Diffusion Of Oxygen Vacancies Research Articles

Modeling and characterization of low frequency noise in self-aligned top-gate coplanar IGZO thin-film transistors

Abstract A modified low-frequency noise (LFN) model was proposed to accurately estimate the quality of the gate dielectric in self-aligned top-gate (SA TG) coplanar structure indium–gallium–zinc oxide (IGZO) thin-film transistors (TFTs). The proposed LFN model was derived by modifying the conventional carrier number with correlated mobility fluctuation model considering the peculiar characteristics of SA TG coplanar IGZO TFTs such as the channel length reduction due to the diffusion of hydrogen atoms or oxygen vacancies from the source/drain to the channel, as well as the relatively large source/drain parasitic resistance. The proposed model was validated by demonstrating that the measured LFN values were in good agreement with the predicted values from the proposed model for all SA TG coplanar IGZO TFTs with SiO2 gate dielectrics deposited under different plasma-enhanced chemical vapor deposition (PECVD) power densities. The near-interface gate dielectric trap densities extracted from each TFT using the proposed LFN model revealed a clear increase as the PECVD power increased, which is considered a major cause of poor positive-bias-temperature-stress stability of the SA TG coplanar IGZO TFT with SiO2 gate dielectric deposited under high PECVD power conditions.

Oxygen plasma-assisted magnetron sputtering deposition of non-stoichiometric Y2O3 films: Influence of oxygen vacancies on etching resistance

Yttrium oxide (Y2O3) films are widely used to protect equipment in plasma etching, a crucial technique in semiconductor processing, due to their exceptional resistance to plasma etching. Since oxygen vacancy affects the performance of Y2O3 and may impact physical etching resistance, the internal relationship necessitates further investigation. In this article, Y2O3 films with varying oxygen vacancy concentrations are prepared by reactive magnetron sputtering with the assistance of oxygen plasma. The formation and development of oxygen vacancies in cubic Y2O3 films and their impact on the physical etching resistance were investigated. The experiment results indicate that the accumulation of oxygen vacancies causes non-stoichiometry and the etching rate is significantly reduced. Combined with density-functional theory, it is revealed that oxygen vacancy distorts the lattice, which increases covalent YO bonding and the formation energy of atoms. Moreover, the vacancy line defects resulting from diffusion and aggregation of oxygen vacancies exert a similar influence on the adjacent yttrium and oxygen layers. The enhancement of physical etching resistance is attributed to the strengthened internal YO bonds led by increasing oxygen vacancy concentration in the cubic Y2O3 films without inducing phase transition. The discovery enriches the understanding of how plasma interacts with Y2O3, and the etching mechanism.

The role of hydrogen on lead-induced localized corrosion of Alloy 690TT

The vital role of hydrogen on lead-induced localized corrosion of Alloy 690TT in the simulated secondary crevice chemistries of pressurized water reactor at 25 °C is investigated by using surface analysis techniques and calculations. Density functional theory (DFT) calculation reveals that there is a coupling effect between lead and hydrogen on inhibiting the kinetic diffusion of oxygen vacancies. Experimental results show that hydrogen causes the change of most easily-corroded location from the grain/carbide interface to the TiN/nucleus interface in the lead-induced corrosion process, which provides a new interpreting sight as for lead-induced stress corrosion cracking mode of nickel-based Alloys.

Praseodymium doped ceria: A new sight on coupled thermo-mechanical properties and oxygen vacancy diffusion via statistical moment approach

Applications of praseodymium doped ceria (PDC) in solid oxide fuel cells require a deep insight into the thermal expansion, stresses, and ionic conduction. Nonetheless, the investigation of thermo-mechanical properties and oxygen vacancy diffusion remains incomplete. Based on free Helmholtz energy, we formulate analytical expressions to directly connect thermal expansion coefficient, elastic moduli, oxygen vacancy–dopant binding and oxygen vacancy migration energies by employing statistical moment method (SMM). The SMM calculations capture the full anharmonicity of lattice thermal vibrations. Our analyses report the significant influences of temperature and dopant content on the thermal expansion coefficient, bulk and Young’s moduli, oxygen vacancy–dopant binding and oxygen vacancy migration energies, and ionic conductivity. The role of Pr dopant on the oxygen vacancy diffusion is fully described by combining the symmetric energy profiles related to blocking effect and asymmetric energy profiles generated from trapping effect. By switching van der Waals (vdW) forces on and off in the SMM calculations, we first show that the vdW forces cause a positive effect on the mechanical properties but reduce the thermal expansion and resist the oxygen vacancy diffusion. Our findings are discussed concerning the results from other calculations and experiments in the literature. The insights on the thermo-mechanical properties and oxygen vacancy diffusion for PDC crystal can be generalized and applied to other ceramic materials that are essential for solid state batteries.

