Yttria-stabilized Zirconia Research Articles

Effect of the sintering parameters on the structure and mechanical properties of zirconia-based ceramics

The paper presents the results of an investigations of the sintered zirconia ceramics that have been stabilized with Y2O3 and CeO2. The initial powders were synthesized via decomposition of the fluoride salts, which determined morphological features and dimensions of the particles. The specific electroconsolidation process, performed using the modified spark plasma sintering device, allowed for the retention of the nanoscale grain sizes and related properties of the sintered ceramic composites. It was found that the as-obtained materials with cerium oxide exhibited high bending strength of 609 MPa, by ca. 33 % higher than that of yttria-stabilized ones (410 MPa). In turn, the best combination of hardness and fracture toughness, K1С = 5.8 МPа·m1/2 аnd Нv = 14.8 GPа, respectively, exhibited ZrO2+3 wt% Y2O3. This result can be attributed to the chemical composition and morphology of the powders, which in turn is influenced by the synthesis conditions and calcination time and temperatures, as well as to the sintering parameters. In particular, yttria-stabilized zirconia showed higher sensitivity to the variations of the sintering temperatures and holding times.

Influence of TiO2dopingand spraying power on the microstructure, mechanical properties and cavitation erosion resistance of YSZ coatings

Yttria-stabilized zirconia (YSZ) and TiO2- doped YSZ (TiYSZ) coatings were prepared using Atmospheric Plasma Spraying (APS) at different power levels to protect of flow passage components from cavitation erosion. We analyzed, the effects of TiO2 doping and spraying power on the coatings' phase structure, microstructure and mechanical properties using XRD, Raman spectroscopy, SEM, Vickers hardness and nano-indentation. We tested the cavitation erosion behavior of TiYSZ coatings and YSZ coatings (as a reference) in a laboratory setting employing vibration-induced cavitation in accordance with ASTM standard G32-16. The results showed that the YSZ coating contained 50% c-phase and 50% t-phase, while the TiYSZ coating contained approximately 78 % c-phase. Spraying power hadlittle effect on the phase structure of either coating. However, higher spraying power increased the density of the coating, leading to greater microhardness. TiYSZ coatings were denser than YSZ at any power level and did not exhibit a distinct microcolumnar grain structure, unlike YSZ. Additionally, TiYSZ coatings displayed better mechanical properties, including higher hardness, elastic modulus, toughness, and fracture strength compared to YSZ. As a result, the cavitation resistance of TiYSZ coatings improved by about 50% compared to YSZ. Furhermore, we found that chemical degradation of YSZ-based ceramics under cavitation erosion conditions plays a role in cavitation erosion. We also observed that cavitation-induced amorphization is a key mechanism contributing to this degradation.

Evaluation of shear bond strength based on substructure materials and ceramic veneering techniques.

Bilayered restorations have both the strength of the substructure material and the esthetics of the veneer material; however, they should have appropriate bonding between the two materials. This study aimed to evaluate the shear bond strength (SBS) according to the substructure material and veneering technique used in bilayered restorations. The experimental group was divided into four groups (n = 15 per group) based on the substructure materials (cobalt-chromium [Co-Cr] alloy and 3 mol% yttrium-stabilized tetragonal zirconia polycrystal [3Y-TZP]) and veneering techniques (pressing and layering). Veneering was performed with disk shape (diameter: 5mm, height: 2mm) on a substructure using each veneering technique. Shear stress was applied to the interface of the substructure and the veneering ceramic using a universal testing machine. The shear bond strength, according to the substructure and veneering technique, was analyzed using a two-way analysis of variance with a post-hoc Tukey's honestly significant difference test. The failure mode was observed, and the surface was analyzed using a scanning electron microscope and energy-dispersive spectroscopy. The shSBS of the Co-Cr alloy and 3Y-TZP substructure was not different (p > 0.05); however, the pressing technique showed a higher SBS than the layering technique (p < 0.05). The SBS did not differ depending on the veneering technique in the Co-Cr alloys (p > 0.05), whereas the SBS in the pressing technique was higher than that in the layering technique for 3Y-TZP (p < 0.05). In the layering technique, the Co-Cr alloy showed a higher SBS than 3Y-TZP (p < 0.05). In the failure mode, mixed failure occurred most frequently in all groups. Extensive elemental interdiffusion was observed through the opaque layer in the Co-Cr alloy, regardless of the veneering technique. In 3Y-TZP, a wider range of elemental interdiffusion was observed in the pressing technique than in the layering technique. In bilayered restorations with a 3Y-TZP substructure, the pressing technique yielded higher bonding strength than layering. Using the layering technique, 3Y-TZP showed a lower SBS than the Co-Cr alloy. In bilayered restorations using 3Y-TZP as a substructure, the veneering technique and thermal compatibility of the materials must be considered.

