photoacoustic imaging (PAI) in vitro. Therefore, due to their biocompatibility and suitability as multimodal imaging probes, CaF2: Ce, Gd, Nd NPs exhibit great potential as a traceable imaging agent in biomedical applications.

Impacts of Crystalline Host Rock on Repository Barrier Materials at 250 °C: Hydrothermal Co-Alteration of Wyoming Bentonite and Steel in the Presence of Grimsel Granodiorite

Direct disposal of dual-purpose canisters (DPC) has been proposed to streamline the disposal of spent nuclear fuel. However, there are scenarios where direct disposal of DPCs may result in temperatures in excess of the specified upper temperature limits for some engineered barrier system (EBS) materials, which may cause alteration within EBS materials dependent on local conditions such as host rock composition, chemistry of the saturating groundwaters, and interactions between barrier materials themselves. Here we report the results of hydrothermal experiments reacting EBS materials—bentonite buffer and steel—with an analogue crystalline host rock and groundwater at 250 °C. Experiment series explored the effect of reaction time on the final products and the effects of the mineral and fluid reactants on different steel types. Post-mortem X-ray diffraction, electron microprobe, and scanning electron microscopy analyses showed characteristic alteration of both bentonite and steel, including the formation of secondary zeolite and calcium silicate hydrate minerals within the bentonite matrix and the formation of iron-bearing clays and metal oxides at the steel surfaces. Swelling clays in the bentonite matrix were not quantitatively altered to non-swelling clay species by the hydrothermal conditions. The combined results of the solution chemistry over time and post-mortem mineralogy suggest that EBS alteration is more sensitive to initial groundwater chemistry than the presence of host rock, where limited potassium concentration in the solution prohibits conversion of the smectite minerals in the bentonite matrix to non-swelling clay species.

How nanoporous silicon-polypyrrole hybrids flex their muscles in aqueous electrolytes: In operando high-resolution x-ray diffraction and electron tomography-based micromechanical computer simulations

Macroscopic strain experiments revealed that Si crystals traversed by parallel, channel-like nanopores functionalized with the muscle polymer polypyrrole exhibit large and reversible electrochemo-mechanical actuation in aqueous electrolytes. On the microscopical level this system still bears open questions, as to how the electrochemical expansion and contraction of PPy acts on to np-Si pore walls and how the collective motorics of the pore array emerges from the single-nanopore behavior. An analysis of in operando X-ray diffraction experiments with micromechanical finite element simulations, based on a 3D reconstruction of the nanoporous medium by TEM tomography, shows that the in-plane mechanical response is dominantly isotropic despite the anisotropic elasticity of the single crystalline host matrix. However, the structural anisotropy originating from the parallel alignment of the nanopores lead to significant differences between the in- and out-of-plane electromechanical response. This response is not describable by a simple 2D arrangement of parallel cylindrical channels. Rather, the simulations highlight that the dendritic shape of the Si pore walls, including pore connections between the main channels, cause complex, inhomogeneous stress-strain fields in the crystalline host. Time-dependent X-ray scattering on the dynamics of the actuator properties hint towards the importance of diffusion limitations, plastic deformation and creep in the nanoconfined polymer upon (counter-)ion adsorption and desorption, the very pore-scale processes causing the macroscopic electroactuation. From a more general perspective, our study demonstrates that the combination of TEM tomography-based micromechanical modeling with high-resolution X-ray scattering experiments provides a powerful approach for in operando analysis of nanoporous composites from the single-nanopore up to the porous-medium scale.

