Barium Zirconate Research Articles

Temperature-dependent optical dispersion of composite cerium oxide and barium zirconate single layers and multi-layers

Temperature-dependent optical dispersion of composite cerium oxide and barium zirconate single layers and multi-layers

Role of Sintering Aids in Electrical and Material Properties of Yttrium- and Cerium-Doped Barium Zirconate Electrolytes

Ceramic proton conductors have the potential to lower the operating temperature of solid oxide cells (SOCs) to the intermediate temperature range of 400–600 °C. This is attributed to their superior ionic conductivity compared to oxide ion conductors under these conditions. However, prominent proton-conducting materials, such as yttrium-doped barium cerates and zirconates with specified compositions like BaCe1−xYxO3−δ (BCY), BaZr1−xYxO3−δ (BZY), and Ba(Ce,Zr)1−yYyO3−δ (BCZY), face significant challenges in achieving dense electrolyte membranes. It is suggested that the incorporation of transition and alkali metal oxides as sintering additives can induce liquid phase sintering (LPS), offering an efficient method to facilitate the densification of these proton-conducting ceramics. However, current research underscores that incorporating these sintering additives may lead to adverse secondary effects on the ionic transport properties of these materials since the concentration and mobility of protonic defects in a perovskite are highly sensitive to symmetry change. Such a drop in ionic conductivity, specifically proton transference, can adversely affect the overall performance of cells. The extent of variation in the proton conductivity of the perovskite BCZY depends on the type and concentration of the sintering aid, the nature of the sintering aid precursors used, the incorporation technique, and the sintering profile. This review provides a synopsis of various potential sintering techniques, explores the influence of diverse sintering additives, and evaluates their effects on the densification, ionic transport, and electrochemical properties of BCZY. We also report the performance of most of these combinations in an actual test environment (fuel cell or electrolysis mode) and comparison with BCZY.

A novel barium zirconate titanate/Fe-MOF nanocomposite: Synthesis, characterization, and photocatalytic mechanism

The synthesis of a metal-organic framework (MOF) matrix of MIL-100 (Fe) loaded with BaTi0.85Zr0.15O3 (BTZ) nanoparticles (NPs) was achieved by an easy one-pot solvothermal procedure and encasing of BTZ NPs. X-ray diffraction (XRD), photoluminescence spectroscopy (PL), UV-Vis reflectance spectroscopy (DRS), Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and N2 adsorption-desorption were deployed for the characterization of the synthesized samples. The degradation efficiency for tetracycline (TC), among the photocatalytic BTZ/MIL-100(Fe) nanocomposites with varied BTZ percentages (10, 20, 30, and 40 wt% BTZ), revealed that (30 wt%), offered the best outcome. At 0.8 g L-1 of the catalyst, pH 9, 30 ppm TC solution, and 180 min irradiation time, as the optimal conditions, the degradation efficiency of TC molecules reached >90. Based on the study of some scavenging agents, the importance of the reactive species in TC photodegradation followed the trend of photogenerated e-, hydroxyl radicals, superoxide radicals, and photogenerated h+. TC degradation occurred through reduction and oxidation pathways via a direct Z-scheme mechanism. This work aims to describe the use of MOF-based materials as a visible-light-driven photocatalyst towards TC.

Zeolitic imidazolate framework-67/barium zirconate titanate nanocomposite, Part I: Synthesis, characterization, and boosted photocatalytic activity