Quantifying Microstructure Features for High-Performance Solid Oxide Cells.

The drive for sustainable energy solutions has spurred interest in solid oxide fuel cells (SOFCs). This study investigates the impact of sintering temperature on SOFC anode microstructures using advanced 3D focused ion beam-scanning electron microscopy (FIB-SEM). The anode's ceramic-metal composition significantly influences electrochemical performance, making optimization crucial. Comparing cells sintered at different temperatures reveals that a lower sintering temperature enhances yttria-stabilized zirconia (YSZ) and nickel distribution, volume, and particle size, along with the triple-phase boundary (TPB) interface. Three-dimensional reconstructions illustrate that the cell sintered at a lower temperature exhibits a well-defined pore network, leading to increased TPB density. Hydrogen flow simulations demonstrate comparable permeability for both cells. Electrochemical characterization confirms the superior performance of the cell sintered at the lower temperature, displaying higher power density and lower total cell resistance. This FIB-SEM methodology provides precise insights into the microstructure-performance relationship, eliminating the need for hypothetical structures and enhancing our understanding of SOFC behavior under different fabrication conditions.

A phase-field model for study of ferroelastic deformation behavior in yttria stabilized zirconia

A modified phase-field model coupled with linear elasticity is formulated to study the effect of ferroelastic domain switching on the deformation behavior of tetragonal-prime yttria-stabilized zirconia. Simulations are performed under uniaxial tension and compression using realistic domain microstructures. This work provides new insights into the mechanism of ferroelastic deformation by studying the evolution of domains under different loading directions and strain rates. The model predicts realistic stress-strain curves consisting of stress-plateaus with accurate domain switching behavior without setting a switching criterion based on a critical stress for nucleation of new domains. The results reveal that the origin of coercive stress lies in the balance between the energy absorbed by the domain switching process and the externally applied energy. Loading in different directions but parallel to the spontaneous strain results in different levels of coercive stress as domain switching absorbs different amounts of energy. For the same reason when the strain-rate increases, the coercive stress also increases. This work establishes the relation between the coercive stress and microstructural changes during ferroelastic domain switching.

High temperature infiltration behavior and reaction characteristics of Colima volcanic ashes on gadolinium zirconate coatings deposited by atmospheric plasma spraying

Volcanic ashes are considered a serious threat to the aircraft industry. At high temperatures, they inflict severe thermochemical damage to the typical 7 wt.% yttria-stabilized zirconia thermal barrier coatings that protect the aircraft turbine. There is a need to evaluate alternative materials with excellent resistance to infiltration of molten siliceous particles, such as gadolinium zirconate. In this work, free-standing thermal barrier coatings of gadolinium zirconate were manufactured by atmospheric plasma spraying, varying deposit parameters to obtain different relative densities to evaluate the infiltration of molten Colima volcanic ashes for 1 h and 10 h at 1250 °C. The infiltration depth and the reaction products resulting from each interaction, were studied by different characterization techniques. In general, the coatings show high resistance to the infiltration of the volcanic ashes, reaching infiltration depths between 50 µm and 80 µm after 10 h of infiltration time. In this sense, gadolinium zirconate coatings are excellent candidates against the infiltration of Colima volcanic ashes compared to the typical yttria-stabilized zirconia-based thermal barrier coatings.