Supramolecular Organic Nanowires of 2,6‐Naphthalene Dicarboxylic Acid Observed in the Lamellar Space of Zn3(PO4)4and Zn1.6Co1.4(PO4)4Host Lattices

AbstractThe formation of unique nanometer‐sized organic supramolecular assemblies was observed in the lamellar space of metal phosphate host lattices. Two new chiral and achiral organic‐inorganic hybrid materials, zinc phosphate, (H3tren)2[Zn3(PO4)4]⋅2NDA (ZnP‐NDA) and zinc‐cobalt phosphate, (H3tren)2[Zn1.6Co1.4(PO4)4]⋅2NDA (ZnCoP‐NDA) have been synthesized under hydrothermal conditions. The crystalline host framework was built with corner‐sharing MO4(M=Zn or Zn/Co) and PO4tetrahedra. In between these framework layers, aromatic dicarboxylic acid, 2,6‐Naphthalene dicarboxylic acids (NDA) are held together by means of strong hydrogen bonding and π‐π stacking interactions resulting in infinite supramolecular zigzag chains. After incorporating the cobalt into inorganic host lattice, astonishingly, the chiral structure tuns achiral. The crystal structures were elucidated by single crystal X‐ray diffraction and characterized by powder XRD, elemental analysis, thermogravimetry and photoluminescence measurements.

Hydrothermal synthesis, crystal structure and photoluminescent properties of 2D layered zinc phosphate intercalated with 4,4ˈbiphenyl dicarboxylic acid (ZnPO-BDA)

Herein, we report a new inorganic-organic hybrid, (H3tren)2⸱[Zn3(PO4)4(BDA)]⸱xH2O (ZnPO-BDA) prepared under hydrothermal conditions. This hybrid structure of zinc phosphate layers pillared with 4,4′-biphenyl-dicarboxylic acid (BDA) was characterized by single-crystal X-ray diffraction. The compound, ZnPO-BDA, crystallizes in the monoclinic crystal system (space group C2) with a = 14.9348(3) Å, b = 8.7058(2) Å, c = 17.6455(5) Å, β = 111.6760(10), V = 2132.02(9) Å3, Z = 2. The crystalline host of the 2D zinc phosphate framework was built with vertex linked ZnO4 and PO4 tetrahedra and anchored with tris(2-aminoethyl)amine (H3tren). Biphenyl dicarboxylic acid (BDA) molecules stack between the phosphate framework layers by means of strong hydrogen bonding, resulting in an interlayer distance of 16.4 Å. ZnPO-BDA displayed blue photoluminescence with an emission maximum at 404 nm on photoexcitation at 340 nm.

Tuning the Magnetization of Manganese (II) Carbonate by Intracrystalline Amino Acids.

Incorporation of organic molecules into the lattice of inorganic crystalline hosts is a common phenomenon in biomineralization and is shown to alter various properties of the crystalline host. Taking this phenomenon as a source of inspiration, it is shown herein that incorporation of specific single amino acids into the lattice of manganese (II) carbonate strongly alters its inherent magnetic properties. At room temperature, the magnetic susceptibility of the amino-acid-incorporating paramagnetic MnCO3 decreases, following a simple rule of mixtures. When cooled below the Néel temperature, however, the opposite trend is observed, namely an increase in magnetic susceptibility measured in a high magnetic field. Such an increase, accompanied by a drastic change in the Néel phase transformation temperature, results from a decrease in MnCO3 orbital overlapping and the weakening of superexchange interactions. It may be that this is the first time that the magnetic properties of a host crystal are tuned via the incorporation of amino acids.

An evolution to Bismuth dopant concentration on properties of CdSe films for solar cell appliances

The deliberated introduction of dopant to the crystalline host lattice is a promising approach towards the adjustment of physical properties. The present work deals with the influence of Bi dopant concentration on crystallographic, optical, topographical and electrical features of CdSe films for absorber layer applications to solar cells. Herein, the deposition of undoped and Bi doped CdSe films having 1%, 3% and 5% Bi dopant concentration is carried out via resistive heating thermal evaporation method. The crystallographic patterns reveal to the polycrystalline nature of films with occurrence of major reflection along (111) plane of cubic CdSe system where the intensity of this peak is substantially altered with Bi dopant. The crystallite size and strain of the CdSe films are appeared in range of 32–53 nm and 3.01 × 10−3–5.06 × 10−3, respectively upon changing the Bi doping. Optical study indicates the manifestation of strong absorption in visible region of spectra and fluctuation in absorbance of CdSe films with change in Bi dopant concentration. The optical band gap of undoped and Bi doped CdSe films is obtained in 1.61–1.69 eV range. Electrical assessment of films points towards creation of Ohmic contacts where the conductivity of films is improved at 1% Bi doping and decreased at higher doping. All the films show spherical shaped grains with variable density where the grain size obtained from AFM analysis is varied from 24 nm to 40 nm with Bi dopant concentration. Hence, the concentration of trivalent Bi dopant plays a pivotal role in modulation of properties of CdSe films for absorber layer appliances.

