Search

Rapid densification of ceramics has been realized and its merits were demonstrated through multiple approaches out of which UHS and flash sintering attract recent attention. So far, however, scalability remains difficult. A rise in throughput and scalability is enabled by the introduction of blacklight sintering powered by novel light source technology. Intense illumination with photon energy above the bandgap (blacklight) allows high absorption efficiency and, hence, very rapid, contactless heating for all ceramics. While heating the ceramic directly with light without any furnace promises scalability, it simultaneously offers highly accurate process control. For the technology transfer to industry, attainable material quality needs to be assured. Here, we demonstrate the excellent microstructure quality of blacklight-sintered ceramics observed with ultrahigh voltage electron microscopy revealing an option to tune nanoporosity. Moreover, we confirm that electronic, electron, oxygen, and lithium-ion conductivities are equal to conventionally sintered ceramics. This gives the prospect of transmitting the merits of rapid densification to the scale of industrial kilns.

BaTiO3 single crystals were deformed in compression along the $$\langle 110\rangle$$ ⟨ 110 ⟩ crystal axis to study the plastic deformability and dislocation structures at high temperatures under different loading conditions. The yield strength is determined from stress–strain curves under strain rate control, load control, strain rate cycling tests, and under step-wise loading conditions to elucidate the impact of measurement approach in yield strength behavior. A comparison between the chosen methods based on stress-dependent strain rate plots indicates that load control measurements are a suitable alternative to the commonly used strain rate-control experiments in metals. This allows avoiding overloading and providing an estimate of the overall achievable strain rates in a ceramic. Activation energies and activation volumes in the temperature range of 1100–1170 °C indicate a similar mechanical deformation behavior to SrTiO3. Graphical abstract

For millennia, ceramics have been densified via sintering in a furnace, a time-consuming and energy-intensive process. The need to minimize environmental impact calls for new physical concepts beyond large kilns relying on thermal radiation and insulation. Here, we realize ultrarapid heating with intense blue and UV-light. Thermal management is quantified in experiment and finite element modelling and features a balance between absorbed and radiated energy. With photon energy above the band gap to optimize absorption, bulk ceramics are sintered within seconds and with outstanding efficiency (≈2 kWh kg−1) independent of batch size. Sintering on-the-spot with blacklight as a versatile and widely applicable power source is demonstrated on ceramics needed for energy storage and conversion and in electronic and structural applications foreshadowing economic scalability.

Crystallographic twins are critical to the properties of numerous materials from magnesium alloys to piezoelectrics. Since the onset of the twin formation is highly sensitive to the triaxial mechanical boundary conditions, non-destructive bulk microscopy techniques are required. Elastic strains can be mapped via X-ray diffraction with a 100-200 nm resolution. However, the interplay of strains with nanotwins cannot be characterized. Here, a method based on dark-field X-ray microscopy to quantify the density of nanotwin variants with twin lamellae of sizes as small as several tens of nanometers in embedded subvolumes (70x200x600 nm3) in millimeter-sized samples is introduced. The methodology is corroborated by correlating the local density of twin variants to the long-ranging strain fields for a high-performance piezoelectric material. The method facilitates direct, in situ mapping and quantification of nanoscale structural changes together with their elastic driving fields, which is the key towards controlling and engineering material's performance at nanometric scales.

High power solid-state Li batteries (SSLB) are hindered by the formation of dendrite-like structures at high current rates. Hence, new design principles are needed to overcome this limitation. By introducing dislocations, we aim to tailor mechanical properties in order to withstand the mechanical stress leading to Li penetration and resulting in a short circuit by a crack-opening mechanism. Such defect engineering, furthermore, appears to enable whisker-like Li metal electrodes for high-rate Li plating. To reach these goals, the challenge of introducing dislocations into ceramic electrolytes needs to be addressed which requires to establish fundamental understanding of the mechanics of dislocations in the particular ceramics. Here we evaluate uniaxial deformation at elevated temperatures as one possible approach to introduce dislocations. By using hot-pressed pellets and single crystals grown by Czochralski method of Li6.4La3Zr1.4Ta0.6O12 garnets as a model system the plastic deformation by more than 10% is demonstrated. While conclusions on the predominating deformation mechanism remain challenging, analysis of activation energy, activation volume, diffusion creep, and the defect structure potentially point to a deformation mechanism involving dislocations. These parameters allow identification of a process window and are a key step on the road of making dislocations available as a design element for SSLB.

