Solid-state Reactive Sintering Method Research Articles

Improvement of microstructure and dielectric properties of Zn1.8SiO3.8 ceramics by doping with rare earth elements (La, Pr, Nd, Sm)

The current crucial focus is improving the performance of microwave dielectric ceramics, aiming for a low dielectric constant and minimal dielectric loss for millimeter-wave applications. In this study, we successfully synthesized Zn1.8SiO3.8-RO (R=La, Pr, Nd, Sm) microwave dielectric ceramics, namely ZLSO, ZPSO, ZNSO, and ZSSO, using the solid-state reaction sintering method. X-ray diffraction peaks indicated that the main phase matched the standard Zn2SiO4 diffraction peaks. As the dopant ion radius increases from Sm³⁺ to La³⁺, the diffraction peak shifts to a lower angle and the cell volume increases. Scanning electron microscopy revealed that the ZLSO, ZPSO, ZNSO, and ZSSO ceramics displayed denser and more uniform grain shape, along with a significant decrease in the densification temperature (1200°C-1250°C) compared to the Zn1.8SiO3.8 (1350°C-1400°C). Further research indicated that substituting rare earth ions maintained a low εr while effectively increasing the Q×f values. The specific properties are as follows: ZLSO: εr = 7.06, Q × f = 59,314GHz, τf = -25.00 ppm/℃; ZPSO: εr = 7.02, Q × f = 111,184GHz, τf = -17.77 ppm/℃; ZNSO: εr = 7.02, Q × f = 127,711GHz, τf = -33.52 ppm/℃; ZSSO: εr = 7.06, Q × f =108,435GHz, τf = -22.9 ppm/℃. Among them, ZNSO exhibited the best microwave dielectric performance. The research not only effectively produces microwave dielectric ceramics with outstanding performance but also systematically uncovers the distinct effects of rare earth elements doping on the dielectric properties of silicate systems. This provides the theoretical groundwork for utilizing 5G millimeter wave bands.

The effect of dual-sites high-entropy strategy on thermal conductivity of pyrochlore ceramics

The emergence of high-entropy materials has developed a new strategy for the design and optimization of ceramics with desired properties. In this work, the (Gd1/7La1/7Nd1/7Sm1/7Eu1/7Dy1/7Ho1/7)2(Ti1/4Zr1/4Sn1/4Hf1/4)2O7 pyrochlore ceramic with dual-sites high-entropy design has been successfully prepared by a solid-state reaction sintering method. The samples possess a single-phase of pyrochlore structure, and all introduced elements are distributed homogeneously at A and B sites, respectively. Based on the synergistic high-entropy design of A and B sites, the thermal conductivity value of high-entropy pyrochlore ceramic could be diminished to 1.37 W∙m−1∙K−1.

Corrosion behavior of CMAS-infiltrated Ba(Mg1/3Ta2/3)O3 ceramic based on material characteristics

Calcium–magnesium–alumina–silicate (CMAS) corrosion is inevitable in thermal barrier coating applications. Herein, Ba(Mg1/3Ta2/3)O3 (BMT) ceramic, which is a promising thermal barrier coating material, was prepared using a solid-state reaction sintering method. The effects of the surface roughness and bulk density on the CMAS corrosion behavior of BMT ceramic were analyzed by investigating the surface morphology, cross-sectional microstructure, compositional evolution, and CMAS wetting behavior before and after CMAS corrosion. The results indicate that the wettability of CMAS on the BMT bulk material with a low surface roughness was lower than that of the material with a high surface roughness owing to the smaller driving capillary force, actual contact area between CMAS and the surface, and CMAS infiltration direction in BMT with a low surface roughness. This effectively inhibited the infiltration of CMAS and reduced its corrosion effect on BMT ceramic. The infiltration of CMAS into the BMT bulk materials with a high density was weaker because there were few channels, such as pores and microcracks, for infiltration. Therefore, reducing the surface roughness and increasing the density of BMT ceramic can be considered an effective method for improving its CMAS corrosion resistance.

