Effects of Zr doping on the surface energy and surface structure of UO2: Atomistic simulations

Xiao, Hongxing; Long, Chongsheng; Chen, Hongsheng; Tian, Xiaofeng; Wei, Tianguo; Zhao, Yi; Gao, Wei

doi:10.1016/j.apsusc.2015.05.168

Cited by 10 publications

(3 citation statements)

References 56 publications

(72 reference statements)

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“…The surface energy can be defined as the excess energy per unit area associated with the surface of a solid as compared with the bulk material [19]. The formula is as follows:…”

Section: Calculation Methods and Modelsmentioning

confidence: 99%

Effect of Cr Doping on the Surface Characteristics of Ni Metal Studied with First-Principles Calculation

Sun

Wang

Han

2018

Acta Metall. Sin. (Engl. Lett.)

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The influence of Cr doping on the surface characteristics of Ni metal, including the surface energy, work function, adsorption and dissociation, has been investigated by means of first-principles calculation based on density functional theory. The results reveal that with the increase in Cr doping amount, the surface energies for all (111), ( 110) and ( 100) surfaces increase, whereas the work functions of ( 111) and (100) surfaces decrease followed by an increase and that of ( 110) surface has been decreasing. On the typical Ni(111) and Ni-Cr(111) surfaces, the adsorption energies follow the sequence O [ OH [ H [ H 2 O, and the doping of Cr increases the chemical activity of surfaces leading to the improvement of adsorption energies. The H 2 O dissociating to OH and H is easier than the subsequent OH dissociating to O and H. The addition of Cr into Ni surface decreases the energy barriers and significantly increases the reaction rate constants.

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“…The surface energy can be defined as the excess energy per unit area associated with the surface of a solid as compared with the bulk material [19]. The formula is as follows:…”

Section: Calculation Methods and Modelsmentioning

confidence: 99%

Effect of Cr Doping on the Surface Characteristics of Ni Metal Studied with First-Principles Calculation

Sun

Wang

Han

2018

Acta Metall. Sin. (Engl. Lett.)

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“…Oleh karena itu, perlu dilakukan pengembangan pelet UO 2 untuk peningkatan kinerja sifat termiknya agar penggunaan elemen bakar burn up tinggi dapat beroperasi dengan selamat dan handal. Salah satu diantaranya adalah peningkatan konduktivitas panas pelet UO 2 yang berkorelasi dengan densitas pelet, mikrostruktur, panjang kisi maupun komposisi fasa [4,[7][8][9][10][11][12].…”

Section: Pendahuluanunclassified

“…Konduktivitas panas suatu material dipengaruhi oleh struktur kristal dan kesempurnaannya, dinamika kisi, kestabilan struktur, porositas dan ukuran butir [10,[14][15][16][17][18]. Hasil perhitungan dispersi phonon dengan simulasi molekular dinamis pada struktur elektronik UO 2 , mengungkapkan bahwa konduktivitas panas UO 2 yang rendah merupakan efek dari ketidakharmonisan struktur yang besar pada optical modes dari phonon sebagai pembawa panas [14].…”

Section: Pendahuluanunclassified

Mikrostruktur Dan Komposisi Fasa Pelet Sinter UO2 Dengan Penambahan Dopan Logam Zirkonium