Using BaTi0.85Zr0.15O3/ZIF-67 (BTZ/ZIF-67) nanocomposite, tetracycline (TC) was photodegraded. Characterization of the samples was carried out using a variety of techniques, including XRD, FESEM-EDS (Field Emission Scanning Electron Microscopy – Energy Dispersive X-ray Spectroscopy), FT-IR (Fourier Transform Infra-Red), TEM (Transmission Electron Microscopy), BET (Brunauer-Emmett-Teller), BJH (Barrett-Joyner-Halenda), PL (Photoluminescence), TG-DTG (Thermogravimetry and Derivative Thermogravimetry), and UV–Vis DRS (Diffuse Reflectance Spectroscopy). BTZ/ZIF-67 nano-composites were synthesized using a one-step co-precipitation method. BTZ (30 %wt)/ZIF-67 showed the most impressive photocatalytic ability among the binary photocatalysts. Averaging the crystallite sizes of the nanocomposite samples identified by Scherrer and Williamson-Hall methods was 43.3 nm and 65.0 nm, respectively. The pHpzc values of samples of BTZ and BTZ (30 %wt)/ZIF-67 were approximately 6.7 and 10.0, respectively. Using the proposed method, we measured 357, 414, and 377 nm absorption edges for ZIF-67, BTZ, and BTZ (30 %wt)/ZIF-67 samples, which correspond to 3.47, 2.99, and 3.28 eV bandgap energies, respectively. The specific surface areas of BTZ, ZIF-67, and BTZ (30 %wt)/ZIF-67 nanocomposite are 122.15, 1218, and 1509 m2g−1, respectively. Under optimum conditions (0.8 g/L of the catalyst, CTC: 30 mg/L, and a pH 5), 89.5 % of total organic carbon (TOC) was removed within 180 min. Compared to BTZ photocatalyst, the BTZ (30 %wt)/ZIF-67 nanocomposite has a significantly larger surface area, thus enhancing photocatalytic activity. A synergistic effect was observed in the photodegradation of TC under Hg-lamp irradiation with the proposed BTZ/ZIF-67 composite. It is possible to alter the photocatalytic activity of the catalyst by changing the BTZ (30 %wt)/ZIF-67 ratio.

Effect of epoxy resin addition on the acoustic impedance, microstructure, dielectric and piezoelectric properties of 1–3 connectivity lead-free barium zirconate titanate ceramic cement-based composites

In this work, 1–3 connectivity barium zirconate titanate ceramic cement-based composites were fabricated using Portland cement and epoxy resin as the matrix. Barium zirconate titanate (BZT) of 40–60 % by volume was used while epoxy was used with cement at 0–7% by volume. Dielectric and piezoelectric properties, and other properties such as acoustic impedance, density and microstructure were investigated. It was found that epoxy resin can be used in combination with BZT to achieve a suitable acoustic impedance value (9–11 × 106 kg/m·s2) matching that of concrete for structural health monitoring application. Thus, when epoxy resin was used at 7 %, BZT volume can be increased to 60 % where the highest d33 value of 93 pC/N was found and remain within the acoustic matching range. In addition, when epoxy resin was increased, both piezoelectric charge coefficient (d33) and piezoelectric voltage coefficient (g33) were also found to increase. This is likely due to the lower porosity thus denser matrix when epoxy resin was used in addition to cement.

Advanced Numerical Modeling of BaZrS3 Chalcogenide Perovskite Cells: Titanium Alloying and Back Surface Field Effects

Chalcogenide perovskites are emerging as superior alternatives to hybrid halide perovskites for photovoltaic applications due to their non-carcinogenic composition and enhanced environmental resilience, including superior resistance to moisture. This study focuses on the computational modeling of BaZrS3 (Barium Zirconium Sulfide) based solar cells, featuring a native bandgap of ∼1.71 eV. Through precise bandgap engineering via Ti alloying at the Zr site, the study aims to optimize the bandgap to the ideal range for photovoltaic efficiency. The device architecture is further refined by adjusting parameters such as layer thickness, doping densities, trap densities and metal contacts. The optimum device efficiencies at this stage were found to be 22.45 % for BaZrS3; 23.91 % for Ba(Zr0.99Ti0.01)S3; 26.64 % for Ba(Zr0.98Ti0.02)S3; and 27.74 % for Ba(Zr0.97Ti0.03)S3. Additionally, the incorporation of various back surface fields (BSFs) (CdTe, CIGS, CZTSe, Cu2Te, FeSi2, GeSe, PbS, µc-Si, SnTe, SnS, Sn2S3, and WSe2) is investigated to enhance photo-absorption. The findings indicate that a Ti alloying concentration of 3 % at the Zr site, coupled with a Cu2Te BSF, achieves the highest efficiency, approximately 30 %. These optimized structures present a robust framework for developing efficient, stable, and non-toxic photovoltaic devices utilizing chalcogenide perovskites.