Study on growth kinetics of passivation film of Ti-6Al-3Nb-2Zr-1Mo alloy Based on point defect model

This study aims to explore the passivation behavior and growth mechanism of the Ti-6Al-3Nb-2Zr-1Mo alloy in an oxygen-free environment, taking into account various film-forming potentials and solution pH levels in the process. The point defect model is employed to study the growth mechanism of the passivation film. A film-forming potential is selected within the stable passivation region for polarization, followed by conventional electrochemical tests, Localized Electrochemical Impedance Spectroscopy, X-ray photoelectron spectroscopy characterization, and Glow Discharge Optical Emission Spectrometry. Experimental findings indicate that the passivation film on the Ti-6Al-3Nb-2Zr-1Mo alloy surface demonstrates characteristics of an n-type semiconductor. Increasing the film-forming potential leads to a decrease in the donor point defect density. Meanwhile, elevating the pH of the solution decreases the oxygen vacancy diffusion coefficient from 7.8 × 1019 to 4.3 × 1019, thus improving the corrosion resistance of the passivation film.

Memristors with Monolayer Graphene Electrodes Grown Directly on Sapphire Wafers.

The development of the memristor has generated significant interest due to its non-volatility, simple structure, and low power consumption. Memristors based on graphene offer atomic monolayer thickness, flexibility, and uniformity and have attracted attention as a promising alternative to contemporary field-effect transistor (FET) technology in applications such as logic and memory devices, achieving higher integration density and lower power consumption. The use of graphene as electrodes in memristors could also increase robustness against degradation mechanisms, including oxygen vacancy diffusion to the electrode and unwanted metal ion diffusion. However, to realize this technological transformation, it is necessary to establish a scalable, robust, and cost-effective device fabrication process. Here we report the direct growth of high-quality monolayer graphene on sapphire wafers in a mass-producible, contamination-free, and transfer-free manner, using a commercially available metal-organic chemical vapor deposition (MOCVD) system. By taking advantage of this approach, graphene-electrode based memristors are developed, and all the processes used in the device fabrication incorporating graphene electrodes can be performed at wafer scale. The graphene electrode-based memristor demonstrates promising characteristics in terms of endurance, retention, and ON/OFF ratio. This work presents a possible and viable route to achieving robust graphene-based memristors in a commercially and technologically sustainable manner, paving the way for the realization of more powerful and compact integrated graphene electronics in the future.

Unveiling the Stability Mechanism of Oriented Ni-Rich Layered Oxides.

Single-crystal and polycrystalline structures are the two main structural forms of the Ni-rich layered cathode for lithium-ion batteries. The structural difference is closely related to the electrochemical performance and thermal stability, but its internal mechanism is unclear and is worthy of further exploration. In this study, both polycrystalline and single-crystal LiNi0.83Co0.12Mn0.05O2 cathodes were prepared by adjusting the calcination temperature and mechanical post-treatment, respectively. Systematic comparisons were made to assess the effects of different grain structures on the electrochemical performance and thermal stability. The study revealed the superior thermal stability of monocrystalline cathodes, attributing it to oxygen vacancies and phase transitions. From the perspective of grain boundaries, it was demonstrated that the diffusion of oxygen vacancies and the reduction of Ni in polycrystalline cathodes exhibit anisotropy. This research elucidates the origins of the superior thermal stability of monocrystalline cathodes in lithium-ion batteries, providing valuable insights into battery material design.

