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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.

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At least 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Synthesis, structural and electrical properties of a new cobalt arsenate NaCo{sub 2}As{sub 3}O{sub 10}

The title compound sodium dicobalt triarsenate NaCo{sub 2}As{sub 3}O{sub 10} has been synthesized by solid state reaction. Crystal structure and electrical properties were studied by X-ray diffraction and complex impedance spectroscopy, respectively. The obtained structural model is supported by charge-distribution (CHARDI) analysis and bond-valence-sum (BVS) validations tools. The structure (triclinic, P−1, a=6.800 (8) Å, b=7.816 (9) Å, c=8.718 (3) Å, α=108.03 (2)°, β=108.48 (3)°, γ=100.11 (2)°) can be described as a three-dimensional framework resulted from corner-connection between cobalt metallic chains running along [−110] and As{sub 3}O{sub 10} groups; the negative charge is balanced by Na{sup +} ions which house the two tunnels parallel to a and b axes. Ball milling was used as mechanical means to reduce the particles sizes of the synthesized powder. At the optimal sintering temperature of 650 °C, 85% of the relative density was obtained. The conductivity measurements show that NaCo{sub 2}As{sub 3}O{sub 10} is a cationic conductor with an activation energy of 0.48 eV and a conductivity of σ=1.2×10{sup −5} S cm{sup −1} at 310 °C. The BVS model is extended to simulate the ionic migration pathways of alkali cations in the anionic framework. - Graphical abstract: 1D pathways link Na atoms along the a-axis with bond valence mismatch |ΔV(Na)|=0.64 v.u. - Highlights: • A new single crystal NaCo{sub 2}As{sub 3}O{sub 10} was grown by solid state reaction and its structure determined by single-crystal X-ray diffraction. • The purity of the powder sample was verified by Rietveld refinement. • The CIS measurements were optimized and the obtained spectra were fitted by electrical equivalent circuits. • The conduction pathways for Na{sup +} cations are simulated by means of the bond valence sum model.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Examining the creep strengthening nanoprecipitation in novel highly reinforced heat resistant steels

Here we studied the creep strengthening nanoprecipitation in novel heat resistant steels strengthened by a high density of stable nanoprecipitates. The results show that the high number density of MX nanoprecipitates within the martensitic laths in these steels comes from the great amount of MX former elements present in their chemical compositions and the high dislocation density generated by the martensitic transformation that takes place during cooling after austenitization. These dislocations act as nucleation sites for these nanoprecipitates during the tempering applied after the austenitization and quenching. Atom probe tomography measurements show that these nanoprecipitates are rich in Nb, V, Cr and N for the HDSN1 and HDSN2 steels and V, Cr and N for the HDSN3 steel. The distribution of the nanoprecipitates within the martensitic laths suggests that the creep strengthening produced by the Nb, V, Cr and N nanoprecipitates in the HDSN1 and HDSN2 steels is more effective at pinning dislocations at high temperature than that obtained in the HDSN3 steel by the V, Cr and N nanoprecipitates. However, the high amount of W in the HDSN3 steel enhances the solid solution strengthening at high temperatures, resulting in a similar high temperature strength for all HDSN steels.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Synthesis and thermoelectric/electrical characterization of electrodeposited Sb{sub x}Te{sub y} thin films

Sb{sub x}Te{sub y} films were potentiostatically electrodeposited from acidic nitric baths at room temperature by controlling the applied potential. Near-stoichiometric Sb{sub 2}Te{sub 3} thin films were obtained at applied potentials between −0.15 and −0.30 V vs. saturated calomel electrode (SCE). Post-annealing in a reducing environment resulted in an improvement in the crystal structure without the evaporation of the Te element. This result was indicated by a significant reduction in the electrical resistance and decrease in the FWHM of the main diffraction peaks. The power factor (σS{sup 2}) increased from 44.2 to 372.1 μW/m K{sup 2} after annealing at 473 K.