Solution-Based Synthesis Routes for the Preparation of Noncentrosymmetric 0-D Oxide Nanocrystals with Perovskite and Nonperovskite Structures.

With the miniaturization of electronic-based devices, the foreseen potential of new optical nanoprobes and the assessment of eventual size and shape effects, elaboration of multifunctional noncentrosymmetric nanocrystals with ferroelectric, pyroelectric, piezoelectric, and nonlinear optical properties are the subject of an increasing research interest. Here, the recent achievements from the solution-based methods (coprecipitation in homogeneous and nanostructured media, sol-gel processes including various chemistries and hydro/solvothermal techniques) to prepare 0-D perovskite and nonperovskite oxides in the 5-500nm size range are critically reviewed. To cover a representative list of covalent- and ionic-type materials, BaTiO3 and its derivatives, niobate compounds (i.e., K/Na/LiNbO3 ), multiferroic BiFeO3, and crystals of lower symmetry including KTiOPO4 and some iodate compounds such as Fe(IO3 )3 and La(IO3 )3 are systematically infocus. The resulting size, morphology, and aggregation state are discussed in light of the proposed formation mechanisms. Because of a higher complexity related to their chemical composition and crystalline structures, improving the rational design of these multifunctional oxides in terms of finely-tuned compositions, crystalline hosts and structure-property relationships still need in the future a special attention of the research community to the detailed understanding of the reaction pathways and crystallization mechanisms.

Investigations of effect of underground excavations using hydrologic and tracer transport modeling

Understanding the effect of underground excavations and barrier capability of the near field are relevant to the geologic disposal of nuclear waste. For a repository in crystalline host rock characterization of the naturally fractured rock and the excavated disturbed zone are of importance to the study of migration of radionuclides. Excavations could weaken the repository components that are part of the engineered barrier system. Permeable excavated disturbed zones could also develop around the repository walls that could create conduits for radionuclides away from the repository. Experimental hydrology and tracer transport data from the Mizunami Underground Research Laboratory in Central Japan have been used to develop a site-scale model for the study area. Upscaled permeability and porosity data of a previously developed discrete fracture network model were used. In this study development and utilization of the model is presented. The model was used to reproduce hydrology and non-reactive transport in the modeling area. The modeling work includes prediction of inflow of water into the research tunnel during excavation of tunnel parts and related draw-down. The modeling work also includes prediction of pressure recovery and changes in tracer distribution as a result of water filling of a tunnel chamber. Modeling results were successfully compared with the project hydrology and tracer concentration histories. Modeling results of inflow and recovery were complementary and together with fracture characterization combined to give a better constraint on the system. The study provides experimental and modeling methods to study the effect of excavations in an underground research laboratory.

Large Spectral Shift of Mn2+ Emission Due to the Shrinkage of the Crystalline Host Lattice of the Hexagonal CsCdCl3 Crystals and Phase Transition.