Low frequency dielectric dispersion in the AgNbO3 ferroelectric ceramic system

Lead-free AgNbO3 ceramic system has been synthesized via solid-state reaction sintering method. High-density material has been obtained, revealing the formation of the pure perovskite structure, without secondary phases. Dielectric response showed three typical anomalies in the temperature dependence of the dielectric permittivity, with evident frequency-dependent dielectric dispersion for temperatures close to both the room temperature and the Curie temperature regions. Results have been analyzed and discussed within the framework of the theoretical models reported in the literature.

Figures of merit of PLZT ferroelectric ceramics for practical applications

Structural, microstructural and pyroelectric properties were investigated in PZT-based ferroelectric ceramics for a composition close to the morphotropic phase boundary (Zr/Ti = 53/47), as a function of the lanthanum content. The samples were prepared via the conventional solid-state reaction sintering method. Three compositions were synthetized and studied following the PbZr0.53Ti0.47O3 + x mole% La nominal formula, where x = 0.0, 2.5 and 5.0. The structural characterization confirmed the presence of both tetragonal and rhombohedral phases for all the studied compositions, showing a decrease in the tetragonality factor (c/a) with the increase of the lanthanum concentration. The observed decrease in the stability of the ferroelectric phase (in favor of the paraelectric one) have been discussed in light of the solubility of the doping cation into the studied PZT perovskite structure. Microstructural properties revealed low pores concentration micrographs, showing homogeneous microstructures and uniform grain-sizes. The pyroelectric response of the as-prepared PLZT samples was also investigated in a wide temperature interval. The lower lanthanum content composition exhibited the best properties, characterized by a high pyroelectric coefficient and enhanced figures of merit. These characteristics make such a composition a promising material for practical applications.

Role of Fe/Co Ratio in Dual Phase Ce0.8Gd0.2O2-δ-Fe3-xCoxO4 Composites for Oxygen Separation.

Dual-phase membranes are increasingly attracting attention as a solution for developing stable oxygen permeation membranes. Ce0.8Gd0.2O2-δ-Fe3-xCoxO4 (CGO-F(3-x)CxO) composites are one group of promising candidates. This study aims to understand the effect of the Fe/Co-ratio, i.e., x = 0, 1, 2, and 3 in Fe3-xCoxO4, on microstructure evolution and performance of the composite. The samples were prepared using the solid-state reactive sintering method (SSRS) to induce phase interactions, which determines the final composite microstructure. The Fe/Co ratio in the spinel structure was found to be a crucial factor in determining phase evolution, microstructure, and permeation of the material. Microstructure analysis showed that all iron-free composites had a dual-phase structure after sintering. In contrast, iron-containing composites formed additional phases with a spinel or garnet structure which likely contributed to electronic conductivity. The presence of both cations resulted in better performance than that of pure iron or cobalt oxides. This demonstrated that both types of cations were necessary to form a composite structure, which then allowed sufficient percolation of robust electronic and ionic conducting pathways. The maximum oxygen flux is jO2 = 0.16 and 0.11 mL/cm2·s at 1000 °C and 850 °C, respectively, of the 85CGO-FC2O composite, which is comparable oxygen permeation flux reported previously.

Effect of Y2O3 content on densification, microstructure and mechanical properties of reaction sintered magnesium aluminate spinel

Dense magnesium aluminate (MgAl2O4) spinels were developed via single-stage solid-state reaction sintering method at 1550–1650oC using combinations of varied commercial grade reactants-three different sources of alumina and two different sources of magnesia. The effect of Y2O3 doping in the concentration range of 1–4 wt % on different spinel batches was studied. Y2O3 addition was found to favour the densification of all the spinels at all dopant concentrations and maximum densification was found for the 2 wt % Y2O3 containing spinel batches. Phase analysis of the Y2O3 containing batches revealed the presence of yttrium aluminum garnet (YAG, Y3Al5O12) at all the sintering temperatures. Owing to similar crystal structure isotropic configuration of YAG (cubic) as that of spinel (cubic), Y2O3 doping was found to favour densification of spinel. Microstructural investigation revealed that Y2O3 containing batches have a controlled grain structure as compared to the without additive batches. Also, 2 wt % Y2O3 containing spinel batches sintered at 1650oC revealed better mechanical properties such as cold modulus of rupture and strength retainment after thermal shock than that of the undoped spinel batches.