BaZrO3 and its application as a photocatalyst for Rhodamine B removal

In this investigation, Barium zirconate (BaZrO3 or BZO) showcasing high photocatalytic efficacy was synthesized by the microwave-assisted hydrothermal method. Photocatalytic activity was investigated through the removal of the Rhodamine B (RhB) dye. Although it has a high band gap (∼5 eV), BZO showed the capacity to remove ∼ 56 % of RhB. Defects, hydroxyl radicals adsorbed on its surface and favorable electronic structure were factors that promoted photocatalytic activity. Furthermore, the BZO exhibited exceptional recyclability, underscoring its potential as a photocatalyst for environmental remediation applications.

Combined magnetron sputtering and laser annealing process for the fabrication of proton conducting thin films

Acceptor doped barium zirconates are known for their exceptional protonic conductivity and the challenges in their fabrication. Within this work, BaZr0.8Y0.2O3-δ (BZY20) films were successfully deposited on a BaZr0.7Ce0.2Y0.1O3-δ/Ni (BZCY72/Ni) substrate using a combination of closed-field unbalanced magnetron sputtering and various annealing techniques such as conventional furnace annealing and laser annealing. Thin films could be tempered at only 800 °C with an additional laser annealing step and exhibit a heigh density as well as a sufficient protonic conductance. The highest measured ionic conductivity was 1.11*10−3 S/cm. The provided synthesis could pave the way for employing metallic supports in protonic ceramic fuel cells by using lower sintering temperatures than normally required.

Fabrication of n‐p heterostructure of polyaniline–barium zirconate nanocomposites sensor device for the detection of diazomethane gas

AbstractNanoparticles of barium zirconate were prepared by sol–gel method and used for the preparation of nanocomposites. Polyaniline fibers and its nanocomposites with barium zirconate were prepared by in‐situ polymerization at various percentages of 1 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt%. The prepared polyaniline nanocomposites were subjected for determination functional group by FTIR spectra and XRD analysis. The surface morphology is important aspect of sensor studies, which is illustrated by SEM and TEM image. DC conductivity of the pristine PANI and its nanocomposites increases with increase in temperature up 200°C. It is evident that the increase in conductivity is due to the hopping of charge carriers from valence band to conduction band. Among all the nanocomposites, 3 wt% of polyaniline nanocomposite shows the high conductivity of 18.6 S/cm. It is also noted that 3 wt% polyaniline nanocomposites have a higher sensitivity of 86.2% at 300 ppm when compared with other compositions. This could be because of formation strong connections between the polyaniline fibers and nano‐oxide as a resulted of enhanced node connections, high surface area and porosity through optimized nanomaterials doping. The nanocomposites sensitivity restored in 89 s after the gas was removed, responding in 23 s at 300 ppm.

