Zinc Adsorption and Hydration Structures at Yttria-Stabilized Zirconia

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Zinc Adsorption and Hydration Structures at Yttria-Stabilized Zirconia Surfaces Binyang Hou, Taeho Kim, Seunghyun Kim, Changyong Park, Chi Bum Bahn, Jongjin Kim, Seungbum Hong, and Ji Hyun Kim J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.7b02907 • Publication Date (Web): 11 Sep 2017 Downloaded from http://pubs.acs.org on September 14, 2017

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The Journal of Physical Chemistry

Zinc Adsorption and Hydration Structures at YttriaStabilized Zirconia Surfaces Binyang Hou†, $,*, ❊, Taeho Kim‡, ❊, Seunghyun Kim‡, Changyong Park†, Chi Bum Bahn§, Jongjin Kim∥, Seungbum Hong∥, ⊥, and Ji Hyun Kim‡,*

†

High Pressure Collaborative Access Team, Geophysical Laboratory, Carnegie Institution of

Washington, Argonne, IL 60439, United States ‡

Department of Nuclear Science and Engineering, School of Mechanical and Nuclear

Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea §

School of Mechanical Engineering, Pusan National University, Busan 46241, South Korea

∥Materials

Science Division, Argonne National Laboratory, Argonne, IL 60439, USA

⊥Department

of Materials Science and Engineering, KAIST, Daejeon 34141, South Korea

ACS Paragon Plus Environment

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ABSTRACT: Zinc adsorption and interfacial hydration on yttria-stabilized zirconia (YSZ) surfaces in contact with aqueous zinc solutions at room temperature and neutral pH have been probed with combined specular high-resolution X-ray reflectivity and element specific (Zn) resonant anomalous X-ray reflectivity techniques. The total and partial zinc-specific electron density profiles in the surface normal direction show the detailed interfacial hydration structures with zinc adsorption. Strongly depending on its crystallographic orientations, the YSZ (110) surface adsorbs zinc species only within adsorbed water layers above the terminal plane, while on (111) surface, zinc further penetrates into the substrate (below the terminal plane). Considering that both surfaces are enriched with oxygen vacancies and metal-depleted sites, on which chemisorbed water species are expected, the observed contrast indicates that specific zinc adsorption is controlled strongly by the intrinsic surface chemistry that resulted from orientationdependent interfacial structures.


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INTRODUCTION Zirconia, ZrO2, is an important material as found in numerous applications, e.g. gas sensor,1 solid oxide fuel cell electrolyte,2 and bio-medical materials.3 The oxide also serves as the passivation layer in protecting the zirconium claddings that enclose the nuclear fuel pellets in pressurized water reactor.4 Although known as an exceptionally stable material, it is still susceptible to water and the degradation takes place gradually over long term, especially under high temperature and/or high pressure.5 Therefore, mitigation of the oxide degradation is of ultimate important for its long-term service and operational safety concerns. Zinc injection in nuclear power plants has been known as an effective way for corrosion mitigation of the structural materials, such as nickel and stainless steel alloys.6-7 Its mechanism is attributed to the effect of Zn2+ inclusion that changes the morphology and composition of the oxide, which thereby stabilizes the oxide thin films.7 The effect of zinc addition on the degradation of zirconia, however, has been rarely studied. Choi et al. reported the chemical constituents of the deposit on Zr-alloy cladding surface after its exposure to Zn2+, and proposed a possible mechanism that Zn2+ substituting nickel species in the oxide deposit layer that stabilizes the oxide structure and slows down its growth.8 However, due to the lack of experimental resolution in their study, a molecular insight into the zinc adsorption on zirconia surface has not yet been reported. With synchrotron based high-resolution X-ray reflectivity (HRXR), we have previously studied the detailed interfacial hydration structures of the 8 mol% yttria-stabilized cubic zirconia (YSZ) in (100), (110), and (111) orientations with sub-Ångström resolution and revealed the orientation-dependent water interaction with the oxide surfaces.9-10 In this work, we study the effect of zinc adsorption on the interfacial hydration structures at room temperature and around


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neutral pH. With element-specific resonant anomalous X-ray reflectivity (RAXR), zinc’s partial electron density profiles are obtained from both model-dependent11 and model-independent12 analysis of the RAXR spectra along with the total hydration structures experimentally determined from HRXRs. Our results clearly show orientation-dependent zinc adsorption behaviors on the major crystalline surfaces of YSZ, which indicate that the zinc adsorption is predominately controlled by the orientation-dependent surface chemistry.

