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Article: Q-carbon as a new radiation-resistant material

Narayan, J. / Joshi, P. / Smith, J. / Gao, W. / Weber, W.J. / Narayan, R.J.

Carbon. 2022 Jan., v. 186

2022

Abstract: We have discovered that Q-carbon is extremely resistant to radiation damage under ion irradiations involving extreme atomic displacements and electronic excitations. Using 5 MeV Au ⁺ ions, the Q-carbon films on sapphire substrates were irradiated in the ... ...

Abstract	We have discovered that Q-carbon is extremely resistant to radiation damage under ion irradiations involving extreme atomic displacements and electronic excitations. Using 5 MeV Au ⁺ ions, the Q-carbon films on sapphire substrates were irradiated in the dose range 3.3–10 dpa (displacements-per-atom). After the ion irradiations, detailed studies on the atomic structure and bonding characteristics showed that atomic structure and bonding characteristics of amorphous Q-carbon remained essentially unchanged to 10 dpa of radiation damage, which is equivalent to over twenty years of neutron damage in a conventional reactor. There was an ion-beam mixed layer below the Q-carbon layer, whose thickness increased from 5 nm to 10 nm, as the dose increased from 3.3 to 10 dpa. This layer was found to be mostly amorphous with a mixture Al₂O₃ and Al₄C₃. This layer, formed as a result of enhanced forward scattering and ballistic ion beam mixing, exhibited composition consistent with detailed TRIM calculations. We also found that nanodiamonds (3 nm average size) embedded in Q-carbon grew to about 60 nm after 6.6 dpa and shrank to about 40 nm after 10 dpa. We discuss the mechanism for the growth and shrinkage of metastable phase of diamond under nonequilibrium ion irradiations.
Keywords	carbon ; nanodiamonds ; neutrons ; shrinkage
Language	English
Dates of publication	2022-01
Size	p. 253-261.
Publishing place	Elsevier Ltd
Document type	Article
ISSN	0008-6223
DOI	10.1016/j.carbon.2021.10.006
Database	NAL-Catalogue (AGRICOLA)

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Book ; Online: High entropy ceramics for applications in extreme environments

Ward, T. Z. / Wilkerson, R. P. / Musico, B. L. / Foley, A. / Brahlek, M. / Weber, W. J. / Sickafus, K. E. / Mazza, A. R.

2024

Abstract: Compositionally complex materials have demonstrated extraordinary promise for structural robustness in extreme environments. Of these, the most commonly thought of are high entropy alloys, where chemical complexity grants uncommon combinations of ... ...

Abstract	Compositionally complex materials have demonstrated extraordinary promise for structural robustness in extreme environments. Of these, the most commonly thought of are high entropy alloys, where chemical complexity grants uncommon combinations of hardness, ductility, and thermal resilience. In contrast to these metal-metal bonded systems, the addition of ionic and covalent bonding has led to the discovery of high entropy ceramics. These materials also possess outstanding structural, thermal, and chemical robustness but with a far greater variety of functional properties which enable access to continuously controllable magnetic, electronic, and optical phenomena. In this perspective, we outline the potential for high entropy ceramics in functional applications under extreme environments, where intrinsic stability may provide a new path toward inherently hardened device design. Current works on high entropy carbides, actinide bearing ceramics, and high entropy oxides are reviewed in the areas of radiation, high temperature, and corrosion tolerance where the role of local disorder is shown to create pathways toward self-healing and structural robustness. In this context, new strategies for creating future electronic, magnetic, and optical devices to be operated in harsh environments are outlined.
Keywords	Condensed Matter - Materials Science ; Condensed Matter - Disordered Systems and Neural Networks
Publishing date	2024-01-02
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Symmetry degeneration and room temperature ferroelectricity in ion-irradiated SrTiO

Zhang, F X / Xue, Haizhou / Keum, J K / Boulle, A / Zhang, Yanwen / Weber, W J

Journal of physics. Condensed matter : an Institute of Physics journal

2020 Volume 32, Issue 35, Page(s) 355405

Abstract: Polar phonon modes associated with room temperature ferroelectricity are observed in ... ...