Synthesis and Characterization of Electrospun Ni-BZY Nano-Fiber Anodes

Solid oxide fuel cell (SOFC) and related Protonic Ceramic Fuel Cell (PCFC) technologies have demonstrated significant promise for the efficient and clean electrochemical conversion of stored energy held in a wide variety of renewable fuels, decreasing dependence on traditional fossil fuels. The high efficiencies of both devices arise from the direct chemical-to-electrical energy transformation, achieved without moving parts and the losses inherent to combustion technologies. As in all fuel cells, electrons are generated via oxidation of fuel at the anode to power an external load before returning to the cathode to reduce an oxidant, usually O2. Separating the two electrodes is a dense, gas-tight, electronically insulating electrolyte that permits ion diffusion to complete the circuit. The SOFC’s solid oxide electrolyte passes oxides from the cathode to the anode, but the large activation barrier associated with this process requires high operating temperatures (≥700 ˚C), exacerbating degradative processes and adding challenges for thermal management. In contrast, the PCFC’s perovskite electrolyte permits protonic diffusion from the anode to the cathode, with a smaller activation barrier leading to lower operating temperatures (450 – 700 ˚C). Despite recent advancements in emerging PCFC materials, the overall efficiency and long-term stability of the device is still impacted in part by the anode’s ability to catalyze fuel oxidation, generate protons, and shuttle electrons to an attached current collector. These processes in turn are strongly linked to the morphology and stability of the anode—often a cermet composed of a Ni catalyst/electronic conductor and protonic ceramic such as yttrium-doped barium zirconate (BZY). In particular, continuity is needed for the Ni, BZY, and pore networks while maximizing boundaries between each phase (three-phase boundary). Traditionally, anodes are fabricated by mixing appropriate powders together without much control over the morphology over the micron-sized components. In this study, we explore an alternative approach to systematically engineer Ni-BZY nanofibers within the anode to enhance overall device performance through improving the underlying electrochemical processes at the anode. Low nickel-content BZY anodes (<40 wt. % Ni) for PCFCs are fabricated through electrospinning, with two distinct methods evaluated for nickel loading. First, uniform BZY nanofibers are synthesized by electrospinning a gel containing BZY metal cations and 5 wt. % Polyvinylpyrrolidone (PVP) as dispersant in ethanol/acetic acid solution followed by sintering at 900°C for 3 h in air, and subsequent electroless deposition of nickel on the fiber surfaces. Second, Ni-BZY is prepared by electrospinning a polymer containing a nickel salt and the same BZY precursors followed by co-sintering at 900°C for 3 h. The Ni-BZY fibers underwent morphological, crystallinity and elemental characterization via SEM, XRD, TEM and Raman microscopy. Initial comparison of the fibers fabricated by both methods has shown that uniform nickel loading of ~35 wt. % on the fibers was achieved in the second method. Slurries containing fibers made from both methods are deposited as anodes onto BZY electrolytes, and the complete cells are tested electrochemically under hydrogen at elevated temperature and compared with a control PCFC constructed using conventional powder materials with comparable nickel loading. In summary, electrospun nanofibers, known for their excellent permeability and faster charge transfer due to their porous structure, present an intriguing alternative for high-performance PCFC anode materials. Figure 1

Thin Film Based Membrane Electrode Assemblies for Solid-State Ammonia Synthesis

Ammonia is the of the most crucial chemicals and currently primarily produced through the Haber-Bosch process causing the industrial ammonia production to emit more CO2 than any other chemical-making reaction. While the current primary function of ammonia lies within the fertilizer production, it can also be directly used as a fuel for power generation or in the maritime industry. Compared to hydrogen, ammonia has superior storage and transportation capabilities due to its greater volumetric energy density and mild conditions for liquefication. Given the need of reducing global carbon emissions, ammonia could be synthesized electrochemically using air, water and electricity by the Solid-State Ammonia Synthesis (SSAS). Protonic ceramic cells operate within an intermediate temperature regime of around 450 - 550 °C which is well suited for this process. Within our work, we present a tubular membrane electrode unit entirely made of ceramic components based on a barium zirconate thin film electrolyte. An ammonia production rate of 9.06 × 10-10 mol s-1 cm-2 and a Faradaicefficiency of 6.58% were achieved using a NiO-BaZr0.7Ce0.2Y0.1O3- δ | BaZr0.8Y0.2O3- δ | Ru@Ba0.5Sr0.5TiO3-δ cell.A key innovation lies in the production of dense BaZr0.8Y0.2O3-δ electrolyte layers, ranging from 1 to 5 µm in thickness, utilizing a Closed-Field Unbalanced Magnetron Sputtering (CFUMS) process. This technique allows precise adjustments of stoichiometric ratios within the perovskite structure, offering improved sputtering yields compared to conventional methods. Furthermore, the crystallinity, phase purity, and microstructure of sputter-deposited thin films are enhanced through selective laser annealing (SLA), resulting in high-density films composed of single-phase BaZr0.8Y0.2O3-δ with average crystallite sizes of 200 nm while avoiding substrate damage from thermal stress. Electrochemical performance was evaluated through impedance spectroscopy, half-cell tests and full cell tests providing insights into the efficacy of the developed tubular membrane reactor for the electrochemical synthesis of ammonia. The results demonstrate the feasibility of utilizing ceramic proton conductors in SSAS, particularly highlighting the potential of high-pressure operation up to 80 bars in tubular cells at relatively low temperatures around 450 °C, thereby achieving attractive NH3 production rates.This research contributes to the evolving landscape of sustainable ammonia synthesis by presenting a novel approach that integrates advanced materials and manufacturing techniques. Electrification and decentralization of the ammonia supply chain will expand the market by supporting its current use as fertilizer source and enable a new route as green energy carrier paving the way for an ammonia-based economy. Figure 1

