Translational Antiphase Boundaries in NaNbO3 Antiferroelectrics

Planar defects are known to be of importance in affecting the functional properties of materials. Translational antiphase boundaries (APBs) in particular have attracted considerable attention in perovskite oxides, but little is known in lead-free antiferroelectric oxides that are promising candidates for energy storage applications. Here, we present a study of translational APBs in prototypical antiferroelectric NaNbO3 using aberration-corrected (scanning) transmission electron microscopy (TEM) techniques at different length scales. The translational APBs in NaNbO3 are characterized by a 2-fold-modulated structure, which is antipolar in nature and exhibits a high density, different from the polar nature and lower density in PbZrO3. The high stability of translational APBs against external electric fields and elevated temperatures was revealed using ex situ and in situ TEM experiments and is expected to be associated with their antipolar nature. Density functional theory calculations demonstrate that translational APBs possess only slightly higher free energy than the antiferroelectric and ferroelectric phase energies with differences of 29 and 33 meV/f.u., respectively, justifying their coexistence down to the nanoscale at room temperature. These results provide a detailed atomistic elucidation of translational APBs in NaNbO3 with antipolar character and stability against external stimuli, establishing the basis of defect engineering of antiferroelectrics for energy storage devices.

Mass transport and charge transfer through an electrified interface between metallic lithium and solid-state electrolytes

All-solid-state Li-ion batteries are one of the most promising energy storage devices for future automotive applications as high energy density metallic Li anodes can be safely used. However, introducing solid-state electrolytes needs a better understanding of the forming electrified electrode/electrolyte interface to facilitate the charge and mass transport through it and design ever-high-performance batteries. This study investigates the interface between metallic lithium and solid-state electrolytes. Using spectroscopic ellipsometry, we detected the formation of the space charge depletion layers even in the presence of metallic Li. That is counterintuitive and has been a subject of intense debate in recent years. Using impedance measurements, we obtain key parameters characterizing these layers and, with the help of kinetic Monte Carlo simulations, construct a comprehensive model of the systems to gain insights into the mass transport and the underlying mechanisms of charge accumulation, which is crucial for developing high-performance solid-state batteries.

Li+ Conductivity of Space Charge Layers Formed at Electrified Interfaces Between a Model Solid-State Electrolyte and Blocking Au-Electrodes

The formation of space charge layers in solid-state ion conductors has been investigated as early as the 1980s. With the advent of all-solid-state batteries as an alternative to traditional Li-ion batteries, possibly improving performance and safety, the phenomenon of space charge formation caught the attention of researchers as a possible origin for the observed high interfacial resistance. Following classical space charge theory, such high resistances result from the formation of the depletion layers. These layers of up to hundreds of nanometers in thickness are almost free of mobile cations. With the prediction of a Debye-like screening effect, the thickness of the depletion layer is expected to scale with the square root of the absolute temperature. In this work, we studied the temperature dependence of the depletion layer properties in model solid Ohara LICGC Li⁺ conducting electrolytes using electrochemical impedance spectroscopy. We show that the activation energy inside the depletion layer increases to ca 0.42 eV compared to ca 0.39 eV in the bulk electrolyte. Moreover, the proportionality between temperature and depletion layer thickness, correlating to the Debye length, is tested and validated.

Characterization and Quantification of Depletion and Accumulation Layers in Solid-State Li+ -Conducting Electrolytes Using In Situ Spectroscopic Ellipsometry

The future of mobility depends on the development of next-generation battery technologies, such as all-solid-state batteries. As the ionic conductivity of solid Li⁺ -conductors can, in some cases, approach that of liquid electrolytes, a significant remaining barrier faced by solid-state electrolytes (SSEs) is the interface formed at the anode and cathode materials, with chemical instability and physical resistances arising. The physical properties of space charge layers (SCLs), a widely discussed phenomenon in SSEs, are still unclear. In this work, spectroscopic ellipsometry is used to characterize the accumulation and depletion layers. An optical model is developed to quantify their thicknesses and corresponding concentration changes. It is shown that the Li⁺ -depleted layer (≈190 nm at 1 V) is thinner than the accumulation layer (≈320 nm at 1 V) in a glassy lithium-ion-conducting glass ceramic electrolyte (a trademark of Ohara Corporation). The in situ approach combining electrochemistry and optics resolves the ambiguities around SCL formation. It opens up a wide field of optical measurements on SSEs, allowing various experimental studies in the future.

Effects of calcium chloride and calcium sulfate in an oral bolus given as a supplement to postpartum dairy cows

An oral calcium bolus (Bovikalc, Boehringer Ingelheim Vetmedica) supplying calcium to dairy cows in the form of calcium chloride and calcium sulfate was evaluated to determine the effect on calcium homeostasis immediately after calving. Cows in the treatment group received one bolus immediately after calving and a second bolus 12 hours later. Control cows received no calcium supplementation. Blood was analyzed for ionized calcium, and urine was collected for urinary pH determination. Postpartum supplementation with the Bovikalc bolus significantly increased serum ionized calcium levels and decreased urine pH values.