Study of the dielectric relaxation mechanisms in KNbO3-based electro-ceramics

Electro-ceramics based on the KNbO3 ferroelectric system were synthesized from the solid-state reaction sintering method. In particular, the electrical properties have been investigated at room temperature in the (1−x)KNbO3−xBaNi1/2Nb1/2O3−δ (KBNN) solid-solution. The dielectric relaxation mechanisms have been analyzed as a function of the oxygen vacancy (δ) concentration and the frequency dispersion of the complex dielectric permittivity was analyzed in a wide frequency range. The obtained results were discussed within the framework of the current models reported in the literature for the dielectric relaxation processes.

Tailoring Li2Si2O5 rod-like particles and their simultaneously strengthening and toughening effects on lithium disilicate glass-ceramics

To achieve high performance of glass-ceramics, it is urgent to open a new path to enhance the mechanical properties. In this study, Li2Si2O5 rods were successfully synthesized by a modified two-step solid-state reaction sintering method. The rod aspect ratio could be controlled by adjusting the second stage sintering time. The evolution process of such Li2Si2O5 rods and their possible formation mechanism were put forward. For the first time, the Li2Si2O5 rods were used to strengthen and toughen the homologous Li2Si2O5 glass-ceramic in a typical quaternary Li2O-SiO2-K2O-La2O3 system, which indicates a high flexural strength and toughness of 315±24 MPa and 2.42±0.6 MPa·m1/2, respectively. In this glass-ceramic, the microstructure features a densely stagger network formed by the elongated rods and smaller Li2Si2O5 crystals in the glass matrix, contributing to the improvement of mechanical properties. The results demonstrate that Li2Si2O5 rods could be an excellent candidate for strengthening and toughening glass-ceramics.

High-Pressure Operation of Proton-Conducting Electrolyzers for High-Temperature Water Splitting

