Hydrides of YPd3: Electronic structure and dynamic stability. (12th January 2015)

• Record Type: Journal Article
• Authors: Sharma, Ramesh; Dwivedi, Shalini; Sharma, Yamini
• Is Part Of: International journal of hydrogen energy. Volume 40:Number 2(2015)
• Page Start: 1071
• Page End: 1082
• Publication Date: 2015-01-12
• Subjects: Hydrides -- Electronic structure -- Optical properties -- Transport properties -- Phonon modes; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2014.11.029
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: Ternary intermetallic YPd3 is known to exhibit superior hydrogen storage capacity compared to pure palladium. To understand the characteristics of YPd3 on hydrogenation, the ground state electronic and dynamical properties were computed by two computational methods, the full potential linearized plane wave and projector augmented wave methods within the density functional theory. Hydrogen can be inserted in YPd3 at various octahedral sites, giving rise to model structures YPd3 H and YPd3 H4 which retain the L12 crystal structure. The calculated energy bands confirm the metallic nature of YPd3 and also exhibit greater dispersion of bands with increase in hydrogen content. Large variations in the optical constants such as transmittance is observed (by ∼40% in the violet region) with insertion of hydrogen, YPd3 may have thus have applications as a sensing device for monitoring hydrogen for using hydrogen safely. The electronic component γ obtained from the temperature dependent specific heats, is related to the density of states at the Fermi level which may be co-related to instability of hydrides. The modes at Γ-point in YPd3 H and at X and M-points in YPd3 H4 give rise to high peaks in the imaginary frequency regime which could drive the dynamical instabilities. From the formation energies and phonon modes it is found that the monohydride YPd3 H is more stable, thus occupation of the octahedral sites at 2Y4Pd by hydrogen atoms results in greater dynamic instability in YPd3 . Highlights: The electronic and dynamical properties YPd3 hydrides were computed. YPd3 has applications as optically readable hydrogen sensor. From the DOS and formation energies the monohydride YPd3 H is found to be more stable. Occupation of 2Y4Pd octahedral sites results in greater dynamic instability in YPd3 .