Structural, electronic, optical, elastic properties and Born effective charges of monoclinic HfO<sub>2</sub>from first-principles calculations

Liu, Qi‐Jun; Zhang, Ning-Chao; Liu, Fusheng; Liu, Zheng‐Tang

doi:10.1088/1674-1056/23/4/047101

Cited by 50 publications

(20 citation statements)

References 71 publications

(151 reference statements)

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“…All m-MO 2 show C 22 >C 11 >C 33 , agreeing with others' calculated results [11,12,35,36] and experimental data [37]. This relationship shows that the resistance to compression decreases in the order of these directions y→x→z.…”

Section: Elastic Propertiessupporting

confidence: 90%

“…For example, diamond and c-BN have an A U of 0.06 and 0.19, respectively [58], far less than that of m-HfO 2 . Data are from a: [53] (this experimental value is for films); b: [54]; c: [11]; d: [55]. , and 4, we find that the bulk modulus is more anisotropic than Young's modulus, which in turn is more anisotropic than the minimum thermal conductivity.…”

Section: Elastic Anisotropymentioning

confidence: 99%

“…Other researchers have investigated the transformation from monoclinic phase to tetragonal phase in HfO 2 [5], as well as its mechanical [11], optical, and elastic properties [12]. Even with this range of study, some properties of IVTMO 2 , particularly their mechanical properties, are not well understood .…”

mentioning

confidence: 99%

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Elastic properties, hardness, and anisotropy in baddeleyite IVTMO2 (M=Ti, Zr, Hf)

Chen

Liang

et al. 2015

Sci. China Mater.

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and HfO 2 thin films. Other researchers have investigated the transformation from monoclinic phase to tetragonal phase in HfO 2 [5], as well as its mechanical [11], optical, and elastic properties [12]. Even with this range of study, some properties of IVTMO 2 , particularly their mechanical properties, are not well understood . For example, elastic anisotropy in thin films usually leads to microcracks, and differences in thermal expansion between a film and matrix might induce a dropping of the film from the matrix.Zhao et al. [10] reported that bulk ZrO 2 has three crystalline structures at normal pressure: cubic (2300−2680°C), tetragonal (1170−2300°C), and monoclinic (<1170°C). Bulk HfO 2 has only two crystalline structures: tetragonal (1750−2800°C) and monoclinic (<1750°C). The most abundant polymorph of TiO 2 found in nature is rutile, and at room temperature it is stable up to 12 GPa, where it directly converts to the baddeleyite-type (monoclinic) phase [13]. Because m-HfO 2 has a larger bulk modulus than the other two metal dioxides [12], it was expected to have high hardness. The bulk modulus was once thought to be good predictor of hardness. Although it is true that a hard material must have a high modulus [14], it is a common misconception that an incompressible material is a hard one. For example, osmium has only a twentieth the hardness of diamond, though its bulk modulus is comparable to diamond, making it one of the most incompressible materials known.It is now well recognized that high bulk and shear moduli do not guarantee high hardness. Other factors-including high electron density, short bond length, high degree of covalent bonding, and near-isotropic deformation-usually dominate a material's intrinsic hardness [15]. Thus, it is important to thoroughly investigate baddeleyite-type IVTMO 2 (we henceforth refer to these m-MO 2 materials as m-TiO 2 , m-ZrO 2 , and m-HfO 2 ), especially their hardness, elasticity, and anisotropy. To our best knowledge, there are no systemic studies of monoclinic metal dioxides, which are stable at room temperature. In the past decade,In this article, we used plane-wave density functional theory to investigate the elasticity, anisotropy, and minimum thermal conductivities of baddeleyite type IVTMO2 (m-TiO2, m-ZrO2, and m-HfO2). The elastic constants and modulus, Poisson's ratio, hardness, sound speed, Debye temperature, and minimum thermal conductivities at high temperature were calculated. These calculations show that m-MO2 is not superhard, with a hardness range of about 8-13 GPa. Among these materials, m-TiO2 is the hardest, while m-HfO2 is the least hard. Their elastic and plastic anisotropy are given in detail. Moreover, the m-HfO2 thin film is the most likely to develop microcracks during preparation because it has the highest elastic anisotropy. Among the three dioxides, m-HfO2 is the best thermal barrier because it has the lowest thermal conductivity.

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Section: Elastic Propertiessupporting

confidence: 90%

Section: Elastic Anisotropymentioning

confidence: 99%

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Elastic properties, hardness, and anisotropy in baddeleyite IVTMO2 (M=Ti, Zr, Hf)

Chen

Liang

et al. 2015

Sci. China Mater.