Abstract	Polar phonon modes associated with room temperature ferroelectricity are observed in SrTiO
Language	English
Publishing date	2020-04-30
Publishing country	England
Document type	Journal Article
ZDB-ID	1472968-4
ISSN	1361-648X ; 0953-8984
ISSN (online)	1361-648X
ISSN	0953-8984
DOI	10.1088/1361-648X/ab8ec7
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Ion irradiation induced strain and structural changes in LiTaO

Zhang, F X / Velisa, G / Xue, H / Sellami, N / Trautmann, C / Zhang, Y / Weber, W J

Journal of physics. Condensed matter : an Institute of Physics journal

2021 Volume 33, Issue 18

Abstract: ... ...

Abstract	LiTaO
Language	English
Publishing date	2021-04-23
Publishing country	England
Document type	Journal Article
ZDB-ID	1472968-4
ISSN	1361-648X ; 0953-8984
ISSN (online)	1361-648X
ISSN	0953-8984
DOI	10.1088/1361-648X/abee3a
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Article ; Online: Local structure of Ni

Zhang, F X / Tong, Y / Velisa, G / Bei, H / Weber, W J / Zhang, Yanwen

Journal of physics. Condensed matter : an Institute of Physics journal

2019 Volume 32, Issue 7, Page(s) 74002

Abstract: The local structure of ... ...

Abstract	The local structure of Ni
Language	English
Publishing date	2019-11-01
Publishing country	England
Document type	Journal Article
ZDB-ID	1472968-4
ISSN	1361-648X ; 0953-8984
ISSN (online)	1361-648X
ISSN	0953-8984
DOI	10.1088/1361-648X/ab5388
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Article: Pressure induced structural transformation in Gd₂Ti₂O₇ and Gd₂Zr₂O₇.

Xiao, H Y / Weber, W J

Journal of physics. Condensed matter : an Institute of Physics journal

2011 Volume 23, Issue 3, Page(s) 35501

Abstract: Ab initio total energy calculations have been performed to study the phase stability of Gd(2)Ti(2)O(7) and Gd(2)Zr(2)O(7) pyrochlores over the pressure range from 0 to 60 GPa. Both compounds are unstable under pressure, and phase transformations to the ... ...

Abstract	Ab initio total energy calculations have been performed to study the phase stability of Gd(2)Ti(2)O(7) and Gd(2)Zr(2)O(7) pyrochlores over the pressure range from 0 to 60 GPa. Both compounds are unstable under pressure, and phase transformations to the defect-cotunnite structure are predicted. The phase transformation pressure of 43.6 GPa for Gd(2)Ti(2)O(7) is considerably larger than the value of 13 GPa for Gd(2)Zr(2)O(7), in good agreement with experiments. The decreased structural stability of Gd(2)Zr(2)O(7) under pressure, relative to Gd(2)Ti(2)O(7), is a consequence of the lower compressibility of the ⟨Zr-O⟩ bond and the higher compressibility of the ⟨Gd-O⟩ bond. In addition, the Gd 4f electrons are found to have only a small effect in determining the pressure induced phase transformation.
Language	English
Publishing date	2011-01-26
Publishing country	England
Document type	Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	1472968-4
ISSN	1361-648X ; 0953-8984
ISSN (online)	1361-648X
ISSN	0953-8984
DOI	10.1088/0953-8984/23/3/035501
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Oxygen vacancy formation and migration in Ce(x)Th(1-x)O2 solid solution.

Xiao, H Y / Weber, W J

The journal of physical chemistry. B

2011 Volume 115, Issue 20, Page(s) 6524–6533

Abstract: A local-density approximation with the Hubbard U correction (LDA+U) method has been employed to investigate oxygen vacancy formation and migration in Ce(x)Th(1-x)O(2). The addition of CeO(2) into ThO(2) significantly decreases the oxygen vacancy ... ...