All-inorganic halide perovskite crystals are considered excellent optical host lattices for various dopants to obtain wavelength-tunable emissions with ultra-broad bands even over a wide spectral range. Here, a series of Mn2+-doped bulk ligand-free CsCdCl3 (CCC) perovskite crystals with a hexagonal shape and size of about 1 millimeter (mm) have been prepared by a facile hydrothermal method. These CCC:Mn2+ (CCC:Mn) crystals emit the representative orange-red photoluminescence (PL) of Mn2+ (4T1(G)-6A1(S)) in the centers of hexagonal octahedrons coordinated with six Cl- ions. A fine-tuning of the Mn2+ concentration from 1 to 50 mol % Cd2+ induces a substantial red shift of emission spectra from 570 to 630 nm due to the shrinkage of the crystalline host lattice, and the maximum intensity of emission is achieved at 20 mol % Mn2+ doping. A further increase in the Mn2+ concentration causes a decrease of the PL intensity due to the phase transition from CCC to CsMnCl3·2H2O (CMCH). The strong excitation bands at 360, 370, 420, and 440 nm can make the excitation of the emissive CCC:Mn crystals possible with ultraviolet (UV) and blue chips for application in white light-emitting diodes (WLEDs). The similarity of the Mn2+-concentration-dependent emission spectra excited by various wavelengths indicates that there is only one type of site for Mn2+ occupation in CCC.

Pressure-Driven Ne-Bearing Polynitrides with Ultrahigh Energy Density

Neon (Ne) can reveal the evolution of planets, and nitrogen (N) is the most abundant element in the Earth’s atmosphere. Considering the inertness of neon, whether nitrogen and neon can react has aroused great interest in condensed matter physics and space science. Here, we identify three new Ne–N compounds (i.e., NeN6, NeN10, and NeN22) under pressure by first-principles calculations. We find that inserting Ne into N2 substantially decreases the polymeric pressure of the nitrogen and promotes the formation of abundant polynitrogen structures. Especially, NeN22 acquires a duplex host-guest structure, in which guest atoms (Ne and N2 dimers) are trapped inside the crystalline host N20 cages. Importantly, both NeN10 and NeN22 not only are dynamically and mechanically stable but also have a high thermal stability up to 500 K under ambient pressure. Moreover, ultra-high energy densities are obtained in NeN10 (11.1 kJ/g), NeN22 (11.5 kJ/g), tetragonal t-N22 (11.6 kJ/g), and t-N20 (12.0 kJ/g) produced from NeN22, which are more than twice the value of trinitrotoluene (TNT). Meanwhile, their explosive performance is superior to that of TNT. Therefore, NeN10, NeN22, t-N22, and t-N20 are promising green high-energy-density materials. This work promotes the study of neon-nitrogen compounds with superior properties and potential applications.

Er<sup>3+</sup>,Yb<sup>3+</sup>:YGdSiO<sub>5</sub> Crystal as Gain Media for Lasers Emitting in the Spectral Range of 1.5–1.6 µm

Solid-state erbium lasers, emitting in the spectral range of 1.5–1.6 µm, are of great interest for several industrial applications. Nowadays the Er:glass is the most widespread laser material for obtaining laser radiation at the wavelength near 1.5 µm. However, the maximal output powers of such lasers are restricted by hundreds of milliwatts because low thermal characteristics of the glass host. By this reason the search for new crystalline hosts doped with erbium ions is the actual task.In this article the investigation results of spectroscopic properties of Er3+,Yb3+:YGdSiO5 (YGSO) crystals are reported. Polarized absorption and luminescence spectra were measured. The lifetimes of energy levels were determined. The excited state absorption spectra were measured. It was shown that excited state absorption band does not overlap with gain band in the range 1.5–1.6 µm. The energy transfer efficiency from ytterbium to erbium ions was estimated. The stimulated emission and gain cross-section spectra for Er3+ ions in YGSO were calculated.

Supramolecular Assembly of His-Tagged Fluorescent Protein Guests within Coiled-Coil Peptide Crystal Hosts: Three-Dimensional Ordering and Protein Thermal Stability.