Fabrication, structure, and physical properties of three-B-site perovskite Ba(Zr1–2xTixCex)O3

In this study, three-B-site perovskite Ba(Zr1–2xTixCex)O3 (x=0–0.2) materials with the co-substitution of Ti4+ and Ce4+ at the Zr-site of barium zirconate (BaZrO3) were successfully prepared. The analyses of XRD & Rietveld method, SEM, and TEM indicated that the substituted ions Ti4+ and Ce4+ entered the BaZrO3 lattice to form a single-phase solid solution, showing a conventional primitive cubic perovskite structure (Pm-3 m space group), and its lattice parameters gradually increased from 0.4192 nm to 0.4206 nm with x value. The sample with x=0.1 exhibited relatively optimal structural uniformity and densification, as well as comprehensive physical properties. The sample Ba(Zr0.8Ti0.1Ce0.1)O3 showed a minimum mean grain size of 1.50 μm. And due to the combined effect of solid solution formation and grain refinement, it displayed an apparent porosity of 1.42 % with a cold modulus of rupture (CMOR) of 123.8 MPa, and a thermal conductivity at ambient temperature of 2.197 W/mK. Furthermore, this three-B-site perovskite Ba(Zr1–2xTixCex)O3 exhibits excellent high-temperature stability. This study demonstrates the promising application of the dense, high-strength, and low-thermal conductivity Ba(Zr0.8Ti0.1Ce0.1)O3 perovskite material in the field of advanced refractory ceramics.

Improved thermal stability and electrical conductivity of dysprosium doped barium zirconium cerate electrolyte

Acceptor-doped perovskites based on the BaCeO3 have been extensively investigated as promising candidates for proton-conducting electrolyte at intermediate temperatures. This operational regime is characterized by proton conduction facilitated via hydroxyl protons that effectively occupy vacancies of oxide ions within the perovskite crystal lattice structure. While the trade-off parameters (proton conductivity and chemical stability) concern the utility of cerium-based electrolytes, acceptor doped compounds hinder the mobility of protons due to dopant-charge and dopant-host interactions. However, Dy-doped compounds reveal a promising behavior relative to most acceptor substituents with marginal constraints at higher doping concentration. As a result, a threshold doping range is essential to combat material inconsistencies such as cationic disorder to proton trapping effect. Therefore in the present study we synthesize the single-phase dysprosium and zirconium co-doped barium cerate at different doping concentrations (BaCe0.8-xZr0.2DyxO3-δ (x = 0.0–0.20)) to showcase the chemical inertness of the compound against oxidizing and reducing atmospheres preserving high ionic conductivity. According to our experimental outcomes, higher ionic conductivity among wet atmospheric conditions suggests the role of moisture to contribute additional charge carriers among the Dy-doped samples via explicitly generated oxygen vacancies. As a result, BaCe0.65Zr0.2Dy0.15O3-δ demonstrates a highest total conductivity, reaching 2.44 x 10-2 S cm−1 at 575 °C, with an associated activation energy of 0.61 eV within the temperature range of 300–600 °C. The study also reveals the optimal operating temperature of the proton conducting electrolyte to avoid mixed ionic (H+ and O2–) conduction.

Effect of current density and operating temperature on degradation of protonic ceramic fuel cells containing BaZr0.8Yb0.2O3-δ electrolyte during long-term operation

Barium zirconate doped with 20 mol% Yb (BaZr0.8Yb0.2O3-δ, BZYb20) is one of the most promising candidates for use as an electrolyte material in protonic ceramic fuel cells (PCFCs) due to its high proton conductivity and high chemical stability under CO2-containing fuel conditions. The long-term durabilities of PCFCs prepared using the BZYb20 electrolyte were evaluated as a function of the current density at 500 and 600 °C over a period of 1000 h. At 600 °C, the internal resistance of the cell increased even under open circuit voltage (OCV) condition. Comparing the voltage lowering rates at a current density of 0.172 A cm−2 based on the current density–voltage curves recorded during the durability tests, rates of 3.0, 5.3, and 9.0%/1000 h were achieved at the OCV, 0.047, and 0.172 A cm−2, respectively. A small amount of Ni elements diffused into the electrolyte from the anode to the cathode side, resulting in the formation of cumulus cloud shapes that corresponded to Ni element segregation at the grain boundaries in the electrolyte layer after long-term durability testing at 0.172 A cm−2. At current densities of 0.047–0.048 A cm−2, the voltage lowering rate at 500 °C was higher than that at 600 °C, with values of 6.0 and 2.6%/1000 h being recorded, respectively. This effect may be due to the higher resistance of the cell at 500 °C compared to that at 600 °C.