Dislocations in oxides can be described as charged line defects and means for one-dimensional doping, which can tune electrical and thermal properties. Furthermore, theoretically it was shown that dislocations can pin ferroelectric domain walls. Broader application of this concept hinges on the development of a methodology to avail this approach to polycrystalline ceramics. To this end, we use different creep mechanisms as a method to introduce multidimensional defects and quantify structural changes. A deformation map for fine-grained barium titanate is provided and the influences of the defects and creep regimes are correlated in this first study to modifications of electrical conductivity, dielectric, ferroelectric, and piezoelectric properties. A plastic deformation of 1.29% resulted in an increase in the Curie temperature by 5 degrees C and a decrease in electromechanical strain by 30%, pointing toward electromechanical hardening by dislocations.

Dislocation networks have been demonstrated to substantially enhance functional properties. As-sintered samples are virtually devoid of dislocations, new innovative techniques for introducing sufficiently high dislocation densities into polycrystalline ceramics are needed. While dislocation-based plasticity at high temperatures has been demonstrated for a large range of ceramic single crystals, plasticity in polycrystals is much less understood. Here, we demonstrate plastic strains in excess of several % based on dislocation motion in polycrystalline SrTiO3 at ≈ 1100 °C with 3.9 µm grain size. Ultra-high voltage electron microscopy reveals an associated increase in dislocation density by three orders of magnitude. Achievable strain rates are comparable to creep-based mechanisms and much less sensitive to applied stress than observed for metals. A specialized testing protocol allows quantification of the deformability via stress exponent, activation volume and activation enthalpy giving additional quantification. In conjunction with TEM images, the mechanical data gives insight into the underlying mechanisms.

Dislocations have been identified to modify both the functional and mechanical properties of some ceramic materials. Succinct control of dislocation-based plasticity in ceramics will also demand knowledge about dislocation interaction with point defects. Here, we propose an experimental approach to modulate the dislocation-based plasticity in single-crystal SrTiO3 based on the concept of defect chemistry engineering, for example, by increasing the oxygen vacancy concentration via reduction treatment. With nanoindentation and bulk compression tests, we find that the dislocation-governed plasticity is significantly modified at the nano-/microscale, compared to the bulk scale. The increase in oxygen vacancy concentration after reduction treatment was assessed by impedance spectroscopy and is found to favor dislocation nucleation but impede dislocation motion as rationalized by the nanoindentation pop-in and nanoindentation creep tests.

Ferroelectrics have become indispensable electroceramic materials in modern electronic applications. While point-defect engineering is a common tool to modify the properties of ferroelectrics, dislocations have not been widely considered, although they were previously shown to alter electrical properties in other oxides. Here, we study the room temperature uniaxial deformation of the perovskite ferroelectric single crystalline KNbO3 in 010 p c and 101 p c orientations. We demonstrate a large plastic deformation in the range of 5%. Dislocation and domain structure were investigated across different length scales using optical microscopy, electron channeling contrast imaging, and transmission electron microscopy. Planar arrangement of dislocations in slip bands was observed, while the predominant appearance of edge dislocations indicates a dominant dislocation motion by the kink-pair mechanism. Increased dislocation density resulted in decreased ferroelectric domain size from 1.8 μm to 0.5 μm after deformation. Piezoresponse force microscopy highlights the effect of dislocations on domain nucleation and their mobility.

Functional and structural ceramics have become irreplaceable in countless high-tech applications. However, their inherent brittleness tremendously limits the application range and, despite extensive research efforts, particularly short cracks are hard to combat. While local plasticity carried by mobile dislocations allows desirable toughness in metals, high bond strength is widely believed to hinder dislocation-based toughening of ceramics. Here, we demonstrate the possibility to induce and engineer a dislocation microstructure in ceramics that improves the crack tip toughness even though such toughening does not occur naturally after conventional processing. With modern microscopy and simulation techniques, we reveal key ingredients for successful engineering of dislocation-based toughness at ambient temperature. For many ceramics a dislocation-based plastic zone is not impossible due to some intrinsic property (e.g. bond strength) but limited by an engineerable quantity, i.e. the dislocation density. The impact of dislocation density is demonstrated in a surface near region and suggested to be transferrable to bulk ceramics. Unexpected potential in improving mechanical performance of ceramics could be realized with novel synthesis strategies.