EXPERIMENTAL SECTION Materials. The single crystal yttria-stabilized zirconia or YSZ substrates (8 mol% Y2O3stabilized ZrO2) were purchased from MTI Corporation in the dimension of 10×10×1.0 mm3 for the (100) and (111) orientations, and 10×10×0.5 mm3 for the (110) orientation. Chemical compositions of the substrates and their d-spacings and unit cell structures along each orientation are described in details elsewhere.9-10 Zinc Acetate Dihydrate (Zn(CH3COO)2·2H2O, 99.999%, trace metal basis) was purchased from Sigma-Aldrich and used as received. The salt was dissolved into de-ionized water (DIW) to make the 10 mM zinc acetate solution with measured pH = 6.95 ± 0.01 at room temperature. Under this condition, the average number of acetate ligand to form a Zn-acetate complex in the solution is less than 0.3,13 and Zn2+ is the most stable aqueous species.14 X-ray reflectivity measurements. The HRXR measurements for the YSZ (100), (110), and (111) in contact with 10 mM zinc acetate solution were carried out at beamline 9C of Pohang Light Source (PLS) at Pohang Accelerator Laboratory (PAL). The X-ray energy was 15.000 keV. Preparations of samples, beamline configuration, and data acquisition and reduction


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procedure for the HRXR measurements are described in details elsewhere.9-10 The Zn-RAXR spectra near Zn K-adsorption edge (9.660 keV) for the YSZ (110) and (111) in contact with 10 mM zinc acetate solution were measured at beamline 6-ID-B of the Advanced Photon Source, Argonne National Laboratory. The measured reflectivity intensities were normalized by incident beam flux. The errors were propagated from the counting statistics. ANALYSIS AND RESULTS High-Resolution X-ray Reflectivity. The measured HRXR intensities (red dots with errors) and the best-fit results (red lines) from the YSZ (100)-, (110)-, and (111)-water interfaces with zinc acetate as a function of momentum transfer, Qz = (4π/λ)sinθ, are presented in Figs. 1a, 1b, and 1c, respectively, where λ is the wavelength of the incident X-ray and θ is the incident angle of the beam with respect to the substrate surface. The data analysis and fitting procedure have been reported in details in our previous work.9-10 The measured HRXR intensities (black dots with errors) and the best-fit results (black lines) from the three surfaces in contact with pure water9-10

Figure 1. HRXR data (circles with errors) and the best-fit results (solid lines) for YSZ a) (100), b) (110), and c) (111) in contact with water (black)9-10 and with 10 mM Zinc acetate solution (red).