36 MATERIALS SCIENCE↗
DOE OSTI2012

La{sub 0.5}Sr{sub 0.5}TiO{sub 3} nanopowders prepared by the hydrothermal method

Graphical abstract: LRTEM image of the single-phase La{sub 0.5}Sr{sub 0.5}TiO{sub 3} particles. It is seen from the figure that the product has a plate-like morphology with average particles sizes in the range of 100–300 nm. In addition, the SAED data taken from an individual particle (lower inset) shows the presence of sharp diffraction rings, which are indicative of polycrystalline La{sub 0.5}Sr{sub 0.5}TiO{sub 3} formation. The high-resolution TEM image (upper inset) shows for further confirmation of a crystalline structure of La{sub 0.5}Sr{sub 0.5}TiO{sub 3} powder. This image shows a clearly resolved crystalline domain with uniform interplanar spacing of 0.276 nm. Highlights: ► La{sub 0.5}Sr{sub 0.5}TiO{sub 3} nanopowder is prepared in 2 M KOH solution by hydrothermal method. ► The solution is heat treated at 220 °C for 24 h in air. ► LRTEM reveals a plate-like morphology of particle with average size of 100–300 nm. ► HRTEM image shows a crystalline domain with interplanar spacing of 0.276 nm. -- Abstract: La{sub 0.5}Sr{sub 0.5}TiO{sub 3} nanopowders were prepared by the hydrothermal method. The influence of processing parameters, including KOH concentration, reaction temperature and reaction time on the obtained products were studied. The structure and morphology of the obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The XRD results show that pure phase La{sub 0.5}Sr{sub 0.5}TiO{sub 3} nanopowders can be successfully synthesized with 2 M KOH concentration at a low temperature of 220 °C for 24 h. In addition, the product has a plate-like shape with particle sizes in the range of 25–100 nm as estimated by TEM.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Graphene oxide foams and their excellent adsorption ability for acetone gas

Graphical abstract: - Highlights: • GO and RGO foams were prepared using a simple and green method, unidirectional freeze-drying. • The porous structure of the foams can be adjusted by changing GO concentrations. • GO and RGO foams show good adsorption efficiency for acetone gas. - Abstract: Graphene oxide (GO) and reduced graphene oxide (RGO) foams were prepared using a unidirectional freeze-drying method. These porous carbon materials were characterized by thermal gravimetric analysis, differential scanning calorimetry, X-ray photoelectron spectroscopy and scanning electron microscopy. The adsorption behavior of the two kinds of foams for acetone was studied. The result showed that the saturated adsorption efficiency of the GO foams was over 100%, and was higher than that of RGO foams and other carbon materials.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Using laser-induced thermal voxels to pattern diverse materials at the solid–liquid interface

We describe a high-resolution patterning approach that combines the spatial control inherent to laser direct writing with the versatility of benchtop chemical synthesis. By taking advantage of the steep thermal gradient that occurs while laser heating a metal edge in contact with solution, diverse materials comprising transition metals are patterned with feature size resolution nearing 1 μm. We demonstrate fabrication of reduced metallic nickel in one step and examine electrical properties and air stability through direct-write integration onto a device platform. In conclusion, this strategy expands the chemistries and materials that can be used in combination with laser direct writing.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Using phase boundary mapping to resolve discrepancies in the Mg 2 Si–Mg 2 Sn miscibility gap

Mg 2 Si–Mg 2 Sn compositions within the Mg–Si–Sn materials system have potential as inexpensive, efficient thermoelectrics. These compositions lie specifically along the pseudobinary line with compositions of Mg 2 Si 1-x Sn x . The alloying and possible nanostructuring within the miscibility gap could further increase the thermoelectric figure of merit (zT) for these materials. However, the solubility limits of the miscibility gap differ greatly in the literature. Such a discrepancy could be a result of differing Mg-compositions due to excess magnesium added during sample annealing. To define these limits better and explain the change in proposed solubility limits based on magnesium content, the three-phase regions on either side of the pseudobinary phase region are phase boundary mapped and defect energy calculations are performed. This study presents a new understanding of the Mg–Si–Sn ternary phase diagram around the pseudobinary phase region. The solubility limits on either side of the pseudobinary should be essentially identical between the Mg-rich and Mg-poor three-phase regions unless the system temperature is brought above about 565 °C, at which eutectic liquid Mg 0.9 Sn 0.1 forms. This creates a second Mg-rich three-phase region which intersects the pseudobinary with a lower Sn solubility. Thus, samples prepared along the pseudobinary line are not well-defined thermodynamically when excess magnesium is added. Excess Mg can push the system into a new three phase region with Mg 2 Si 1-x Sn x composition different from that of the true miscibility gap. This understanding presents new guidelines for evaluating the miscibility gap and assists strategies for microstructure engineering and thermoelectric material processing.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Synthesis, crystal structure and electrical proprieties of new phosphate KCoP{sub 3}O{sub 9}