Solid-state transformation composite filler: A new strategy to strengthen ceramic/metal joint

Residual stress is the main hindrance to achieve a robust ceramic/metal brazed joint. In this study, yttria stabilized zirconia (YSZ) particles was fabricated into solid-state transformation composite filler, which was proposed as a new strategy to strengthen Ti3SiC2/Cu brazed joint. After detailed characterization conducted on YSZ particles and brazed joint, the abnormal expansion properties of YSZ and its strengthening brazed joint mechanism were clarified. The content of Y2O3 in YSZ had significant effects on the phase transformation of ZrO2 from tetragonal to monoclinic. When 3 mol.% Y2O3 was added, the maximum phase transformation occurred at about 500 ◦C, half of brazing temperature, during the cooling process. The phase transformation of ZrO2 effectively released residual stress in the joint, which was induced by both temperature changes and residual stress. The abnormal volume expansion during phase transformation decreased the thermal mismatch of brazed joint further to strengthen brazed joint.

Design and analysis of a planar and multilayer metamaterial with the dual-functions of an ultra-broadband and high absorptivity absorber and a multi-wavelength resonator

This absorber exhibits a hierarchical structure, featuring layers of ZnO, Zr, yttria-stabilized zirconia (YSZ), Zr, YSZ, Al, YSZ and Al from top to bottom. Simulation analyses were conducted using COMSOL Multiphysics® simulation software (version 6.1). The primary innovation of this multilayer metamaterial lies in its entirely planar configuration, enabling switchable functionality: one ultra-broadband with high absorptivity (facilitated by the ZnO layer) and three narrowband absorption peaks (achieved through the Al layer). The simulation results clearly demonstrate that when light was incident from the ZnO direction onto this designed structure, the investigated planar and multi-functional absorber exhibited excellent absorber characteristics. Over an ultra-wide broadband range from 395 to 2070[Formula: see text]nm, the average absorptivity reached an impressive 95.03%. When light was incident from the Al direction onto the investigated planar and dual-functional absorber, three narrowband absorption peaks were observed at wavelengths 355, 550 and 1200[Formula: see text]nm. The second innovation highlights the effectiveness of ZnO as an anti-reflection layer, elevating the absorptivity of the ultra-broadband absorber. The third innovation establishes that Al is the optimal metal choice. It is worth noting that while using no Al layer or substituting Al with other metals did not diminish the absorptivity of the ultra-broadband absorber, alternative metals might adversely affect the absorptivity of the multi-wavelength absorber.

Electric field/current enhanced grain growth behavior of 8mol% Y2O3 stabilized cubic ZrO2 (8Y-CSZ) polycrystals

The effect of the flash event on grain growth behavior was examined in 8 mol% yttria-stabilized cubic zirconia (8Y-CSZ) polycrystals under direct and alternating electric fields/currents. Even at the same specimen temperature, the rate of the grain growth is accelerated in the flash event than in the heat treatment without electric field/current (0 V), suggesting that the non-thermal effect caused additionally under the flash event contributes to the acceleration of the grain growth. Although the grain growth behavior can be characterized by the empirical equation (dtn –d0n = kt) with the same grain growth exponent of n = 3 irrespective of the electric field/current, the activation energy for the grain growth is lowered under the flash event. This suggests that the non-thermal effect caused by the flash event does not affect the mechanism of the grain growth, but would accelerate the rate-controlling process of the grain growth. The non-thermal effects can be further accelerated in fine-grained specimens under the alternating current flash and/or by increasing the input power density. Since the grain growth is rate-controlled by the grain boundary cation diffusivity, the non-thermal effect under the flash event would accelerate the grain boundary cation diffusivities through the formation of excess oxygen vacancies depending on the polarity and the power density.

