Atomic Layer Engineering of Ferroelectricity in Dion-Jacobson Perovskites.

Recent advances in "hybrid-improper" ferroelectricity in Dion-Jacobson (DJ)-type layered perovskites have caused renewed interest in the search for new ferroelectrics. Here, we present an approach for the tailored synthesis of a new homologous series of DJ-type layered perovskites Cs(Bi2Srn-3)(Tin-1Nb)O3n+1. Starting from CsBi2Ti2NbO10 (n = 3), higher-order homologous phases with n = 4 and 5 were successfully synthesized by repeated solid-state calcination with SrTiO3. Characterizations by X-ray diffraction, electron diffraction, transmission electron microscopy, Raman scattering, and second harmonic generation showed the detailed structural features in Cs(Bi2Srn-3)(Tin-1Nb)O3n+1, and the polar structures could be stabilized by proper or hybrid-improper ferroelectricity, depending on the odd or even number of the perovskite layers. Our results provide important insights into the competition between the different mechanisms and the consequences of the ferroelectric properties in homologous layered perovskites.

Stress-Induced Martensitic Transformation in Na3YCl6.

Martensitic transformation with volume expansion plays a crucial role in enhancing the mechanical properties of steel and partially stabilized zirconia. We believe that a similar concept could be applied to unexplored nonoxide materials. Herein, we report the stress-induced martensitic transformation of monoclinic Na3YCl6 with an ∼3.4% expansion. In situ synchrotron X-ray diffraction and atomistic simulations showed that anisotropic crystallographic transformation from monoclinic to rhombohedral Na3YCl6 occurs exclusively under uniaxial pressure; no effect is observed under hydrostatic pressure conditions. The uniaxially pressed powder compact of monoclinic Na3YCl6 showed a large indentation impression and low Young's modulus, in contrast to its high bulk modulus, suggesting that these unique mechanical properties are induced by the martensitic transformation.

High Capacity Li2 S-Li2 O-LiI Positive Electrodes with Nanoscale Ion-Conduction Pathways for All-Solid-State Li/S Batteries.

All-solid-state lithium-sulfur (Li/S) batteries are promising next-generation energy-storage devices owing to their high capacities and long cycle lives. The Li2 S active material used in the positive electrode has a high theoretical capacity; consequently, nanocomposites composed of Li2 S, solid electrolytes, and conductive carbon can be used to fabricate high-energy-density batteries. Moreover, the active material should be constructed with both micro- and nanoscale ion-conduction pathways to ensure high power. Herein, a Li2 S-Li2 O-LiI positive electrode is developed in which the active material is dispersed in an amorphous matrix. Li2 S-Li2 O-LiI exhibits high charge-discharge capacities and a high specific capacity of 998 mAh g-1 at a 2 C rate and 25 °C. X-ray photoelectron spectroscopy, X-ray diffractometry, and transmission electron microscopy observation suggest that Li2 O-LiI provides nanoscale ion-conduction pathways during cycling that activate Li2 S and deliver large capacities; it also exhibits an appropriate onset oxidation voltage for high capacity. Furthermore, a cell with a high areal capacity of 10.6 mAh cm-2 is demonstrated to successfully operate at 25 °C using a Li2 S-Li2 O-LiI positive electrode. This study represents a major step toward the commercialization of all-solid-state Li/S batteries.

Lone-Pair-Induced Intra- and Interlayer Polarizations in Sillén-Aurivillius Layered Perovskite Bi4NbO8Br.

Sillén-Aurivillius layered perovskite oxyhalides Bi4MO8X (M = Nb, Ta; X = Cl, Br) are of great interest because of their potential as lead-free ferroelectrics in addition to their function as visible-light-responsive photocatalysts. In this work, we revisited the crystal structure of Bi4NbO8Br (space group: P21cn), revealing that the intralayer polarization is not based on the reported NbO6 octahedral tilting but is derived from the stereochemically active Bi3+ lone pair electrons (LPEs) and the octahedral off-centering of Nb5+ cations. The revised structure (space group: Ic) has additional interlayer polarizations (calculated: 0.6 µC/cm2), in agreement with recent experiments on Bi4NbO8Br. The occurrence of polarization due to stereochemically active LPEs and Nb-site off-centering is similar to Aurivillius-type ferroelectrics (e.g., Bi2WO6), with comparable spontaneous polarizations in the in-plane direction (calculated: 43.5 µC/cm2). This, together with the out-of-plane polarization, indicates that Sillén-Aurivillius compounds have great potential as ferroelectric materials.

Long-term effect of immobilization in external rotation after first-time shoulder dislocation: an average 18-year follow-up.