Abnormal conjugated dopamine levels in patients with normoprolactinaemic amenorrhoea and in insulin-dependent diabetic patients

We determined the circulating dopamine levels in 17 patients with insulin-dependent diabetes mellitus (IDDM), of whom eight had amenorrhoea (DM-AM) and nine were normally menstruating (DM). Seven non-diabetic women with normoprolactinaemic, normogonadotrophic secondary amenorrhoea (AM) and nine normally menstruating women (controls) were studied. In all subjects basal blood concentrations of free dopamine (f-DA), conjugated dopamine (c-DA), epinephrine (E), norepinephrine (NE), prolactin (PRL), luteinizing hormone (LH), thyroid-stimulating hormone (TSH) and oestradiol-17 beta were determined and all subjects, except for three AM patients, had a Metoclopramide test performed for measurements of f-DA, c-DA, PRL, LH and TSH. Plasma c-DA was significantly (p less than 0.05) increased in patients with amenorrhoea compared to the respective control groups. In diabetic patients c-DA levels were significantly (p less than 0.05) lower compared to controls. The ratio between basal f-DA and c-DA concentrations was significantly (p less than 0.01) higher in diabetic patients compared with non-diabetic patients. After Metoclopramide stimulation DM-AM patients showed a significant (p less than 0.05) rise in c-DA, whereas this was not seen in other groups. DM-AM patients had significantly (p less than 0.05) lower basal PRL and LH levels than DM patients and controls. In addition DM-AM patients had a significantly (p less than 0.05) lower PRL response to Metoclopramide compared with DM patients. There were no significant correlations between catecholamines and basal as well as Metoclopramide stimulated pituitary hormones. This study suggests that the abnormal pituitary hormone secretion in patients with amenorrhoea may in part be caused by an increased dopaminergic activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Possible altered dopaminergic modulation of pituitary function in normal-menstruating women with insulin dependent diabetes mellitus (IDDM)

In order to assess whether a possible altered dopamine activity in normal-menstruating diabetic patients may influence the pituitary hormone secretion we have measured the basal serum concentrations of Prl, LH and FSH in 28 patients with insulin dependent diabetes mellitus (IDDM) and in 55 normal-menstruating women at day 3 to 6 of the menstrual cycle. In addition basal levels of oestradiol-17 beta, TSH, thyroxine (T4), triiodothyronine (T3) and resin-T3 uptake (RT3U) were determined in 17 patients with IDDM and in 17 controls. The responses of FSH, LH, Prl, GH and TSH to metoclopramide (MTC) administration (10 mg iv) were studied in 17 patients and 17 controls. In 10 patients with IDDM and 8 controls the short-term variations in pituitary hormones and blood glucose concentration were evaluated. Patients with IDDM had significantly lower basal levels of Prl (P less than 0.01) and TSH (P less than 0.05) and significantly (P less than 0.05) higher basal levels of GH than normal women. No significant (P greater than 0.05) differences were found regarding basal serum concentrations of FSH, LH, oestradiol, T4, T3 and RT3U. During the 3 h period the mean coefficient of variation of Prl, FSH, LH and GH was not significantly (P greater than 0.05) different between diabetic patients and controls. Both groups responded significantly (P less than 0.01) in Prl and TSH to MTC but the TSH response was significantly (P less than 0.05) lower in patients with IDDM. The Prl response to MTC was not significantly (P greater than 0.05) different within the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Gonadotropin responses to gonadotropin-releasing hormone and prolactin responses to thyrotropin-releasing hormone and metoclopramide in women with amenorrhea and insulin-treated diabetes mellitus

Gonadotropin responses to GnRH and PRL responses to TRH and metoclopramide (MTC) were investigated in nine consecutive women with amenorrhea and insulin-treated diabetes mellitus. Nine normal menstruating diabetic women, 12 normal women in the early follicular phase, and nine consecutive nondiabetic women with functional amenorrhea served as controls. No significant differences were found in relation to diabetes regulation within the two diabetic groups. Amenorrheic patients with diabetes mellitus had significantly lower basal PRL levels than normal women and estradiol levels compared to the other groups. Basal plasma LH concentrations were significantly lower in women with amenorrhea and diabetes mellitus than in nondiabetics with amenorrhea, whereas plasma FSH levels were similar in all groups. The LH response to GnRH was significantly lower in amenorrheic patients with diabetes mellitus than in normal women, and a significant correlation (r = 0.81, P less than 0.01) was found between the LH response to GnRH and the basal estradiol level in these women. The FSH response to GnRH and the PRL response to TRH were similar in all groups. Amenorrheic diabetics had significantly lower PRL responses to MTC compared to other groups, and nondiabetics with amenorrhea had significantly lower PRL response than normal women. It is concluded that diabetic patients with functional amenorrhea have low basal and MTC-stimulated PRL levels, low basal LH levels, and decreased LH response to GnRH despite low estrogen levels. These hormonal changes may in part be caused by a raised central dopaminergic activity leading to a depression of pituitary ovulatory mechanisms.

Clinical and hormonal characteristics in women with anovulation and insulin-treated diabetes mellitus

Clinical characteristics and basal hormonal parameters related to ovulatory function were investigated in 22 diabetic patients with anovulation (group 1) and in nine normally menstruating diabetic patients (group 2) and 45 nondiabetic patients with anovulation (group 3). No significant differences according to control of the diabetes were demonstrated within the two diabetic groups. Groups 1 and 3 did not differ according to classification of anovulation. Group 1 had significantly (P less than 0.01) lower levels of prolactin (PRL), 17 beta-estradiol (E2), thyrotropin (TSH), 3,3',5-triiodothyronine (T3), and thyroxine (T4) than those of group 3, and significantly (P less than 0.01) lower levels of E2 and TSH than those of group 2. The urinary excretion of cortisol was significantly higher in group 1 than in group 2 (P less than 0.05) and group 3 (P less than 0.01). These data suggest a derangement in pituitary-gonadal feedback mechanisms or a depression of pituitary function in anovulatory diabetic patients, and we hypothesize that an increased central/peripheral dopamine and/or cortisol activity in these patients may to some extent influence the hypothalamic-pituitary axis.