Chemical structure of grain-boundary layer in SrTiO_3 and its segregation-induced transition: A continuum interface approach

Grain-boundary（GB） structures are commonly imaged as discrete atomic columns, yet the chemical modifications are gradual and extend into the adjacent lattices, notably the space charge, hence the two-dimensional defects may also be treated as continuum changes to extended interfacial structure. This review presents a spatially-resolved analysis by electron energy-loss spectroscopy of the GB chemical structures in a series of SrTiO3 bicrystals and a ceramic, using analytical electron microscopy of the pre-Cs-correction era. It has identified and separated a transient layer at the model Σ5 grain-boundaries（GBs） with characteristic chemical bonding, extending the continuum interfacial approach to redefine the GB chemical structure. This GB layer has evolved under segregation of iron dopant, starting from subtle changes in local bonds until a clear transition into a distinctive GB chemistry with substantially increased titanium concentration confined within the GB layer in 3-unit cells, heavily strained, and with less strontium. Similar segregated GB layer turns into a titania-based amorphous film in SrTiO3 ceramic, hence reaching a more stable chemical structure in equilibrium with the intergranular Ti2O3 glass also. Space charge was not found by acceptor doping in both the strained Σ5 and amorphous GBs in SrTiO3 owing to the native transient nature of the GB layer that facilitates the transitions induced by Fe segregation into novel chemical structures subject to local and global equilibria. These GB transitions may add a new dimension into the structure–property relationship of the electronic materials.

Space Charge Layer Eff ect in Sulfide Solid Electrolytes in All-Solid-State Batteries: In-situ Characterization and Resolution

All-solid-state lithium batteries(ASSLBs)have advantages of safety and high energy density,and they are expected to become the next generation of energy storage devices.Sulfide-based solid-state electrolytes(SSEs)with high ionic conduc-tivity and low grain boundary resistance exhibit remarkable practical application.However,the space charge layer(SCL)eff ect and high interfacial resistance caused by a mismatch with the current commercial oxide cathodes restrict the develop-ment of sulfide SSEs and ASSLBs.This review summarizes the research progress on the SCL eff ect of sulfide SSEs and oxide cathodes,including the mechanism and direct evidence from high performance in-situ characterizations,as well as recent progress on the interfacial modification strategies to alleviate the SCL eff ect.This study provides future direction to stabilize the high performance sulfide-based solid electrolyte/oxide cathode interface for state-of-the-art ASSLBs and future all-SSE storage devices.

Suspension mechanism and application of sand-suspended slurry for coalmine fire prevention

North and west China has abundant coal resources, however, such resources make these regions prone to serious mine fire disasters. Although the copious sand and fly ash resources found in these areas can be used as fire-fighting materials, conventional grouting is expensive because of water shortage and loess particles. A new compound material(i.e., a sand-suspended colloid), which comprises a mineral inorganic gel and an organic polymer, is developed in the current study to improve the quality of sand injection and reduce water wastage when grouting. The new material can steadily suspend the sand, through the addition of a small amount of colloid yielding steady sand-suspended slurry. The process of producing the slurry is convenient and quick, overcoming the shortage of sand-suspending thickeners which need heat and are difficult to produce. The space work model based on the theory of the double-electric layer is established to study the suspended mechanism of the solid particles in the sand-suspended colloid.The dispersion effect of the sand-suspended colloid is demonstrated by the incorporation of the electrostatic effect by the double-electric layer and the steric hindrance effect on the sand particles, ensuring the stability of the colloid system and the steady suspension of sand particles in the sand-suspended colloid.Mechanical analysis indicates that the sand is suspended steadily under the condition that the rock sand particles stress on the lower part of the fluid is less than the yield stress of the colloid. Finally, the fireprevention technology of sand suspension was applied and tested in the Daliuta Coal Mine, achieving successful results.