The use of biomaterials for the inclusion and stabilization of biopolymers is an ongoing challenge. Herein, we disclose three-dimensional (3D) coiled-coil peptide crystals with metal ions that include and overgrow His-tagged fluorescent proteins within the crystal. The protein guests are found within two symmetry-related growth sectors of the crystalline host that are associated with faces of the growing crystal that display ligands for metal ions. The fluorescent proteins are included within this "hourglass" region of the crystals at a notably high level, display order within the crystal hosts, and demonstrate sufficiently tight packing to enable energy transfer between a donor-acceptor pair. His-tagged fluorescent proteins display remarkable thermal stability to denaturation over extended periods of time (days) at high temperatures when within the crystals. Ultimately, this strategy may prove useful for the prolonged storage of thermally sensitive biopolymer guests within a 3D crystalline matrix.

Exploring the governing transport mechanisms of corrosive agents in a Canadian deep geological repository

All nuclear energy producing nations face a common challenge associated with the long-term solution for their used nuclear fuel. After decades of research, many nuclear safety agencies worldwide agree that deep geological repositories (DGRs) are appropriate long-term solutions to protect the biosphere. The Canadian DGR is planned in either stable crystalline or sedimentary host rock (depending on the final site location) to house the used nuclear fuel in copper-coated used fuel containers (UFCs) surrounded by highly compacted bentonite. The copper-coating and bentonite provide robust protection against many corrosion processes anticipated in the DGR. However, it is possible that bisulfide (HS−) produced near the host rock-bentonite interface may transport through the bentonite and corrode the UFCs during the DGR design life (i.e., one million years); although container performance assessments typically account for this process, while maintaining container integrity. Because the DGR design life far exceeds those of practical experimentation, there is a need for robust numerical models to forecast HS− transport. In this paper we present the development of a coupled 3D thermal-hydraulic-chemical model to explore the impact of key coupled physics on HS− transport in the proposed Canadian DGR. These simulations reveal that, although saturation delayed and heating accelerated HS− transport over the first 100s and 10,000s of years, respectively, these times of influence were small compared to the long DGR design life. Consequently, the influence from heating only increased total projected HS− corrosion by <20% and the influence from saturation had a negligible impact (<1%). By comparing the corrosion rate results with a simplified model, it was shown that nearly-steady DGR design parameters governed most of the projected HS− corrosion. Therefore, those parameters need to be carefully resolved to reliably forecast the extent of HS− corrosion.

A systematic approach for surface exploration of sites – analysis of international exploration programs

Abstract. The site selection procedure for a high-level radioactive waste repository in Germany is based on the Repository Site Selection Act (StandAG, 2017), which comprises three phases. In phase 2 the Federal Company for Radioactive Waste Disposal (BGE) will conduct surface exploration. Based on the exploratory findings, the further developed preliminary safety analyses, the common requirements and criteria, and potential socioeconomic analyses will be applied feeding into proposed sites for underground exploration. Commissioned by the BGE, the Federal Institute for Geosciences and Natural Resources (BGR) contributes to this procedure with the projects GeoMePS and ZuBeMErk, which collate and assess geoscientific and geophysical methods and programs for surface exploration. Their common goal is to develop recommendations for surface exploration of siting regions. For this purpose, the BGR has developed a systematic approach that includes (1) deducing exploration targets, (2) compilation of geoscientific and geophysical exploration methods in a database structure, and (3) analysis of case studies of national and international exploration programs for high-level radioactive waste disposal. Exploration targets are based on the common criteria and requirements as defined by the StandAG. The identified exploration targets (Kneuker et al., 2020) together with a large number of geoscientific and geophysical exploration methods were integrated and linked within the BGR database “GeM-DB”. All methods were evaluated according to their suitability and applicability for (a) the three defined host rocks (crystalline rock, claystone, rock salt) and (b) the previously defined exploration targets. In step (3) the BGR reviews national and international waste disposal programs exploring for crystalline rock, claystone, and rock salt. Here, the focus is on nondestructive and minimally invasive surface exploration techniques, such as geophysical airborne and ground-based methods or investigations in drill holes and on drill cores. The aims are to identify gaps in the method catalogue of the GeM-DB and to infer exploration directives for surface exploration during phase 2. An example is the analysis of the Swedish site selection process, especially the site investigation program. There, the site investigations are, e.g. the basis for the discipline-specific site descriptive models, which were applied for design and safety assessments (SKB, 2001). The Swedish site investigation program along with programs of other countries considering crystalline host rocks, such as Finland and Canada, show a common ground, which could be adapted for surface exploration of crystalline host rock regions in Germany. The assessment and evaluation of selected programs exploring for rock salt and claystone is currently in progress. The entire systematic approach of the projects GeoMePS and ZuBeMErk aims to develop recommendations for a nondestructive and minimally invasive surface exploration program of siting regions in Germany, regarding the lithological, structural, mechanical, and hydrogeological characterization of the different host rock formations.

