Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Densification”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Fabrication and characterization of powder metallurgy tantalum components prepared by high compaction pressure technique

The present study has investigated the consolidation behaviors of tantalum powders during compaction and sintering, and the characteristics of sintered components. For die compaction, the densification behaviors of the powders are simulated by finite element analyses based on the yield function proposed by Shima and Oyane. Accordingly, the green density distribution for coarser particles is predicted to be more uniform because they exhibits higher initial relative tap density owing to lower interparticle friction. It is also found that cold isostatic pressing is capable of producing higher dense compacts compared to the die pressing. However, unlike the compaction behavior, the sintered density of smaller particles is found to be higher than those of coarser ones owing to their higher specific surface area. The maximum sintered density was found to be 0.96 of theoretical density where smaller particles were pressed isostatically at 400 MPa followed by sintering at 2000 °C. Moreover, the effects of processing conditions on grain size and texture were also investigated. The average grain size of the sintered specimen is 30.29 μm and its texture is less than 2 times random intensity. Consequently, it is concluded that the higher pressure compaction technique is beneficial to produce high dense and texture-free tantalum components compared to hot pressing and spark plasma sintering. - Highlights: • Higher Ta density is obtained from higher pressure and sintering temperature. • High compaction method enables P/M Ta to achieve the density of 16.00 g·cm{sup −3}. • A P/M Ta component with fine microstructure and random orientation is developed.

36 MATERIALS SCIENCE↗
DOE OSTI2017

The effect of Si on the microstructure and mechanical properties of spark plasma sintered boron carbide

Highlights: • Si addition leads to a dense final product at a low sintering temperature. • The added Si preferentially formed SiC and borosilicate glass instead of replacing the chain atoms in boron carbide. • The hardness of our Si-containing boron carbide is 30–35% greater than currently in-use commercial boron carbide plates. - Abstract: Fully dense boron carbide discs were achieved by spark plasma sintering boron carbide powders with 10 wt% silicon. The silicon did not diffuse into boron carbide grains to produce a solid solution of Si-doped boron carbide; instead the silicon reacted with impurities in the starting powder to form β-SiC and borosilicate glass. The resultant new phases facilitated densification of the multiphase ceramic through liquid phase-assisted sintering. The resultant material exhibits improved hardness (34.3 GPa Vikers hardness under 1 kg load) with toughness comparable to both Si-free and commercially available boron carbide.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Preparation, microstructure and properties of AlN/CBC composites

Highlights: • AlN/CBC composites can be prepared by gelcasting and pressureless sintering method. • Suitable sintering additive content and increasing sintering temperature help to improve properties of composite. • Relative density, C content and microstructure et al. have effect on properties of composite. - Abstract: Gelcasting method with nontoxic biopolymer as gel former can be used to prepare ceramics with complex shape. AlN ceramic bonded carbon (AlN/CBC) composites with light weight were fabricated by gelcasting and pressureless sintering method using nontoxic agarose as gel former with Y{sub 2}O{sub 3} + CaF{sub 2} as sintering additive. The effect of sintering additive content and sintering temperature on the microstructure, flexural strength and thermal conductivity of composites was investigated. The results reveal that, as the temperature decreases, the raw powders solidify into three-dimensional net structures through abundant hydrogen bonds in the agarose. High sintering temperature facilitates densification and improves mechanical and thermal properties of the composites. Increasing sintering additive content can also tune the density and raise flexural strength. The AlN/CBC composite containing 7 wt% sintering additive content, which was sintered at 2000 °C, exhibits the highest thermal conductivity. Relative density, C content and microstructure uniformity have effects on properties of AlN/CBC composite.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Meso-scale microstructural agglomerate quantification in boron carbide using X-ray microcomputed tomography

