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Pressure and atomic size effects of IV cation on mechanical and electronic properties of Zn-IV-N2 (IV[dbnd]Si, Ge and Sn): First principles calculation
(2024-09-01)
Boonkhuang, Apiwat
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Kongnok, Thanundon
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Meethan, Weerachon
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Busayaporn, Wutthikrai
;
Phacheerak, Kanoknan
Zn-IV-N<inf>2</inf> compounds, incorporating Si, Ge, and Sn, have emerged as pivotal materials for their mechanical and electronic properties, influencing optoelectronic devices and photovoltaic applications. Employing density functional theory (DFT), we comprehensively investigate the structural, elastic, mechanical, and electronic characteristics of ZnIVN<inf>2</inf> (IV[dbnd]Si, Ge, Sn) under ambient and pressure conditions up to 20 GPa. Our findings suggest that a larger atomic size of the group IV cation can be more easily compressed than a smaller size. The mechanical stability criteria and the phonon dispersion show mechanical and dynamic stability in both ambient pressure and under high pressure up to 20 GPa. The ZnSiN<inf>2</inf> and ZnGeN<inf>2</inf> exhibit linear increments in bulk modulus (B), shear modulus (G), and Young's modulus (E) under pressure, while ZnSnN<inf>2</inf> experiences a decrease in G and E. Notably, the energy gap of ZnSiN<inf>2</inf>, ZnGeN<inf>2</inf>, and ZnSnN<inf>2</inf> (4.62 eV indirect, 2.82 eV, 1.16 eV, respectively) increases with pressure due to higher N s orbital energy, approaching the UV region. In the valence band, a hybridization of N p and Si/Ge/Sn p orbitals is observed, offering opportunities to tailor the band gap for optimal applications in optoelectronic devices. Preferentially adjusting group-IV elements over group-II elements is recommended for optimizing band gap modulation. The correlation between larger atomic size and decreased band gap energy highlights the potential to fine-tune material properties through controlled variations in group-IV elements.
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Investigating the phase transition and properties of CaSiN2 under pressure based on first-principles calculations
(2023-12-01)
Meethan, Weerachon
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Kongnok, Thanundon
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Fongkaew, Ittipon
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Bootchanont, Atipong
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Saisopa, Thanit
In this study, we apply first-principles calculations to examine the pressure-induced phase transformation of CaSiN<inf>2</inf> in a range of pressure of 0–100 GPa. Its pressure-induced transitions at 1.3 GPa, 15.3 GPa, and 55.8 GPa followed the order of α- CaSiN<inf>2</inf> → β- CaSiN<inf>2</inf> → α- CaSiN<inf>2</inf> → γ- CaSiN<inf>2</inf>, for α- CaSiN<inf>2</inf> → β- CaSiN<inf>2</inf>, β- CaSiN<inf>2</inf> → α- CaSiN<inf>2</inf>, and α- CaSiN<inf>2</inf> → γ- CaSiN<inf>2</inf>, respectively. The stability of the phases of CaSiN<inf>2</inf> was confirmed based on calculations of the Born criterion of elastic stability. Its behavior transitioned in the sequence of brittle (0–1.3 GPa) → ductile (1.3–55.8 GPa) → brittle (55.8–100 GPa). The structure of its projected orbital band reflected insulating behavior by CaSiN<inf>2</inf> under a range of pressure of 0–55.8 GPa with a direct band gap, which transformed into metallic behavior by the γ- CaSiN<inf>2</inf> phase under pressures higher than 55.8 GPa, due to a shift in energy to higher levels around the Γ point of the N p orbitals and Si p orbitals. The Si-N bonds in CaSiN<inf>2</inf> were found to be covalent, while ionic bonding dominated the Ca-Si and Ca-N bonds in the range of pressure of 0–100 GPa. We also investigate and discuss its mechanical properties, Vickers hardness (H<inf>v</inf>), average sound velocity v<inf>m,</inf> and Debye temperature (θ<inf>D</inf>).