Advances in low-temperature solid oxide fuel cells: An explanatory review

This review article explores recent advancements and potential advantages of low-temperature solid oxide fuel cells (LT-SOFCs), offering a comprehensive overview of critical developments in the field. It highlights the significance of utilizing oxygen ion conducting electrolytes such as La0.8Sr0.2Ga0.8Mg0.2O3–type (LSGM) perovskties and yttria-stabilized zirconia (YSZ) in LT-SOFCs, emphasizing their role in facilitating efficient oxygen transport at lower temperatures. Furthermore, the review discusses the importance of electrode tailoring at the nanoscale using techniques like sol-gel and pulsed laser deposition (PLD), which have been shown to enhance the oxygen reduction reaction (ORR) at the cathode, thereby improving overall cell performance. One of the key focal points of the review is the exploration of perovskite structures and their imperative characteristics in LT-SOFCs. Specifically, it elucidates how oxygen defects within perovskites contribute to the migration of oxygen ions, consequently augmenting electrical conductivity within the cell. This discussion underscores the significance of understanding the fundamental principles governing ion transport mechanisms in electrolyte materials, which is crucial for the development of next-generation LT-SOFCs with improved efficiency and performance. Moreover, the review highlights recent advancements in the fabrication of nanoscale electrolyte films, which have shown promising results in reducing series resistance and enhancing cell performance at lower temperatures. Techniques such as atomic layer deposition (ALD), and spark plasma sintering (SPS) are discussed in the context of fabricating these nanoscale membranes, underscoring their potential for revolutionizing LT-SOFC technology. Overall, this review consolidates recent research findings and technological advancements in the field of LT-SOFCs, shedding light on the novel approaches and strategies employed to overcome existing challenges and propel the development of more efficient and practical fuel cell systems. By synthesizing key insights and highlighting future research directions, this review serves as a valuable resource for researchers and engineers working towards the advancement of LT-SOFC technology.

Effect of Hydrothermal, Chemical, and Mechanical Degradation on Flexural Strength and Phase Transformation of Ground, Glazed, and Polished Zirconia.

Objectives: Evaluation of the effect of grinding on flexural strength of zirconia after low temperature degradation (LTD) and pH-cycling. Materials and Methods: Sixty-four bar-shaped specimens of yttria-stabilized tetragonal polycrystalline zirconia were milled, sintered, wet-polished, and divided into 8 groups (N=8). The four control groups were not aged while artificial aging was performed in the 4 experimental groups in three steps including LTD in steam for 40h, pH-cycling, and tooth brushing for artificial aging. All groups underwent surface preparations as follows: standard polishing without surface treatment (Sp), grinding with a blue-yellow band diamond instrument (Gr); grinding with a diamond rotary instrument (DRI) and then over-glazing (Gl); grinding with a DRI followed by two-step intraoral polishing (Po); standard polishing and aging (Sp-Ag); grinding and aging (Gr-Ag), grinding, over-glazing and aging (Gl-Ag); and grinding, polishing and aging (Po-Ag). Monoclinic content was assessed in one specimen of each group by X-ray diffraction (XRD). The 3-point flexural strength test was performed in a universal testing machine. The results were analyzed with two-way ANOVA and Tukey's test (α=0.05). Results: Mean flexural strength (Mpa) was significantly higher in groups Gr and Po compared to group Sp (both, P<0.0001) and group Gl (both, P<0.0001). In XRD analyses, the highest monoclinic phase before aging was observed in group Gr (12.6%), and after aging in group Gr-Ag (51.2%). Conclusion: Grinding and polishing increased the flexural strength, while glazing did not exhibit any significant effect on this parameter. Furthermore, aging did not adversely affect flexural strength.