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were also re-plotted in Figs. 1 to see the effect of zinc injection in modifying the interfacial hydration structures. The HRXR probes the total electron density profile in the surface normal direction and is sensitive to the interfacial structure change within a few nanometers nearby the substrate-water interface.15-16 In Figs. 1a) and 1c), changes in X-ray reflectivity are apparent on (100) and (111)-water interfaces when the de-ionized water is replaced by zinc acetate solution (pH = 6.95 ± 0.01). On the other hand, the X-ray reflectivity change was not as distinct on (110) surface (Fig. 1b) when the water is replaced by zinc acetate solution. Nevertheless, there is still noticeable change in the lower momentum transfer region of the X-ray reflectivity. These measurements were performed in sequence with samples covered by deionized water first and zinc-acetate solution replacing it later. This operation allows direct comparison between the two conditions without encountering sample-to-sample variation. As HRXR is a surface sensitive technique,15-16 these observations clearly show that there are significant changes in the interfacial hydration structures of YSZ surfaces by replacing the de-ionized water with zinc acetate solution. Resonant Anomalous X-ray Reflectivity. To resolve the positions of zinc species at the YSZsolution interfaces and investigate how the adsorbed zinc species are involved in altering the interfacial hydration structure, the Zn-specific RAXR spectra were measured for the YSZ (110) and (111) orientations near the zinc K-edge, 9.660 keV. The X-ray intensities resonate around the absorption edge of zinc, originating from the energy (E) dependent structure factor at a fixed momentum transfer (qo), |F(qo, E)|2. Normalized by the non-resonant structure factor, |F(qo)|2, the RAXR signals are shown in Fig. 2 for both orientations. The RAXR spectra for both YSZ (110) and (111) in contact with 10 mM zinc acetate solution show amplitude variation and phase flipping as a function of momentum transfer, which clarifies the existence of adsorbed zinc


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species, Zn2+, at the interfaces. Considering the subtle changes in the non-resonant HRXR spectra for YSZ (110) surface (Fig. 1b), the clear zinc signals in the RAXR spectra (Fig. 2a) are remarkable, demonstrating the efficacy of the method in probing a hidden element-specific subprofile otherwise indistinguishable from the total profile obtained by the HRXR measurement alone.11 The RAXR amplitude is proportional to the total coverage of adsorbate, therefore the profound signals from YSZ (111) surface compared to the weak signals from YSZ (110) surface semi-quantitatively indicates the different affinity of zinc on each surface at the given solution condition of 10 mM zinc acetate concentration at pH 6.95 ± 0.01. Since the model dependent fit to the data is nearly identical to the model independent fit, here we only present the model independent fit result to avoid the redundancy.

Figure 2. RAXR data (circles with errors) and the model-independent best-fit results (red solid lines) from a) YSZ (110) and b) YSZ (111) surfaces in contact with 10 mM zinc acetate solution. The intensities at each fixed qo are shifted for clarity.


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Figure 3. Electron density profiles derived from the best-fits to the HRXRs for YSZ in contact with water (black)9-10 and with 10 mM zinc acetate solution (red dash); and zinc partial density profiles derived from the model-independent (M.I.) (blue dashed lines) and model-dependent (M.D.) (green dashed lines) analysis to the RAXR spectra at a) the (100), b) the (110), and c) the (111) surfaces. Light blue arrows indicate the Zn2+ adsorbed layers, and yellow arrows indicate the atomic compositions in the top unit cell layers of the substrate oxide without accounting the vacancy-filling water. 9-10

Figure 4. The resonant anomalous dispersion terms, f’(E) and f”(E), for the interfacial zinc species at YSZ surfaces that are obtained from the model-independent fits to the RAXR spectra from YSZ (111) surface in contact with 10 mM zinc acetate solution.


