Deep hydration of an Li7–3x La3Zr2 M III x O12 solid-state electrolyte material: a case study on Al- and Ga-stabilized LLZO

Single crystals of an Li-stuffed, Al- and Ga-stabilized garnet-type solid-state electrolyte material, Li7La3Zr2O12 (LLZO), have been analysed using single-crystal X-ray diffraction to determine the pristine structural state immediately after synthesis via ceramic sintering techniques. Hydrothermal treatment at 150 °C for 28 d induces a phase transition in the Al-stabilized compound from the commonly observed cubic Ia\overline{3}d structure to the acentric I\overline{4}3d subtype. LiI ions at the interstitial octahedrally (4 + 2-fold) coordinated 48e site are most easily extracted and AlIII ions order onto the tetrahedral 12a site. Deep hydration induces a distinct depletion of LiI at this site, while the second tetrahedral site, 12b, suffers only minor LiI loss. Charge balance is maintained by the incorporation of HI, which is bonded to an O atom. Hydration of Ga-stabilized LLZO induces similar effects, with complete depletion of LiI at the 48e site. The LiI/HI exchange not only leads to a distinct increase in the unit-cell size, but also alters some bonding topology, which is discussed here.

Enhanced electrocatalysts fabricated via quenched ultrafast sintering: physicochemical properties and water oxidation applications

The synthesis of transition metal oxides is typically time- and energy-consuming. Recently, fast sintering methods have demonstrated great potential to reduce ceramic sintering time and energy use, improving the commercial prospects of these materials. In this article, a quenched ultrafast high-temperature sintering (qUHS) technique is developed to sinter metastable brownmillerite SrCoO2.5 (SCO) in less than a minute. Surprisingly, SCO fabricated by qUHS shows higher activity for the oxygen evolution reaction (OER) compared to solid-state-reaction-synthesized SCO. Comparing samples produced by these two techniques, the increased OER performance of SCO qUHS is likely due to the synergistic combination of surface Co chemical state, higher mesoporosity and enhanced hydroxyl ion (OH-) adsorption. This work demonstrates the potential of qUHS for producing high-performance electrocatalysts and provides detailed insights into the impact of ultrafast sintering on the materials' physical properties and electrocatalytic activity.

SINTERING AND DURABILITY OF CLAYAND DIOPSIDE-CONTAINING CERAMIC AND FAIENCE WALL MATERIALS

The paper summarizes the research results of sintering and durability of wall ceramic materi-als modified by diopside-containing raw products and based on low-melting-point clays and loams, and kaolinand high-melting-point clay faience. Mechanical-and-physical properties of ceramic materials are identified and studied after annealing, depending on the diopside content. It is shown that depending on the content and introduction of clay minerals in the ceramic mixture, both coarse (0.5–1 mm) and fine (0.06 mm, dominating particle size of 0.01–0.015 mm) dis-persed diopside particles can be used. It is found that for loams with the clay mineral content of less than 10 wt.%, the addition of finely-dispersed diopside particles is more efficient. The latter provides ceramic sintering at 1000–1100 °С and increases its strength by 1.5–2 times. The intro-duction of dispersion diopside particles in the faience mixture lowers the annealing temperature from 1250 to 1150 °С with a simultaneous increase in its strength.

Simultaneous PAN Carbonization and Ceramic Sintering for Fabricating Carbon Fiber-Ceramic Composite Heaters

In this study, a single firing was used to convert stabilized polyacrylonitrile (PAN) fibers and ceramic forming materials (kaolin, feldspar, and quartz) into carbon fiber/ceramic composites. For the first time, PAN carbonization and ceramic sintering were achieved simultaneously in one thermal cycle and the microscopic morphologies and physical features of the obtained carbon fiber/ceramic composites were characterized in detail. The obtained carbon fiber/ceramic composite showed comparable flexural strength as commercial ceramic tiles. Meanwhile, the composite showed exceptional electro-thermal performance based on the electro-thermal performance of the carbonized PAN fibers, which could reach 108 ℃ after 15 s, 204 ℃ after 90 s, and 292 ℃ after 450 s at 5 V (2.6 A), thereby making the ceramic composite a good candidate as an indoor climate control heater, defogger device, kettle, and other heating element.

Effectively immobilizing lead through a melanotekite structure using low-temperature glass-ceramic sintering

An energy-efficient and reliable Pb immobilization strategy was developed for the beneficial use of Pb-laden wastes through low-temperature thermal stabilization.