Antiviral and antibacterial activities of yttria-stabilized zirconia

Antiviral and antibacterial activities of yttria stabilized zirconia (YSZ) powder were evaluated against Escherichia coli, Staphylococcus aureus, bacteriophage Qβ, and bacteriophage Φ6 using ISO procedures. For comparison, the same evaluation was also conducted using Y2O3 and ZrO2 powders. Against all these bacteria and viruses, YSZ exhibited antibacterial and antiviral activities, but the extent of its activity differed depending on the bacteria and virus. Those differences in activity might be attributable to electrostatic interactions between the YSZ surface or ions and bacteria and viruses, the degree of adsorption attributable to specific interactions between Y or ZrO2 and phosphate ions, and differences in protein denaturation including lipid bilayer deformation.

Influence of Zr-doping on the structure and transport properties of rare earth high-entropy oxides

Fluorite-type ceria-based ceramics are well established as oxygen ion conductors due to their high conductivity, superseding state-of-the-art electrolytes such as yttria-stabilized zirconia. However, at a specific temperature and oxygen partial pressure they occasionally exhibit electronic conduction attributed to polaron hopping via multivalent cations (e.g. Pr and Ce). (Ce, La, Pr, Sm, Y)O2−δ is a high-entropy oxide with a fluorite-type structure, featuring low concentrations of multivalent cations that could potentially mitigate polaron hopping. However, (Ce, La, Pr, Sm, Y)O2−δ undergoes a structural transition to the bixbyite-type structure above 1000 °C. In this study, we introduce Zr doping into (Ce, La, Pr, Sm, Y)O2−δ to hinder the structural transition at elevated temperatures. Indeed, the fluorite structure at elevated temperatures is stabilized at approximately 10 at.% Zr doping. The total conductivity initially increases with doping, peaking at 5 at.% Zr doping, and subsequently decreases with further doping. Interestingly, electronic conductivity in (Ce, La, Pr, Sm, Y)1−x Zr x O2−δ under oxidizing atmospheres is not significant and is lowest at 8 at.% Zr. These results suggest that ceria-based high-entropy oxides can serve as oxygen ion conductors with a significantly reduced electronic contribution. This work paves the way for new compositionally complex electrolytes as well as protective coatings for solid oxide fuel cells.

CaO–MgO–Al2O3–SiO2 corrosion resistance of multi-rare-earth-oxide-doped zirconia thermal barrier coating

As a thermal barrier coating (TBC) material, 8 wt% yttria-stabilized zirconia (8YSZ) exhibits poor resistance against calcium–magnesium–aluminosilicate (CMAS) corrosion. This is caused by the penetration of molten CMAS glass and the depletion of Y3+, which limits the lifetime of 8YSZ. In this study, a multi-rare-earth-oxide-doped zirconia (15 wt% (Lu0.2Yb0.2Dy0.2Gd0.2Y0.2)–ZrO2, denoted as 15LYDGY–SZ) ceramic was prepared to examine its interaction with CMAS. The sluggish diffusion effect and the competition between various dopant elements toward reaction with CMAS effectively slow down the atomic diffusion and limit the transformation of tetragonal phase into monoclinic phase in 15LYDGY–SZ ceramic. Compared with the currently used 8YSZ ceramic, the corrosion resistance of 15LYDGY–SZ to CMAS and its retention rate of fracture toughness after CMAS corrosion are improved. The results show that the multi-rare-earth-oxide-doped zirconia ceramic prepared in this study is a promising candidate material for the development of future TBCs.

