Electronic structure of UAl2 and UGa2

Shekar, N. V. Chandra; Sahu, P. Ch.; Kathirvel, V.; Chandra, Sharat

doi:10.1007/s12648-012-0165-4

Cited by 5 publications

(4 citation statements)

References 18 publications

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“…(Some figures may appear in colour only in the online journal) Transition metal (TM) carbides and nitrides have many industrial applications due to their high hardness, high melting point, excellent thermal conductivity, good wear and corrosion resistance [1]. The exploration of novel phases of TM carbides and nitrides is an alternative route in the quest for super hard materials as compared to systems formed with low atomic number (Z) elements like cubic boron nitride [2][3][4]. The essence of this approach is to have maximum valence electron charge density, basically contributed by the TM, and forming a p-d hybridized covalent bond between C and TM respectively.…”

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“…The essence of this approach is to have maximum valence electron charge density, basically contributed by the TM, and forming a p-d hybridized covalent bond between C and TM respectively. Among TMs Os is the least compressible and has the highest valence 3 Address for correspondence: High Pressure Physics Section, Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamilnadu, India. electron charge density of 0.572 electrons Å−3 .…”

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Synthesis of novel Ru₂C under high pressure–high temperature conditions

Kumar

Shekar

Chandra

et al. 2012

J. Phys.: Condens. Matter

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We report here, for the first time, synthesis of the Fe(2)N type hexagonal phase of ruthenium carbide by a high pressure-high temperature technique using a laser heated diamond anvil cell (LHDAC). The synthesis is carried out by laser heating a mixture of pure elements, Ru and C, at very low 'pressure' of 5 GPa and T ~ 2000 K. The structure of the temperature quenched high pressure phase is characterized by in situ high pressure x-ray diffraction (HPXRD) and is corroborated by ex situ TEM imaging and diffraction, carried out for the first time on the retrieved sample synthesized by LHDAC. The lattice parameters of Ru(2)C at ambient pressure are found to be a = 2.534 Å and c = 4.147 Å. In situ HPXRD studies up to 14.2 GPa yield a bulk modulus of 178(4) GPa. Electronic structure calculations reveal the system to be metallic in nature with a degree of covalence along the Ru-C bond. As ruthenium is isoelectronic to osmium, this result for Ru(2)C has significant implications in the synthesis and study of osmium carbides.

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Synthesis of novel Ru₂C under high pressure–high temperature conditions

Kumar

Shekar

Chandra

et al. 2012

J. Phys.: Condens. Matter

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“…However, new literature about ab initio studies of UAl 2 have not tested the DFT þ U approach to the best of our knowledge, for example see Refs. [41,65]. It is generally agreed that the actinideeactinide separation could enhance the localization of 5f electrons then diluting uranium atoms in a periodic cell should result in a wider density of states.…”

Section: Calculation Methodsmentioning

confidence: 99%

Energetics and electronic structure of UAl4 with point defects

Kniznik

Alonso

Gargano

et al. 2015

Journal of Nuclear Materials

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“…There is immense interest in the search for new super-hard materials with improved chemical and thermal stability [1,2]. Among the naturally occurring materials, diamond has the best mechanical properties, but the major drawback with diamond is that it reacts with iron and hence cannot be used for machining steel.…”

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confidence: 99%

Structural stability of W₂B₅under high pressure

Kumar

Shekar

Sahu

2015

Philosophical Magazine Letters

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High-pressure structural stability studies have been carried out on tungsten boride W 2 B 5 up to maximum pressure of 36 GPa using a Mao-Bell diamondanvil cell at beamline BR-12 of the ELETTRA synchrotron facility (λ = 0.68881 Å). The hexagonal phase (S.G:P6 3 /mmc) of W 2 B 5 is stable up to the maximum pressure studied. The bulk modulus is estimated to bẽ 347 GPa using the Birch-Murnaghan equation of state. The variation of lattice parameters and bond lengths B-B and W-B have been studied and the c-axis is seen to be marginally more compressible than the a-axis. IntroductionThere is immense interest in the search for new super-hard materials with improved chemical and thermal stability [1,2]. Among the naturally occurring materials, diamond has the best mechanical properties, but the major drawback with diamond is that it reacts with iron and hence cannot be used for machining steel. The search for materials with good mechanical properties has been in specific covalent substances, covalent and ioniccovalent compounds, and partially covalent compounds of transition metals (TM) with light elements. Compounds formed between TM and light elements like B have wideranging industrial applications owing to their high hardness, high melting point, excellent thermal conductivity, good wear and corrosion resistance properties [3][4][5][6]. The observed superiority of mechanical properties of TM borides, as compared to the nitrides or carbides, is attributed to the 'puckered layer of B atoms' in the boron lattice. Interest in this field has been renewed on account of the recent finding of a hardness greater than 45 GPa in ReB 2 [7]. However, WB 4 has been reported to have a hardness of 43 GPa [8] with a bulk modulus 339 GPa. Also an enhancement of the hardness of WB 4 up to 50 GPa with 1% doping of rhenium has been reported. In fact, tungsten borides offer a more economically viable option in the quest for super-hard materials. Because of wide-ranging interest in tungsten boride systems, various experimental studies and first-principle calculations have been reported [9][10][11][12][13][14][15]. High-pressure structural stability studies have been carried out on WB 4 [8] and the bulk modulus estimated to bẽ 326 GPa. There is considerable debate on the ratio of B to W in WB 4 , and recent

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Electronic structure of UAl2 and UGa2

Cited by 5 publications

References 18 publications

Synthesis of novel Ru₂C under high pressure–high temperature conditions

Synthesis of novel Ru₂C under high pressure–high temperature conditions

Energetics and electronic structure of UAl4 with point defects

Structural stability of W₂B₅under high pressure

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Electronic structure of UAl2 and UGa2

Cited by 5 publications

References 18 publications

Synthesis of novel Ru2C under high pressure–high temperature conditions

Synthesis of novel Ru2C under high pressure–high temperature conditions

Energetics and electronic structure of UAl4 with point defects

Structural stability of W2B5under high pressure

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Synthesis of novel Ru₂C under high pressure–high temperature conditions

Synthesis of novel Ru₂C under high pressure–high temperature conditions

Structural stability of W₂B₅under high pressure