Dataset and article "Room-temperature bulk plasticity and tunable dislocation densities in KTaO3"

Received: 3 June 2024 Revised: 28 June 2024 Accepted: 3 July 2024 DOI: 10.1111/jace.20040 RAPID COMMUNICATION Room-temperature bulk plasticity and tunable dislocation densities in KTaO3 Xufei Fang1,a,#Jiawen Zhang2,#Alexander Frisch1,aOliver Preuß3 Chukwudalu Okafor1,aMartin Setvin4Wenjun Lu2 1Institute for Applied Materials, Karlsruhe Institute of Technology, Karlsruhe, Germany 2Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen, China 3Department of Materials and Earth Sciences, Technical University of Darmstadt, Darmstadt, Germany 4Department of Surface and Plasma Physics, Charles University, Praha, Czech Republic Correspondence Xufei Fang, Institute for Applied Materials, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany. Email: [email protected] Wenjun Lu, Department of Mechanical and Energy Engineering, Southern University of Science and Technology, 518055 Shenzhen, China. Email: [email protected] Editor’s Choice The Editor-in-Chief recommends this outstanding article. Funding information European Research Council (ERC), Grant/Award Number: 101076167; Deutsche Forschungsgemeinschaft, Grant/Award Number: 510801687; DFG, Grant/Award Number: 414179371; Czech Science Foundation, Grant/Award Number: GACR 20–21727X; Shenzhen Science and Technology Program, Grant/Award Number: JCYJ20230807093416034; National Natural Science Foundation of China, Grant/Award Number: 52371110; Guangdong Basic and Applied Basic Research Foundation, Grant/Award Number: 2023A1515011510 Abstract We report room-temperature bulk plasticity mediated by dislocations in singlecrystal cubic potassium tantalate oxide (KTaO3), contrasting the conventional knowledge that single-crystal KTaO3is susceptible to brittle fracture. A mechanics-based combinatorial experimental approach using cyclic Brinell indentation, scratching, and uniaxial bulk compression consistently demonstrates room-temperature dislocation plasticity in KTaO3from the mesoscale to the macroscale. This approach also delivers tunable dislocation densities and plastic zone size. Scanning transmission electron microscopy analysis underpins the activated slip system to be <110>{1 10}. Given the growing significance of KTaO3as an emerging electronic oxide and the increasing interest in dislocations for tuning the physical properties of oxides, our findings are expected to trigger synergistic research interest in KTaO3with tunable dislocation densities. KEYWORDS bulk compression, cyclic deformation, dislocation, KTaO3, scanning transmission electron microscopy #These authors contribute equally to this work. aPreviously in the Department of Materials and Earth Sciences at the Technical University of Darmstadt where this work was initiated. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2024 The Author(s). Journal of the American Ceramic Society published by Wiley Periodicals LLC on behalf of American Ceramic Society. 7054 wileyonlinelibrary.com/journal/jace J Am Ceram Soc. 2024;107:7054–7061. FANG et al. 7055 1 INTRODUCTION Ceramics are generally known for their brittleness at room temperature, primarily due to the lack of dislocationmediated plasticity. Recent advancements have demonstrated room-temperature dislocation plasticity in various ceramic materials at small scales using techniques like nanoindentation1–3 and nano-/micropillar compression.4,5 These methods minimize flaw populations and favor plastic flow over cracking or suppress crack propagation through locally high compressive hydrostatic stress (as seen in nanoindentation with shallow depth) or by reducing the deformed volumes (in nano-/micropillar compression). In contrast, ceramics that exhibit bulk and mesoscale plasticity under ambient conditions are relatively rare, despite their long research history. Alkali halide crystals, such as LiF, NaCl, and KCl, have been extensively studied for their dislocation mechanics since the 1950s. Classic studies by Johnston and Gilman on LiF single crystals have systematically explored dislocation multiplication, nucleation, and mobility through dislocation etch pit studies.6–8 Similarly, NaCl crystals have been pivotal in understanding dislocation-based fracture toughness9,10 and electro-plasticity as well as the charge of dislocations in ionic crystals.11 Another notable group of ductile ceramics includes simple oxides with