Structural optimization for the thermal conductivity and thermal cycling behavior in thermal barrier coatings and analysis of thermomechanical properties by computational investigation

The microstructure affects the service life and performance in thermal barrier coatings (TBCs). A series of yttria-stabilized zirconia (YSZ) coatings with embedded micro-agglomerated particles (EMAP) are prepared using plasma co-spraying technology. The thermal conductivity and thermal cycling behavior between EMAP coatings with various transfer speeds and traditional YSZ coating are explored. Experimental and finite element simulations are conducted to explore the effect of pore structure characteristics on the thermomechanical properties of coatings. Results show that the thermal conductivity of EMAP coatings is lower than that of traditional YSZ coating, with EMAP coating deposited at 200 mm/s transfer speed having the lowest thermal conductivity. The thermal cycling life of EMAP coatings at transfer speeds of 600 mm/s and 800 mm/s is improved by 20.00 % and 58.33 % compared to traditional YSZ coating. This paper suggests the mechanism of excellent thermal insulation and service life of porous coatings.

Experimental investigation of some photon interaction parameters of popular restorative dental materials with a non-destructive technique

Dental restorative materials are widely used to restore esthetics and function in prosthetic treatments. In this paper, reflection coefficients and effective atomic numbers of some restorative materials (Polyetheretherketone (PEEK), feldspathic porcelain (veneering porcelain on cobalt–chromium alloy as metal framework), lithium disilicate glass-ceramic, zircon core (veneering porcelain on yttria-stabilized tetragonal zirconia polycrystal), monolithic zirconia, and zirconia-reinforced lithium silicate glass ceramic) were measured by using 59.54 keV energy gamma rays emitted from an Am-241 radioactive source. The scattering peaks of the restorative materials were detected using an HPGe detector. The gamma radiation absorption parameters of these materials (MAC, LAC, MFP, and HVL) were also investigated using a ULEGe detector for 59.54 keV photons. It is observed that the largest MAC value is Monolithic zirconia. The material with the highest reflection parameter was found to be PEEK. Of the dental restorative materials investigated, PEEK has the lowest effective atomic number value of 21.650 and Monolithic zirconia has the highest effective atomic number value of 37.841. Effective atomic numbers can be used in non-destructive analysis and medical imaging, as is well known. In addition, the calibration curve obtained can be used in the qualitative analysis of different restorative and implant materials.

Performance of Atmospheric Plasma-Sprayed Thermal Barrier Coatings on Additively Manufactured Super Alloy Substrates

This work represents a preliminary study of atmospheric plasma-sprayed (APS) Yttria-Stabilized Zirconia (YSZ)-based thermal barrier coatings (TBCs) deposited on forged and additive manufactured (AM) HAYNES®282® (H282) superalloy substrates. The effect of different feedstock morphologies and spray gun designs with radial and axial injection on APS-deposited YSZ layer characteristics such as microstructure, porosity content, roughness, etc., has been investigated. The performance of TBCs in terms of thermal cycling fatigue (TCF) lifetime and erosion behaviour were also comprehensively investigated. In view of the high surface roughness of as-built AM surfaces compared to forged substrates, two different types of NiCoCrAlY bond coats were examined: one involved high-velocity air fuel (HVAF) spraying of a finer powder, and the other involved APS deposition of a coarser feedstock. Despite the process and feedstock differences, the above two routes yielded comparable bond coat surface roughness on both types of substrates. Variation in porosity level in the APS topcoat was observed when deposited using different YSZ feedstock powders employing axial or radial injection. However, the resultant TBCs on AM-derived substrates were observed to possess similar microstructures and functional properties as TBCs deposited on reference (forged) substrates for any given YSZ deposition process and feedstock.

Ni migration on porous yttria-stabilized zirconia and yttria-micropatterned fuel electrodes in solid oxide fuel cells