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Elastic properties of A2Ti6O13 ( A = H, Li, Na, K and Rb): a computational study
(2023-09-21)
Simalaotao, Kodchakorn
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Thanasarnsurapong, Thanasee
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Maluangnont, Tosapol
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Phacheerak, Kanoknan
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Boonchun, Adisak
The elastic properties of the alkali hexatitanate family A <inf>2</inf>Ti<inf>6</inf>O<inf>13</inf> (A = H, Li, Na, K, and Rb) are investigated based on density functional theory within a generalized gradient approximation plus Hubbard U (GGA+U) approach. The results showed that all members of the family are wide-band semiconductors and the calculated lattice parameters are consistent with experimental values. In terms of mechanical stability, the results indicated that the alkali hexatitanates are highly incompressible to uniaxial stress, with the largest elastic constant C<inf>22</inf> reaching values as high as 265 GPa in K<inf>2</inf>Ti<inf>6</inf>O<inf>13</inf>. The obtained elastic constants, using the stress-strain method, were used to calculate bulk modulus, shear modulus, Young’s modulus, brittleness and ductility, elastic anisotropy, Vickers hardness, sound velocities, and the Debye temperature. It was found that the member of the family with the highest atomic number of the alkaline group, Rb<inf>2</inf>Ti<inf>6</inf>O<inf>13</inf>, had the highest values of bulk, shear, and Young’s modulus, as well as the lowest values of shear and compression anisotropy, and a high Vickers hardness.
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Influence of pressure on elasticity, mechanical properties, and Li diffusion in battery electrode material LiCoO2: First-principles calculations
(2023-09-01)
Sailuam, Wutthigrai
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Fongkaew, Ittipon
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Busayaporn, Wutthikrai
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Klinkla, Rakchat
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Phacheerak, Kanoknan
This study used first-principles calculations based on density functional theory with generalized gradient approximation (GGA) of the Perdew Burke and Ernzerhof (PBE) parameterized form to investigate the influence of pressure on the structural, elastic, and mechanical properties of rhombohedral LiCoO<inf>2</inf>. The results indicate that rhombohedral LiCoO<inf>2</inf> remains stable up to 10 GPa. The calculated ground state properties agree well with experimental and other calculation data, validating the approach. Additionally, the calculated elastic constants, bulk modulus, Young's modulus, shear modulus, and Poisson's ratio at 0 GPa agree with previous results. The study found that all elastic constants continuously increase with increasing pressure. The deformation resistances along the axial direction are stronger than those in shape. The relationship between elasticity and length is such that C<inf>11</inf> > C<inf>33</inf>, indicating that the incompressibility along the a axis is stronger than that along the c axis. The analysis of Poisson's ratio (ν) and Pugh's criterion B/G strongly suggests that rhombohedral LiCoO<inf>2</inf> exhibits ductile behavior under pressure up to 10 GPa. The material is clearly anisotropic behavior, but the material exhibits improved isotropic behavior as pressure increases. Regarding Li ion diffusion in rhombohedral LiCoO<inf>2</inf>, the study found that the migration pathway for Li ions in rhombohedral LiCoO<inf>2</inf> is a direct route that extends from the V<inf>Li</inf> site to the closest Li site. The diffusion process is hindered by a diffusion energy barrier of 0.87 eV, which is in good agreement with available theoretical data. Furthermore, the Li ion diffusion energy barrier increases with pressure because the decrease in d<inf>mean</inf> and polyhedral volume, along with changes in angle and torsional distortion factors of CoO<inf>6</inf> octahedra, which can reduce the charging and discharging speeds of Li-ion batteries that use rhombohedral LiCoO<inf>2</inf> as the cathode material.