Crystals of new tricyclophosphate KCoP{sub 3}O{sub 9} have been grown from solid state reaction and characterized by single crystal X-ray diffraction. KCoP{sub 3}O{sub 9} crystallizes in the hexagonal system, space group P6{sup ¯}c2, with a=6.616 (7) Å; c=9.788 (3) Å; V=371.06 (13) Å{sup 3}, Z=2. The final agreement factors are R=0.014, ωR=0.038, S(F{sup 2})=1.231. The structure of the title compound can be described as a three-dimensional framework built up of corner sharing CoO{sub 6} and PO{sub 4} polyhedra containing wide tunnels oriented along [001] direction and others, less broad, along [100] and [010] directions. The structural model was validated by bond valence sum (BVS) and charge distribution (CD) methods. Ball milling was used to reduce the particles sizes of the synthesized powder. At the optimal sintering temperature of 800 °C, a relative density of 85% was obtained. The microstructure was characterized by scanning electron microscopy. The electrical conductivity was 8.4×10{sup −7} S cm{sup −1} and 1.7×10{sup −4} S cm{sup −1} at 480 °C and 680 °C respectively. The activation energy deduced from the slope is 2.2 eV at low temperature region and 1.2 eV at high temperature region. The BVS model is extended to simulate the ionic migration pathways of alkali cations in the anionic framework. The BVS calculation shows one-dimensional pathways migration along c-axis. - Graphical abstract: 1D pathways link K atoms along c-axis with bond valence mismatch |ΔV(K)|=0.8 v.u. - Highlights: • A new single crystal KCoP{sub 3}O{sub 9} was grown by solid state reaction and its structure determined by single-crystal X-ray diffraction. • The purity polycrystalline of KCoP{sub 3}O{sub 9} sample was verified by Rietveld refinement. • The CIS measurements were optimized and the obtained spectra were fitted by electrical equivalent circuits. • The conduction pathways for the K{sup +} cations are simulated by means of the bond valence sum model.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Steam Corrosion Investigation of Single Silicon Carbide Nanostructures

Silicon carbide (SiC) has been advanced as an alternative to zircaloy for use as an accident-tolerant fuel cladding material in next-generation water-cooled reactors. This is due, in large part, to the predicted superior corrosion resistance of SiC, as compared to zircaloy, particularly at the high temperatures that are obtained in a nuclear reactor under accident conditions. The other favorable performance metrics of SiC include its enhanced mechanical stability, low neutron absorption, low chemical reactivity, and high radiation stability. Past reports, which include theoretical and isolated experimental activities, have studied the corrosion of bulk-scale SiC in reactor-like conditions. This report will present high-temperature steam corrosion results from single SiC nanofiber-based constructs. The changes in microstructure, and the evolution of oxide thickness and SiC recession with progressive corrosion will be characterized at the atomic-to-nanoscale using transmission electron microscopy (TEM). Furthermore, the corrosion-induced degradation in mechanical properties of the SiC nanofibers will be characterized using three-point bending tests involving an atomic-force microscope (AFM) in the contact mode.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Laboratory micro- and nanoscale X-ray tomographic investigation of Al–7 at.%Cu solidification structures