Lattice Reduction Aided MMSE Tomlinson-Harashima Precoding Based on VBLAST Algorithm for MIMO Systems

A lattice reduction aided (LRA) minimum mean square error (MMSE) Tomlinson-Harashima pre-coding (THP) was proposed based on vertical Bell Labs layered space time (VBLAST) algorithm for multiple input multiple output (MIMO) systems. The extended channel was used to provide optimal tradeoff between residual interference and noise amplification. The processing based on lattice reduction method helps achieve maximal diversity order. The VBLAST algorithm was applied to get the optimal processing ordering for successive interference cancellation (SIC) at transmitter. Simulation results show that the proposed algorithm outperforms conventional THP and the LRA zero-forcing (ZF) THP with full diversity order.

Forecasting the underground waters regime in the pitching aquifers in Huainan mining area

Huainan area is an important coal base of the east of China. In the early part of the 1980s, the study of the underground waters dynamic state in the area was gradually paid close attention to. This paper introduces the observation system of the groundwater dynamic state in the multilayered pitching aquifer, and expounds the hydrogeologic feature and the waterpower relations among aquifers. Furthermore, based on the analysis of the relations of the groundwater dynamic state to surface water, meteoric water and mining shaft outflow rate, this paper establishes main water filled aquifers of mining shaft (C 3-1 ,C 3-2 ,C 3-3 and O 2).In the light of the actual situation of the greatly changing aquifer occurrence and steep dip angle, the “two layer space curved surface seepage model" and the calculating step are all suggested. Since 1991,the groundwater dynamic state of the next year has been predicted (numerical simulation) every year. Contracting with the measured data, we gain a relatively ideal effect.

GROUP TRANSMIT ANTENNA SELECTION BASED ON GIS TECHNOLOGY FOR V-BLAST SYSTEM

The conventional transmit antenna selection for Vertical Bell Laboratories Layered Space Time (V-BLAST) system is very complex because it needs to compute the inverse of channel matrices time after time. In this paper, a new group transmit antenna selection scheme for V-BLAST system is proposed. The 1st group transmit antennas are decided according to a certain selection criterion among the available antennas. Then, with Group Interference Suppression (GIS) technology, the interferences of the transmit symbols from the selected antennas can be suppressed. Finally, the 2nd group transmit antennas are decided among the residual available antennas. Simulations show that its performance is lower than that of the conventional selection scheme. However, the new selection scheme has lower complexity than the conventional one.

Ionization behavior of deep level donors in passive film formed on surface of stainless steel in 5% salt solution

Deep level donor＇s ionization behavior of passive film formed on the surface of stainless steel was investigated by Mott-Schottky plots. It is indicated that transformation process of deep level donors＇ ionization behavior of passive film on surface of stainless steel can be divided into 4 stages with rising immersion time. At the initial immersion stage （10 min）, Fe（II） located in the octahedral sites of the unit cell is not ionized and the deep level does not appear in Mott-Schottky plots. At the second stage （9-38 h）, Fe（II） located in the octahedral sites starts to be ionized, which results in deep level donors＇ generation and density of deep level donors almost is constant with augmenting immersion time but the thickness of space charge layer is more and more thicker with rising immersion time. At the third stage （48 h-12 d）, density of deep level donors rises with increasing immersion time and the thickness of passive films space charge layer decreases. At last stage （above 23 d）, both the space charge layer＇s thickness and density of deep level donors are no longer changed with increasing immersion time. In the overall immersion stage, the shallow level donors＇ density is invariable all the time. The mechanism of deep level donor＇s ionization can be the generation of metal vacancies, which results in crystal lattice＇s aberration and the aberration energy urges the ionization of Fe（ II ） in octahedral sites.

Removal of rhodamine B from aqueous solutions using vanadium pentoxide/titanium butyl oxide hybrid xerogels

A stable and insoluble V2O5·n H2O/tetra-n-butyl titanate（TBO） hybrid xerogel was synthesized by the sol–gel method. This novel material proved to be an efficient absorbent with an absorption capacity of 179 mg·g^-1for Rhodamine B（Rh B） in water due to its unique layered structure, which can effectively accommodate Rh B molecules between its layers as demonstrated by XRD and FTIR spectroscopic analyses.