rock-salt structures, for instance, single-crystal MgO. Discovered to be plastically deformable in bulk compression12,13 as early as in the late 1950s, MgO continues to be studied for its fundamental role in the Earth’s lower mantle14 and as a model system for understanding the elementary dislocation mechanics in oxides.15 Due to the wide bandgap of the aforementioned ductile crystals, their application in electronic devices is limited. Consequently, more attention has been directed towards other ductile semiconductors such as ZnS16 and perovskite oxides. In 2001, Brunner et al.17 reported the surprising discovery of room-temperature plasticity in SrTiO3 (cubic structure) perovskite oxide, demonstrating a plastic strain up to ∼7% under uniaxial bulk compression. Owing to its prototypical nature in condensed matter physics18,19 and its role as a model electronic oxide, SrTiO3 has been extensively studied thereafter for its dislocation plasticity, ranging from macroscale20 and mesoscale21,22 to nanoscale.23–26 Later in 2016, Mark et al.27 reported unexpected bulk plasticity in single-crystal KNbO3, which is orthorhombic (peudo-cubic) at room temperature.28 This finding in KNbO3was further confirmed by Höfling et al. in 202129 and Preuß et al. in 2023.30 So far, SrTiO3and KNbO3have remained the only two perovskite oxides reportedinthe literatureregardingroom-temperaturebulk plasticity. In light of the increasing interest in using dislocations as one-dimensional line defects in ceramic oxides to harvest both functional and mechanical properties,31,32 there is a pressing need to seek more room-temperature ductile ceramics as well as to engineer dislocations into such functional oxides for harnessing dislocation-tuned properties. Recently, we achieved this by developing an experimental toolbox for tuning dislocation densities and plastic zone sizes,33 for example, in SrTiO3. However, the pursuit of finding more room-temperature ductile ceramics remains largely unexplored so far. With the abundant techniques and experimental protocols recently established for roomtemperature dislocation engineering,33 we begin our quest to discover other ceramics that can be plastically deformed at room temperature at meso-/macroscale. Here we report the third ductile perovskite oxide (potassium tantalate oxide, KTaO3), independent of Khayr et al.,34 on its room-temperature plasticity, with tunable dislocation densities and plastic zone size using a mechanics-based combinatorial experimental approach viacyclicBrinellindentation,scratching,anduniaxialbulk compression. KTaO3recently received much attention, owing to its potential for functional oxide electronics35,36 and tunable ferroelectricity that is achieved through Nb doping.37 These physical properties extend applications of KTaO3toward piezocatalysis, pyrocatalysis,38 and photocatalysis.39,40 Dislocations represent an additional degree of freedom that translates into all these applications, and it is therefore likely to spark more research interest in dislocation-tuned functional properties in KTaO3. 2 EXPERIMENTAL PROCEDURE For cyclic Brinell indentation and scratching tests, a samplewith a geometryof∼1×5×5mmwasused.Thesynthetic undoped single-crystal KTaO3sample was prepared by solidification from a nonstoichiometric melt in Oak Ridge National Laboratory. The tests were run on a universal hardness tester (Finotest; Karl-Frank GmbH), following the experimental procedure established by the current authors.21,22 TheindenterwasmountedwithaBrinell indenter with a diameter of 2.5 mm (hardened steel ball; Habu Hauck Prüftechnik GmbH) and a movable stage (Physik Instrumente GmbH & Co. KG). For both cyclic indentation and scratching tests, a dead weight of 1 kg was used. For scratching tests, a speed of 0.5 mm/s (lateral motion) was adopted. Additionally, silicone oil was used as a lubricant to reduce the indenter wear and to suppress sample crack formation. After mechanical deformation, the sample was cleaned with acetone and dried in air. The surface slip traces in the plastic zones were visualized using a laser confocal microscope (LEXT OLS4000; 15512916, 2024, 11, Downloaded from https://ceramics.onlinelibrary.wiley.com/doi/10.1111/jace.20040 by Cochrane Czech Republic, Wiley Online Library on [22/01/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License 7056 FANG et al. Olympus IMS). Dark-field imaging mode was used on a Zeiss optical