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Zinc Partial Profiles. The zinc partial density profiles (Fig. 3 blue dashed lines) on YSZ (110) and (111) surfaces in contact with 10 mM zinc acetate solution were initially determined from the model-independent fits12 to the measured RAXR spectra (Fig. 2). The anomalous dispersion terms of the adsorbed zinc species were estimated from the model-independent best fits to the RAXR spectra on (111) surface (Fig. 4). The obtained resonant terms were then used for the model-independent fitting to the RAXR spectra measured on (110) surface. The zinc partial density profiles were refined by the model-dependent fits11 using the anomalous resonant terms determined in Fig. 4. For each i-th adsorption layer of zinc species, three parameters are used: position (zi), occupancy per unit cell area (ρi), and distribution width (σi) assuming a Gaussian distribution for each layer. The terminal plane of the substrate (a hypothetical crystal plane as truncated) is defined as z = 0 (Figure 3). The adsorbed zinc layers on the (110) surface are described by the following parameters: z1 = 1.740 ± 0.003 Å, ρ1 = 0.174 ± 0.002, and σ1 = 0.150 ± 0.010 Å; z2 = 3.525 ± 0.011 Å, ρ2 = 0.133 ± 0.004, and σ2 = 0.438 ± 0.016 Å; and z3 = 5.372 ± 0.014 Å, ρ3 = 0.278 ± 0.004, and σ3 = 0.748 ± 0.012 Å. The adsorbed zinc layers on the (111) surface are described by the following parameters: z1 = -0.592 ± 0.006 Å, ρ1 = 0.270 ± 0.008, and σ1 = 0.150 ± 0.020 Å; z2 = 2.168 ± 0.005 Å, ρ2 = 0.676 ± 0.005, and σ2 = 0.376 ± 0.006 Å; and z3 = 4.863 ± 0.012 Å, ρ3 = 0.749 ± 0.012, and σ3 = 0.882 ± 0.012 Å. The zinc partial electron density profiles from these model-dependent analyses of the RAXR spectra are shown in green dashed lines in Fig. 3b) and 3c). The model-dependent and model-independent results agree well each other in terms of layer positions and coverage. The rest of the parameters from modeldependent fit to all three YSZ orientations and zinc acetate solution interfaces follow the same definitions as our previous studies9-10 and are nearly identical to the YSZ-water interfaces except for those ad-layers partially replaced by the zinc. The complete parameters are listed in Table 1.


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Model Dependent Best-fit Results with Errors Parameters (100)* Scale factor (S)

(110)

9.691e6 ± 2.25e5 3.455e6 ± 1.48e5

(111) 9.589e6 ± 2.23e5

Statistical Distribution Roughness (σR, Å)

0.866 ± 0.102

0.689 ± 0.088

1.1280 ± 0.059

Top UC Lattice Constant (a1, Å)

2.478 ± 0.012

1.802 ± 0.004

2.847 ± 0.149

2nd UC Lattice Constant (a2, Å)

2.563 ± 0.015

1.812 ± 0.005

2.951 ± 0.003

3rd UC Lattice Constant (a3, Å)

2.579 ± 0.023

1.831 ± 0.002

2.981 ± 0.004

4th UC Lattice Constant (a4, Å)

2.570 ± 0.002

1.822 ± 0.004

2.979 ± 0.003

5th UC Lattice Constant (a5, Å)

2.572 ± 0.002

1.819 ± 0.002

2.980 ± 0.002

2.576

1.821

2.981

Top UC Metal Fractional Depletion (y1)

0.4750 ± 0.031

0.121 ± 0.024

0.586 ± 0.047

2nd UC Metal Fractional Depletion (y2)

0.327 ± 0.013

0.062 ± 0.018

0.127 ± 0.037

3rd UC Metal Fractional Depletion (y3)

0.052 ± 0.011

Negligible

0.016 ± 0.006

4th UC Metal Fractional Depletion (y4)

0.007 ± 0.008

Negligible

0.005 ± 0.002

Position of Vacancy-filling H2O (z0, Å)

-1.383 ± 0.072

0.049 ± 0.028

-0.806 ± 0.221

1st Adsorbed Layer Position (za1, Å)

0.549 ± 0.032

1.713 ± 0.034

1.097 ± 0.102

1 Adsorbed Layer Metal Occupancy (N1)

0.733 ± 0.027

0.123 ± 0.012

1.713 ± 0.091

1st Adsorbed Layer Pos. Distr. Wdt. (σa1, Å)

0.739 ± 0.022

0.295 ± 0.021

0.493 ± 0.042

2nd Adsorbed Layer Position (za2, Å)

2.427 ± 0.017

3.428 ± 0.049

3.095 ± 0.205

2nd Adsorbed Layer Occupancy (N2)

2.175 ± 0.120

1.132 ± 0.122

4.076 ± 0.766

2nd Adsorbed Layer Pos. Distr. Wdt. (σa2, Å)

0.316 ± 0.027

0.422 ± 0.012

0.340 ± 0.083

1st Bulk H2O Layer Position (z0, B, Å)