In this work, we present our progress on high-temperature water splitting (HTWS) and hydrogen production at elevated pressure using proton-conducting ceramics. The electrochemical performance of the proton-conducting electrolyzer unit-cell stack is analyzed at 550 °C and pressures up to 12 bar.Proton-conducting ceramics are a promising new class of electrochemical cells due to their high proton conductivity at intermediate temperatures in comparison to more-conventional solid-oxide or molten-carbonate counterparts. Materials exploration continues for fabricating proton conducting cells to achieve better electrochemical performance during operation. Recently, lower ohmic resistance and degradation rates have been observed using the highly proton-conductive and chemically stable perovskite BaCe0.4 Zr0.4 Y0.1 Yb0.1 O3−δ (BCZYYb4411). In this study we work with a composite of Ni–BZCYYb4411 as the fuel electrode (cathode), BCZYYb4411 as the electrolyte and BCFZY as the steam electrode (anode). The cathode and electrolyte layers of the membrane-electrode assemblies used in this study are synthetized using the solid-state reactive sintering (SSRS) method. SSRS is an attractive MEA-fabrication method, as it greatly reduces the number of costly and time-consuming high-temperature sintering processes. During SSRS, single-phase protonic-ceramic perovskite is formed from parent oxides during high-temperature co-sintering of the anode-electrolyte layers. This is in contrast to more-traditional processing, in which the desired phase is first formed in powder form through calcination of parent oxides, while MEA formation is executed in follow-on high-temperature sintering steps.The cathode support is formed by dry-pressing to produce a 57-mm-dia x 1.5-mm-thick disc. The electrolyte (~ 10 mm) layer is deposited using an ultrasonic spray atomizer. The process control and narrow particle size distribution delivered by the ultrasonic atomizer consistently produces a high-density electrolyte, while minimizing thickness. We are now extending the use of ultrasonic spray deposition to other critical components such as the air-steam electrode and interfacial layers.As shown in Figure 1a, the protonic-ceramic membrane-electrode assembly (MEA) is bonded to a composite ceramic frame and assembled into a sealed cell stack with metallic interconnects, current collectors, sealing gaskets and end plates. The stack is placed in a preloaded spring-based mechanical compression system that axially compresses the electrolyzer stack while avoiding any direct compression of the MEA. The assembly is placed in a sealed vessel (Figure 1b); anode and cathode gas pressures are balanced across the MEA, and with the surrounding inert vessel gas (N2). Downstream back-pressure regulators maintain electrolyzer and vessel pressures to minimize the risk of cell fracture.Despite the challenges associated with high pressure operation, this technology is key to address some of the main issues associated with proton conducting ceramics. Higher pressure operation should lead to higher efficiencies by decreasing the electron hole concentration in the electrolyte usually associated with the electron leakage problem. Also, electrode activity can be enhanced at higher pressures, enabling higher currents at lower driving voltages. Figure 1c shows an increased electrolyzer performance of almost 50% when the operating pressure is raised to 12.5 bar. This is evidence of the better kinetics and lower power required to electrolyze at higher pressures.In parallel, the high-pressure protonic-ceramic electrolyzer delivers a pure, dry, pressurized hydrogen product stream that does not require downstream separation processes. Pressurized operation reduces downstream compression needs. Elevated-pressure operation is also beneficial for the synthesis of electrofuels, where green hydrogen is transformed into higher-value chemical. These chemistries often require high temperatures and pressures to achieve meaningful production rates. Ammonia serves as an example, the second-most-produced global chemical that contributes nearly 1.5% of global annual CO2 emissions. We are currently integrating our high-pressure electrolysis operation with ruthenium-based catalysts for electrochemical ammonia synthesis. In this talk, our progress in electrochemical energy storage with proton-conducting ceramics will be reviewed. Figure 1

Band structure, photoelectric properties, and electronic transition mechanism of CuGa1-xTixS2 compound synthesized by solid-state reaction sintering method

Band structure, photoelectric properties, and electronic transition mechanism of CuGa1-xTixS2 compound synthesized by solid-state reaction sintering method

Structural, microstructural and dielectric characterizations of (Bi0.5Na0.5)TiO3based lead-free ferroelectric ceramics

(1–[Formula: see text][Formula: see text][Formula: see text]TiO3–[Formula: see text]BaTiO3lead-free ceramics have been obtained from the conventional solid-state reaction sintering method. The structural properties were investigated from X-ray diffraction and Raman spectroscopy techniques. Results revealed well-crystallized ceramic samples with perovskite structure. Microstructural properties, obtained from scanning electron microscopy measurements, have shown high density with very low porosity level. The dielectric response, analyzed as a function of the temperature and several frequencies, showed very broad peaks with a strong frequency dependence of the temperature for the maximum dielectric permittivity for the modified system. Results were analyzed considering the influence of the BaTiO3 content on the studied physical properties.