BACKGROUND: Immobilization in external rotation (ER) after a first-time shoulder dislocation was introduced to reduce the risk of recurrence compared with immobilization in internal rotation (IR), but its efficacy remains controversial. The purpose of this study was to determine the long-term effect of immobilization in ER after a first-time shoulder dislocation. METHODS: Between October 2000 and March 2004, 198 patients with a first-time anterior dislocation of the shoulder (average age 37) were randomly assigned to immobilization in ER (ER group = 104 shoulders) or IR (IR group = 94 shoulders) for 3 weeks. At an average 2-year follow-up, 159 patients (80.3%) were available for evaluation. In the current study, these 159 patients were further followed up and interviewed by telephone. The following items were evaluated: recurrent instability, apprehensive feeling, surgical intervention, limitation in the range of motion, return to sports, and the Single Assessment Numeric Evaluation (SANE) score. RESULTS: The average follow-up period was 18.2 years (range, 16-20 years). Fifty-six patients were available for follow-up with the follow-up rate of 35%. The number of recurrent patients was 6 of 27 (22%) in the ER group and 6 of 29 (21%) in the IR group (P = .889). The number of surgically stabilized patients was 3 of 27 (11%) in the ER group and 10 of 29 (34%) in the IR group (P = .038). In total, the recurrence rate was 33% (9 of 27) in the ER group and 55% (16 of 29) in the IR group (P = .100). Adding the surgical cases and those with the SANE score ≤70% as failure cases, the failure rate in the ER group (26%) was significantly lower than that in the IR group (52%) (P = .048). Among those who survived without surgical intervention, there were no significant differences in apprehensive feeling, return to sports, limited range of motion, and the SANE score between the groups. CONCLUSIONS: Immobilization in ER reduced the risk of surgical intervention compared with IR in the long term.

Formation Mechanism of ß-Li3PS4 through Decomposition of Complexes.

ß-Li3PS4 is a solid electrolyte with high Li+ conductivity, applicable to sulfide-based all-solid-state batteries. While a ß-Li3PS4-synthesized by solid-state reaction forms only in a narrow 300-450 °C temperature range upon heating, ß-Li3PS4 is readily available by liquid-phase synthesis through low-temperature thermal decomposition of complexes composed of PS43- and various organic solvents. However, the conversion mechanism of ß-Li3PS4 from these complexes is not yet understood. Herein, we proposed the synthesis mechanism of ß-Li3PS4 from Li3PS4·acetonitrile (Li3PS4·ACN) and Li3PS4·1,2-dimethoxyethane (Li3PS4·DME), whose structural similarity with ß-Li3PS4 would reduce the nucleation barrier for the formation of ß-Li3PS4. Synchrotron X-ray diffraction clarified that both complexes possess similar layered structures consisting of alternating Li2PS4- and Li+-ACN/DME layers. ACN/DME was removed from these complexes upon heating, and rotation of the PS4 tetrahedra induced a uniaxial compression to form the ß-Li3PS4 framework.

Reconstruction of the Alveolar Bone Using Bone Augmentation With Selective Laser Melting Titanium Mesh Sheet: A Report of 2 Cases.

Bone augmentation is used to supplement bone defects during dental implant treatment. In this technique, the area filled with bone prosthetic material is covered with an artificial space-making device or titanium mesh sheet, which must be manually adapted to the bone defect during the procedure before being fixed in place. Selective laser melting (SLM) method can be used to preadapt the titanium mesh sheet based on preoperative CT data. This method enables shorter surgery times compared with conventional titanium mesh sheet methods, as well as regeneration of an ideal alveolar bone shape. Here, we present 2 cases of bone augmentation using the SLM titanium mesh sheet method. The postoperative course was without complications in both cases; neither patient experienced mesh exposure or infection during healing. The SLM titanium mesh sheet method should be considered as a new and effective bone augmentation method.

Inverse Charge Transfer in the Quadruple Perovskite CaCu3Fe4O12.

Structural and spectroscopic analyses revealed that the quadruple perovskite CaCu3Fe4O12 undergoes an "inverse" electron charge transfer in which valence electrons move from B-site Fe to A'-site Cu ions (∼3Cu(∼2.4+) + 4Fe(∼3.65+) → ∼3Cu(∼2.2+) + 4Fe(∼3.8+)) simultaneously with a charge disproportionation transition (4Fe(∼3.8+) → ∼2.4Fe(3+) + ∼1.6Fe(5+)), on cooling below 210 K. The direction of the charge transfer for CaCu3Fe4O12 is opposite to those reported for other perovskite oxides such as BiNiO3 and ACu3Fe4O12 (A = Sr(2+) or the large trivalent rare-earth metal ions), in which the electrons move from A/A'-site to B-site ions. This finding sheds a light on a new aspect in intermetallic phenomena for complex transition metal compounds.