Preliminary safety assessments in the high-level radioactive waste site selection procedure in Germany

Abstract. The Federal Company for Radioactive Waste Disposal (BGE) is a German waste management organization responsible for implementing the search for a site with the best possible safety for the disposal of high-level radioactive waste for at least 1 million years, following the amendments of the Repository Site Selection Act in 2017. The selection procedure is meant to be a participatory, transparent, learning and self-questioning process based on scientific expertise. This contribution provides an overview of the methodology of the forthcoming preliminary safety assessments as a major part of the next steps in the site selection procedure. This procedure overall consists of three phases with increasing levels of detail for identification of the best site. The first phase consists of two steps. The objective of the first step was to determine sub-areas in the three considered host rocks, salt (halite), claystone and crystalline host rock, by applying legally defined exclusion criteria, minimum requirements and geoscientific weighing criteria. A total of 90 sub-areas that cover approximately 54 % of the area of Germany were identified due to their general suitable geological conditions. The results were published in September 2020. The second step of phase one is currently in progress and includes representative preliminary safety assessments that aim to assess the extent to which the safe containment of the radioactive waste can be expected in the investigated sub-area. The requirements for conducting preliminary safety assessments in the site selection procedure are defined by a governmental directive released in October 2020. Representative preliminary safety assessments have to be performed for each sub-area and consist of the compilation of all geoscientific information relevant to the safety of a repository, the development of preliminary safety and repository concepts and the analysis of the disposal system. In addition, a systematic identification and characterization of uncertainties has to be undertaken and the need for exploration, research and development must be determined. The application of the representative preliminary safety assessments as well as the following renewed application of geoscientific weighting criteria will lead to the identification of siting regions within the larger sub-areas identified in step one. These regions will be considered, first for surface-based geoscientific and geophysical exploration, including e.g. seismic exploration and drilling of boreholes. Subsequently, the last phase of the site selection will proceed with subsurface exploration. Finally, all suitable sites will be proposed and the German government and parliament will decide the actual site. This process is expected to be finalized in 2031.

The anisotropic properties of granites – effects of tectonic emplacement mode on potential crystalline host rocks for nuclear waste deposits in Germany

Abstract. For permanent nuclear waste disposal sites, crystalline rocks, especially granitic/granodioritic batholiths, are considered an appropriate host rock. Principally, three types of granitic plutons occur in the extra-alpine crystalline basement of Germany that were consolidated during the late Paleozoic Variscan orogeny of Central Europe: (i) Pre-Variscan voluminous granodiorites that are hardly affected by the subsequent continent–continent collision; (ii) voluminous granites in various tectonic settings intruded during the late orogenic stage of the Variscides; (iii) post-orogenic granites related to vast Permian intracontinental extension. Thus, in terms of the syn-intrusive tectonic setting and post-intrusive processes there are significant differences. Although it can be expected that different tectonic environments caused significant differences in the material properties, for Germany, however, there is no systematic study regarding the fabric of such plutonites. In order to find the most suitable “granite” we investigate the primary anisotropy of granites evolved during the emplacement and crystallization of the melt. For this we sample rocks of all three principal types and various syn-intrusive tectonic settings, i.e., compression, extension, strike-slip, transtension, and transpression. By means of combined measurements of the “Anisotropy of the Magnetic Susceptibility” and the “Shape Preferred Orientation” we characterize the syn-intrusive flow pattern, i.e., the magmatic foliation and lineation. The Crystallographic Preferred Orientation is analyzed by a combination of neutron time-of-flight experiments and electron backscatter diffraction measurements at the Frank Laboratory of Neutron Physics at JINR, Dubna, Russia, and the TU Bergakademie Freiberg respectively. Furthermore, special attention is given to the systematic mapping of annealed microcracks evolved during late magmatic fluid escape and/or post-crystallization hydrothermal activity. In a second step we compare the primary anisotropy with the post-magmatic fracture pattern of the particular granites. Those fractures constitute probable fluid pathways and, thus, the first-order risk for a potential permanent nuclear waste disposal. All datasets are organized in a Geological Information System allowing for a complete traceability of the different investigation steps. The results of this study will serve as a basis for a future detailed exploration.