The introduction of dislocations is a recently proposed strategy to tailor the functional and especially the electrical properties of ceramics. While several works confirm a clear impact of dislocations on electrical conductivity, some studies raise concern in particular when expanding to dislocation arrangements beyond a geometrically tractable bicrystal interface. Moreover, the lack of a complete classification on pertinent dislocation characteristics complicates a systematic discussion and hampers the design of dislocation-modified electrical conductivity. We proceed by mechanically introducing dislocations with three different mesoscopic structures into the model material single-crystal SrTiO3 and extensively characterizing them from both a mechanical as well as an electrical perspective. As a final result, a deconvolution of mesoscopic structure, core structure, and space charge enables us to obtain the complete picture of the effect of dislocations on functional properties, focusing here on electric properties.

Lithium dendrites are amongst the key challenges hindering Solid-State Li Batteries (SSLB) from reaching their full potential in terms of energy and power density. The formation and growth of these dendrites cause an inevitable failure at charge rates far below the threshold set by industry (>5 mA/cm2) and are supposedly caused by stress accumulation stemming from the deposited lithium itself. Herein, we demonstrate that MHz pulsed currents can be used to increase the current density by a factor of six, reaching values as high as 6.6 mA/cm2 without forming Li dendrites. To understand the origin of this improvement we propose an extension of previous mechanisms by considering the Li activity as a critical factor. The Li activity becomes relevant when Li is geometrically constrained, and the local plating rate exceeds the exchange current density. Over a critical Li activity, the solid-state electrolyte close to the tip of the dendrite fractures and releases the accumulated elastic energy. These events deteriorate the functional and mechanical performance of the SSLB. Since the buildup of a critical Li activity requires a certain time, the application of current pulses at shorter time scales can be used to significantly improve the rate-performance of SSLB, representing a potential step towards the practical realization of electric vehicles and other emerging applications.

Dislocations are 1D crystallographic line defects and are usually seen as detrimental to the functional properties of classic semiconductors. It is shown here that this not necessarily accounts for oxide semiconductors in which dislocations are capable of boosting the photoconductivity. Strontium titanate single crystals are controllably deformed to generate a high density of ordered dislocations of two slip systems possessing different mesoscopic arrangements. For both slip systems, nanoscale conductive atomic force microscope investigations reveal a strong enhancement of the photoconductivity around the dislocation cores. Macroscopic in-plane measurements indicate that the two dislocation systems result in different global photoconductivity behavior despite the similar local enhancement. Depending on the arrangement, the global photoresponse can be increased by orders of magnitude. Additionally, indications for a bulk photovoltaic effect enabled by dislocation-surrounding strain fields are observed for the first time. This proves that dislocations in oxide semiconductors can be of large interest for tailoring photoelectric functionalities. Direct evidence that electronic transport is confined to the dislocation core points to a new emerging research field.

Most oxide ceramics are known to be brittle macroscopically at room temperature with little or no dislocation-based plasticity prior to crack propagation. Here, we demonstrate the size-dependent brittle to ductile transition in SrTiO3 at room temperature using nanoindentation pop-in events visible as a sudden increase in displacement at nominally constant load. We identify that the indentation pop-in event in SrTiO3 at room temperature, below a critical indenter tip radius, is dominated by dislocation-mediated plasticity. When the tip radius increases to a critical size, concurrent dislocation activation and crack formation, with the latter being the dominating process, occur during the pop-in event. Beyond the experimental examination and theoretical justification presented on SrTiO3 as a model system, further validation on α-Al2O3, BaTiO3, and TiO2 are briefly presented and discussed. A new indentation size effect, mainly for brittle ceramics, is suggested by the competition between the dislocation-based plasticity and crack formation at small scale. Our finding complements the deformation mechanism in the nano-/microscale deformation regime involving plasticity and cracking in ceramics at room temperature to pave the road for dislocation-based mechanics and functionalities study in these materials.

The introduction of dislocations is a recently proposed strategy to tailor the functional and especially the electrical properties of ceramics. While several works confirm a clear impact of dislocations on electrical conductivity, some studies raise concern in particular when expanding to dislocation arrangements beyond a geometrically tractable bicrystal interface. Moreover, the lack of a complete classification on pertinent dislocation characteristics complicates a systematic discussion and hampers the design of dislocation-modified electrical conductivity. We proceed by mechanically introducing dislocations with three different mesoscopic structures into the model material single-crystal SrTiO