Abstract	A local-density approximation with the Hubbard U correction (LDA+U) method has been employed to investigate oxygen vacancy formation and migration in Ce(x)Th(1-x)O(2). The addition of CeO(2) into ThO(2) significantly decreases the oxygen vacancy formation and migration energies. ThO(2) containing 50% CeO(2) exhibits the lowest calculated formation energy, 3.7 eV, and the lowest calculated migration energy, 0.2 eV, occurs for a CeO(2) content of 75%, suggesting that introducing CeO(2) into ThO(2) promotes the formation of mobile oxygen vacancies. If the ceria content is less than about 35%, the reduced Ce(x)Th(1-x)O(2) becomes antiferromagnetic (AFM), whereas the ferromagnetic (FM) state dominates for x values above about 35%, which may allow the tailoring of magnetic properties by varying the CeO(2) content.
Language	English
Publishing date	2011-05-26
Publishing country	United States
Document type	Journal Article
ISSN	1520-5207
ISSN (online)	1520-5207
DOI	10.1021/jp202016s
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Article ; Online: Temperature measurements during high flux ion beam irradiations.

Crespillo, M L / Graham, J T / Zhang, Y / Weber, W J

The Review of scientific instruments

2016 Volume 87, Issue 2, Page(s) 24902

Abstract: A systematic study of the ion beam heating effect was performed in a temperature range of -170 to 900 °C using a 10 MeV Au(3+) ion beam and a Yttria stabilized Zirconia (YSZ) sample at a flux of 5.5 × 10(12) cm(-2) s(-1). Different geometric ... ...

Abstract	A systematic study of the ion beam heating effect was performed in a temperature range of -170 to 900 °C using a 10 MeV Au(3+) ion beam and a Yttria stabilized Zirconia (YSZ) sample at a flux of 5.5 × 10(12) cm(-2) s(-1). Different geometric configurations of beam, sample, thermocouple positioning, and sample holder were compared to understand the heat/charge transport mechanisms responsible for the observed temperature increase. The beam heating exhibited a strong dependence on the background (initial) sample temperature with the largest temperature increases occurring at cryogenic temperatures and decreasing with increasing temperature. Comparison with numerical calculations suggests that the observed heating effect is, in reality, a predominantly electronic effect and the true temperature rise is small. A simple model was developed to explain this electronic effect in terms of an electrostatic potential that forms during ion irradiation. Such an artificial beam heating effect is potentially problematic in thermostated ion irradiation and ion beam analysis apparatus, as the operation of temperature feedback systems can be significantly distorted by this effect.
Language	English
Publishing date	2016-02
Publishing country	United States
Document type	Journal Article
ZDB-ID	209865-9
ISSN	1089-7623 ; 0034-6748
ISSN (online)	1089-7623
ISSN	0034-6748
DOI	10.1063/1.4941720
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: Effect of Holstein genotype on innate immune and metabolic responses of heifers to lipopolysaccharide (LPS) administration

Cousillas-Boam, G / Weber, W.J / Benjamin, A / Kahl, S / Heins, B.J / Elsasser, T.H / Kerr, D.E / Crooker, B.A

Domestic animal endocrinology. 2020 Jan., v. 70

2020

Abstract: Heifers (n = 4/genotype) from unselected (stable genotype since 1964, UH) and contemporary (CH) Holsteins that differed in milk yield (6,200 and 11,100 kg milk/305 d) were used to assess the impact of selection on innate immune and acute-phase response ... ...