Advancements in sustainable proton-conducting electrochemical cells: Direct recycling of sintered nickel oxide-doped barium zirconate half cells

The ongoing evolution in energy production and conversion technologies has brought solid oxide electrochemical cells (SOCs) to the forefront, recognized for their high efficiency and environmental benefits. However, establishing sustainable and scalable manufacturing processes for SOCs presents formidable challenges, including sourcing large-scale raw materials and implementing effective recycling methods for spent cells and manufacturing scraps. In response, we demonstrate closed-loop direct recycling of proton-conducting solid oxide electrochemical half cells, incorporating active comminution and cell regeneration using the recycled materials. This innovative approach achieves over 92 % material recovery and an impressive 100 % recovery in full cell performance, addressing a significant gap in current sustainable manufacturing practices while setting a new standard for the industry. This technology not only addresses a significant gap in current sustainable manufacturing practices but also sets a precedent for future advancements in the sustainable SOC field, potentially influencing broader practices in the recycling of multi-functional ceramics.

EReaxFF force field development for BaZr0.8Y0.2O3-δ solid oxide electrolysis cells applications

The use of solid-oxide materials in electrocatalysis applications, especially in hydrogen-evolution reactions, is promising. However, further improvements are warranted to overcome the fundamental bottlenecks to enhancing the performance of solid-oxide electrolysis cells (SOECs), which is directly linked to the more-refined fundamental understanding of complex physical and chemical phenomena and mass exchanges that take place at the surfaces and in the bulk of electrocatalysis materials. Here, we developed an eReaxFF force field for barium zirconate doped with 20 mol% of yttrium, BaZr0.8Y0.2O3-δ (BZY20) to enable a systematic, large-length-scale, and longer-timescale atomistic simulation of solid-oxide electrocatalysis for hydrogen generation. All parameters for the eReaxFF were optimized to reproduce quantum-mechanical (QM) calculations on relevant condensed phase and cluster systems describing oxygen vacancies, vacancy migrations, electron localization, water adsorption, water splitting, and hydrogen generation on the surfaces of the BZY20 solid oxide. Using the developed force field, we performed both zero-voltage (excess electrons absent) and non-zero-voltage (excess electrons present) molecular dynamics simulations to observe water adsorption, water splitting, proton migration, oxygen-vacancy migrations, and eventual hydrogen-production reactions. Based on investigations offered in the present study, we conclude that the eReaxFF force field-based approach can enable computationally efficient simulations for electron conductivity, electron leakage, and other non-zero-voltage effects on the solid oxide materials using the explicit-electron concept. Moreover, we demonstrate how the eReaxFF force field-based atomistic-simulation approach can enhance our understanding of processes in SOEC applications and potentially other renewable-energy applications.

Structural, optical, photoluminescence and radiation-shielding investigation of magnesium doped barium zirconate (BaZrO3) ceramics

Magnesium-doped barium zirconate (BaZrO3) powders with various Mg atomic ratios (0.1, 0.2, 0.3, 0.4, and 0.5) have been synthesized by using the solid-state reaction method. The structure and microstructure were studied via scanning electron microscopy, X-ray powder diffraction (XRD), energy dispersive X-ray (EDX), Raman, and Fourier transform infrared (FTIR) spectroscopy. The optical properties were investigated using UV–Vis and photoluminescence spectroscopy. XRD results showed that the synthesized powders have a cubic crystal system with a grain size in the range of 23–27 nm. The band gap is estimated to be about 3.5–3.59 eV. The photoluminescence shows UV and visible emissions. The neutron and gamma shielding features were calculated and assessed based on Phy-X software of energies ranging from 0.015 to 15 MeV. The gamma shielding parameters were generally reduced by adding Mg instead of Ba. The neutron shielding parameter was enhanced gradually. Based on these results, the ability to use the synthesized samples in radiation and neutron shielding applications can be deduced.