Solid electrolytes potentially enable rechargeable batteries with lithium metal anodes possessing higher energy densities than today's lithium ion batteries. To do so the solid electrolyte must suppress instabilities that lead to poor coulombic efficiency and short circuits. In this work, lithium electrodeposition was performed on single-crystal Li6La3ZrTaO12 garnets to investigate factors governing lithium penetration through brittle electrolytes. In single crystals, grain boundaries are excluded as paths for lithium metal propagation. Vickers microindentation was used to introduce surface flaws of known size. However, operando optical microscopy revealed that lithium metal penetration propagates preferentially from a different, second class of flaws. At the perimeter of surface current collectors smaller in size than the lithium source electrode, an enhanced electrodeposition current density causes lithium filled cracks to initiate and grow to penetration, even when large Vickers defects are in proximity. Modeling the electric field distribution in the experimental cell revealed that a 5-fold enhancement in field occurs within 10 micrometers of the electrode edge and generates high local electrochemomechanical stress. This may determine the initiation sites for lithium propagation, overriding the presence of larger defects elsewhere.

Dislocations have been recently introduced as a novel tool to tailor the conductivity of functional ceramics. However, tuning strategies suffer from poor insight into the structural complexity of dislocations and their networks. Here, we demonstrate that dislocations can be used to both enhance and reduce the overall conductivity in the same ceramic material. Accurate control of the arrangement of dislocations within the dislocation network enables tailoring TiO2 bulk samples to behave like being chemically modified either with an acceptor or donor dopant. Our approach combines ultra-high voltage electron microscopy, oxygen partial pressure, and temperature dependent electrical conductivity measurements combined with time-of-flight secondary ion mass spectrometry. This allows us to focus on mechanically tailored interaction of next neighbor dislocations and to differentiate between percolating conductive pathways and separated charge carrier zones. This seemingly simple approach purposefully tailors the conductivity of TiO2, opening new avenues to engineer functional ceramics beyond common chemical doping strategies.

Recently, several creative processing techniques yielded thermoelectrics with reduced thermal conductivity and, thereby, an enhanced figure or merit. These were based on engineered complex microstructures with attendant dislocation structures. In this study, we implement highly controlled mesoscopic dislocation structures into the model thermoelectric SrTiO3 in order to quantify phonon scattering at dislocations. Both single crystals and polycrystalline material have been furnished with enhanced dislocation densities increased by a factor of 150–300 by plastic deformation. Thermal conductivity was measured using laser flash analysis between room temperature and 325 °C. Etch pit techniques and ultra-high voltage electron microscopy afford quantification of dislocation density. Experimental results were compared to predictions by the Debye-Callaway model. The latter revealed that dislocation densities of 1015 m−2 would be necessary for the reduction of thermal conductivity of SrTiO3 in the investigated temperature range, which could not be realized using the plastic deformation mechanism applied.

This article presents an X-ray microscopy approach for mapping deeply embedded dislocations in three dimensions using a monochromatic beam with a low divergence. Magnified images are acquired by inserting an X-ray objective lens in the diffracted beam. The strain fields close to the core of dislocations give rise to scattering at angles where weak beam conditions are obtained. Analytical expressions are derived for the image contrast. While the use of the objective implies an integration over two directions in reciprocal space, scanning an aperture in the back focal plane of the microscope allows a reciprocal-space resolution of ΔQ/Q < 5 × 10−5 in all directions, ultimately enabling high-precision mapping of lattice strain and tilt. The approach is demonstrated on three types of samples: a multi-scale study of a large diamond crystal in transmission, magnified section topography on a 140 µm-thick SrTiO3 sample and a reflection study of misfit dislocations in a 120 nm-thick BiFeO3 film epitaxially grown on a thick substrate. With optimal contrast, the half-widths at half-maximum of the dislocation lines are 200 nm.

This study introduces a simple analytical model for fracture toughness to bridge the length scales from grain size to bulk thickness by assembling a virtual crack path from the angles recorded on an unfractured microstructure, which is a great challenge in fracture mechanics due to the high geometrical complexity. Good agreement is found between a crack deflection angle distribution measured from 5764 crack segments and the prediction by the model and the possible influence of residual stress is quasi quantitatively discussed. A total of 7.4% of the crack segments observed acted as crack bridges, while 7.3% was predicted by the model. A quantification of how high an angle needs to be to turn crack deflection into crack bridging is given. The ratio of fracture toughness from grain boundary to grain, G1c(gb)/G1c(g), was measured indirectly from all samples to be between 0.3 and 0.35.