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STRUCTURAL, OPTICAL, AND VISIBLE-LIGHT DRIVEN PHOTACATALYTIC PROPERTIES OF Yb-DOPED BiVO4 NANOPARTICLES PREPARED VIA RAPID SONOCHEMICAL PROCESS
(2023-01-01)
Boonyarattanakalin, Kanokthip
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Noinonmueng, Tanisara
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Kansaard, Thanaphon
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Wechprasit, Tirapat
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Mekprasart, Wanichaya
This work represents the synthesis and structural, morphological, and optical characterization of rare-earth Yb-doped BiVO<inf>4</inf> materials with different Ytterbium (Yb3+) contents (0% - 5%). Yb-doped BiVO<inf>4</inf> specimens in form of fine nanoparticles were synthesized by a rapid and facile sonochemical process. The structural and morphological characterizations were observed by X-ray diffraction technique (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Important optical properties of the prepared samples were investigated by the diffuse reflectance technique and the corresponding optical band gaps were calculated by the mean of the Kullbelka-Munk equation. From the characterized results, it is acknowledged that incorporated Yb dopant has a significant effect on the crystalline structure of BiVO<inf>4</inf> by reducing in monoclinic phase in the pristine sample while the increasing Yb doping composition resulted in the mixed phases of monoclinic and tetragonal phases since Yb3+ ions could probably induce the stabilization of the tetragonal phase in BiVO<inf>4</inf> material. Moreover, extensive doping with Yb3+ exhibits considerable influence on not only structural but also optical and relevant visible - driven photocatalytic properties of BiVO<inf>4</inf> by means of the color degradation of RhB dye solution
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A first principles investigation on the structural, elastic, and mechanical properties of MAX phase M3AlC2 (M= Ta, Ti, V) as a function of pressure
(2022-03-01)
Sailuam, Wutthigrai
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Fongkaew, Ittipon
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Limpijumnong, Sukit
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Phacheerak, Kanoknan
This study investigated the structural, elastic, and mechanical properties of hexagonal M<inf>3</inf>AlC<inf>2</inf> (M = Ta, Ti, and V) within MAX phases by first-principles calculations. The considered properties of M<inf>3</inf>AlC<inf>2</inf> (M = Ta, Ti, and V) compounds at 0 GPa were in reasonable agreement with available experimental and other theoretical data. The elastic stability shows that no structural phase transition occurred in pressure up to 20 GPa for all compounds. The resistances to linear compression were more forceful than the resistances to compression in shape. The bulk modulus, shear modulus, and Young's modulus for M<inf>3</inf>AlC<inf>2</inf> (M = Ta, Ti, and V) compounds follow the order Ta<inf>3</inf>AlC<inf>2</inf> > V<inf>3</inf>AlC<inf>2</inf> > Ti<inf>3</inf>AlC<inf>2</inf>. The Bader charge analysis result shows the increasing of covalence bond in their structure after the pressure increased. Furthermore, Pugh's criterion B/G and Poisson's ratio v confirmed that the M<inf>3</inf>AlC<inf>2</inf> (M = Ta, Ti, and V) compounds had intrinsic brittleness. The sound velocity and Debye temperature of all compounds increased with pressure increasing. The bond stiffness and the shear anisotropy affected by pressure were reported and discussed.
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Effect of pressure on structural and elastic properties of SnSe: First-principles calculations
(2022-02-01)
Phacheerak, Kanoknan
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Thanomngam, Pitiporn
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Limpijumnong, Sukit
Selected structural and elastic properties of an orthorhombic SnSe at an ambient pressure and under high pressures were investigated using first-principles calculations. At ambient pressure, the calculated structural parameters and elastic constants show a good agreement with previously reported values. Effects of pressure on structural and elastic properties were presented and discussed in detail. Moreover, the pressure dependence of selected structural and elastic properties, which relate to phase transition from an orthorhombic phase to the high-pressure phase, was analyzed. We suggested that the phase transition is related to the compression along the c- and b-axis which correspond to C<inf>33</inf> and C<inf>22,</inf> respectively.