microscope (Zeiss Axio Imager2; Carl Zeiss AG) to exclude potential crack formation underneath the surface. For uniaxial bulk compression, single-crystal samples (Hefei Single Crystal Material Technology) with a dimension of 3×3×6 mm were used. The long axis of the samples was aligned in the <001>direction. The samples were six-sided polished to mirror finish to minimize surface damage. Uniaxial compression was performed with a constant strain rate of 1.5 ×10−4s−1(MTS E45). The deformation images were collected in the VIC-gauge 2D software (Correlated Solution, Inc.). Before compression, two Al2O3plates were placed on top and bottom of the KTaO3specimen to offer smoother contact surfaces. To visualize the dislocation structures in the plastic zone, transmission electron microscopy (TEM) lamellae were lifted out along the scratching direction using a focused ion beam (FIB). The lamellae with a thickness of ∼80 nm were prepared and thinned by a FIB (Helios Nanolab 600i, FEI). Microstructures of KTaO3including dislocations were characterized by a 200 kV-TEM (FEI Talos F200X G2, Thermo Fisher Scientific, USA) with STEM mode. The annular bright field-scanning transmission electron microscopy (ABF-STEM) images were collected with inner and outer semi-collection angles of 12–20 mrad. 3 RESULTS AND ANALYSES 3.1 Brinell indentation and scratching Figure 1A–C demonstrates the surface plastic deformation after1cycle(1x)and10cycles(10x)Brinell indentation.The surface slip traces are aligned vertically and horizontally after 1x and 10x indentation (Figure 1A), and the slip trace number increases from 1x to 10x indentation (Figure 1B). The depth profiles of these two indentation imprints in Figure 1C (corresponding to the two yellow dashed lines in Figure 1A,B) indicate a maximum depth of ∼120 nm after 1x and ∼220 nm after 10x indentation. The plastic zone size inboth caseshasadiameterof∼150 µm,suggesting thatthe surface is nominally flat in the indented region. In addition to the cyclic Brinell indentation test, cyclic scratching tests were performed using the same indenter. Figure 1D,E reveals an increase in the slip trace densities with the increasing scratching number from 1x to 10x. For scratching,eachcycleisdefined as one traversal. The maximum depth of the scratch tracks (Figure 1F, corresponding to the two yellow dashed lines in Figure 1D,E) was measured to increase from ∼100 nm (1x) up to ∼250 nm (10x). Different from the sink-in feature in the 1x scratching as well as the 1x and 10x indentation imprints, the 10x scratching depth profile exhibits two shoulders (pile-up, indicated by the two red arrows in Figure 1F). This pile-up was likely caused by the “plastic plowing” of the material by the spherical indenter during the back-and-forth cyclic scratching (scratching directions indicated by the yellow arrows in Figure 1E). This pile-up is strong evidence of good room-temperature plastic deformation of this material. To rule out the possible cracking underneath the indentation imprints/scratch track, dark-field imaging mode (sensitive to under-surface cracks, featured as white contrasts) was used. No visible cracks were found up to 25 cycles of scratching. This observation is consistent with the results obtained on other ductile oxides (e.g., SrTiO321,22) at room temperature. Worth mentioning is that both the Brinell ball indentation and scratching test results in KTaO3closely resemble the slip trace features in SrTiO3with the same (001) surface being deformed. The plastic zone size is also almost identical for KTaO3 observed here as in SrTiO321 under the same loading conditions. Such similarities suggest that the lattice friction stress in KTaO3shall be sufficiently low to allow easy dislocation glide and multiplication at room temperature. Note that single-crystal SrTiO3was reported to plastically yield around 110–150 MPa during bulk compression along the [001] orientation (summarized literature results by Stich et al.41). If the deformation behavior is similar for these two perovskite oxides, then the yield strength of single-crystal KTaO3should be around the same range. To this end, further validation with uniaxial bulkcompressionwasperformedonKTaO3alongthe [001] direction. 