Regulation oxygen vacancy in Ba0.9La0.1Co0.7Fe0.2Nb0.1O3-δ cathode with improved hydration activity for proton ceramic fuel cells

Proton ceramic fuel cells (PCFCs) are gaining attention due to their high energy conversion efficiency. However, the development of PCFCs is hindered by the lack of efficient and robust cathode materials. This article proposes a solution by introducing certain cationic deficiency into the Ba0.9La0.1Co0.7Fe0.2Nb0.1O3-δ (BLCFN) cathode matrix, which results in abundance of oxygen vacancies as well as enhanced proton defects. Consequently, the catalytic activity and hydration activity of the BLCFN oxygen electrode are improved during the reduction reaction process. Specifically, the polarization impedance (Rp) of the (Ba0.9La0.1)0.95Co0.7Fe0.2Nb0.1O3-δ (BL95CFN) decreases by 20% compared to the pristine BLCFN, reaching 0.12 Ω·cm2 at 700 °C in air. The Rp of BL95CFN decreases by 12% in a steam environment of 20 vol%. This enhancement is attributed to the higher concentration of oxygen vacancies, which leads to an improved proton diffusion rate and hydration performance. The peak power density of the anode-supported BL95CFN | BZCYYb | BZCYYb-NiO single cell reaches 641 mW cm−2 at 700 °C, and the performance of this single cell remains stable for nearly 100 h. These findings highlight the vital role of adjusting oxygen vacancy and proton diffusion, providing a feasible strategy for improving the performance and stability of PCFC cathode materials.

Oxygen vacancy migration and impact on high voltage DC polarization in 0.8BaTiO3–0.2BiZn0.5Ti0.5O3

AbstractElectrical polarization and defect transport are examined in 0.8BaTiO3–0.2BiZn0.5Ti0.5O3, an attractive capacitor material for high power electronics. Oxygen vacancies are suggested to be the majority charge carrier at or below 250°C with a grain conduction hopping activation energy of 0.97 eV and 0.92 eV for thermally stimulated depolarization current (TSDC) and impedance spectroscopy measurements, respectively. At higher temperature, thermally generated electronic conduction with an activation energy of 1.6 eV is dominant. Significant oxygen vacancy concentration is indicated (up to ∼1%) due to cation vacancy formation (i.e., acceptor defects) from observed Bi (and likely Zn) volatility. Oxygen vacancy diffusivity is estimated to be 10−12.8 cm2/s at 250°C. Low diffusivity and high activation energies are indicative of significant defect interactions. Dipolar oxygen vacancy defects are also indicated, with an activation energy of 0.59 eV from TSDC measurements. The large oxygen vacancy content leads to a short lifetime during high voltage (30 kV/cm), high temperature (250°C) direct current (DC) electrical measurements.

Approaching the Ideal Linearity in Epitaxial Crystalline-Type Memristor by Controlling Filament Growth.

Brain-inspired neuromorphic computing has attracted widespread attention owing to its ability to perform parallel and energy-efficient computation. However, the synaptic weight of amorphous/polycrystalline oxide based memristor usually exhibits large nonlinear behavior with high asymmetry, which aggravates the complexity of peripheral circuit system. Controllable growth of conductive filaments is highly demanded for achieving the highly linear conductance modulation. However, the stochastic behavior of the filament growth in commonly used amorphous/polycrystalline oxide memristor makes it very challenging. Here, the epitaxially grown Hf0.5Zr0.5O2-based memristor with the linearity and symmetry approaching ideal case is reported. A layer of Cu nanoparticles is inserted into epitaxially grown Hf0.5Zr0.5O2 film to form the grain boundaries due to the breaking of the epitaxial growth. By combining with the local electric field enhancement, the growth of filament is confined in the grain boundaries due to the fact that the diffusion of oxygen vacancy in crystalline lattice is more difficult than that in the grain boundaries. Furthermore, the decimal operation and high-accuracy neural network are demonstrated by utilizing the highly linear and multi-level conductance modulation capacity. This method opens an avenue to control the filament growth for the application of resistance random access memory (RRAM) and neuromorphic computing.

Effect of Mn (as an acceptor) on the structural and electrical properties of non-stoichiometry Sodium Bismuth Titanate/NBT ceramics