X-ray computed tomography across multiple length scales provides an opportunity to non-destructively visualize and quantify the micro- to nano-scale microstructural features of solidification structures in three dimensions. Aluminum–7 at.%copper samples were directionally solidified at three cooling rates (0.44, 0.67, and 1.33 °C/s), resulting in systematic changes in the as-solidified microstructure, which are difficult to quantify using traditional microscopic techniques. The cooling rate of a material affects its ultimate microstructure, and characterizing that microstructure is key to predicting and understanding its bulk properties. Here, two different laboratory X-ray computed tomography instruments were used to characterize as-solidified microstructures, including micro-scale computed tomography with approximately 1 mm field-of-view, ∼ 1.7 μm resolution, and nano-scale X-ray computed tomography ∼ 65 μm FOV, 150 nm resolution. Micro-scale X-ray radiography and computed tomography enabled a quantitative investigation of changes in the primary dendritic solidification structure with increasing cooling rate. Nano-scale absorption contrast X-ray computed tomography resolved the distinct phases of the lamellar eutectic structure and three dimensional measurements of the ∼ 1 μm interlamellar spacing. It is found that the lamella eutectic structure thickness is inversely proportional to the cooling rate. Nano-scale Zernike phase contrast was also used to image voids at eutectic colony boundaries. The application and resolution of these two instruments are discussed with respect to the resolvable features of the solidification structures. - Highlights: • Al–Cu eutectic is a model system for studying solidification microstructure. • X-ray computed tomography provides a 3D picture of these complex structures. • Micro-scale tomography images the primary and secondary dendritic structures. • Nano-scale tomography images the eutectic lamella and measures its thickness. • The ∼ 1 micrometer thickness of the eutectic lamella correlates to the cooling rate.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Microstructural and chemical characterization of a purple pigment from a Faiyum mummy portrait

Results are presented from analyses that were conducted to explain the presence of chromium, detected noninvasively using energy dispersive X-ray fluorescence (XRF), in the unusually large (2-3mm diameter) rough gem-like purple pigment particles in the paint used for a Faiyum mummy portrait. An approximately 50 µm diameter particle of the chromium-containing purple pigment was extracted from the Portrait of a Bearded Man, dated to Roman Imperial Egypt in the second century, circa 170-180 CE, accession #32.6 in the Walters Art Museum collection. The particle was characterized using energy dispersive X-ray fluorescence analysis, electron microscopy, diffraction, and atom probe tomography. It is demonstrated that the purple pigment particle is a heterogeneous organic pigment, specifically, a lake pigment likely derived from either plant or insect matter, which contains minor percentages of both transition metals and alkali / alkali earth metals, with nanometer-scale crystallites of lead carbonates and sulfates. The analyses revealed for the first time the nanoscale microstructure and stratigraphy in an ancient lake pigment. Results suggest that similarities with respect to time-period and place of production may be developed among unprovenienced Faiyum mummy portraits to help localize workshops or artists, using analyses focused on lake pigments to characterize specifically metal-based mordants.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Microstructure and phase evolution in single phase CuInSe{sub 2} particles synthesized using elemental precursors

This paper reports solid-state formation reaction pathways for CuInSe{sub 2} particles synthesized by ultrasonic irradiation of elemental precursors followed by thermal annealing. Effective heat of formation (EHF) model is used to predict the first formed and consecutively formed phases of Cu+Se, In+Se compounds. The XRD patterns showed that CuSe and In{sub 4}Se{sub 3} phases are formed by ultrasonication of Cu+Se and In+Se precursors as predicted by the EHF model. As-sonicated Cu+In+Se precursors are thermally annealed and the CuInSe{sub 2} reaction is investigated based on the crystallographic relation between the binary phases. According to this model, when either CuSe{sub 2} or In{sub 4}Se{sub 3} phases are involved in the CuInSe{sub 2} formation, the reaction is categorized under suppressed reactions due to the missing epitaxial relation. An activated reaction is reported between CuSe and InSe phases due to the epitaxial match. The experimental findings support the crystallographic model by the completion of CuInSe{sub 2} formation reaction at 350 °C annealing temperature, which is after the phase transformation of CuSe{sub 2} to CuSe at 342 °C. - Graphical abstract: Ultrasonically irradiation and thermally annealing of Cu+In+Se mixture result in nanocrystalline CuInSe{sub 2} particles due to the proposed reaction pathways. - Highlights: • Nanocrsytalline CuInSe{sub 2} particles are synthesized from elemental precursors. • Sonochemistry is successfully utilized to prepare binary selenide phases. • Nanocrystalline CuInSe{sub 2} phase started to form with thermal annealing at 250 °C. • Single phase CuInSe{sub 2} is achieved at 350 °C.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Synthesis and Characterization of Chitosan-Grafted-Poly(2-Hydroxyaniline) Microstructures for Water Decontamination