Abstract	Heifers (n = 4/genotype) from unselected (stable genotype since 1964, UH) and contemporary (CH) Holsteins that differed in milk yield (6,200 and 11,100 kg milk/305 d) were used to assess the impact of selection on innate immune and acute-phase response to an endotoxin (lipopolysaccharide; LPS). Jugular catheters were implanted 24 h before LPS administration. Blood samples were collected at −1, −0.5, 0, 1, 2, 3, 4, 6, 8, and 24 h relative to iv administration of 0.5 μg LPS/kg BW. Rectal body temperature (BT) was determined at these sampling times and at 5 and 7 h. Dermal biopsies were collected after the 24 h blood sample and processed to isolate fibroblasts. Plasma was analyzed for tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), serum amyloid A (SAA), xanthine oxidase (XO), and nitrate + nitrite (NOx), cortisol, glucose, and IGF-1 content. Isolated fibroblasts were exposed to IL-1β or LPS and IL-6 and IL-8 content of culture media determined. Exposure to LPS increased BTs and plasma concentrations of TNF-α, IL-6 SAA, XO, cortisol, and glucose (P < 0.05) in both genotypes. Plasma concentrations of TNF-α, XO, NOx, and glucose did not differ (P > 0.25) between the genotypes, but IL-6 and SAA concentrations were reduced (P < 0.05) in CH relative to UH heifers while cortisol and IGF-1 concentrations tended (P < 0.08) to be reduced in CH heifers. After 36 h exposure to LPS, concentrations of IL-6 were greater (P < 0.05) in culture media from incubations of CH than UH fibroblasts but concentrations of IL-8 did not differ between genotypes. There was a trend (P = 0.08) for IL-8 concentrations to be reduced in media from CH fibroblasts exposed to IL-1β for 24 h but IL-6 concentrations did not differ between genotypes. Results indicate 50 yr of selection has reduced the robustness of the innate immune and acute-phase response to LPS in the contemporary Holstein heifer.
Keywords	Holstein ; amyloid ; blood sampling ; blood serum ; body temperature ; cortisol ; endotoxins ; fibroblasts ; genotype ; glucose ; heifers ; interleukin-6 ; interleukin-8 ; lipopolysaccharides ; milk yield ; nitrates ; nitrites ; tumor necrosis factor-alpha ; xanthine oxidase
Language	English
Dates of publication	2020-01
Publishing place	Elsevier Inc.
Document type	Article
Note	NAL-AP-2-clean
ZDB-ID	594468-5
ISSN	1879-0054 ; 0739-7240
ISSN (online)	1879-0054
ISSN	0739-7240
DOI	10.1016/j.domaniend.2019.07.002
Database	NAL-Catalogue (AGRICOLA)

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Article: Correlation between Cr3+ Luminescence and Oxygen Vacancy Disorder in Strontium Titanate under MeV Ion Irradiation

Crespillo, M. L / Agulló-López F / Graham J. T / Weber W. J / Zhang Y

The Journal of Physical Chemistry C. 2017 Sept. 14, v. 121, no. 36

2017

Abstract: Strontium titanate (SrTiO3), a model system with a strongly correlated electronic structure, has attracted much attention recently because of its outstanding physicochemical properties and considerable potentials for technological applications. The ... ...

Abstract	Strontium titanate (SrTiO3), a model system with a strongly correlated electronic structure, has attracted much attention recently because of its outstanding physicochemical properties and considerable potentials for technological applications. The capability to control oxygen vacancy profiles and their effect on valence states of cations will increase significantly the functionality of devices based on transition metal oxides. This work presents new insights into the near-infrared luminescence emission of Cr3+ centers in stoichiometric SrTiO3 induced using 3 MeV protons at temperatures of 100 K, 170 K, and room temperature. The study covers a wide spectral range, including near-infrared, visible, and near-UV regions. Our main purpose is to investigate the role of the oxygen vacancies introduced by energetic charged particles on the shape and yield of induced luminescence spectra, in particular to explore the interplay between the Cr3+ luminescence at 1.55 eV and oxygen disorder. A clear correlation is found between the decay of the Cr luminescence yield during irradiation and the growth of a band at 2.0 eV, well-resolved below 170 K, which has been very recently attributed to d–d transitions of electrons self-trapped as Ti3+ in the close vicinity of oxygen vacancies. This correlation suggests irradiation-induced oxidation of the Cr3+ (Cr3+ → Crn+, n > 3) via trapping of irradiation-induced holes, while the partner electrons are self-trapped as Ti3+. These new results provide effective guidelines for further understanding the electronic and photocatalytic behavior of STO:Cr3+.
Keywords	ambient temperature ; cations ; chromium ; electrons ; guidelines ; irradiation ; luminescence ; models ; oxidation ; oxides ; oxygen ; photocatalysis ; physical chemistry ; physicochemical properties ; protons ; strontium ; trapping
Language	English
Dates of publication	2017-0914
Size	p. 19758-19766.
Publishing place	American Chemical Society
Document type	Article
ISSN	1932-7455
DOI	10.1021%2Facs.jpcc.7b04352
Database	NAL-Catalogue (AGRICOLA)

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