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“…The peaks of the loss function spectra correspond to the transition from the metallic to dielectric behavior of the materials, which coincides with the strong reduction of the light reflection (at 500 and 700 nm); such transition energy is named the plasma frequency. For example, the plasma frequency of 1_3Li occurs at 700 nm with the peak intensity of 13, where the metallic → dielectric behavior transition takes place 59 …”

Section: Resultsmentioning

confidence: 99%

Adsorption and diffusion of lithium ions on lead‐free two‐dimensional halide perovskite surface toward energy storage applications

et al. 2021

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Summary Lead‐free halide perovskite materials have recently been deployed for energy storage applications such as lithium‐ion batteries and photo‐rechargeable batteries. Yet, the detailed interactions between the lithium ions and the lead‐free halide perovskite remain elusive, inhibiting deeper understanding of the halide perovskite materials for the energy storage applications. In this manuscript, we systematically investigate the adsorption of lithium ions on an experimentally verified two‐dimensional (2D) lead‐free halide perovskite Cs2CuBr4 via first‐principles calculations. The simulation demonstrates that the lithium ion can reside on multiple sites at the halide perovskite surface near the bromine atoms, albeit initiating severe structural distortions in the substrate. The lithium ions move relatively easily on the halide perovskite surface, which is demonstrated by the small energy barriers of 0.15 eV. The lithium substitution at the A‐site of the ABX3‐type halide perovskite material causes a systematic band gap reduction when more lithium ions are available. More importantly, the hole polaron formation in the Li+/perovskite systems leads to a strong displacement of the lithium ion away from the halide perovskite surface plane, suggesting the light‐driven lithium ion tunneling effect and the photo‐charging behavior of the 2D halide perovskite, which is a prerequisite for the photo‐battery materials. Other secondary battery active species including Na+, K+, Mg+, Ca2+ and Al3+ ions adsorb onto the halide perovskite substrate in a similar way as the Li+ ion does, suggesting the possibility of applying the 2D lead‐free halide perovskite materials for more types of secondary batteries. This study facilitates the fundamental understanding of the halide perovskite materials for the energy storage applications, and suggests that the 2D lead‐free halide perovskite material is viable for lithium‐ion batteries and photo‐batteries, pending further improvement in the stability.

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“…These functions are completely determined by the band structures of the considered materials. Hence, knowledge of the complex dielectric function ε(ω) is capable of characterizing the optical response of all materials when subjected to an electromagnetic wave flux [30].…”

Section: Optical Propertiesmentioning

confidence: 99%

DFT and TB-mBJLDA studies of structural, electronic and optical properties of Hg1-xCdxTe and Hg1-xZnxTe

Aouail¹,

Belkaid²,

Oukebdane³

et al. 2021

Rev. Mex. Fís.

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In this paper, the fundamental semiconductor properties of Hg1-xCdxTe and Hg1-xZnxTe are investigated by ab initio calculations based on the FP-LAPW method. Structural properties have been calculated using LDA and GGA approximations. The electronic properties are studied using the LDA and GGA approximations, and the potential TB-mBJLDA coupled with the lattice parameters aLDA and aGGA. The optical properties are determined from the optimal gap energies based on the TB-mBJLDA potential. Lattice parameters aLDA obtained by the LDA calculations predict values that are in good agreement with the experimental results and are better than those results obtained by the GGA calculations. The use of TB-mBJLDA potential coupled with the lattice parameter aGGA gives gap energy values in good agreement with the experimental results for all alloys except Hg1-xZnxTe (x=0.5, 0.75) where the (TB-mBJ LDA+aLDA) is more suitable. Optical constants are calculated from the dielectric function in the energy range (0-30 eV). The spectrum of real and imaginary parts of the dielectric function, the energy loss function, the refractive index, the extinction coefficient, the absorption coefficient, and the reflectivity show that optical properties of Hg1-xCdxTe are comparable to those of Hg1-xZnxTe. Our results are found to be in reasonable agreement with existing data reported in the literature.

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Structural, electronic, optical, elastic properties and Born effective charges of monoclinic HfO₂from first-principles calculations

Abstract: Qi-Jun(刘其军) a) † , Zhang Ning-Chao(张宁超) a) , Liu Fu-Sheng(刘福生) a) , and Liu Zheng-Tang(刘正堂) b) a) Bond and Band Engineering Group,

Cited by 50 publications

References 71 publications

Elastic properties, hardness, and anisotropy in baddeleyite IVTMO2 (M=Ti, Zr, Hf)

Elastic properties, hardness, and anisotropy in baddeleyite IVTMO2 (M=Ti, Zr, Hf)

Adsorption and diffusion of lithium ions on lead‐free two‐dimensional halide perovskite surface toward energy storage applications

DFT and TB-mBJLDA studies of structural, electronic and optical properties of Hg1-xCdxTe and Hg1-xZnxTe

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Structural, electronic, optical, elastic properties and Born effective charges of monoclinic HfO2from first-principles calculations

Abstract: Qi-Jun(刘其军) a) † , Zhang Ning-Chao(张宁超) a) , Liu Fu-Sheng(刘福生) a) , and Liu Zheng-Tang(刘正堂) b) a) Bond and Band Engineering Group,

Cited by 50 publications

References 71 publications

Elastic properties, hardness, and anisotropy in baddeleyite IVTMO2 (M=Ti, Zr, Hf)

Elastic properties, hardness, and anisotropy in baddeleyite IVTMO2 (M=Ti, Zr, Hf)

Adsorption and diffusion of lithium ions on lead‐free two‐dimensional halide perovskite surface toward energy storage applications

DFT and TB-mBJLDA studies of structural, electronic and optical properties of Hg1-xCdxTe and Hg1-xZnxTe

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Structural, electronic, optical, elastic properties and Born effective charges of monoclinic HfO₂from first-principles calculations