Frequent inactivation of A20 in B-cell lymphomas.

A20 is a negative regulator of the NF-kappaB pathway and was initially identified as being rapidly induced after tumour-necrosis factor-alpha stimulation. It has a pivotal role in regulation of the immune response and prevents excessive activation of NF-kappaB in response to a variety of external stimuli; recent genetic studies have disclosed putative associations of polymorphic A20 (also called TNFAIP3) alleles with autoimmune disease risk. However, the involvement of A20 in the development of human cancers is unknown. Here we show, using a genome-wide analysis of genetic lesions in 238 B-cell lymphomas, that A20 is a common genetic target in B-lineage lymphomas. A20 is frequently inactivated by somatic mutations and/or deletions in mucosa-associated tissue lymphoma (18 out of 87; 21.8%) and Hodgkin's lymphoma of nodular sclerosis histology (5 out of 15; 33.3%), and, to a lesser extent, in other B-lineage lymphomas. When re-expressed in a lymphoma-derived cell line with no functional A20 alleles, wild-type A20, but not mutant A20, resulted in suppression of cell growth and induction of apoptosis, accompanied by downregulation of NF-kappaB activation. The A20-deficient cells stably generated tumours in immunodeficient mice, whereas the tumorigenicity was effectively suppressed by re-expression of A20. In A20-deficient cells, suppression of both cell growth and NF-kappaB activity due to re-expression of A20 depended, at least partly, on cell-surface-receptor signalling, including the tumour-necrosis factor receptor. Considering the physiological function of A20 in the negative modulation of NF-kappaB activation induced by multiple upstream stimuli, our findings indicate that uncontrolled signalling of NF-kappaB caused by loss of A20 function is involved in the pathogenesis of subsets of B-lineage lymphomas.

Charge-order melting in charge-disproportionated perovskite CeCu3Fe4O12.

A novel quadruple perovskite oxide CeCu3Fe4O12 has been synthesized under high-pressure and high-temperature conditions of 15 GPa and 1473 K. (57)Fe Mössbauer spectroscopy displays a charge disproportionation transition of 4Fe(3.5+) → 3Fe(3+) + Fe(5+) below ∼270 K, whereas hard X-ray photoemission and soft X-ray absorption spectroscopy measurements confirm that the Ce and Cu valences are retained at approximately +4 and +2, respectively, over the entire temperature range measured. Electron and X-ray diffraction studies reveal that the body-centered cubic symmetry (space group Im3̅, No. 204) is retained at temperatures as low as 100 K, indicating the absence of any types of charge-ordering in the charge-disproportionated CeCu3Fe4O12 phase. The magnetic susceptibility and neutron powder diffraction data illustrate that the antiferromagnetic ordering of Fe ions is predominant in the charge-disproportionated CeCu3Fe4O12 phase. These findings suggest that CeCu3Fe4O12 undergoes a new type of electronic phase in the ACu3Fe4O12 series and that the melting of the charge-ordering in CeCu3Fe4O12 is caused by the substantial decrease in the Fe valence and the resulting large deviation from the ideal abundance ratio of Fe(3+):Fe(5+) = 1:1 for rock-salt-type charge-ordering.

Mechanochemical synthesis of fluoride-ion conducting glass and glass-ceramic in ZrF4-BaF2 binary system.

Fluoride glasses in the binary system ZrF4-BaF2 were prepared via mechanochemical treatment. The glass-forming region of the ZrF4-BaF2 system obtained using the mechanochemical method was wider than that obtained using the conventional melt-quenching method. The glass-ceramic 60ZrF4·40BaF2 (mol%) sample was obtained by heat treatment and shows a higher conductivity of 1.2 × 10-6 S cm-1 at 200 °C than the pristine glass. This study revealed that mechanochemical treatment was effective for the synthesis of fluoride glasses.

MXene Electrodes for All Strain-Free Solid-State Batteries.