Highlights: • First known quantification of agglomerate defect distributions comprising of carbonaceous and aluminum nitride phases B{sub 4}C. • In-depth statistical analyses of the size, orientation, and morphology of the defects. • The determination of directional dependence of the hot-pressing direction on the agglomerate distributions. - Abstract: Failure in brittle materials is governed, in part, by the specific microstructure of that material, with heterogeneous microstructures generally leading to reduced mechanical properties and performance. In ceramics used for armor, an increase in compressive strength can be an indicator of improved ballistic performance. In hot-pressed boron carbide (B{sub 4}C) ceramic plates, failure has been attributed to carbonaceous flakes observed on the fracture surfaces of failed specimens. However, this current work shows agglomerates, in addition to the carbonaceous flakes, are present in this boron carbide. The density and distribution of these agglomerates are believed to influence the ballistic performance. Therefore, it is of interest to improve the quantification of meso-scale microstructural agglomerates so that strategies can be developed to mitigate them. This work is focused on the microstructural characterization of dumbbell-shaped compression specimens that were machined from a single tile of pressure-aided densification (PAD) B{sub 4}C, using high-resolution micro-computed tomography (microCT). Large clusters of non-B{sub 4}C agglomerates, up to 125 μm in diameter, were observed in addition to the typical smaller carbonaceous flakes and aluminum-based phases. Agglomerate size distribution, orientation, morphology, and spacing were quantified both parallel and perpendicular to the pressing direction. This defect quantification provides valuable information for a better understanding of the material microstructure which is a critical step in improving armor materials for the future.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Compressive deformation behavior and strain rate sensitivity of Al-cenosphere hybrid foam with mono-modal, bi-modal and tri-modal cenosphere size distribution

Highlights: • Cenospheres of different size ranges and distributions are used in hybrid aluminium foam. • Microstructure and deformation response of hybrid foam cenosphere size distribution. • Hybrid foam with bi or tri-modal cenosphere distribution exhibits higher strength and energy absorption. • The plateau stresses and energy absorption increased marginally with strain rate. • In case of bi- or tri-modal size distribution, strain rate sensitivity and strain rate sensitivity parameter is marginally lower. - Abstract: AlSi12Cu1Mg1 aluminium alloy-cenosphere closed cell hybrid foams with different kinds of cenosphere size distribution (mono-modal, bi-modal and tri-modal) are used to see the effect of cenosphere size distribution on their deformation behavior under quasi static compressive loading conditions at different strain rates. The stress strain curves are almost similar type irrespective of the cenosphere size distribution and strain rate. However, the plateau stress and energy absorption increased significantly when one used bi-modal and or tri-modal cenosphere size distribution instead of mono-modal cenosphere size distribution. These plateau stresses and energy absorption also increased marginally with strain rate. The densification strain remained almost invariant with strain rate and cenosphere size distribution. The strain rate sensitivity and strain rate sensitivity parameter is relatively lower in case of bi-modal and tri-modal cenosphere size distribution particularly at higher relative density.

36 MATERIALS SCIENCE↗
DOE OSTI2026

RU-net for automatic characterization of TRISO fuel cross sections

During irradiation, phenomena such as kernel swelling and buffer densification may impact the performance of tristructural isotropic (TRISO) particle fuel. Post-irradiation microscopy is often used to identify these irradiation-induced morphologic changes. However, each fuel compact generally contains thousands of TRISO particles. Manually performing the work to get statistical information on these phenomena is cumbersome and subjective. Here, to reduce the subjectivity inherent in that process and to accelerate data analysis, we used convolutional neural networks (CNNs) to automatically segment cross-sectional images of microscopic TRISO layers. CNNs are a class of machine-learning algorithms specifically designed for processing structured grid data. They have gained popularity in recent years due to their remarkable performance in various computer vision tasks, including image classification, object detection, and image segmentation. In this research, we generated a large irradiated TRISO layer dataset with more than 2,000 microscopic images of cross-sectional TRISO particles and the corresponding annotated images. Based on these annotated images, we used different CNNs to automatically segment different TRISO layers. These CNNs include RU-Net (developed in this study), as well as three existing architectures: U-Net, Residual Network (ResNet), and Attention U-Net. The preliminary results show that the model based on RU-Net performs best in terms of Intersection over Union (IoU). Using CNN models, we can expedite the analysis of TRISO particle cross sections, significantly reducing the manual labor involved and improving the objectivity of the segmentation results.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2018