The lead free Na0.5Bi0.5TiO3 (NBT) ceramic is proven as a potential piezoelectric candidate; however, non-stoichiometry NBT serves as an outstanding oxide-ion conductor proposed by (M. Li et al., Nature Materials 13 (2014) 31–35). According to this point here we have systematically report the structural and electrical properties of non-stoichiometry Na0.5Bi0.49TiO3/NB0.49T and B-site Mn3+ acceptor-modified NB0.49T system. Therefore, we are trying to prepare the nominal formula of Na0.5Bi0.49Ti1-xMnxO3; NB0.49T ceramic with 0.0≤x ≤ 0.05 by solid state reaction method. The bulk oxide ion conductivity gradually increases with respect to the doping concentration and the maximum value was obtained for x = 0.05 composition. This conductivity maximum is in good consistent with R. A. De Souza's oxygen vacancy diffusivity limit concept for perovskite systems (Advanced Functional Materials, 25 (2015)). On doping of 5mol% of Mn in the Ti-site/B-site NB0.49T system, it was observed that the oxygen-ion conduction inside the grain boundary increased considerably. Grain conductivity of NaBi0.49TiO3 at 500 °C is ∼3.0 ± 0.5 mS cm−1, which is approximately 122 % greater than that pure NBT compositions. Additionally, NB0.9T -exhibited a conductivity value of 4.7 mS/cm at 500 °C, which increases to 9.2 mS/cm on 5 mol% Mn-modification. The observed increase in conductivity was ascribed due to the electrostatic interactions between Mn–Ti or Mn–O bond. Therefore, our current findings on NB0.49T illustrates that present approach should be applicable to modify the system for SOFC application.

Strong Immunity to Drain-Induced Barrier Lowering in ALD-Grown Preferentially Oriented Indium Gallium Oxide Transistors.

Drain-induced barrier lowering (DIBL) is one of the most critical obstacles degrading the reliability of integrated circuits based on miniaturized transistors. Here, the effect of a crystallographic structure change in InGaO [indium gallium oxide (IGO)] thin-films on the DIBL was investigated. Preferentially oriented IGO (po-IGO) thin-film transistors (TFTs) have outstanding device performances with a field-effect mobility of 81.9 ± 1.3 cm2/(V s), a threshold voltage (VTH) of 0.07 ± 0.03 V, a subthreshold swing of 127 ± 2.0 mV/dec, and a current modulation ratio of (2.9 ± 0.2) × 1011. They also exhibit highly reliable electrical characteristics with a negligible VTH shift of +0.09 (-0.14) V under +2 (-2) MV/cm and 60 °C for 3600 s. More importantly, they reveal strong immunity to the DIBL of 17.5 ± 1.2 mV/V, while random polycrystalline In2O3 (rp-In2O3) and IGO (rp-IGO) TFTs show DIBL values of 197 ± 5.3 and 46.4 ± 1.2 mV/V, respectively. This is quite interesting because the rp- and po-IGO thin-films have the same cation composition ratio (In/Ga = 8:2). Given that the lateral diffusion of oxygen vacancies from the source/drain junction to the channel region via grain boundaries can reduce the effective length (Leff) of the oxide channel, this improved immunity could be attributed to suppressed lateral diffusion by preferential growth. In practice, the po-IGO TFTs have a longer Leff than the rp-In2O3 and -IGO TFTs even with the same patterned length. The effect of the crystallographic-structure-dependent Leff variation on the DIBL was corroborated by technological computer-aided design simulation. This work suggests that the atomic-layer-deposited po-IGO thin-film can be a promising candidate for next-generation electronic devices composed of the miniaturized oxide transistors.

Comprehensive understanding of charge and mass transport in BaZr0.1Ce0.7Y0.1Yb0.1O3−δ

This work reports transport properties of BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb1711), studied during oxidation/reduction and hydration/dehydration using electrical conductivity relaxation (ECR) measurements. The oxidation/reduction displayed typical monotonic conductivity relaxation behavior, attributed to the ambipolar diffusion of oxygen vacancies (Vo∙∙) and electron-holes (h∙), and oxygen surface exchange coefficient (k) were >1 order of magnitude higher than bulk diffusivities (D˜), indicating a diffusion-controlled process. Whereas, hydration/dehydration displayed a temperature-dependent gradual transition from monotonic to non-monotonic relaxation profile. At lower temperatures, transient defect concentration profile indicated that overall hydration/dehydration involved an acid-base-type reaction, comprising the diffusion of oxygen vacancy (Vo∙∙) and proton (Hi∙) couples. However, at higher temperatures and high [h∙], it involved a combination of a hydrogenation reaction (comprising component H via diffusion of h∙ and Hi∙ couple) and an oxidation reaction (involving component O via diffusion of h∙ and Vo∙∙ couple), thus giving rise to a two-fold non-monotonic relaxation profile. The k and D˜ values for oxygen vacancies (kVO∙∙; DVO∙∙) were lower than those for protons (kHi∙;DHi∙) with the respective Ea being 57.51 ± 3.14 and 60.72 ± 1.48 kJ∙mol−1 for oxygen-vacancies and 68.78 ± 12.65 and 71.05 ± 13.87 kJ∙mol−1 for protons.