3.2 Uniaxial bulk compression The engineering stress-strain curve in Figure 2A and the deformation process in Figure 2B demonstrate the bulk plastic deformation. Unlike the room-temperature bulk stress-strain curves in SrTiO317,42 and KNbO3,27,29 here for KTaO3it exhibits an upper yield point and a lower yield point (indicated in Figure 2A). The upper yield point (Figure 2A)isσy_up =274 MPa and the lower yield point is σy_low =250 MPa. This load drop behavior is not uncommon for ceramics that undergo plastic deformation. For instance, similar yield behavior was reported in bulk compression of sapphire at high temperature43 and discussed in single-crystal LiF at room temperature.44 Due to the initially low mobile dislocation density in such ceramic crystals, dislocation multiplication was proposed to have causedsuchastressdrop insteadofdue tothe unpinning of 15512916, 2024, 11, Downloaded from https://ceramics.onlinelibrary.wiley.com/doi/10.1111/jace.20040 by Cochrane Czech Republic, Wiley Online Library on [22/01/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License FANG et al. 7057 FIGURE 1 Laser microscope images featuring the plastic deformation on the (001) surface after Brinell ball indentation (A, B) and scratching (D, E). Note 1x and 10x stand for 1-cycle and 10-cycle deformation, respectively. The yellow arrows in (D, E) indicate the scratching direction. Depth profiles (C, F) corresponding to the yellow dashed lines were extracted, with the unperturbed sample surface corresponding to the zero point in the y-axis. FIGURE 2 Bulk compression of single-crystal KTaO3along the <001>direction: (A) engineering stress-strain curve; (B1–B6) Screenshots of the in-situ bulk compression at different strains. The black arrows indicate the slip traces and the red arrow indicates the crack formation. The scale bar in (B1) is consistent for all six sub-figures. 15512916, 2024, 11, Downloaded from https://ceramics.onlinelibrary.wiley.com/doi/10.1111/jace.20040 by Cochrane Czech Republic, Wiley Online Library on [22/01/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License 7058 FANG et al. a Cottrell cloud as in the case of α-iron, where dislocation pinning results from the impurities such as carbon.45 Following the upper yield point and then the lower yield point, the stress increased from 250 MPa (i.e., the lower yield point in Figure 2A)upto∼300 MPa, where another load drop was observed (red arrow in Figure 2A). On the one hand, the stress increase after the lower yield point indicates work hardening behavior, as evidenced by the increased number of slip traces (dark lines that lie 45◦to the loading axis), indicated by the black arrows in Figure 2B3-B4. These slip traces confirm that the dislocation glide occurs on the {110} planes. On the other hand, the load drop (red arrow in Figure 2A) was found to correspond to the primary fracture event observed by the in-situ deformation (Figure 2B5, where the bright features on the top right corner indicate a main crack formed, see the red arrow). The deformed sample was captured (Figure 2B6, at a strain of ∼6.3%) right before the sample shattered into pieces at a maximum strain of ∼6.5%. Note the sample in Figure 2B6 is already full of cracks as reflected by the white contrast. The observed yield stress during bulk compression agrees with the stress analysis using Hertzian contact for the Brinell ball indentation in Figure 1,aswillbe rationalized in the following. Consider that the postmortem plastic zone imprint (Figure 1A)hasadiameter of D=150 µm, with the load of P=1 kg (9.8 N), we estimate the mean pressure p0underneath the indenter to be ∼555 MPa using the expression p0=P/(πD2/4).46 The maximum shear stress (upon plastic yield) during spherical indentation can be calculated according to Swain & Lawn,46 giving a value of about τmax =255 MPa (0.46p0). Note that the critical resolved shear stress (τCRSS) in the current uniaxial bulk compression is half of the value of the yield strength (here we take the upper yield strength σy_up =274 MPa in Figure 2A), giving τCRSS =137 MPa. The estimation above is made on the Brinell indentation imprint, which is already in the plastic deformation regime. Consider that Hertzian contact theory is used for elastic deformation, the τmax is expected to be larger than τCRSS. As both the τmax and τCRSS are much smaller than the theoretical shear strength (∼19 GPa for KTaO3,estimated by G/2π, G is the shear modulus) for homogeneous dislocation nucleation, this suggests that the plastic deformation under the large Brinell indenter as well as the uniaxial bulk compression is mediated by dislocation multiplication and dislocation glide. It is thus expected that the lattice friction stress for dislocation glide in KTaO3 at room temperature shall be close to τCRSS =137 MPa (which is likely an upper bound). This value is higher but close to that in SrTiO3(∼90 MPa47)andKNbO 3 (∼30 MPa27,29). 