Chitosan as a biopolymer, biodegradable, safe, non-toxic and widely abundant in nature was grafted with poly(2-hydroxyaniline) (P2-HA) through aqueous chemical oxidative copolymerization using ammonium persulphate in acetic acid medium. The grafting conditions were studied by varying grafting parameters. The effect of oxidant, 2-hydroxyaniline (2-HA) and acetic acid concentrations on the rate of copolymerization was studied. The synthesized graft characterized using UV–Vis, FTIR, TGA, XRD, and scanning electron microscope and compared with chitosan and P2-HA. The grafting enhances the thermal properties of chitosan. The effect of temperature on the rate of grafting copolymerization reaction was studied. The apparent activation energy (Ea) of the copolymerization reaction found to be 21.1116 kJ/mol. Also, ΔH{sup *} and ΔS{sup *}, were calculated and found to 22.8630 kJ/mol and −109.4290 J/mol K respectively. The mechanism of the grafting copolymerization reaction discussed. Chitosan, P2-HA and chitosan-graft-P2-HA used for the removal of Cr, Fe, Mn, Cu and Zn divalent ions from a contaminated water samples. The adsorption isotherm parameters are given.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Magnetic properties and adsorptive performance of manganese–zinc ferrites/activated carbon nanocomposites

Owing to the unique microstructure and high specific surface area, activated carbon (AC) could act as an excellent adsorbent for wastewater treatment and good carrier for functional materials. In this paper, manganese–zinc ferrites (Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}: MZF) were anchored into AC by hydrothermal method, resulting in the excellent magnetic response for AC nanocomposites in wastewater treatment. All results demonstrated the magnetic nanoparticles presented a spinel phase structure and existed in the pores of AC. The saturation magnetization (Ms) of MZF/AC nanocomposites increased with the ferrites content, while the pore volume and specific surface area declined. The Sample-5 possessed the specific surface area of 1129 m{sup 2} g{sup −1} (close to 1243 m{sup 2} g{sup −1} of AC) and Ms of 3.96 emu g{sup −1}. Furthermore, the adsorptive performance for organic dyes was studied and 99% methylene blue was adsorbed in 30 min. The magnetic AC nanocomposites could be separated easily from solution by magnetic separation technique. - Graphical abstract: The Sample-5 presented both good magnetic response and high BET surface area up to 1129 m{sup 2} g{sup −1} (close to AC of 1243 m{sup 2} g{sup −1}), which could be separated completely for about 60 s. MZF/AC nanocomposites (Sample-3, 4, 5) in our work could be used as the magnetic absorbents, which could be separated easily by an outer magnet after the MB adsorption. - Highlights: • Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} (MZF) as few as possible was implanted into activated carbon (AC) for the higher surface area. • Sample-5 possessed the high specific surface area (1129 m{sup 2} g{sup −1}) and the suitable Ms (3.96 emu g{sup −1}). • Methylene blue was adsorbed almost completely by MZF/AC nanocomposites in 30 min. • MZF/AC nanocomposites were separated easily from solution by magnetic separation technique.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Deformation behavior of crystalline/amorphous Al-Si nanocomposites with nanolaminate or nanofibrous microstructures

