Perovskite oxyhydrides may find diverse applications, ranging from catalysis, topochemical synthesis to solid state ionics, but the understanding of their hydride transport behavior has remained limited. Here, gaseous hydrogen exchange and release experiments were analyzed using the Kissinger method to estimate the activation energy (E a) for H/D exchange and H2 release in BaTiO3–x H x (x = 0.35–0.60) and LaSrCoO3H0.70. It is revealed that, for each BaTiO3–x H x at a given hydride concentration (x), both H/D exchange and H2 release experiments provide similar E a values. For BaTiO3–x H x with different x, the obtained E a values significantly decrease with increasing x until around 0.4; beyond 0.4, it becomes nearly constant (200–220 kJ mol–1). This observation suggests that the diffusion process in the low hydride concentration (x < 0.4) includes oxide as well as hydride diffusion, whereas, for 0.4 < x (<0.75), only hydride migrates, with second-nearest-neighbor (2NN) jumps as a rate-determining process, which is supported by DFT calculations. The Kissinger analysis of LaSrCoO3H0.70 yielded a similar E a of 170–190 kJ mol–1, consistent with the 2NN hopping scenario. The presented method provides a facile tool for designing and improving hydride conductivity in oxyhydrides regardless of the presence of electronic conductivity.

Correlated motion dynamics of electron channels and domain walls in a ferroelectric-gate thin-film transistor consisting of a ZnO/Pb(Zr,Ti)O3 stacked structure J. Appl. Phys. 110, 084106 (2011); 10.1063/1.3651098 V 5 + ionic displacement induced ferroelectric behavior in V-doped ZnO films Appl. Phys. Lett. 90, 242903 (2007); 10.1063/1.2748081Off-centered polarization and ferroelectric phase transition in Li-doped ZnO thin films grown by pulsed-laser ablation

We examined the role of the large intestine in zinc absorption in rats in three separate experiments. In the first experiment, we examined apparent zinc absorption in rats fed diets containing graded levels of zinc carbonate (0.015-0.535 mmol Zn/kg diet) and evaluated zinc status on the basis of the zinc concentrations in serum and several tissues. The zinc absorption and the serum zinc concentration increased with the zinc content of the diet up to 0. 153 mmol Zn/kg diet. Femoral and pancreatic zinc levels increased linearly up to 0.229 mmol Zn/kg diet. In the second experiment, a zinc carbonate suspension was administered into the cecum via an implanted cannula or into the stomach via an orogastric tube, and the rats were fed diets with or without a highly fermentable fiber, guar gum hydrolysate (GGH, 50 g/kg diet), with coprophagy prevention. The amount of instilled zinc corresponded to the amount of zinc ingested as a component of the diet by the rats of a control group, 0.229 mmol Zn/kg diet. Apparent absorption of cecally instilled zinc was approximately half that observed when zinc was administered into the stomach in both diet groups. Serum and femur zinc concentrations in the cecum-administered groups were approximately 50 and 25% lower, respectively, than those in rats administered zinc into the stomach. The results demonstrate that, in vivo, the absorptive efficiency in the large intestine is not sufficient to satisfy the rat's zinc requirement and does not change when the luminal environment is substantially altered by feeding GGH. In Experiment 3, the effects of cecocolonectomy on zinc absorption were examined in rats with gastric acid suppression. In the cecocolonectomized groups, serum zinc concentration was lower as a result of treatment with a proton pump inhibitor, omeprazole, than in vehicle-treated rats, but not in sham-operated groups. These findings suggest that the cecum and colon contribute to zinc absorption when absorption in the small intestine is impaired.