Rock-welding materials development for deep borehole nuclear waste disposal

We report that various versions of deep borehole nuclear waste disposal have been proposed in the past in which effective sealing of a borehole after waste emplacement is generally required. In a high temperature disposal mode, the sealing function will be fulfilled by melting the ambient granitic rock with waste decay heat or an external heating source, creating a melt that will encapsulate waste containers or plug a portion of the borehole above a stack of the containers. However, there are certain drawbacks associated with natural materials, such as high melting temperatures, inefficient consolidation, slow crystallization kinetics, the resulting sealing materials generally being porous with low mechanical strength, insufficient adhesion to waste container surface, and lack of flexibility for engineering controls. In this study, we showed that natural granitic materials can be purposefully engineered through chemical modifications to enhance the sealing capability of the materials for deep borehole disposal. The present work systematically explores the effect of chemical modification and crystallinity (amorphous vs. crystalline) on the melting and crystallization processes of a granitic rock system. The approach can be applied to modify granites excavated from different geological sites. Several engineered granitic materials have been explored which possess significantly lower processing and densification temperatures than natural granites. Finally, those new materials consolidate more efficiently by viscous flow and accelerated recrystallization without compromising their mechanical integrity and properties.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Surfactant selection as a strategy for tailoring the structure and properties of UCT manganese oxides

Mesoporous manganese oxides were synthesized using the UCT inverse micelle templating method with four different Pluronic surfactants to investigate the effects on the morphology, microstructure and desulfurization behavior of these materials. All of the as-synthesized samples exhibited similar hierarchical microstructures, but the size and shape of the primary nanoparticles for each sample was different. The primary nanoparticle sizes for these samples vary between 2.3 and 7.0 nm. Most of the samples are crystalline and are composed of a mixture of Mn 3 O 4 and Mn 5 O 8 phases. The adsorption behavior of these samples was tested using a fixed bed reactor at a temperature of 200 °C. Microstructural analysis of the samples after the desulfurization tests revealed a transformation of the mesoporous manganese oxide to a dense manganese sulfide phase; this involves a volumetric expansion of the crystal, leading to densification and a rapid decay in the sorption capacity after the breakthrough point. The variation in the structure and properties of these materials is related to ratio of the PEO and PPO chain segment lengths in the Pluronic surfactants used. This indicates that the ratio must dictate the volume, shape and assembly of the inverse micelles in the UCT synthesis.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Development of a high-temperature Inconel 625 heat exchanger by model design and binder jetting additive manufacturing

A nickel-based Inconel 625 superalloy heat exchanger for high-temperature applications was developed via binder jetting additive manufacturing. The material properties were characterized first on printed and sintered parts. Two sintering temperatures were used to investigate the effects of the temperature on densification and microstructure. For channel geometry design, the heat transfer capabilities of the heat exchanger were optimized for the cross-section geometry of fluid flow channels in a counterflow configuration, and a stress analysis was conducted to investigate the effects of channel geometry. After headers were incorporated into the heat exchanger as a one-piece component, a prototype was printed. A complete depowdering was achieved via compressed air blowing, and sintering was performed with the developed profile. Ultimately, a one-piece heat exchanger with a nearly full density was obtained. Heat transfer tests were performed on this unit, and the results were compared with those from the simulations. In this study, systematic processes were developed for an additively manufactured Inconel-based heat exchanger for high-pressure, high-temperature heat transfer applications.

36 MATERIALS SCIENCE↗
DOE OSTI2010

Structural characteristics, sinterability and electrical conductivity of Ba-site non-stoichiometric Ba{sub x}Ce{sub 0.50}Zr{sub 0.40}Y{sub 0.10}O{sub 3-{delta}}

