Optoelectronic and thermal properties of LiXH3(X =Ba, Sr and Cs) for hydrogen storage materials: A first principle study

Alam

Int J of Quantum Chemistry

et al. 2019

Self Cite

This first principles study explores the structural, electronic, optical, and thermoelectric properties of the CsTmCl3 halide perovskite using density functional theory. The structural and thermoelectric properties are calculated without considering the spin‐orbit coupling (SOC), while both the electronic and optical properties are calculated with and without the SOC effect. A comparison of the results obtained with and without SOC reveals that inclusion of the SOC effect reduces the band gap from 1.18 to 0.99 eV due to shifting of the Tm‐d states toward the Fermi level. However, direct nature of the band gap remains the same in both the cases. The effect of SOC on the optical properties is, however, only visible in shifting of the third characteristic peak to lower energies. Strong optical absorption in the visible and ultraviolet regions shows effectiveness of CsTmCl3 in the optical devices working in these regions. Moreover, the calculated transport properties reveal CsTmCl3 as a useful thermoelectric material at room temperature.

σ_{αβ} ((),, T, μ) = \frac{1}{Ω} \int \frac{1}{N} ([], \sum_{i, k} e^{2} τ_{k} v_{α} ((), i, \overset{k}{true}) v_{β} ((), i, \overset{k}{true})) \frac{δ ((), ε - ε_{i, k})}{δ ((), ε)} ([], \frac{- \partial f_{ο} (T, ε, μ)}{\partial ε}) italicdε,

S_{αβ} = \frac{1}{italiceT normalΩ σ_{αβ} ((),, T, μ)} \int σ_{αβ} ((), ε) ((), ε - μ) \times ([], \frac{- \partial f_{ο} (T, ε, μ)}{\partial ε}) italicdε,

κ = \frac{1}{e^{2}} {K_{B}}^{2} T \int ([], \sum_{i, k} e^{2} v_{α} v_{β} τ_{k}) ((), \frac{{(ε - μ)}^{2}}{K_{B} T}) ([], \frac{- \partial f_{ο} (T, ε, μ)}{\partial ε}) italicdε,

italicZT = \frac{S^{2} italicσT}{κ},

where N , υ α and υ β , α and β , e , Ω, τ k , μ , and f 0 are the number of k points, group velocities, tensors indices, charge on an electron, unit cell volume...…”

Section: Resultsmentioning

confidence: 99%

“…When two or more semiconductors or conductors are joined, then the potential difference is produced. As result of this potential difference, electrons move from one material to another and electrical power is generated . The Seebeck coefficient ( S ) vs temperature ( T ) plot is shown in Figure by black bulleted line.…”

Section: Resultsmentioning

confidence: 99%

A theoretical study of the structural, thermoelectric, and spin‐orbit coupling influenced optoelectronic properties of CsTmCl₃ halide perovskite

Alam

Int J of Quantum Chemistry

et al. 2019

Self Cite

“…Some of the compounds of this structural group are CaCoH 3 , CaNiH 3 , LiTH 3 (T: Fe, Co, Ni, Cu), SrPdH 3 , and SrLiH 3 . ABH 3 perovskite‐type hydrides have been studied in recent years with regard to experimental and theoretical methods to get detailed information about their possible applications . The hydrogen storage techniques should satisfy some necessary conditions like suitable gravimetric and volumetric hydrogen storage capacities, reversibility, and good kinetics in order to get a suitable hydrogen storage material.…”

Section: Introductionmentioning

confidence: 99%

“…In literature, according to hydrogen stability in the structure and limited combinations of cations, the works have been developed on oxides than hydrides . However, the hydrides containing lightweight elements have received considerable attention with their high thermal stability and absorption/desorption capacity in the process of hydrogen storage . As an alternative material in use of hydrogen storage, this work presents structural, mechanical, electronic, and lattice dynamical characteristics of CaXH 3 compounds with different X elements.…”

Section: Introductionmentioning

confidence: 99%

“…[16][17][18][19] Among them, the perovskite-type hydrides have been promising candidate for solid-state type of future hydrogen storage materials. [20][21][22][23][24][25][26][27][28] There are numerous number of perovskite compounds that can be obtained as carbides, nitrides, fluorides, chlorides, bromides, oxides, hydrides, and iodides. 29,30 On the other hand, oxides and hydrides are the most prominent structures which may be applicable in the use of hydrogen storage.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

CaXH ₃ (X = Mn, Fe, Co) perovskite‐type hydrides for hydrogen storage applications

et al. 2019

Summary Hydrogen storage is one of the attractive research interests in recent years due to the advantages of hydrogen to be used as energy source. The studies on hydrogen storage applications focus mainly on investigation of hydrogen storage capabilities of newly introduced compounds. The present paper aims at characterization of CaXH3 (X: Mn, Fe, or Co) perovskite‐type hydrides for the first time to understand their potential contribution to the hydrogen storage applications. CaXH3 compounds have been investigated by density functional theory studies to reveal their various characteristics and hydrogen storage properties. CaXH3 compounds have been optimized in cubic crystal structure and the lattice constants of studied compounds have been obtained as 3.60, 3.50, and 3.48 Å for X: Mn, Fe, and Co compounds, respectively. The optimized structures have negative formation enthalpies pointing out that studied compounds are thermodynamically stable and could be synthesized experimentally. The gravimetric hydrogen storage densities of X: Mn, Fe, and Co compounds were found in as 3.09, 3.06, and 2.97 wt%, respectively. The revealed values for hydrogen storage densities indicate that CaXH3 compounds may be potential candidates for hydrogen storage applications. Moreover, various mechanical parameters of interest compounds like elastic constants, bulk modulus, and Poisson's ratio have been reported throughout the study. These compounds were found mechanically stable with satisfying Born stability criteria. Further analyses based on Cauchy pressure and Pugh criterion, showed that they have brittleness nature and relatively hard materials. In addition, the electronic characteristics, band structures, and associated partial density of states of CaXH3 hydrides have been revealed. The dynamic stability behavior of them was verified based on the phonon dispersion curves.

Enhancement of hydrogen storage properties of Ca ₃ CH antiperovskite compound with hydrogen doping

Gençer

Sürücü

2019

Int J Energy Res

The doping effect of hydrogen on the Ca 3 CH x (x = 1, 4, 7, 9, and 10) antiperovskite compounds has been examined using density functional theory (DFT). The results of the structural optimizations show that all these compounds have negative formation energy implying the energetic stability and synthesizability. The band structures that are essential for the electronic properties have been determined along with the partial density of states (DOS) showing the metallic behavior of these compounds. In addition, the electrondensity distribution has been determined, and the charge of each ion in the structures has been obtained with the Bader partial charge analysis. Moreover, the electronic stability of these compounds has been determined using the band filling theory and the number of the electrons at the Fermi level. The results of the formation enthalpy and the electronic stability investigations imply that the most stable structure is Ca 3 CH among the considered compounds. Ca 3 CH 10 has the gravimetric storage capacity as 7.10 wt% that is the largest capacity among the considered compounds. Also, Ca 3 CH 9 has the smallest hydrogen desorption temperature as 468.4 K among the studied compounds.