3.3 TEM characterization of dislocations To directly prove that the dislocation densities in the plastic zone can be tuned via dislocation multiplication by increasing the number in the deformation cycles, we performed TEM analysis in the 1x and 10x scratched regions. As illustrated in Figure 3A, there are a few dislocations with long segments in the area of view after 1x scratching. These long segments are aligned on the {110} planes. This is consistent with the slip trace observation during bulk deformation (Figure 2B). After 10x scratching, the dislocation density increased dramatically and the dislocation lines were heavily tangled up with each other, where the dislocation density is estimated to be higher than 1014/m2. Although the majority of the dislocations are still projected in the <110>directions, many short and curved dislocation segments are generated. These features are a result of the cyclic scratching, which strongly promotes dislocation multiplication and interaction. Such profuse dislocation multiplication significantly increases the dislocation plasticity, which is in line with the observation of the pile-up behavior after 10x Brinell ball scratching. Further analysis of the Burgers vector and the line vector of the dislocations suggest a Burgers vector of <110>and both edge and screw types of dislocations are generated. It is thus confirmed that KTaO3has the same slip system as in the case of SrTiO318 and KNbO3(pseudo-cubic),27 namely, the <110>{1 10} slip systems are activated at room temperature. 4DISCUSSION Single-crystal KTaO3was reported to be very susceptible to brittle cleavage along the (001) surface.48 Independent of the current work, Khayr et al.34 studied the dislocation structural properties of plastically deformed KTaO3 without direct visualization of the deformation features such as slip traces (Figures 1,2) and dislocation mesostructures (Figure 3). Here we present compelling evidence of room-temperature plasticity in single-crystal KTaO3,with successful dislocation engineering at both the mesoscale and the bulk scale without inducing visible cracks. This crack suppression is attributed to the profuse dislocation multiplication and good dislocation mobility under the blunt spherical Brinell indenter, which proves to be more advantageous than pyramidal indenters such as Vickers indenter that is widely used for indentation fracture toughness evaluation in brittle solids.49,50 The choice of KTaO3was made based on its structural and atomic similarities to the other two ductile 15512916, 2024, 11, Downloaded from https://ceramics.onlinelibrary.wiley.com/doi/10.1111/jace.20040 by Cochrane Czech Republic, Wiley Online Library on [22/01/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License FANG et al. 7059 FIGURE 3 Visualization of dislocations (dark lines) in annular bright field-scanning transmission electron microscopy (ABF-STEM): (A) after 1x scratching; (B) after 10x scratching. The dislocation density is tunable depending on the number of cyclic scratching. The orientations in (A1) are consistent for all four sub-figures. perovskite oxides SrTiO3and KNbO3.KTaO 3has a cubic structure at room temperature similar to SrTiO3, also Ta and Nb have the same ionic radii of 0.64 Å (for +5 charge state and 6-fold coordination).51 This led to our original hypothesis that KTaO3might also be ductile at room temperature, like SrTiO3and KNbO3.At this stage, the underlying mechanisms for yielding such dislocation plasticity in KaTiO3remain unclear. Nevertheless, considering that KTaO3, SrTiO3,andKNbO 3are very similar in crystal structure and much often used together for comparison in their physical properties,35 it is likely that the dislocation mechanisms in these materials are similar, particularly concerning the dislocation core structure. For instance, TEM observations and atomistic simulations in SrTiO352,53 as well as in KNbO328 suggest that the dislocations are dissociated into partials, which facilitates good dislocation mobility at room temperature. To confirm if this is the case for KTaO3, future work will involve high-resolution TEM characterization as well as molecular dynamics simulations in this direction. It is worth noting that, due to the earlier discovery of room-temperature bulk dislocation plasticity and the simple dislocation introduction process in SrTiO3, most of the dislocation-based functional and mechanical properties studies54–56 have been reported using this model material. Now with the simple and efficient dislocation engineering demonstrated here in KTaO3, and considering that KTaO3has been deemed as the “new kid on the spintronics block”,35 it is expected that our finding will serve as a fundamental building block for upcoming versatile studies in KTaO3tuned by dislocations. 