The influence of barium content on the structural characteristics, sinterability and electrical conductivity of proton conductor Ba{sub x}Ce{sub 0.50}Zr{sub 0.40}Y{sub 0.10}O{sub 3-{delta}} (x = 0.95, 0.97, 1.00, 1.03, 1.05) is investigated. Compositions with barium deficiency show the presence of fluorite precipitate detected by powder X-ray diffraction, whilst pure perovskite phase is present for other samples. Barium deficiency promotes the densification process of the samples. The electrical conductivity of Ba{sub x}Ce{sub 0.50}Zr{sub 0.40}Y{sub 0.10}O{sub 3-{delta}} increases with barium content, which is mainly ascribed to the decreased activation energy due to the increasing lattice volume, especially for the case in wet 5% H{sub 2}/Ar. The present results suggest that it is very important to control the stoichiometry of cations to obtain desirable perovskite type high temperature proton conductors.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Unusual ferromagnetism in high purity ZnO sintered ceramics

We report our novel result regarding the observation of unusual but clean ferromagnetic (FM) signature at room temperature (RT) in high pure (99.999%) ZnO bulk ceramics processed by slow step sintering schedule (SSSS). All the sintered samples showed ferromagnetic signature at room temperature. However, sample sintered at 850 {sup o}C showed more prominent M-H loop and saturation magnetization with respect to samples sintered at 500 {sup o}C and 1300 {sup o}C. Observation of FM behavior in sintered ceramics may be attributed to the presence of defects like cation (Zn)/anion (O) vacancies and interstitials created during the processing of sample. It is anticipated that SSSS promotes enhanced physical bulk as well as surface densification and at the same time confined the outgassing of free oxygen and Zn from the bulk which are acting as suitable defect sites inside the sintered grains and grain boundary junctions. Our micro-Raman and X-ray photoelectron studies revealed the existence of these defects which are believed to be the origin of the unconventional ferromagnetism (FM) of ZnO bulk ceramic at room temperature.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Effect of carbon nanofibers on the infiltration and thermal conductivity of carbon/carbon composites

Highlights: {yields} The CNFs improve the infiltration rate and thermal properties of carbon/carbon composites. {yields} The densification rate increases with the CNF content increasing at the beginning of infiltration. {yields} The values of the thermal conductivity of the composite obtain their maximum values at 5 wt.%. -- Abstract: Preforms containing 0, 5, 10, 15 and 20 wt.% carbon nanofibers (CNFs) were fabricated by spreading layers of carbon cloth, and infiltrated using the electrified preform heating chemical vapor infiltration method (ECVI) under atmospheric pressure. Initial thermal gradients were determined. Resistivity and density evolutions with infiltration time have been recorded. Scanning electron microscopy, polarized light micrograph and X-ray diffraction technique were used to analyze the experiment results. The results showed that the infiltration rate increased with the rising of CNF content, and after 120 h of infiltration, the density was the highest when the CNF content was 5 wt.%, but the composite could not be densified efficiently as the CNF content ranged from 10 wt.% to 20 wt.%. CNF-reinforced C/C composites have enhanced thermal conductivity, the values at 5 wt.% were increased by nearly 5.5-24.1% in the X-Y direction and 153.8-251.3% in the Z direction compared to those with no CNFs. When the additive content was increased to 20 wt.%, due to the holes and cavities in the CNF web and between carbon cloth and matrix, the thermal conductivities in the X-Y and Z directions decreased from their maximum values at 5 wt.%.

36 MATERIALS SCIENCE↗
DOE OSTI2012

High dielectric constant observed in (1 − x)Ba(Zr{sub 0.07}Ti{sub 0.93})O{sub 3}–xBa(Fe{sub 0.5}Nb{sub 0.5})O{sub 3} binary solid-solution

Binary solid-solutions of the (1 − x)Ba(Zr{sub 0.07}Ti{sub 0.93})O{sub 3}–xBa(Fe{sub 0.5}Nb{sub 0.5}O{sub 3}) system, with 0.1 ≤ x ≤ 0.9,were fabricated via a solid-state processing technique. X-ray diffraction analysis revealed that all samples exhibited a single perovskite phase. The BaFe{sub 0.5}Nb{sub 0.5}O{sub 3} also promoted densification and grain growth of the system. Dielectric measurements showed that all samples displayed a relaxor like behavior. The x = 0.1 sample presented a dielectric-frequency and temperature with low loss tangent (<0.07 at 10 kHz). For x > 0.2 samples, the dielectric data showed a broad dielectric constant–temperature curve with a giant dielectric characteristic. In addition, a high dielectric constant > 50,000 (at 10 kHz and temperature > 150 °C) was observed for the x = 0.9 sample.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Influence of processing route on electrical properties of Bi{sub 4}Ti{sub 3}O{sub 12} ceramics obtained by tape-casting technology