Recovery of ion-damaged 4H-SiC under thermal and ion beam-induced ultrafast thermal spike-assisted annealing

The recovery effect of isochronal thermal annealing and inelastic energy deposited during 100 MeV Ag swift heavy ion (SHI) irradiation is demonstrated in the case of 4H-SiC pre-damaged by elastic energy deposition of 300 keV Ar ion. The Ar-induced fractional disorder follows a nonlinear two-step damage build-up. The fractional disorder level of 0.3 displacements per atom (dpa) is established as the threshold above which the lattice rapidly enters the amorphous phase, characterized by the presence of highly photo-absorbing defects. The SHI-induced recovery suggests that the damage annealing, in the pre-damaged region (∼350 nm) where the Se for 100 MeV Ag is almost constant (∼16.21 keV/nm), is more pronounced than the damage creation by SHI. This allows the disorder values to saturate at a lower value than the present initial disorder. Furthermore, the thermal effect due to SHI irradiation of an amorphous nano-zone embedded in a crystalline host matrix has been evaluated using the 3D implementation of the thermal spike. The recovery process by SHI is ascribed to the thermal spike-induced atomic movements resulting from the melting and the resolidification of the crystalline–amorphous interface.

Effect of Liquid Crystalline Host on Structural Changes in Magnetosomes Based Ferronematics.

The effect of the liquid crystalline host on structural changes in magnetosomes based on ferronematics is studied using the surface acoustic wave (SAW) technique supported by some capacitance and light transmission measurements. The measurement of the attenuation response of SAW propagating along the interface between LC and the piezoelectric substrate is used to study processes of structural changes under magnetic field. The magnetosome nanoparticles of the same volume concentration were added to three different nematic LCs, 5CB, 6CB, and E7. Unlike to undoped LCs, the different responses of SAW attenuation under the influence of magnetic and electric fields in LCs doped with magnetosomes were observed due to characteristic structural changes. The decrease of the threshold field for doped LCs as compared with pure LCs and slight effects on structural changes were registered. The threshold magnetic fields of LCs and composites were determined from capacitance measurements, and the slight shift to lower values was registered for doped LCs. The shift of nematic-isotropic transition was registered from dependencies of SAW attenuation on temperature. The acoustic anisotropy measurement approved the previous supposition about the role of bulk viscosity in used SAW measurements. In addition, capacitance and light transmition investigations supported SAW results and pointed out conclusions about their magnetic field behavior. Obtained results are discussed and confronted with previous ones and coincide well with those observed using acoustic, optical, or dielectric techniques.

Front Cover: Pyridine Ring Modification of Indane‐1,3‐dione Dimers for Control of their Crystal Structure (Asian J. Org. Chem. 10/2021)

Four 2,2’-dipyridylindane-1,3-dione 2,2’-dimers with various substituents and orientations of the pyridine rings were synthesized. Detailed analyses found that only the chloro derivative affords 1D-channel-containing open-type structure. This study revealed how the atomic geometry around the pyridine N-atom affects the selective formation of the desired channel-containing structure, opening the door for further utilization of 1,3-indanedione dimers as new types of molecular crystalline host. More information can be found in the Full Paper by Yumi Yakiyama et al.