5.892 ± 0.105

5.259 ± 0.335

6.579 ± 0.165

1 Bulk H2O Layer Displacement (σ0, B, Å)

1.132 ± 0.109

1.139 ± 0.089

0.271 ± 0.039

1st Bulk H2O Layer Vibrational Ampl. (σavg.,B, Å)

0.822 ± 0.098

1.459 ± 0.217

0.224 ± 0.016

1.740 ± 0.003

-0.592 ± 0.006

0.174 ± 0.002

0.270 ± 0.008

1stAdsorbed Zn2+ Layer Pos. Distr. Wdt. (σ1, Å)

0.150 ± 0.010

0.150 ± 0.020

2nd Adsorbed Zn2+ Layer Position (z2, Å)

3.525 ± 0.011

2.168 ± 0.005

Bulk Lattice Constant (a0, Å)

st

st

1stAdsorbed Zn2+ Layer Position (z1, Å) 1stAdsorbed Zn2+ Layer Occupancy (ρ1, Å)

Negligible


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2nd Adsorbed Zn2+ Layer Occupancy (ρ2, Å)

Negligible

2nd Adsorbed Zn2+ Layer Pos. Distr. Wdt. (σ2, Å)

0.133 ± 0.004

0.676 ± 0.005

0.438 ± 0.016

0.376 ± 0.006

3rd Adsorbed Zn2+ Layer Position (z3, Å)

4.390 ± 0.022

5.372 ± 0.014

4.863 ± 0.012

3rd Adsorbed Zn2+ Layer Occupancy (ρ3, Å)

0.257 ± 0.018

0.278 ± 0.004

0.749 ± 0.012

3rd Adsorbed Zn2+ Layer Pos. Distr. Wdt. (σ3, Å)

0.366 ± 0.024

0.748 ± 0.012

0.882 ± 0.012

Table 1. Fitting Parameters Derived from the Model-Dependent Best-Fit Result for YSZ-10 mM Zinc Acetate Solution Interfaces. *Fitting Parameters for (100) Surface Are from HRXR Data only, the Exact Position and Coverage of Zn2+ Need to be Determined from RAXR Data.

DISCUSSION From the quantitative analysis of the RAXRs for (110) and (111) orientations, it is clear that there exist multiple layers of adsorbed zinc species on each surface (Figs. 3b and 3c), although the exact speciation for each layer remains yet to be studied. Our observation is apparently similar to the electrostatically driven formation of multiple layers of Zn2+ adsorption near the surface of muscovite (001),17 but it could have also been caused by a different mechanism. The point of zero charge (PZC) of powder averaged 8 mol% YSZ is known to be near pH=7-9,18 which can cause slightly positive-charged or neutral surface at pH=7, and Zn2+ adsorption will bias the surface charge towards positive. Therefore, we cannot rule out the possibility of coadsorption of acetate counter-ion in this region, which may contribute the total electron density profile.

From the sub-profiles of these adsorbed zinc layers, the (110) surface shows inner-sphere (IS), outer-sphere (OS), and “extended” outer-sphere (EOS) profiles, borrowing the terminologies from Lee et al.,17 which all stay above the terminal plane (z = 0). These layers seem to simply replace the original hydration layers by a small fraction of the total atomic occupancy, i.e., Zn2+ replaces some amount of metal species in the first ad-layer9-10 as well as replacing the adsorbed