Crack deflection angles and fracture modes were investigated by elaborative observation of 5764 crack deflections, generated at 77 K, 159 K, 293 K and 500 K, in silicon nitride (Si 3 N 4 ) ceramics. In addition, the effects of grain boundary toughness on crack propagation in Si 3 N 4 ceramics were statistically analyzed based on a two-dimensional, polycrystalline model. The results demonstrated that temperature (77–500 K) had little influence on crack advance, but the change of grain boundary toughness contributed a lot to the change of crack propagation. The distribution of deflection angles varied distinctly and the fraction of transgranular fracture increased when the grain boundary toughness increased.

A flexural bearing mechanism has enabled the development of a self-sealing box for protecting air sensitive samples during transfer between glove boxes, micro-machining equipment, and microscopy equipment. The simplicity and self-actuating feature of this design makes it applicable to many devices that operate under vacuum conditions. The models used to design the flexural mechanism are presented in detail. The device has been tested in a Zeiss Merlin GEMINI II scanning electron microscope with Li3PS4 particles, showing effective isolation from air and corrosion prevention.

Lithium is both the most electropositive and lightest metal, making it the ideal anode material. Non-flammable ceramic electrolytes paired with Li metal anodes could potentially result in safe, energy dense batteries surpassing state-of-the-art lithium ion batteries. Oxide solid electrolytes typically have high shear moduli, far beyond that of Li metal, which one criterion [1] suggests should suppress lithium metal dendrites. However, our group has recently shown that fracture of the solid electrolyte initiating at surface defects can create pathways for dendritic growth of metallic Li that short-circuit the device. [2] In this work, in-situ optical microscopy has been conducted to characterize the propagation of Li dendrites through single crystal solid electrolytes under a variety of electrochemical conditions. The complete absence of grain boundaries excludes that class of internal defects as paths for propagation. A unique morphological structure of the lithium dendrite observed within the single crystal support a Griffith flaw based fracture model, and in addition, suggest a local field-intensification mechanism of dendrite growth within the solid. Results for the single crystals compared to those from polycrystalline solid electrolytes, in literature and from our own work. Additionally, it is shown that the initiation of Li propagation through single crystals may be affected by the electrode geometry. Under certain circumstances, Li infiltration is observed to initiate at the perimeter of the electronic conductor contact with the electrolyte – especially at corners with high local curvature. This behavior suggests that localized field and current concentration is also important, and may determine which supercritical surface sites dominate Li metal propagation during electrodeposition. Reference s : [1] Monroe, C. & Newman, J. The Impact of Elastic Deformation on Deposition Kinetics at Lithium/Polymer Interfaces. J. Electrochem. Soc. 152, 396–404 (2005). [2] Porz, L. et al. Mechanism of Lithium Metal Penetration through Inorganic Solid Electrolytes. Adv. Energy Mater. 1701003, 1–12 (2017). Figure 1

Vast energy density improvements may be achieved in Li-ion rechargeable batteries with lithium metal anodes. However, lithium metal batteries containing liquid electrolytes have been unsuccessful thus far due to safety concerns associated with short circuits that occur when Li dendrites grow through the liquid electrolyte during the charging process. In contrast, thin film batteries using Li metal negative electrodes with an inorganic solid electrolyte (e.g., LiPON) appear to withstand dendrite penetration over extended cycling [1]. Recently, however, multiple research groups have reported and investigated cases where ceramic solid electrolytes paired with a Li metal anode experience a short circuit event [2,3]. The mechanism by which short circuit events occur in all-solid-state Li-ion batteries is unclear. Thus, in this project, the growth of lithium metal filled cracks through four types of solid electrolytes, glassy Li2S-P2S5 (LPS), β-Li3PS4­, polycrystalline and single crystal Li6La3ZrTaO12 (LLZTO), was studied using galvanostatic electrodeposition experiments coupled with in-situ and ex-situ microscopy. An electrochemomechanical model for growth of lithium-filled cracks was developed. For current densities up to 5 mA/cm2, only the as-fractured surface of glassy LPS exhibits lithium metal deposition at the surface alone, without penetration of the solid electrolyte. All other surfaces of the LPS and LLZTO samples studied had observable defects, the maximum initial sizes of which were characterized. Electrodeposition of lithium at these surfaces is accompanied by the filling, and then propagation, of lithium metal filled cracks. The experiments and model suggest that above a critical current density, the Li plating overpotentials, and corresponding mechanical stresses, reach values sufficiently large to propagate pre-existing surface defects. The results can be summarized, Figure 1, as a plot of the overpotential and corresponding mechanical stress necessary to extend a pre-existing sharp crack as a function of the crack length, for materials parameters suitable to LPS and LLZO. The prevailing failure mechanism in brittle solid electrolytes is Griffith-like, and differs from the amplification of kinetic perturbations at the metal interface that results in dendrite growth in liquid electrolytes. The results show that the shear-modulus criterion proposed by Monroe and Newman [4,5] for prevention of dendrites is not the determining factor for the high modulus, brittle inorganic electrolytes studied here. We suggest that stabilization of inorganic solid electrolyte interfaces against lithium metal penetration will require scrupulous attention to minimize interfacial defects. Acknowledgments Tushar Swamy and Lukas Porz contributed equally to this work. The authors gratefully acknowledge support from the US Department of Energy, Office of Basic Energy Science, through award number DE-SC0002633 (J. Vetrano, Program Manager). Brian W. Sheldon acknowledges additional support by the US Department of Energy, Office of Basic Energy Sciences under the award number DE-FG02-10ER46771. The authors also acknowledge use of the MIT Nanomechanical Technology Laboratory (A. Schwartzman, Manager). References 1. J. Li, C. Ma, M. Chi, C. Liang, and N. J. Dudney, Adv. Energy Mater., 5, 1401408–1401414 (2015) 2. Y. Suzuki et al., Solid State Ionics, 278, 172–176 (2015) 3. R. Sudo et al., Solid State Ionics, 262, 151–154 (2014) 4. C. Monroe and J. Newman, J. Electrochem. Soc., 151, A880–A886 (2004) 5. C. Monroe and J. Newman, J. Electrochem. Soc., 152, A396–A404 (2005) Figure 1