Filament-based memristor switching model

The filaments rupture and recovery in oxide-type memristors have been theoretically studied. The model is based on the kinetics of oxygen vacancies and includes Joule heating of the oxide medium, which enhances the diffusion and drift of oxygen vacancies in an external electric field. The current-voltage characteristic of the model structure was obtained. Comparison with experimental results allowed for the determination of the constants used in the modeling. The peculiarity of the current-voltage characteristic observed in experimental works is explained.

Investigation of the passive film of nanocrystalline 304 stainless steel in 3.5 wt% NaCl solution under hydrostatic pressure

In this paper, the effect of hydrostatic pressure on the passive film of coarse crystalline 304 stainless steel (304 SS) and sputtered nanocrystalline stainless steel (304 NC) in 3.5 wt% NaCl solution has been investigated using in-situ electrochemical measurement techniques. The results indicate that nanosizing promotes the growth of the passive film. Hydrostatic pressure changes the nucleation mechanism of the passive film, decreases the carrier density and oxygen vacancy diffusivity, and decreases the content of oxides and hydroxides within the film, significantly deteriorating the corrosion resistance of the passive film. The point defect model (PDM) was introduced to elaborate the microscopic process of the surface passivation of stainless steel under hydrostatic pressure.

Achieving simultaneously low loss tangent and high resistivity in MgO modified Sr0.979Y0.014TiO3 colossal-permittivity ceramics via inhibiting the diffusion of oxygen vacancies

Colossal permittivity (CP, Ɛr) ceramics are highly desired for promising applications in modern electronic industry. However, actual applications of CP ceramics were seriously limited by large dielectric loss(tanδ), strong temperature/frequency/electric field dependence, and resistance degradation behavior. Here, we proposed a novel strategy to inhibit the diffusion of oxygen vacancies to obtain a CP Sr0.979Y0.014TiO3 (SYT14) ceramic with a combination of low tanδ and high insulation resistivity (ρ), by MgO addition, due to the formation of [MgTi″−VO••], [MgTi″−2YSr•] and highly insulated phase at the grain boundary. SYT14-7M (x = 0.7 wt% MgO) ceramic has excellent comprehensive properties, such as, Ɛr is 28156, tanδ is 0.0136, and ρ is 7.02 × 1011 Ω•cm. The phenomenon of “resistance oscillation” reflects the active degree of oxygen vacancy diffusion behavior. The highly insulated phase forming at the grain boundary can significantly inhibit oxygen vacancy diffusion and electron migration. The temperature range related to active oxygen vacancy diffusion is between 400 and 500 °C.

Thermal activation energy on electrical degradation process in BaTiO3 based multilayer ceramic capacitors for lifetime reliability

For a high capacitance and high lifetime reliability of multilayer ceramic capacitors for automotive applications, the activation energy on thermal activation process can typically be calculated by using Arrhenius based Prokopowicz–Vaskas equation as a method for lifetime prediction. In this study, it is clearly observed that the activation energy shows to be constant in the range of ~ 1.5 eV for the prototype MLCCs, higher than the activation energy values of ~ 1.0 eV related to the motion or diffusion of oxygen vacancies reported in the previous literature. The activation energy value of ~ 1.5 eV for three prototype MLCCs is close to a half the energy band gap (Eg/2 ≈ 1.6 eV) of BaTiO3 obtained from specific environment, where oxygen vacancies are stabilized by external containment such as the effect of rare earth oxide additives. Due to an obvious difference in activation energy values, it difficult to explain the conduction mechanism for failure by only oxygen vacancy migration. Therefore, the concepts of electronic processes and oxygen vacancy should be considered together to understand conduction mechanism for failure of BaTiO3-based MLCCs in thermal activation processes. It can be useful as an indicator for future MLCC development with high lifetime reliability.