Highlights: • Bi{sub 4}Ti{sub 3}O{sub 12} thick films were obtained by SSR and PPM methods. • Both systems crystallize in an orthorhombic structure. • Textured characteristics were evidenced. • Grain morphology affects the P–E loops. - Abstract: Bismuth titanate powders (Bi{sub 4}Ti{sub 3}O{sub 12}-BIT) were fabricated by solid state reaction (SSR) and polymeric precursor method (PPM). From these powders, Bi{sub 4}Ti{sub 3}O{sub 12} pellets were obtained by tape-casting using plate-like templates particles prepared by a molten salt method. The BIT phase crystallizes in an orthorhombic structure type with space group Fmmm. Agglomeration of the particles, which affects the densification of the ceramic, electrical conduction and leakage current at high electric fields, was monitored by transmission electronic microscopy (TEM) analyses. FEG-SEM indicated that different shape of grains of BIT ceramics was influenced by the processing route. Both SSR and PPM methods lead to unsaturated P–E loops of BIT ceramics originating from the highly c-axis orientation and high conductivity which was affected by charge carriers flowing normally to the grain boundary of the crystal lattice.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Influence of sintering conditions on the microstructure and optical properties of Eu: CaF{sub 2} transparent ceramic

Highlights: • Eu: CaF2 ceramics sintering at different conditions were fabricated by HP method. • The results show that the temperatures have great effect on the microstructure. • The ceramic sintered at 600 °C/30 MPa has high transmittance and pore-free structure. • The diffusion and densification process mainly occurs between 350 °C and 500 °C. • The optical losses in ceramic were caused by structure defects and polishing damage. - Abstract: Nanopowders of the 5 at.% Eu doped CaF{sub 2} have been synthesized by co-precipitated method. X-ray diffraction (XRD) indicated that the samples corresponds to the cubic CaF{sub 2} phase and scanning electron microscopy (SEM) showed that the morphology of nanopowders were approximately spherical. The Eu: CaF{sub 2} transparent ceramics were fabricated by hot-pressing (HP) method at different P-T conditions in a vacuum environment. The fracture surface, the relative density, average grain size and shrinkage displacements were also studied to analysis the influence of sintering conditions on Eu: CaF{sub 2} ceramic. In comparison with other samples, the proper sintering temperature and pressure was 600 °C/30 MPa. The transmittance of ceramic was up to 79.7% and 88.85% at the wavelength of 760 nm and 2400 nm. Furthermore, the emission spectra of Eu: CaF{sub 2} transparent ceramics under 393.5 nm excitation was also discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Sintering behaviors, phases, and dielectric properties of MO-TeO2-V2O5 (M = Ca, Sr, Ba) ultralow temperature ceramics