Dielectric properties and electrocaloric effect of yttrium-modified BaTiO3 ceramics

The electrocaloric effect (ECE) is a promising candidate to replace the vapor-compression cooling technology, which has reached its end of improving the energy utilization efficiency. In the present work, the Y-modified BaTiO3 ceramics with nominal compositions of Ba(Ti1-xYx)O3 (abbreviated as BT-100xY, where x = 0.0125, 0.025, 0.0375, 0.050 and 0.0625) have been prepared through the conventional solid-state reaction sintering method. The dielectric properties and electrocaloric effect of BT-100xY ceramics have been investigated in detail. The XRD patterns indicate that all the BT-100xY ceramics possess pure perovskite structure without secondary phases. The temperature dependence of dielectric permittivity reveals that the BT-1.25Y, 2.5Y, 3.75Y and 5.0Y are normal ferroelectrics, and the BT-6.25Y is a relaxor ferroelectric. The ECE is calculated through the indirect equation based on Maxwell relation. The BT-2.5Y exhibits the largest ΔT = 1.26 K and the largest ΔS = 1.68 J/kg · K among all the BT-100xY ceramics, and the BT-2.5Y also exhibits the largest ΔT/ΔE = 0.296 × 10−6 K · m/V and the largest ΔS/ΔE = 0.394 × 10−6 J · m/kg · K∙V. The ECE in our work is comparable with or even larger than that of BaTiO3-based ceramics previously reported, which indicates that the BT-100xY ceramics are promising ECE materials.

Performance Evaluation of Intermediate Temperature Proton-Conducting Soec with BaZr0.6Ce0.2Y0.2O3-δ Electrolyte

A solid oxide steam electrolysis cell (SOEC) has attracted much attention for the production of a clean H2 from water by using renewable electricity. Activation energy of proton conduction in proton conducting perovskite oxides BaZr x Ce1-x-y Y y O3-δ (BZCY) is much lower than that of yttria stabilized zirconia which is practically used for the high temperature SOECs [1]. Hence the cells using the proton conductors (H+-SOEC) are expected to operate at lower temperatures than that of YSZ-base SOEC. In general, the solid solutions, i.e. BaCe1−x−y Zr x M y O3-δ (M = Y, Yb etc.) tend to be more tolerant to CO2 and steam with increasing Zr contents [2], and thus the Zr-rich side BaCe1−x−y Zr x M y O3-δ are recently attractive as a practical electrolyte for H+-SOECs. However, the poor sinterability and relatively large grain-boundary resistances retards the application of Zr-rich phase to device application.In this study, we successfully fabricated the thin film electrolysis cells using Zr-rich side BaZr0.6Ce0.2Y0.2O3−δ (BZCY622) electrolytes. The cathode-supported cells were fabricated by a solid-state reactive sintering method assisted by zinc nitrate sintering additives. The cell comprises of a porous Ni-BZCY622 cermet cathode support, dense electrolyte film with a 20 mm thickness and La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) porous anode. The cells with a 15 nm-thick interlayer of La0.5Sr0.5CoO3- δ (LSC) was also fabricated by sputtering deposition of LSC nanofilms on the surface of the electrolyte films before printing LSCF anodes. The cell with and without LSC yielded electrolysis currents of 420 and 200 mA cm-2, respectively, at 1.5 V cell bias at 600 ºC. EIS measurements confirmed that both polarization and ohmic resistances decreased with a use of LSC interlayer, which implies that LSC layer promotes proton transfer at the anode/electrolyte interface and thus reduce the proton transfer resistance and promote anode reactions. Y. Guo, R. Ran and Z. Shao, Int. J. Hydrogen Energy, 35, 5611, (2010). P. Sawant, S. Varma, B. N. Wani and S. R. Bharadwaj, Int. J. Hydrogen Energy, 37, 3848, (2012).

Effect of doping CeO2 and Sc2O3 on structure, thermal properties and sintering resistance of YSZ