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water (as IS adsorption) and some water in the adsorbed water layer (as OS adsorption) and first bulk water layer (as EOS adsorption). On the other hand, the (111) surface shows quite distinct behavior in the zinc layer distribution, which includes not only the inner-sphere and outer-sphere adsorbed layers above the terminal plane, but also a penetrating layer underneath it into the oxide substrate. There are plenty of vacancy sites within the top surface layer, which can adapt a whole water molecule (physisorbed) or adsorb as dissociated form (chemisorbed), near the termination plane as discussed in our previous studies9-10. The penetrating zinc species we observed here likely replaces the vacancy-filling water at the defective sites caused by the metal depletion. The spacing between the zinc layers on the (111) surface is also larger than that on the (110) surface (indicated in Fig. 3 and implied by the parameters in Zinc Partial Profiles section). This is, however, consistent with their regular d-spacing in the substrate (d-spacing along (111) surface is larger than that along (110) surface). Due to the fact that zirconium atoms are surrounded by eight oxygen atoms in the crystal, the observed consistency of some of the adsorbed zinc layers to the original lattice metal layer can be attributed to mimicking the zirconium atom by a zinc species with eight-fold oxygen coordination. However, this has a consequence that the Zn-speciation must be layer-by-layer different because hydration coordination of Zn2+ is normally known as six-fold (i.e. Zn(H2O)62+)19 or less in aqueous solution (hence likely existing in the OS and EOS layers) and an eight-coordinated zinc is observed only in a very limited case of solid compound.20 Therefore, coordination chemistry of the adsorbed zinc layers, especially the penetrating Zn species on (111) surface (Fig. 3c), remains controversial and needs further study. Regardless of the unknown speciation, the current result of Zn-RAXR is consistent with the previous HRXR result that was best described with existence of substantial metal-depletion vacancies, and the


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accompanying oxygen vacancies induced by the metal-depletion, in addition to the intrinsic oxygen vacancies for all three surfaces,10 where the pre-existing vacancy-filling waters can be exchanged with the Zn-species. Both HRXR and Zn-RAXR results point to a conclusion that the systematic spacing of the adsorbed zinc layers, especially the IS species on (110) surface and the penetrating Zn and IS species (111) surface, respectively, might be attributed to the d-spacing of the crystalline substrates and the influence of solid state chemistry on the local coordination geometry. Another consequence from the different surface chemistry between the two surfaces of YSZ is that the zinc adsorption on the (111) surface changes the water network more significantly so that the total layering features become qualitatively different from the pristine hydration structures. For example, the spacing between the 2nd adsorbed water and 1st bulk water layer becomes smaller with zinc adsorption. This change is likely attributed to the complicate nearsurface interactions that would determine the interfacial structure.21 However, the adsorption of the Zn2+ (hydration) ions may change the surface charge and re-orientate the water molecules also, therefore change the interfacial hydration dramatically. The (100) surface, although merely indicative from the total electron density profile, is also likely experiencing a significant modification of the original hydration structure by the zinc adsorption. It is worthy to mention that both (100) and (111) surfaces are terminated with oxygen atoms only, while the (110) surface is terminated with both metal and oxygen atoms (indicated by yellow arrows in Fig. 3).910, 21-22

The effect of local coordination geometry of the solid substrate seems to have an impact

on the hydration structure (water network) nearby the terminal planes. The changes of the interfacial structure on all three surfaces are, however, limited within a range less than ~15 Å (shown in Figure 3).


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CONCLUSION In conclusion, considering the similar aspects of surface defects, i.e., the depleted metal vacancies near the terminal planes,9-10 these zinc adsorption behaviors and the modification of the original hydration structure are rather distinct and they are predominantly determined by the orientation-dependent surface chemistry. Our results clearly show the presence of multiple layers of adsorbed zinc species at the interface and their influences on the modification of the interfacial hydration structures.

ASSOCIATED CONTENT AUTHOR INFORMATION Corresponding Authors *E-mail: [email protected] (B.H.). *E-mail: [email protected] (J.H.K.). $

Current Address: Department of Chemistry and Physical Science, School of Natural and Social

Sciences, Mount Vernon Nazarene University, Mount Vernon, OH 43050, USA

Author Contributions


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The manuscript was written through the contributions of all authors. All authors have given approval to the final version of the manuscript. ❊These authors contributed equally.

