Comprehensive understanding of the crystal structure of perovskite-type BaYO with Zr substitution: a theoretical and experimental study.

We previously reported that Zr substitution improves the chemical stability of BaYO and nominally 20 mol% Zr-substituted BaYO is an oxide-ion conductor at intermediate temperatures (500-700 °C). However, the influence of Zr substitution on the structural properties of BaYO was poorly understood. This paper aims to comprehensively understand the crystal structure of BaYO with Zr substitution by powder X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS) measurements, and first-principles calculations.

Theoretical and Experimental Studies on the Ability of Intracrystalline Pores of β-La(SO) To Accommodate Various Gas Species with a Special Focus on Ammonia Insertion Behaviors.

β-La(SO) is a microporous inorganic crystal with one-dimensional perforated pores where HO molecules can be inserted. To evaluate the nature of the pores and extend the application range, we investigate the ability to accommodate various hydrogen compound molecules XH (CH, NH, HF, HS, HCl, and HI) by insertion. The stable structures of the XH molecules in the pores of β-La(SO) and the change in the Gibbs energy for XH insertion Δ () are estimated by first-principles calculations.

Theoretical study on proton diffusivity in Y-doped BaZrO with realistic dopant configurations.

We theoretically revisit the proton diffusivity in yttrium-doped barium zirconate (Y-doped BaZrO3) with realistic dopant configurations under processing conditions. In a recent study employing the replica exchange Monte Carlo method, the equilibrium Y configurations at typical sintering temperatures were shown to deviate from the random configuration assumed in earlier theoretical studies. In the present study, we took this observation into account and evaluated the effect of the Y configuration on the proton diffusivity.

Proton Conductive BaZr Ce Y O : Influence of NiO Sintering Additive on Crystal Structure, Hydration Behavior, and Conduction Properties.

Y-doped BaZrO , BaCeO and BaZr Ce O show high proton conductivity at intermediate temperature and are promising electrolyte candidates in electrochemical devices. However, in most cases, the present cell fabrication process seems to be unavailable to avoid the addition of NiO, which is either added to improve the sinterability of these electrolyte or diffuses from the electrode substrate during co-sintering. In this work, a systematic investigation was performed to study the effect of NiO on BaZr Ce Y O (BZCY20) covering the full Ce range from 0 to 0.

Experimental Study of Hydration/Dehydration Behaviors of Metal Sulfates M(SO) (M = Sc, Yb, Y, Dy, Al, Ga, Fe, In) in Search of New Low-Temperature Thermochemical Heat Storage Materials.

To identify potential low-temperature thermochemical heat storage (TCHS) materials, hydration/dehydration reactions of M(SO) (M = Sc, Yb, Y, Dy, Al, Ga, Fe, In) are investigated by thermogravimetry (TG). These materials have the same rhombohedral crystal structure, and one of them, rhombohedral Y(SO), has been recently proposed as a promising material. All M(SO)·HO hydrate/dehydrate reversibly between 30 and 200 °C at a relatively low (=0.

Multi-step hydration/dehydration mechanisms of rhombohedral Y(SO): a candidate material for low-temperature thermochemical heat storage.

To evaluate rhombohedral Y(SO) as a new potential material for low-temperature thermochemical energy storage, its thermal behavior, phase changes, and hydration/dehydration reaction mechanisms are investigated. Rhombohedral Y(SO) exhibits reversible hydration/dehydration below 130 °C with relatively small thermal hysteresis (less than 50 °C). The reactions proceed two reaction steps in approximately 0.

Correlation between Concentrations of Ni and Y in Y-Doped BaZrO Electrolyte in Co-Sintered Cells: A Case of Controlled NiO Activity by Using MgO-NiO Solid Solution as Anode Substrate.

BaZrYO (BZY20) is promising to be applied as an electrolyte in fuel cells, electrolysis cells, etc. However, when a half cell composed of a BZY20 electrolyte layer and a BZY20-NiO composite anode substrate is co-sintered (1400-1600 °C), Ni diffuses from the anode substrate into the electrolyte layer. Y content in the electrolyte layer decreases dramatically, since BZY20 cannot be equilibrated with NiO at such high temperature.

Correlation between Phase Behavior and Electrical Conductivity of 10 mol % Y-Doped BaZrO: An Anomalous Dispersion Effect-Aided Synchrotron Radiation XRD Study Combined with TEM Observation and Electrochemical Analysis.

Y-doped BaZrO (BZY) has high proton conductivity and is a promising electrolyte candidate for fuel cells and electrolytic cells at an intermediate temperature range. However, the conductivity of BZY has a large discrepancy in the literature. In particular, for BaZrYO (BZY10), the reported bulk conductivity varies in the range of more than 2 orders of magnitude.

Detrimental Effect of Sintering Additives on Conducting Ceramics: Yttrium-Doped Barium Zirconate.

Y-doped BaZrO (BZY) is currently the most promising proton-conductive ceramic-type electrolyte for application in electrochemical devices, including fuel cells and electrolyzer cells. However, owing to its refractory nature, sintering additives, such as NiO, CuO, or ZnO are commonly added to reduce its high sintering temperature from 1600 °C to approximately 1400 °C. Even without deliberately adding a sintering additive, the NiO anode substrate provides another source of the sintering additive; during the co-sintering process, NiO diffuses from the anode into the BZY electrolyte layer.

La(NbY)O: discovery of a novel fluorite structure-based ionic conductor.

A novel fluorite structure-based compound of La(NbY)O shows superior chemical stability and proton conduction.

Discovery of Rapid and Reversible Water Insertion in Rare Earth Sulfates: A New Process for Thermochemical Heat Storage.

Thermal energy storage based on chemical reactions is a prospective technology for the reduction of fossil-fuel consumption by storing and using waste heat. For widespread application, a critical challenge is to identify appropriate reversible reactions that occur below 250 °C, where abundant low-grade waste heat and solar energy might be available. Here, it is shown that lanthanum sulfate monohydrate La (SO ) ⋅H O undergoes rapid and reversible dehydration/hydration reactions in the temperature range from 50 to 250 °C upon heating/cooling with remarkably small thermal hysteresis (<50 °C), and thus it emerges as a new candidate system for thermal energy storage.

Tetravalent dysprosium in a perovskite-type oxide.

The existence of tetravalent dysprosium in perovskite-type oxide barium zirconate is confirmed in this work. This discovery will stimulate many researchers in diverse fields such as catalysts, solid state ionics, sensors, and fluorescent materials.

Solid acid proton conductors: from laboratory curiosities to fuel cell electrolytes.

The compound CsH2PO4 has emerged as a viable electrolyte for intermediate temperature (200-300 degrees C) fuel cells. In order to settle the question of the high temperature behavior of this material, conductivity measurements were performed by two-point AC impedance spectroscopy under humidified conditions (p[H2O] = 0.4 atm).

High-performance solid Acid fuel cells through humidity stabilization.

Although they hold the promise of clean energy, state-of-the-art fuel cells based on polymer electrolyte membrane fuel cells are inoperable above 100 degrees C, require cumbersome humidification systems, and suffer from fuel permeation. These difficulties all arise from the hydrated nature of the electrolyte. In contrast, "solid acids" exhibit anhydrous proton transport and high-temperature stability.