6-8 wt% yttria-stabilized zirconia (YSZ) has been widely employed as thermal barrier coating (TBC) to protect the high-temperature components of aero-engine and gas-turbine. However, the phase transition and sintering densification at high temperature seriously limit its application above 1200 °C. On account of this, CeO2 and Sc2O3 were doped into the YSZ by solid-state reaction sintering method in this paper. The effects of doping on the crystal structure, phase transition behavior and sintering resistance were investigated on the basis of XRD, Raman and FESEM, and the evolution of thermal properties of the ceramics was also analyzed. The results indicated that doped CeO2 increases the cell volume and tetragonal degree, but doped Sc2O3 was opposite. Co-doping caused not only significant difference in atomic mass and radius but also the formation of a large number of oxygen vacancies in the ceramics. Therefore, CeScYSZ showed the lowest thermal conductivity (1.53 W‧m−1‧K−1), which was about 23% lower than that of YSZ (2.00 W‧m−1‧K−1). More importantly, the oxygen vacancy also effectively stabilized the octet lattice, while the increase of lattice energy caused by Sc-O bond made it difficult for ions to misplace, which finally well prevented the transformation from t phase to m phase. There was no detrimental m-ZrO2 phase formation in the CeScYSZ after 120 h at 1500 °C. Besides, Co-doping could simultaneously overcome the poor sintering resistance caused by single CeO2 doping and the lower thermal expansion coefficient caused by single Sc2O3 doping, thus the CeScYSZ should be an ideal long-acting thermal protection material at higher temperatures.

Enhanced electrical properties of lead-free (Ba1−xCax)(Ti0.94Zr0.01Sn0.05)O3 piezoelectric ceramics by optimizing phase ratio and sintering temperature

It is challenging for material chemists to develop lead-free ceramics due to the toxicity of lead for human health and environment. (Ba, Ca)(Ti, Zr)O3 and (Ba, Ca)(Ti, Sn)O3 lead-free piezoelectric ceramics have attracted much attention due to their superior piezoelectric properties. In this study, Ca2+, Zr4+ and Sn4+ were simultaneously doped at A-sites and B-sites, respectively, to clarify the structure and enhance the electrical performance. (Ba1−xCax)(Ti0.94Zr0.01Sn0.05)O3 (BCxTZS) lead-free piezoelectric ceramics were successfully fabricated by conventional solid-state reactive sintering method. The effects of Ca2+ content (x) and sintering temperature on microstructure, phase structure and electrical properties of BCxTZS were investigated. Herein, BCxTZS ceramics are the coexistence of R-O phases as 0.01 ≤ x ≤ 0.02, and they become O-T phases as 0.02 < x ≤ 0.08. The excellent electrical performances with d33 = 511 pC N−1, kp = 43% and Qm = 126 were achieved by optimizing the phase ratio and sintering temperature. The superior d33 along with the comparable Qm with PZT ceramics indicates that BCxTZS ceramics are promising lead-free piezoelectric ceramics.

Effects of non-stoichiometry on the microstructure and microwave dielectric properties of Ba1+xCu2V2O8 (x = 0.15, 0.25, 0.35) ceramics

The Ba1+xCu2V2O8 (x = 0.15, 0.25, 0.35) ceramics were synthesized using the conventional solid-state reaction sintering method. The effects of the non-stoichiometry on the crystalline phases, densification sintering, microtopography, and microwave dielectric properties of the Ba1+xCu2V2O8 (x = 0.15, 0.25, 0.35) ceramics were studied. In the sample (x = 1) prepared according to the stoichiometry, only the single crystalline phase of BaCu2V2O8 existed. The excess of Ba2+ ions directly led to the precipitation of a new Ba2V2O7 phase. The detection of element composition using EDS also confirmed the results of the phase composition. The SEM results indicated that the microstructure of the ceramics became loose with the increase of Ba2+ ion content. The theoretical microwave dielectric properties were calculated according to the general formula of compounds. The results of the calculation showed that the precipitation of the Ba2V2O7 phase was the main factor affecting the microwave dielectric properties of the ceramics. The measured results of microwave dielectric properties were consistent with the calculated results. The microwave dielectric properties of the Ba1.35Cu2V2O8 sample calcined at 725 °C for 6 h were shown as follow: er = 12.25, Qf = 46,320 GHz, τf = − 35.3 ppm/°C.