Highlights: • Introduction of TeO{sub 2} to MO-V{sub 2}O{sub 5} (M = Ca,Sr,Ba) ceramics promoted a M{sub 2}V{sub 2}O{sub 7} phase formation, and obtain excellent dielectric properties and a densification sintering at below 600°. • Chemical compatibility of ULTCC ceramics with aluminum electrode indicated that aluminum did not react with MO-TeO{sub 2}-V{sub 2}O{sub 5} ceramics. • Aluminum easily encouraged the transformation of M{sub 2}V{sub 2}O{sub 7} structures to M{sub 3}(VO{sub 4}){sub 2} structures and other structures under the ultra-low temperature sintering. - Abstract: Influences of TeO{sub 2} on phase evolutions and sintering behaviors of MO-TeO{sub 2}-V{sub 2}O{sub 5} (M = Ca, Sr, Ba) ultralow temperature ceramics were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Dielectric properties of MO-TeO{sub 2}-V{sub 2}O{sub 5} (M = Ca, Sr, Ba) ceramics and their chemical compatibility with an aluminum electrode were also studied. Introducing TeO{sub 2} to MO-V{sub 2}O{sub 5} (M = Ca, Sr, Ba) ceramics obviously decreased the sintering temperature and promoted formation of M{sub 2}V{sub 2}O{sub 7} (M = Ca, Sr, Ba) phases. Also, dielectric properties mainly depend on the amount of TeO{sub 2} added to MO-TeO{sub 2}-V{sub 2}O{sub 5} ceramics. Investigation of chemical compatibility with aluminum shows that aluminum does not react chemically with MO-TeO{sub 2}-V{sub 2}O{sub 5} ceramics; however, aluminum causes transformation of M{sub 2}V{sub 2}O{sub 7} phases to other phases (such as M{sub 3}(VO{sub 4}){sub 2}) to be easier. Sintering temperature of MO-TeO{sub 2}-V{sub 2}O{sub 5} (M = Ca, Sr, Ba) ceramics can be regulated below 600 °C, which is much less than the melting point of aluminum. In addition, MO-TeO{sub 2}-V{sub 2}O{sub 5} (M = Ca, Ba) ceramics maintain quality factors of ∼18,000 GHZ, a dielectric constant of 10–12, and dielectric loss lower than 10{sup −4}.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Optical, morphological and durability studies of quaternary chalcogenide Ge-Sb(As)-(S,Te) films

Highlights: • Films of two glassy chalcogenide systems of Ge{sub x}-Sb/As{sub 40-x}-S{sub 50}-Te{sub 10} were studied. • Optical constants as function of films composition are obtained in 0.25–30 μm range. • The transparent zone of the films is in the (0.6–2.5) μm spectral range. • The vibrational modes were determined from IR-SE, FTIR and Raman. • The stability of the films after QT was proved by AFM, SEM and SE analyses. - Abstract: Thin films from two glassy systems of Ge{sub x}Sb{sub 40-x}S{sub 50}Te{sub 10} and Ge{sub x}As{sub 40-x}S{sub 50}Te{sub 10}, with compositions x = 10, 20 and 27 at. %, were deposited on optical glass substrates by vacuum thermal evaporation of powdered parent chalcogenide glasses. The complex refractive index and dielectric constants of the films are determined by ellipsometry in a wide spectral range of 0.25–30 μm. In the transparent spectral region of 0.6–2.5 μm the refractive index values are within 2.9–2.3 and 3.3–2.4 for the As-contained and Sb-contained films, respectively. From the IR and Raman data analysis the basic chemical and oxygen-related impurity bonds are identified. The films durability properties were established by applying the US Military Standard quality tests. The quality-test-induced-changes in surface morphology were evaluated. The films are relatively stable after quality test treatments, which cause a small degree of densification and surface roughening for Sb-containing films and surface flattening for As-containing ones.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Unveiling the structural transformations in glassy solid electrolyte adapted to high-stress cycles

Brittleness of glass–ceramic and ceramic ion conductors is considered as a main roadblock for their implementation as electrolytes in solid-state batteries where the fractures often occur due to the pressure exerted by metallic lithium. In this regard, nano- and micro-scale ductility of the solid electrolyte allows reducing such pressure without formation of cracks. Among different types of solid state ion conductors, phosphate invert glasses seem to be promising in achieving such ductility. We report the mechanical behavior of lithium phosphorous oxynitride (LiPON) invert glass probed by static and cyclic nanoindentation. Repeated application of high intensity stress results in densification and shear deformation of material allowing LiPON to accommodate the ~ 22% nominal strain imposed by the nanoindenter without cracking. Ability to do this under repeated loading indicates robustness of LiPON when used in lithium metal batteries under cyclic charge and discharge. Using Raman spectroscopy with unsupervised K-means clustering we reveal pressure-induced formation of P 2 O 7 units which migrate to the periphery of the residual hardness impressions with cycling resulting in surface morphology of LiPON superficially similar to that of deformed bulk metallic glass.

36 MATERIALS SCIENCE↗