Synthesis and Characterization of Sol-Gelled Barium Zirconate as Novel MTA Radiopacifiers.

Barium zirconate (BaZrO3, BZO), which exhibits superior mechanical, thermal, and chemical stability, has been widely used in many applications. In dentistry, BZO is used as a radiopacifier in mineral trioxide aggregates (MTAs) for endodontic filling applications. In the present study, BZO was prepared using the sol-gel process, followed by calcination at 700-1000 °C. The calcined BZO powders were investigated using X-ray diffraction and scanning electron microscopy. Thereafter, MTA-like cements with the addition of calcined BZO powder were evaluated to determine the optimal composition based on radiopacity, diametral tensile strength (DTS), and setting times. The experimental results showed that calcined BZO exhibited a majority BZO phase with minor zirconia crystals. The crystallinity, the percentage, and the average crystalline size of BZO increased with the increasing calcination temperature. The optimal MTA-like cement was obtained by adding 20% of the 700 °C-calcined BZO powder. The initial and final setting times were 25 and 32 min, respectively. They were significantly shorter than those (70 and 56 min, respectively) prepared with commercial BZO powder. It exhibited a radiopacity of 3.60 ± 0.22 mmAl and a DTS of 3.02 ± 0.18 MPa. After 28 days of simulated oral environment storage, the radiopacity and DTS decreased to 3.36 ± 0.53 mmAl and 2.84 ± 0.27 MPa, respectively. This suggests that 700 °C-calcined BZO powder has potential as a novel radiopacifier for MTAs.

Reactive Magnetron Sputtering for Y-Doped Barium Zirconate Electrolyte Deposition in a Complete Protonic Ceramic Fuel Cell

Yttrium-doped barium zirconate is a commonly used electrolyte material for Protonic Ceramic Fuel Cells (PCFC) due to its high protonic conductivity and high chemical stability. However, it is also known for its poor sinterability and poor grain boundary conductivity. In this work, in response to these issues, reactive magnetron sputtering was strategically chosen as the electrolyte deposition technique. This method allows the creation of a 4 µm tick electrolyte with a dense columnar microstructure. Notably, this technique is not widely utilized in PCFC fabrication. In this study, a complete cell is elaborated without exceeding a sintering temperature of 1350 °C. Tape casting is used for the anode, and spray coating is used for the cathode. The material of interest is yttrium-doped barium zirconate with the formula BaZr0.8Y0.2O3−δ (BZY). The anode consists of a NiO-BZY cermet, while the cathode is composed of BZY and Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSFC) in a 50:50 weight ratio. The electrochemical impedance spectroscopy analysis reveals a global polarization resistance of 0.3 Ω cm2, indicating highly efficient interfaces between electrolytes and electrodes.

Highly functional molten sodium hydroxide-BaZrO3 composite electrolyte with hybrid ionic conductivity for low-temperature solid oxide fuel cells

Proton-conducting barium zirconate perovskite attracts considerable attention as an electrolyte for solid oxide fuel cells (SOFCs). To obtain BaZrO3-based electrolytes with high ionic conductivity at low temperatures, composite electrolytes named BaZrO3+x wt% NaOH are designed and synthesized. A study is conducted to explore the effects of molten-state NaOH and a small amount of Na2CO3 generated during SOFC operation on the performance of composite electrolytes systematically. As a result of the addition of NaOH, the composite electrolyte is created with rich surfaces and solid-liquid interfaces, compared to traditional condensed electrolytes.The solid-liquid interface can serve as a high-speed ion conduction channel. In-situ surface oxygen deficiency induced by NaOH and the bridge function of carbonate enable rapid ion migration along the interface of the composite electrolyte. The fuel cell with the prepared electrolyte can deliver an excellent maximum power density (MPD) of 1039 mW cm-2 at 550 °C. At 350 °C, the cells are also able to show a very impressive power density of 365 mW cm-2. The concise design, convenient preparation process, and outstanding performance of the fuel cell collectively offer an effective strategy for advancing the manufacture of electrolyte materials for low-temperature operation.