5 CONCLUSION We found that single-crystal KTaO3with a cubic structure can be plastically deformed at room temperature via bulk uniaxial compression, Brinell ball indentation, and scratching. The room-temperature slip systems in KTaO3 are identified to be <110>{1 10}, the same as those observed in SrTiO3and KNbO3deformed at room temperature. 15512916, 2024, 11, Downloaded from https://ceramics.onlinelibrary.wiley.com/doi/10.1111/jace.20040 by Cochrane Czech Republic, Wiley Online Library on [22/01/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License 7060 FANG et al. For the single crystals compressed along the <001>direction in this work, the bulk yield strength of KTaO3was ∼274 MPa, and the critical resolved shear stress is estimated to be ∼137 MPa (likely the upper bound) to move the dislocations. Unlike the discrete slip bands generated during bulk compression, the Brinell ball indentation and scratching generate continuous plastic zones extending up to hundreds of micrometers with dislocation densities exceeding ∼1014/m2after 10-cycle scratching. It remains an open question at this stage to pinpoint the fundamental mechanisms responsible for the room-temperature dislocation plasticity in KTaO3. Our findings are expected to open new avenues to investigate dislocation-tuned mechanical and functional properties in KTaO3. ACKNOWLEDGMENTS X. Fang and A. Frisch acknowledge the European Research Council (ERC) under grant number 101076167 (MECERDIS) for supporting the research.Views and opinions expressed are, however, those of the authors only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. C. Okafor acknowledges the financial support by the Deutsche Forschungsgemeinschaft (DFG, grant No. 510801687). O. Preuß thanks the DFG for the funding (grant No. 414179371). M. Setvin acknowledges the support from the Czech Science Foundation, project GACR 20–21727X. W. Lu is supported by the Shenzhen Science and Technology Program (grant number JCYJ20230807093416034), the National Natural Science Foundation of China (grant number 52371110), and the Guangdong Basic and Applied Basic Research Foundation (grant number 2023A1515011510). The authors acknowledge the use of the facilities at the Southern University of Science and Technology Core Research Facility. M. Setvin and X. Fang would like to thank L. A. Boatner at Oak Ridge National Laboratory for providing the KTaO3crystal for the indentation tests. We thank Prof. Rödel at TU Darmstadt for the discussion. Open access funding enabled and organized by Projekt DEAL. ORCID Xufei Fang https://orcid.org/0000-0002-3887-0111 REFERENCES 1. Basu S, Barsoum MW. Deformation micromechanisms of ZnO single crystals as determined from spherical nanoindentation stress–strain curves. J Mater Res. 2007;22(9):2470–77. 2. Page TF, Oliver WC, McHargue CJ. The deformation behavior of ceramic crystals subjected to very low load (nano)indentations. J Mater Res. 2011;7(2):450–73. 3. Fang X, Bishara H, Ding K, Tsybenko H, Porz L, Höfling M, et al. Nanoindentation pop-in in oxides at room temperature: dislocation activation or crack formation? J Am Ceram Soc. 2021;104:4728–41. 4. 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Switching the electrical resistance of individual dislocations in single-crystalline SrTiO3. Nat Mater. 2006;5(4):312–20. How to cite this article: Fang X, Zhang J, Frisch A, Preuß O, Okafor C, Setvin M, et al. Room-temperature bulk plasticity and tunable dislocation densities in KTaO3. J Am Ceram Soc. 2024;107:7054–61. https://doi.org/10.1111/jace.20040 15512916, 2024, 11, Downloaded from https://ceramics.onlinelibrary.wiley.com/doi/10.1111/jace.20040 by Cochrane Czech Republic, Wiley Online Library on [22/01/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License