The structural, mechanical, electronic, and optical properties of Janus Hf2CXY (X, Y = O, S, Se or Te, X ≠ Y) MXenes

Abstract

Janus functionalized MXenes have attracted growing interest due to their exceptional properties. In this work, the structural, mechanical, electronic, and optical properties of Janus Hf2CXY (X, Y = O, S, Se or Te, X ≠ Y) MXenes are investigated using density functional theory. The results of the formation energy, phonon spectrum analysis, and elastic properties validate their structural stability. The Young’s modulus (Y), shear modulus (G), and Poisson’s ratio (υ) of Janus Hf2CXY MXenes can be modulated by the different surface functional groups. It is found that the Janus Hf2COS is a semiconductor with an indirect band gap, while other Hf2CXY MXenes exhibit metallic character. Furthermore, we also explore the effect of strain on the electronic and optical properties of Hf2COS. The results show that the semiconductor to metal transition can occur under compressive strain, and the dielectric spectrum and static dielectric constant can be altered by the tensile strain. These results demonstrate Janus Hf2CXY MXenes’ potential applications in electronic and optical nanodevices.

Mechanical characteristics and failure behavior of puckered and buckled allotropes of antimonene nanotubes: a molecular dynamics study

“…On the other hand, the stiffness of the armchair and zigzag Compared with other nanotubes, the antimonene nanotubes are stiffer than statene, bismuthene and SiGe nanotubes 105,106 and comparable to silicene, arsenene, germanene, tellurene, and phosphorene nanotubes, [107][108][109][110][111][112] but softer than carbon, borophene, WS 2 , MoSe 2 , MoSSe, TiS 2 and g-C 3 N 4 nanotubes at 1 K temperature. 105,[113][114][115][116] Additionally, the snapshots taken from the deformation process of SbNT specimens were employed in combination with stress-strain curves to broaden the understanding of the failure mechanisms. The snapshots are colored by the stress per atom values to point out the stress distribution throughout the specimens.…”

“…Compared with other nanotubes, the antimonene nanotubes are stiffer than statene, bismuthene and SiGe nanotubes 105,106 and comparable to silicene, arsenene, germanene, tellurene, and phosphorene nanotubes, 107–112 but softer than carbon, borophene, WS 2 , MoSe 2 , MoSSe, TiS 2 and g-C 3 N 4 nanotubes at 1 K temperature. 105,113–116…”

Highly efficient and thermally stable broadband near-infrared emitting garnet Ca3Sc2Ge3O12:Cr3+,Ce3+ phosphors for multiple pc-LED applications

“…This represents a moderate-strong (1 o S o 5) electron-lattice coupling corresponding to broadband near-infrared emission, but cannot adequately explain the excellent thermal stability of CSGG:Cr 3+ . 21 In addition to the activation energy theory, another commonly used thermal quenching theory is the thermal ionization theory. At high temperatures, the excited state electrons absorb energy and are ionized to the conduction band (CB) of the main lattice, and then the charge is captured by the quenching center, where DE 0 is the energy barrier from the excited state to CB.…”

“…5,[12][13][14][15][16][17][18][19] In particular, Cr 3+ ions are considered as an ideal emission center for broadband NIR emission due to their wide absorption in the blue/red region and tunable NIR emission depending on the crystal field strength. Therefore, Cr 3+ -activated NIR phosphors have attracted considerable research attention, such as La 3 Ga 5 GeO 14 :Cr 3+ , 20 LiInGeO 4 :Cr 3+ , 21 LiIn 2 SbO 6 :Cr 3+ , 2 and Ca 3 Ga 2 Ge 3 O 12 :Cr 3+ . 22 However, the emission of Cr 3+ derives from the parity forbidden d-d transition, which greatly affects the luminescence efficiency.…”

Recent progress in structural modification of polymer gel electrolytes for use in solid-state zinc-ion batteries

“…or polymer organic compounds into the gel electrolyte, the gel can break and recombine with some functional groups in the organic materials to achieve the purpose of modifying the gel electrolyte. 102,103,141 By incorporating various organic substances, the gel electrolyte was modified in multiple aspects, including enhancing its resistance to freezing and heating. Several examples of diverse organic additives are summarized here.…”