Yulianto

Mutiara

2018

urania

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ABSTRAKMIKROSTRUKTUR DAN KOMPOSISI FASA PELET SINTER UO 2 DENGAN PENAMBAHAN DOPAN LOGAM ZIRKONIUM. Telah dilakukan karakterisasi pelet UO 2 sebagai bahan bakar PWR dengan penambahan dopan logam zirkonium pada pelet UO 2 . Penelitian ini bertujuan untuk mengetahui pengaruh penambahan logam zirkonium terhadap mikrostruktur dan komposisi fasa pelet UO 2 maupun stoikiometri (O/U) ratio. Logam zirkonium yang ditambahkan diharapkan terdistribusi merata dalam pelet UO 2 sehingga dapat meningkatkan kualitas pelet UO 2 . Pelet UO 2 difabrikasi dengan cara kompaksi dan penyinteran pada variasi penambahan logam zirkonium sebesar 0,3%, 0,5% dan 0,9%berat. Pelet UO 2 hasil kompaksi kemudian disinter pada temperatur 1700 o C dengan laju pemanasan 250 o C/jam selama 3 jam dalam media campuran gas hidrogen.Pelet UO 2 hasil sinter dikarakterisasi meliputi pengamatan visual, pengukuran densitas, pengamatan mikrostruktur menggunakan mikroskop optik dengan perbesaran 500x dan analisis fasa dengan difraksi sinar-X (XRD). Hasil analisis menunjukkan bahwa dengan penambahan dopan logam Zr sebesar 0,3%; 0,5% dan 0,9%berat tidak terdapat cacat maupun retak pada pelet UO 2 hasil sinter . Pelet sinter mempunyai rentang densitas 91%-93% TD dan memenuhi persyaratan sebagai bahan bakar PWR. Sementara itu, hasil analisis mikrostruktur pelet UO 2 dengan variasi persentase logam zirkonium diketahui bahwa keberadaan logam zirkonium tidak dapat dikonfirmasikan. Sementara itu, hasil evaluasi data uji XRD menggunakan perangkat lunak HighScore melalui pencocokan kurva hasil uji dengan struktur dari data base diperoleh struktur dan komposisi fasa dalam pelet hasil sinter. Fasa yang terbentuk pada pelet sinter UO 2 tanpa penambahan Zr dan dengan variasi penambahan Zr adalah senyawa UO 2 dan UO 3. Fraksi senyawa UO 3 dalam pelet sinter UO 2 berbanding lurus dengan persentase penambahan zirkonium yang ditunjukkan oleh stoikiometrinya (O/U) berdasarkan fraksi fasa yang terbentuk.

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Growth morphology of CL-20/HMX cocrystal explosive: insights from solvent behavior under different temperatures

Han

Li²,

Gou

et al. 2017

J Mol Model

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A 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) /1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX)-isopropanol (IPA) interfacial model was constructed to investigate the effect of temperature on cocrystal morphology. A constant volume and temperature molecular dynamics (NVT-MD) simulation was performed on the interfacial model at various temperatures (295-355 K, 20 K intervals). The surface electrostatic potential (ESP) of the CL-20/HMX cocrystal structure and IPA molecule were studied by the B3LYP method at 6-311++G (d, p) level. The surface energies, polarities, adsorption energy, mass density distribution, radial distribution function (RDF), mean square displacement (MSD) and relative changes of attachment energy were analyzed. The results show that polarities of (1 0 0) and (0 1 1) cocrystal surfaces may be more negative and affected by IPA solvent. The adsorption energy per area indicates that growth of the (1 0-2) face in IPA conditions may be more limited, while the (1 0 0) face tends to grow more freely. MSD and diffusion coefficient (D) analyses demonstrated that IPA molecules gather more easily on the cocrystal surface at lower temperatures, and hence have a larger effect on the growth of cocrystal faces. RDF analysis shows that, with the increasing of temperature, the strength of hydrogen bond interactions between cocrystal and solvent becomes stronger, being highest at 335 K for the (1 0 0) and (0 1 1) interfacial models. Results of relative changes of modified attachment energy show that (1 0 0) and (0 1 1) faces tends to be larger than other faces. Moreover, the predicted morphologies at 295 and 355 K are consistent with experimental values, proving that the CL-20/HMX-IPA interfacial model is a reasonable one for this study. Graphical Abstract Construction of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) /1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX)-isopropanol (IPA) interfacial model, analysis, and morphology prediction of cocrystal.

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Effects of Zr doping on the surface energy and surface structure of UO2: Atomistic simulations

Cited by 10 publications

References 56 publications

Effect of Cr Doping on the Surface Characteristics of Ni Metal Studied with First-Principles Calculation

Effect of Cr Doping on the Surface Characteristics of Ni Metal Studied with First-Principles Calculation

Mikrostruktur Dan Komposisi Fasa Pelet Sinter UO2 Dengan Penambahan Dopan Logam Zirkonium

Growth morphology of CL-20/HMX cocrystal explosive: insights from solvent behavior under different temperatures

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