Notes Authors declare no competing financial interest. ACKNOWLEDGMENTS This work was financially supported from the International Collaborative Energy Technology R&D Program (No.20138530030010) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted from the Ministry of Trade Industry and Energy. BH and CP acknowledge support from High Pressure Collaborative Access Team (HPCAT), supported by DOE-NNSA under Award No. DE-NA0001974 and DOE-BES under Award No. DE-FG0299ER45775. Authors acknowledge the use of beamtime at beamlines 9C of PLS and 6-ID-B of the Advanced Photon Source (APS). The Advanced Photon Source is a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Authors thank Curtis Kenney-Benson at HPCAT, Drs. Su Yong Lee and Yongsam Kim at beamline 9C of PLS, and Jong-woo Kim and Philip Ryan at 6-ID-B of APS for their technical support.

ABBREVIATIONS YSZ, yttria-stabilized zirconia; HRXR, high-resolution X-ray reflectivity; CTR, crystal truncation rod; RAXR, anomalous resonant X-ray reflectivity


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1. Maskell, W. C., Progress in the Development of Zirconia Gas Sensors. Solid State Ionics 2000, 134, 43-50. 2. He, X. D.; Meng, B.; Sun, Y.; Liu, B. C.; Li, M. W., Electron Beam Physical Vapor Deposition of Ysz Electrolyte Coatings for Sofcs. Applied Surface Science 2008, 254, 71597164. 3. Le Coadou, C.; Karst, N.; Emieux, F.; Sicardy, O.; Montani, A.; Bernard-Granger, G.; Chevalier, J.; Gremillard, L.; Simonato, J. P., Assessment of Ultrathin Yttria-Stabilized Zirconia Foils for Biomedical Applications. J. Mater. Sci. 2015, 50, 6197. 4. Rickover, H. G.; Geiger, L. D.; Lustman, B., History of the Development of Zirconium Alloys for Use in Nuclear Reactors; Tid--26740, 1975. 5. Arthur T. Motta, A. C., and Robert J. Comstock, Corrosion of Zirconium Alloys Used for Nuclear Fuel Cladding. Annual Review of Materials Research 2015, 45. 6. Lin, C. C., A Review of Corrosion Product Transport and Radiation Field Buildup in Boiling Water Reactors. Progress in Nuclear Energy 2009, 51, 207-224. 7. Chajduk, E.; Bojanowska-Czajka, A., Corrosion Mitigation in Coolant Systems in Nuclear Power Plants. Progress in Nuclear Energy 2016, 88, 1-9. 8. Choi, J.-S.; Park, S.-C.; Park, K.-R.; Yang, H.-Y.; Yang, O.-B., Effect of Zinc Injection on the Corrosion Products in Nuclear Fuel Assembly. Natural Science 2013, 5, 173-181. 9. Hou, B.; Kim, S.; Kim, T.; Kim, J.; Hong, S.; Bahn, C. B.; Park, C.; Kim, J. H., The Hydration Structure at Yttria-Stabilized Cubic Zirconia (110)-Water Interface with SubÅngström Resolution. Scientific Reports 2016, 6, 27916. 10. Hou, B.; Kim, S.; Kim, T.; Park, C.; Bahn, C. B.; Kim, J.; Hong, S.; Lee, S. Y.; Kim, J. H., Orientation-Dependent Hydration Structures at Yttria-Stabilized Cubic Zirconia Surfaces. The Journal of Physical Chemistry C 2016, 120, 29089-29097. 11. Park, C.; Fenter, P. A.; Sturchio, N. C.; Regalbuto, J. R., Probing Outer-Sphere Adsorption of Aqueous Metal Complexes at the Oxide-Water Interface with Resonant Anomalous X-Ray Reflectivity. Phys. Rev. Lett. 2005, 94, 4. 12. Park, C.; Fenter, P. A., Phasing of Resonant Anomalous X-Ray Reflectivity Spectra and Direct Fourier Synthesis of Element-Specific Partial Structures at Buried Interfaces. J. Appl. Crystallogr. 2007, 40, 290-301. 13. Kolat, R.; Powell, J., Acetate Complexes of the Rare Earth and Several Transition Metal Ions. Inorg. Chem. 1962, 1, 293-296. 14. Reichle, R. A.; McCurdy, K. G.; Hepler, L. G., Zinc Hydroxide: Solubility Product and Hydroxy-Complex Stability Constants from 12.5–75 C. Canadian Journal of Chemistry 1975, 53, 3841-3845. 15. Fenter, P. A., X-Ray Reflectivity as a Probe of Mineral-Fluid Interfaces: A User Guide. In Application of Synchrotron Radiation in Low-Temperature Geochemistry and Environmental Science, Fenter, P. A.; Rivers, M. L.; Sturchio, N. C.; Sutton, S. R., Eds. Geochemical Society and Mineralogical Society of America: Washington, 2002; pp 149-220. 16. Fenter, P.; Sturchio, N. C., Mineral-Water Interfacial Structures Revealed by Synchrotron X-Ray Scattering. Prog. Surf. Sci 2004, 77, 171-258. 17. Lee, S. S.; Fenter, P.; Park, C.; Sturchio, N. C.; Nagy, K. L., Hydrated Cation Speciation at the Muscovite (001)-Water Interface. Langmuir 2010, 26, 16647-16651. 18. Herrera, A. M.; Martins de Oliveira Jr., A. A.; Novaes de Oliveira, A. P.; Hotza, D., Processing and Characterization of Yttria-Stabilized Zirconia Foams for High-Temperature Applications. Journal of Ceramics 2013, 2013, 8.