This study investigates the mechanism of Ni migration and methods for preventing Ni migration by utilizing ceramic obstacles that can block or slow Ni movement during solid oxide fuel cell (SOFC) operation. A patterned thin-Ni model anode on mirror-polished yttria-stabilized zirconia (YSZ) substrate exhibited dynamic movement during operation, as reported previously. In this study, we attempt to elucidate the mechanism of Ni migration that occurs only on the surface of solid-state Ni by blocking or slowing this movement using porous patterns of different materials. Porous micropatterns of 100 % YSZ and 80 wt% yttria (Y2O3) + YSZ composites were fabricated on a YSZ electrolyte, and velocity changes and blocking of Ni were observed. The porous YSZ structure changed the velocity of the Ni. In contrast, no Ni migration occurred in the Y2O3/YSZ composite porous structure, despite migration occurring in the neighboring smooth YSZ area in the same cell. The Ni-migrated areas were separated by the Y2O3/YSZ porous area, indicating that Ni migration was not caused by microscale differences in temperature or supplied gas diffusion, and Ni moved only on the cell surface, not via Ni-containing gases because temperatures and gases cannot form micropatterns.

Flexural Strength of Different Monolithic Computer-Assisted Design and Computer-Assisted Manufacturing Ceramic Materials Upon Accelerated Aging.

The durability of ceramic is crucial, which is probably influenced by aging. This study evaluated the effect of aging on flexural strength of different ceramics. One-hundred twenty ceramic discs (Ø 12 mm, 1.5 mm thickness) were prepared from zirconia-reinforced lithium silicate (ZLS, C), lithium disilicate (LS2, E), precolored yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP, Ip), and customized color Y-TZP (Ic). Samples were randomly divided into two groups for accelerated aging (A) between 5 and 55°C water baths, 30-second immersing time each, for 10,000 cycles, and nonaged group (N), serving as control. Biaxial flexural strength (σ) was evaluated utilizing the piston-on-three-balls at 0.5 mm/min speed. Analysis of variance and Tukey comparisons were determined for significant differences (α = 0.05). Weibull analysis was applied for survival probability, Weibull modulus (m), and characteristic strength (σo). Microstructures were evaluated with scanning electron microscopy and X-ray diffraction (XRD). The highest σ and σo were seen for IcN, followed by IcA, IpN, IpA, EN, CA, CN, and EA, respectively. CN showed the highest m, while EA showed the lowest m. Significant differences of σ for each ceramic were indicated (p < 0.05). Aging caused a significant difference in σ (p < 0.05). XRD showed t→m phase transformation of Ip and Ic after aging. Aging affected strength of ceramics. Comparable strength between LS2 and ZLS was evidenced, but both were less strength than Y-TZP either aging or non-aging. Comparable strength between precolored Y-TZP and customized color Y-TZP was indicated. Better resisting aging deterioration of Y-TZP than LS2 and ZLS is suggested for fabrication restorative reconstruction.

Ionic control of magnetism in all-solid-state CoOx/yttria-stabilized zirconia heterostructures

Magneto-ionic gating, a procedure that enables the modulation of materials' magnetic properties by voltage-driven ion motion, offers alternative perspectives for emerging low-power magnetic storage and spintronic applications. Most previous studies in all-solid-state magneto-ionic systems have focused on the control of interfacial magnetism of ultrathin (i.e., 1–3 nm) magnetic films, taking advantage of an adjacent ionic conducting oxide, usually GdOx or HfOx, that transports functional ionic species (e.g., H+ or O2−). Here, we report on room-temperature OFF–ON ferromagnetism by solid-state magneto-ionics in relatively thick (25 nm) patterned CoOx films grown on an yttria-stabilized zirconia (YSZ) layer, which acts as a dielectric to hold electric field and as an O2− ion reservoir. Upon negatively biasing, O2− ions from the CoOx tend to migrate toward the YSZ gate electrode, leading to the gradual generation of magnetization (i.e., OFF-to-ON switching of a ferromagnetic state). X-ray absorption and magnetic circular dichroism studies reveal subtle changes in the electronic/chemical characteristics, responsible for the induced magnetoelectric effects in such all-oxide heterostructures. Recovery of the initial (virtually non-magnetic) state is achieved by application of a positive voltage. The study may guide future development of all-solid-state low-power CMOS-compatible magneto-ionic devices.