(Invited) Oxide Ion Conductivity and Oxide Vacancy Diffusion Coefficient of Stabilized ZrO2 and Doped CeO2 Discussed Based on Classical Defect Chemistry with Particular Focus on Valence State (2+, 3+, and 4+) of Doped Cations

So far tremendous works have been reported on the oxide-ion conductivity of fluorite-type oxides typically stabilized zirconia and doped ceria. It is well known that the oxide-ion conductivity vs. dopant concentration plot shows maximum around 10 mol percent dopant concentration and the maximum conductivity varies with the dopant species. Interests tend to be focused on the higher and the stabler conductivity. For the aim, explorations are made on the dopant survey and the phase stability of the solid solution.Generally, conductivity is considered proportional to the product of carrier concentration and carrier mobility. For the fluorite-type oxide ion conductors, it is considered that carrier is oxygen vacancy, V O ··, and mobility is proportional to oxygen vacancy diffusion coefficient, DV . However, such defect chemical approach to the fluorite-type oxides is not popular. When we assume that the mobility is constant following the classical hypothesis, we cannot explain the conductivity maximum.The author has been trying to discuss the oxide-ion conduction in fluorite-type oxide solid solutions in terms of oxygen vacancy concentration, cV ,and DV .Using the literature data on conductivity and composition relationship, the author has already calculated DV for some compositions of stabilized zirconia and doped ceria as a function of composition. The data have been published in a short review [1] and books [2,3]. However, the published graphical displays were so crowded that the physical meanings seem still unclear.In this presentation, discussion is made on the conductivity of stabilized zirconia and doped ceria in the following order to make clear the characteristic feature of DV with the variation of valence state and chemical species of dopant oxides.1: zirconia base solid solutions 1a: with divalent cation oxides 1b: with trivalent cation oxides2: ceria base solid solutions 2a: with divalent cation oxides 2b: with trivalent cation oxides3: stabilized zirconia – ceria solid solutions 3a: stabilized zirconia base solid compositions 3b: ceria base solid compositions 3c: trivalent cerium formation by partial reductionIt is clarified that DV of fluorite type oxide is affected by the dopant cation not only by different valent but also by the same valent cations.

High-speed mapping of surface charge dynamics using sparse scanning Kelvin probe force microscopy

Unraveling local dynamic charge processes is vital for progress in diverse fields, from microelectronics to energy storage. This relies on the ability to map charge carrier motion across multiple length- and timescales and understanding how these processes interact with the inherent material heterogeneities. Towards addressing this challenge, we introduce high-speed sparse scanning Kelvin probe force microscopy, which combines sparse scanning and image reconstruction. This approach is shown to enable sub-second imaging (>3 frames per second) of nanoscale charge dynamics, representing several orders of magnitude improvement over traditional Kelvin probe force microscopy imaging rates. Bridging this improved spatiotemporal resolution with macroscale device measurements, we successfully visualize electrochemically mediated diffusion of mobile surface ions on a LaAlO3/SrTiO3 planar device. Such processes are known to impact band-alignment and charge-transfer dynamics at these heterointerfaces. Furthermore, we monitor the diffusion of oxygen vacancies at the single grain level in polycrystalline TiO2. Through temperature-dependent measurements, we identify a charge diffusion activation energy of 0.18 eV, in good agreement with previously reported values and confirmed by DFT calculations. Together, these findings highlight the effectiveness and versatility of our method in understanding ionic charge carrier motion in microelectronics or nanoscale material systems.

Oxygen vacancy diffusion and dynamics in Gd-doped CeO2: A GGA+U study

Using a generalized gradient approximation + Hubbard U method in the framework of density functional theory, we investigate the oxygen vacancy (VO) diffusion and dynamics in 3 × 3 × 3 CeO2 supercells with two Gd substitutions for Ce and an oxygen vacancy. Results show that (i) VO always migrates along the <100> direction, and (ii) VO would rather migrate across the Ce–Ce edges than across Ce–Gd or Gd–Gd edges. Especially, Gd only positively influences the migrations of oxygen vacancies within the third nearest neighbor, indicating that the increased Gd doping is required for extending the positive influence to the long-distance diffusion of oxygen vacancy, which offers an accountable explanation for the enhanced ion conduction experimentally observed in CeO2 with high Gd doping. The negative influence of heavy Gd doping on the VO diffusion is also discussed in detail. The outcome of the current work has implications in illuminating the role of dopants toward expediting the oxygen vacancy diffusion and in promoting the performance in CeO2-based materials and devices for environmentally friendly applications.