Li deposition is observed and measured on a solid electrolyte in the vicinity of a metallic current collector. Four types of ion-conducting, inorganic solid electrolytes are tested: Amorphous 70/30 mol% Li2S-P2S5, polycrystalline β-Li3PS4, and polycrystalline and single-crystalline Li6La3ZrTaO12 garnet. The nature of lithium plating depends on the proximity of the current collector to defects such as surface cracks and on the current density. Lithium plating penetrates/infiltrates at defects, but only above a critical current density. Eventually, infiltration results in a short circuit between the current collector and the Li-source (anode). These results do not depend on the electrolytes shear modulus and are thus not consistent with the Monroe–Newman model for “dendrites.” The observations suggest that Li-plating in pre-existing flaws produces crack-tip stresses which drive crack propagation, and an electrochemomechanical model of plating-induced Li infiltration is proposed. Lithium short-circuits through solid electrolytes occurs through a fundamentally different process than through liquid electrolytes. The onset of Li infiltration depends on solid-state electrolyte surface morphology, in particular the defect size and density.

Li-ion batteries that include all solid-state components show promise as an emerging energy storage technology, as the solid electrolyte can improve safety and enable longer cycle life than current batteries based on flammable and reactive liquid electrolytes. Mechanical compatibility and durability of the solid components during large intercalation-induced volume changes are key concerns. For example, deformation and fracture of the solid electrolyte during cycling is expected to slow Li-ion conduction and create pathways for dendritic growth of metallic Li that can short-circuit the device. Identification and evaluation of key mechanical parameters of solid electrolytes is critical to predicting designs mitigating mechanical degradation. With Li conductivity in excess of 10-4 S/cm, 70/30 mol% Li2S-P2S5 (LPS) is among the most promising solid electrolytes to date. Here we fabricated LPS and verified its amorphous structure and high ionic conductivity by X-ray diffraction and electrochemical impedance spectroscopy, respectively. We evaluated mechanical properties including Young’s elastic modulus, hardness, and fracture toughness via instrumented indentation as 18.5 +/- 0.9 GPa, 1.9 +/- 0.2 GPa, and 0.23 +/- 0.04 MPa m1/2, respectively. These measurements were enabled by immersion of the sample in nonreactive fluids that stabilized composition of this moisture-sensitive compound. We found Young’s modulus to be in agreement with prior published values derived with alternative measurement techniques, and report the first measurements of hardness and fracture toughness. While the stiffness and hardness of this solid electrolyte material were much lower than that of active materials within battery electrodes, the fracture toughness was also surprisingly low relative to typical glass and ceramic materials. Thus, the mechanical behavior of this candidate solid electrolyte is compliant (low resistance to reversible deformation) and brittle (low resistance to fracture). We will discuss the relationship between these observed mechanical properties and integration of these materials as solid electrolytes in all-solid-state batteries.