A halophyte, the common ice plant (Mesembryanthemum crystallinum L.), shows the maximal growth under salinity, in which almost all crops die. The NaCl-stimulated growth, which is referred to as halophilism, is an important trait for adaptation to salinity, but the mechanism is still unclear. To elucidate factors contributing to the halophilism, we tested the effects of NaCl on growth, ion accumulation, and expression of ion homeostasis-related genes in suspension-cultured cells. Among nine ions analyzed, Na + , Cl − , K + , and NO 3 − were accumulated significantly in the cells showing halophilism than that in the salt-untreated cells, and the accumulation of these ions was positively correlated with the growth. Also, the expression of ion homeostasis-related genes for plasma membrane transporters and channels for incorporation of nitrate (McNRT1), sodium (McHKT1), potassium (McKmt1), cations/Cl − (McCCC1), for tonoplast antiporters H + /Cl − (McCLC1) and Na + /H + (McNHX1), and V-ATPase subunit c (McVmac1) for sequestration of Cl − and Na + into the vacuole, and for enzymes catalyzing biosynthesis of proline (McP5CS) and ononitol (McImt1) was higher in the cells showing halophilism than that in the salt-untreated cells. These results indicate that the ion accumulation and the expression of ion homeostasis-related genes contribute to the NaCl-stimulated growth enhancement in the halophyte, the common ice plant. Abbreviations: CCC: cation/Cl-cotransporter; CLC: H+/Cl-antiporter; DW: dry weight; FW: fresh weight; HAK: high affinity potassium; HKT: high potassium transporter; Imt: myo-inositol O-methyl transferase; MIP: major intrinsic protein; NHX: Sodium/proton antiporter; P5CS: delta 1-pyrroline-5-carboxylate synthase; PCV: Packed cell volume; PEG: polyethylene glycol; XTH: xyloglucan endotransglucosylase/ hydrolase The growth enhancement of the ice plants by NaCl was positively correlated with K + accumulation and the increased expression of ion homeostasis related genes contribute to the halophilism. 0 mM 100 mM ARTICLE HISTORY

Coexistence of two phases of AgNbO3 is shown to explain the experimentally observed polarization–electric field hysteresis loop better than either phase in isolation, based on detailed first-principles calculations of the structural changes and stabilities of different phases of this compound. Calculations confirm a ferroelectric phase transition, whereby the symmetry of the AgNbO3 crystal switches from antiferroelectric Pbcm to ferroelectric Pmc21, under an electric field of 9 MV/cm. The calculated spontaneous polarization (0.61 C/m2) under this field compares well with the experimental value of 0.52 C/m2. After transforming, the structure remains in the ferroelectric state even after the electric field is removed, despite the structure being energetically metastable. As the energy difference between the antiferroelectric and ferroelectric phases is only +0.5 meV/f.u. and the potential energy barrier between them (∼40 meV/f.u.) is comparable to thermal fluctuation energies, it is possible for these two phases to coexist at temperatures well below the paraelectric-antiferroelectric transition temperature (∼626 K). The exploitation of this phenomenon in AgNbO3 and related materials may provide a useful strategy for developing high-performance piezoelectric materials.

The properties of a potentially new class of ferroelectric materials based on wurtzite-structured ZnO thin films are examined using the first-principles calculations. Theoretical P-E hysteresis loops were calculated using the fixed-D method for both unstrained and (biaxially) strained single crystals. Ferroelectric polarization switching in ZnO (S.G. P63mc) is shown to occur via an intermediate non-polar structure with centrosymmetric P63/mmc symmetry by displacement of cations relative to anions in the long-axis direction. The calculated coercive electric field (Ec) for polarization switching was estimated to be 7.2 MV/cm for defect-free monocrystalline ZnO. During switching, the short- and long-axis lattice parameters expand and contract, respectively. The large structural distortion required for switching may explain why ferroelectricity in this compound has not been reported experimentally for pure ZnO. Applying an epitaxial tensile strain parallel to the basal plane is shown to be effective in lowering Ec during polarization, with a 5% biaxial expansion resulting in a decrease of Ec to 3.5 MV/cm. Comparison with calculated values for conventional ferroelectric materials suggests that the ferroelectric polarization switching of wurtzite-structured ZnO may be achievable by preparing high-quality ZnO thin films with suitable strain levels and low defect concentrations.

Ferroelectricity in stuffed aluminate sodalites, (Ca1−xSrx)8[AlO2]12(WO4)2 (x ≤ 0.2) (C1−xSxAW), is demonstrated in the present study. Pyroelectric measurements clarified switchable spontaneous polarization in polycrystalline C1−xSxAW, whose polarization values were on the order of 10 −2 C/cm 2 at room temperature. A weak anomaly in the dielectric permittivity at temperatures near the ferroelectric transition temperature suggested improper ferroelectricity of C1−xSxAW for all investigated values of x. A comprehensive study involving synchrotron X-ray powder diffraction measurements, molecular dynamics simulations, and first-principles calculations clarified that the ferroelectric phase transition of C1−xSxAW is driven by freezing of the fluctuations of WO4 tetrahedra in the voids of an [AlO2]12 12− framework. The voltage response and electromechanical coupling factor of C1−xSxAW estimated from the present results indicate that this material exhibits excellent performance as a pyroelectric energy harvester, suggesting that aluminate sodalites exhibit great promise as a class of materials for highly efficient energy harvesting devices.

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