All-solid-state batteries with nonflammable inorganic solid electrolytes are the key to addressing the safety issues of lithium-ion batteries with flammable organic liquid electrolytes. However, conventional electrode materials suffer from substantial volume changes during Li+ (de)intercalation, leading to mechanical failure of interfaces between electrode materials and solid electrolytes and then severe performance degradation. In this study, we report strain-free charge storage via the interfaces between transition metal carbides (MXenes) and solid electrolytes, where MXene shows negligible structural changes during Li+ (de)intercalation. Operando scanning electron transmission microscopy with electron energy-loss spectroscopy reveals the pillar effect of trapped Li+ in the interlayer spaces of MXene to achieve the strain-free features. An all strain-free solid-state battery, which consists of a strain-free Ti3C2Tx negative electrode and a strain-free disordered rocksalt Li8/7Ti2/7V4/7O2 positive electrode, demonstrates long-term stable operation while preserving the interfacial contact between electrode materials and solid electrolytes.

Microscopic Degradation Mechanism of Argyrodite-Type Sulfide at the Solid Electrolyte-Cathode Interface.

Interfacial engineering of sulfide-based solid electrolyte/lithium-transition-metal oxide active materials in all-solid-state battery cathodes is vital for cell performance parameters, such as high-rate charge/discharge, long lifetime, and wide temperature range. A typical interfacial engineering method is the surface coating of the cathode active material with a buffer layer, such as LiNbO3. However, cell performance reportedly degrades under harsh environments even with a LiNbO3 coating, such as high temperatures and high cathode potentials. Therefore, we investigated the interfacial degradation mechanism focusing on the solid electrolyte side for half cells employing the cathode mixture of argyrodite-type Li6PS5Cl/LiNbO3-coated LiNi0.5Co0.2Mn0.3O2 exposed at 60 °C and 4.25 and 4.55 V vs Li/Li+ using transmission electron microscopy/electron diffraction (TEM/ED) and X-ray absorption spectroscopy (XAS). The TEM/ED results indicated that the ED pattern of the argyrodite structure disappeared and changed to an amorphous phase as the cells degraded. Moreover, the crystal phases of LiCl and Li2S appeared simultaneously. Finally, XAS analysis confirmed the decrease in the PS4 units of the argyrodite structure and the increase in local P-S-P domains with delithiation from the interfacial solid electrolyte, corresponding to the TEM/ED results. In addition, the formation of P-O bonds was confirmed during degradation at higher cathode potentials, such as 4.55 V vs Li/Li+. These results indicate that the degradation of this interfacial region determines the cell performance.

Design of Cathode Coating Using Niobate and Phosphate Hybrid Material for Sulfide-Based Solid-State Battery.

Coating the surface of the cathode active material of all-solid-state batteries with sulfide-based solid electrolytes is key for improving and enhancing the battery performance. Although lithium niobate (LiNbO3) is one of the most representative coating materials, its low durability at a highly charged potential and high temperature is an impediment to the realization of high-performance all-solid-state batteries. In this study, we developed new hybrid coating materials consisting of lithium niobate (Li-Nb-O) and lithium phosphate (Li-P-O) and investigated the influence of the ratio of P/(Nb + P) on the durability performance. The cathode half-cells, using a sulfide-based solid electrolyte Li6PS5Cl/cathode active material, LiNi0.5Co0.2Mn0.3O2, coated with the new hybrid coating materials of LiPxNb1-xO3 (x = 0-1), were exposed to harsh conditions (60 °C and 4.55 V vs Li/Li+) for 120 h as a degradation test. P substitution resulted in higher durability and lower interfacial resistance. In particular, the hybrid coating with x = 0.5 performed better, in terms of capacity retention and interfacial resistance, than those with other compositions of niobate and phosphate. The coated cathode active materials were analyzed using various analytical techniques such as scanning electron microscopy/energy-dispersive X-ray spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy (XAS) to elucidate the improvement mechanism. Moreover, the degraded cathodes were observed using time-of-flight secondary-ion mass spectrometry, TEM/electron diffraction, and XAS. These analyses revealed that the Nb-O-P coordination in the hybrid coating material captured O by P. The coordination suppressed the release of O from the coating layer as a decomposition side reaction to realize a higher durability than that of LiNbO3.

Magnetization controlled by crystallization in soft magnetic Fe-Si-B-P-Cu alloys.

Soft magnetic materials have low coercive fields and high permeability. Recently, nanocrystalline alloys obtained using annealing amorphous alloys have attracted much interest since nanocrystalline alloys with small grain sizes of tens of nanometers exhibit low coercive fields comparable to that of amorphous alloys. Since nanocrystalline soft magnetic materials attain remarkable soft magnetic properties by controlling the grain size, the crystal grains' microstructure has a substantial influence on the soft magnetic properties. In this research, we examined the magnetic properties of Fe-Si-B-P-Cu nanocrystalline soft magnetic alloys obtained by annealing amorphous alloys. During crystallization, the observation findings reveal the correlation between the generated microstructures and soft magnetic properties.