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19. Burgess, J., Metal Ions in Solution; Halsted Press, 1978. 20. Levin, I.; Amos, T. G.; Nino, J. C.; Vanderah, T. A.; Randall, C. A.; Lanagan, M. T., Structural Study of an Unusual Cubic Pyrochlore Bi1.5zn0.92nb1.5o6.92. Journal of Solid State Chemistry 2002, 168, 69-75. 21. Mayernick, A. D.; Batzill, M.; van Duin, A. C. T.; Janik, M. J., A Reactive Force-Field (Reaxff) Monte Carlo Study of Surface Enrichment and Step Structure on Yttria-Stabilized Zirconia. Surf. Sci. 2010, 604, 1438. 22. Ballabio, G.; Bernasconi, M.; Pietrucci, F.; Serra, S., Ab Initio Study of Yttria-Stabilized Cubic Zirconia Surfaces. Phys. Rev. B 2004, 70, 075417.

TOC Graphic


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Figure 1. HRXR data (circles with errors) and the best-fit results (solid lines) for YSZ a) (100), b) (110), and c) (111) in contact with water (black)9-10 and with 10 mM Zinc acetate solution (red). 224x76mm (144 x 144 DPI)


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Figure 2. RAXR data (circles with errors) and the model-independent best-fit results (red solid lines) from a) YSZ (110) and b) YSZ (111) surfaces in contact with 10 mM zinc acetate solution. The intensities at each fixed qo are shifted for clarity. 326x177mm (96 x 96 DPI)



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Figure 3. Electron density profiles derived from the best-fits to the HRXRs for YSZ in contact with water (black)9-10 and with 10 mM zinc acetate solution (red dash); and zinc partial density profiles derived from the model-independent (M.I.) (blue dashed lines) and model-dependent (M.D.) (green dashed lines) analysis to the RAXR spectra at a) the (100), b) the (110), and c) the (111) surfaces. Light blue arrows indicate the Zn2+ adsorbed layers, and yellow arrows indicate the atomic compositions in the top unit cell layers of the substrate oxide without accounting the vacancy-filling water.9-10 165x52mm (144 x 144 DPI)


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Figure 4. The resonant anomalous dispersion terms, f’(E) and f”(E), for the interfacial zinc species at YSZ surfaces that are obtained from the model-independent fits to the RAXR spectra from YSZ (111) surface in contact with 10 mM zinc acetate solution. 126x109mm (144 x 144 DPI)



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TOC Graphic 104x74mm (144 x 144 DPI)


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Zinc Adsorption and Hydration Structures at Yttria-Stabilized Zirconia

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