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Effects of Er Dopant on Structural and Optical Properties of BiVO4 Powders Prepared via Sonochemical Process
(2022-01-01)
Noinonmueng, Tanisara
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Kansaard, Thanophon
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Wechprasit, Tirapat
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Mekprasart, Wanichaya
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Boonyarattanakalin, Kanokthip
In this work, we investigate the crucial effect of Er dopant on structural, morphological and optical properties of BiVO<inf>4</inf> prepared by one-step sonochemical process. The Er doping content was varied from 0% to 10%. The structural and morphological characterization were performed by X-ray diffraction technique (XRD), Raman spectroscopy and scanning electron microscopy. XRD and Raman spectra reveal the structural transition from monoclinic to tetragonal structure induced by Er dopant. Optical properties of the prepared samples were investigated by diffuse reflectance technique and the corresponding optical band gaps were calculated indicating two optical band gaps of two major phases of the doped samples. The Er dopant has highly influence on an enhancement in photocatalytic performance under visible irradiation of BiVO<inf>4</inf> as doping content is 8%. This improved performance could be due to the size reduction and morphological change due to phase transformation induced by Er dopant accompanying mixture of optical band gaps that can assist the retardment of electron-hole pair recombination.
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Pressure Dependence of Structural and Elastic Properties of Na2O: First-Principles Calculations
(2022-01-01)
Phacheerak, Kanoknan
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Thanomngam, Pitiporn
The effect of high pressures, up to 40 GPa, on the structural and elastic properties of sodium oxide in cubic structure (c-Na<inf>2</inf>O) were investigated by first-principles calculations. The generalized gradient approximation (GGA) with the Perdew-Burke-Ernzerhof (PBE) functional was employed in the calculations. The calculated structural and elastic properties at zero pressure are consistent with the available results. The pressure dependence of structural and elastic properties was presented and discussed in detail. Under pressure, the elastic constants satisfy the Born criteria, indicating that c-Na<inf>2</inf>O is mechanically stable. Moreover, other elastic properties such as bulk modulus (B), shear modulus (G), and Young's modulus (E) under pressures were analyzed. Furthermore, the B/G values tend to increase with the increasing pressure, which means that pressure can improve the ductility of c-Na<inf>2</inf>O.
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The pressure effect on the structural, elastic, and mechanical properties of orthorhombic MgSiN2 from first-principles calculations
(2021-10-01)
Bootchanont, Atipong
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Phacheerak, Kanoknan
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Fongkaew, Ittipon
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Limpijumnong, Sukit
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Sailuam, Wutthigrai
Pressure effect on lattice parameters, elastic moduli, Poisson's ratio, Cauchy pressure, elastic anisotropy, and Vickers hardness of orthorhombic MgSiN<inf>2</inf> by means of first-principles calculations based on density functional theory (DFT) by generalized gradient approximation (GGA) in the functional form by Perdew, Bruke, and Ernzerhof (PBE) of the exchange-correlation were presented. The structural properties, elastic moduli, B<inf>0</inf>/G, Poisson's ratio (ν) and Cauchy pressure under pressure up to 10 GPa were calculated. The optimized structural and ground state properties under ambient pressure were in agreement with the available experiments and other calculations. The orthorhombic MgSiN<inf>2</inf> was mechanically stable under pressure up to 10 GPa by the elastic stability criteria investigation. Under pressure, the relationship of elasticity in length was C<inf>33</inf> > C<inf>11</inf> > C<inf>22</inf>, indicating that it is easier to compress along the b-axis than along the a-axis and c-axis, respectively. The calculated bulk modulus, shear modulus, Young's modulus and Poison's ratio index all increased with an increase in the pressure. The B<inf>0</inf>/G, Poisson's ratio (ν) and Cauchy pressure analyses implied that orthorhombic MgSiN<inf>2</inf> was single crystal, and a critical pressure for brittle-to-ductile transition was found to be 2 GPa. The Cauchy pressure of {100} plane, {010} plane and {001} plane, Vickers hardness (H<inf>v</inf>) and the shear anisotropy as a function of pressure were investigated from the calculation.

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