Role of A- and B-site excess doping on the improvement of the piezoelectric properties of BaTiO3 lead-free piezoceramics

Excess Li, Al, and Si co-doped BaTiO3 (BT) piezoceramics were synthesized using a conventional solid-state reaction sintering method. The influences of excess A- and B-site doping on the crystalline structure, dielectric, ferroelectric, and piezoelectric properties of BT ceramics were studied and discussed. While ceramics had a tetragonal crystal structure, weak secondary phases appeared with an increase in the doping content. Compared to pure BT ceramics, the dielectric constant of the Li/Al/Si-doped ceramics decreased, but the dielectric loss decreased and remained at a relatively low level of approximately 0.017 with a Li–Al content of x and 0.02 with an excess Si doping content of Δ. The remnant polarization 2Pr reached the maximum values of 12.55 μC/cm2 at x = 0.07 for excess Li–Al doped ceramics and 18.58 μC/cm2 at Δ = 1.6% for excess Si doped ceramics. The piezoelectric constant d33 was significantly improved owing to the excess doping of Li–Al and Si without decreasing the Curie temperature, and its maximum value was approximately 212 pC/N at x = 0.032. The excess Si doping at the B-site helped to improve and stabilize the piezoelectric properties of the ceramics in a wide excess composition range.

Hot corrosion behavior of NdYbZr2O7 exposed to V2O5 and Na2SO4 + V2O5 molten salts

In order to evaluate the application prospects of NdYbZr2O7 as a novel TBC material, NdYbZr2O7 ceramic was synthesized via a solid-state reaction sintering method, and its hot corrosion behavior exposed to V2O5 and Na2SO4 + V2O5 molten salts at 900 °C, 1000 °C, and 1100 °C was comparatively investigated. For the V2O5 salt, the primary corrosion products were granular (Nd,Yb)VO4 as well as cube-like m-ZrO2. The corrosion layer consisted of two distinct layers, one of which was Zr-rich layer and another was V-rich layer. In the case of Na2SO4 + V2O5, NaVO3, as an intermediate product, played an important role in dissolving the NdYbZr2O7 ceramic. Herein, the (Nd,Yb)VO4 exhibited a rod/plate-like morphology, which could be attributed to the synergistic effect of low driving force and low nucleation rate. Since the molten salt infiltration rate was superior to the pore filling rate throughout the hot corrosion, the thickness of corrosion layer increased with the rise of temperature. The hot corrosion mechanisms of NdYbZr2O7 ceramic in various molten salts were discussed based on the phase diagram, Lewis acid-base rule and chemical thermodynamics. On this basis, the NdYbZr2O7 coating was prepared by atmospheric plasma spray (APS) and it exhibits a higher corrosion resistance compared to YSZ coating.

고체 산화물 연료전지를 위한 SrCo0.8Nb0.1Ta0.1O3-δ 공기극 펄스레이저 증착

Recently, new perovskite cathode material, SrCoSUB0.8/SUBNbSUB0.1/SUBTa0.1OSUB3-δ/SUB (SCNT) was reported, showing high oxygen reduction reaction (ORR) activity. This study demonstrates thin film deposition of SCNT by pulsed laser deposition technique applied to anodic aluminum oxide (AAO) based thin-film solid oxide fuel cells (TF-SOFCs) to assess the possibility of SCNT application to TF-SOFCs. The SCNT powder and the target were prepared by the solid state reactive sintering method (SSRS). This target was then mounted to the pulsed laser depositing machine and deposited on the Si wafer, and the nano-porous substrate, AAO. The physical structure and the chemical phase were investigated by the field emission scanning electron microscope, focused ion beam scanning electron microscope, and X-ray diffraction. On the top of the AAO, thin Pt film and yttria stabilized zirconia (YSZ) were first deposited by sputtering and the SCNT was deposited on the top of it afterward. The open circuit voltage of AAO cell was tested at 500°C, and successful polarization activity of SCNT was observed.