Deformation mechanisms in sputter-deposited crystalline Al/amorphous Si nanocomposites with nanolaminate or nanofibrous morphology are characterized by nanoindentation, micropillar compression testing and transmission electron microscopy (TEM). The nanofibrous composite having crystalline Al nanofibers with ~40–50 nm in length and 15–20 nm in diameter embedded in amorphous Si exhibits strain hardening to a maximum flow stress of 2.9 GPa and no shear band (SB) formation in compression up to plastic strain exceeding 24%. On the other hand, nanolaminate composite that is composed of 80 nm crystalline Al layers and 20 nm amorphous Si layers exhibits catastrophic SBs starting at plastic strains in the range of 5–10%. Cross-sectional TEM of the deformed samples reveals a high density of stacking faults and twin boundaries in Al nanofibers and no microshear bands in the nanofibrous composite, suggesting plastic deformation in amorphous Si phase and crystalline Al nanofibers. Further, molecular dynamics simulations revealed that the plastic deformation in amorphous Si phase in the cosputtered films could be favored by the decrease in flow strength of amorphous Si with increasing Al solute concentration trapped in Si.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Enhanced visible light photocatalytic activity of porous LaMnO{sub 3} sub-micron particles in the degradation of rose bengal

Highlights: • The monodispersed LaMnO{sub 3} microstructure was prepared by hydrothermal method. • The growth of different shaped LaMnO{sub 3} particles was obtained by varying annealing temperatures. • Porous LaMnO{sub 3} microstructure possessed superior photocatalytic activity in rose bengal dye. • The morphology and high surface area influence the enhanced photocatalytic activity. - Abstract: A perovskite LaMnO{sub 3} micro/nanostructure is a promising high-efficiency photocatalytic materials for the removal of various organic pollutants. This study presents the preparation of sub-micron LaMnO{sub 3} particles with polyvinyl pyrrolidone (PVP) as a structure directing agent to control the primary morphology and aggregations. Furthermore, the sample was annealed at different temperatures to improve the crystallinity and perovskite phase formations. The possible formation mechanism was explained based on the annealing temperatures. An attempt has been made to study the effect of different morphologies of LaMnO{sub 3} particles for the degradation of RB dye under visible light irradiation. The removal efficiency of 95% for RB dye in 60 min evidences the superior degradation capability of highly porous LaMnO{sub 3} particles. The photocatalytic activity not only depends on porous structure, but also strongly based on crystallinity, and specific surface area of LaMnO{sub 3} particles. Hence, the porous morphology displays a superior photocatalytic activity than other LaMnO{sub 3} microstructures.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Heavy ion irradiation-induced microstructural evolution in pyrochlore Lu{sub 2}Ti{sub 2}O{sub 7} at room temperature and 723 K

Polycrystalline pyrochlore Lu{sub 2}Ti{sub 2}O{sub 7} pellets were irradiated with 600 keV Kr{sup 3+} at room temperature and 723 K to a fluence of 4×10{sup 15} ions/cm{sup 2}, corresponding to an average ballistic damage dose of 10 displacements per atom in the peak damage region. Irradiation-induced microstructural evolution was examined by grazing incidence X-ray diffraction, and cross-sectional transmission electron microscopy. Incomplete amorphization was observed in the sample irradiated at room temperature due to the formation of nano-crystal which has the identical structure of pyrochlore, and the formation of nano-crystal is attributed to the mechanism of epitaxial recrystallization. However, an ordered pyrochlore phase to a swelling disordered fluorite phase transformation is occurred for the Lu{sub 2}Ti{sub 2}O{sub 7} sample irradiated at 723 K, which is due to the disordering of metal cations and anion vacancies. - Graphical Abstract: Polycrystalline pyrochlore Lu{sub 2}Ti{sub 2}O{sub 7} pellets were irradiated with 600 keV Kr{sup 3+} to a fluence of 4×10{sup 15} ions/cm{sup 2} at room temperature and 723 K, Incomplete amorphization was observed in the sample irradiated at room temperature due to the formation of nano-crystal. However, an ordered pyrochlore phase to a swelling disordered fluorite phase transformation is occurred for the Lu{sub 2}Ti{sub 2}O{sub 7} sample irradiated at 723 K, which is due to the disordering of metal cations and anion vacancies. - Highlights: Pyrochlore Lu{sub 2}Ti{sub 2}O{sub 7} pellets were irradiated by heavy ions at RT and 723 K. At RT irradiation, ~75% of amorphization was achieved. The nano-crystals were formed in the damage layer at RT irradiation. The formed nano-crystals enhanced the radiation tolerance of Lu{sub 2}Ti{sub 2}O{sub 7}. A pyrochlore to fluorite phase transformation was observed at 723 K irradiation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