ON THE STABILITY OF FORCED DISSIPATIVE NONLINEAR SYSTEM

This paper, applying the stratification theory, proves the instability of certain initial (boundary) Value problem of forced dissipative nonlinear system in atmospheric dynamies. An example in given.

Research progress on space charge layer effect in lithium-ion solid-state battery

The development of lithium-ion solid electrolyte provides new ideas for solving the safety problems of secondary lithium-ion batteries(LIB) and, at the same time, the improvement of energy density. However, the consequent solid-solid interfacial problems have become a typical bottleneck to the performance. It has been considered that the space charge layer(SCL) formed at the interface to balance the sharp electrochemical inherent difference of properties is one of the most important factors that affect the ion transportation along and across the interface. Its existence may hinder ion transportation and increase the interfacial impedance but may also help to provide a new percolation path for lithium ion and so to enhance the ion migration. However the mechanism of SPL formation and its regulation on ion transport is not very clear, so it has raised a lot of attention and interest from LIB researchers. The purpose of this article is to try to gain some knowledge of SCL and, at the same time to browse through the related research in recent years. Hopefully, it may help those interested in solid electrolyte development for all-solidstate lithium-ion batteries(ASSB) in the future.

Thermal Stability and Thermal Aging of Poly(vinyl chloride)/MgAl Layered Double Hydroxides Composites

MgAl-LDH（layered double hydroxides） were prepared with CO（NH2）2, NH4 Cl and NH3·H2O by the coprecipitation method, respectively. Corresponding composite membranes were prepared by the coating method. LDHs were characterized by WAXS, CO2-TPD and SEM. The morphology of the PVC/LDHs composite membranes were characterized by means of SEM. The thermal stability of the membranes was analyzed by air aging box and TGA-FTIR. The SEM results show that nano-particles can be compatible with poly（vinyl chloride）（PVC） matrix homogeneously by the stirring-ultrasound blend method with two steps. Furthermore, the air aging box results proved that MgAl-CO（NH2）2-LDH has the best effect on thermal stability of PVC. TGA-FTIR results show that MgAl-CO（NH2）2-LDH could adsorb more HCl that resulted from the degradation of PVC and improve the pyrolysis temperature of the first degradation stage by 15 K compared with PVC.

Interfacial compatibility issues in rechargeable solid-state lithium metal batteries:a review

Solid-state lithium metal batteries(SSLBs)contain various kinds of interfaces,among which the solid electrode|solid electrolyte(ED|SE)interface plays a decisive role in the battery's power density and cycling stability.However,it is still lack of comprehensive knowledge and understanding about various interfacial physical/chemical processes so far.Although tremendous efforts have been dedicated to investigate the origin of large interfacial resistance and sluggish charge(electron/ion)transfer process,many scientific and technological challenges still remain to be clarified.In this review,we detach and discuss the critical individual challenge,including charge transfer process,chemical and electrochemical instability,space charge layers,physical contact and mechanical instability.The fundamental concepts,individual effects on the charge transfer and potential solutions are summarized based on material's thermodynamics,electrode kinetics and mechanical effects.It is anticipated that future research should focus on quantitative analysis,modeling analysis and in-situ microstructure characterizations in order to obtain an efficient manipulation about the complex interfacial behaviors in all solid-state Li batteries.

Observation of an EPIR Effect in Nd_(1-x)Sr_xMnO_3 Ceramics with Secondary Phases

Nd1-xSrxMnO3 （x ： 0.3, 0.5） ceramics containing a secondary phase are synthesized by high-energy ball milling and post heat-treatment method. The 4-wire and 2-wire measuring modes are used to investigate the transport character of the grain/phase boundary （inner interface） and electrode-bulk interface （outer interface）, respectively, and the results indicate that there is a similar nonlinear I-V behaviour for both of the inner and outer interfaces, however, the electric pulse induced resistance change （EPIR） effect can only be observed at the outer interface.