The electronic structure and optical properties of Ca3(Mn1−xTix)2O7from first-principle calculations

Wang, Fengqi; Cai, Wei; Fu, Chunlin; Gao, Rongli; Chen, Gang; Deng, Xiaoling; Wang, Zhenhua; Zhang, Chaoyang

doi:10.1142/s2010135x19500073

Cited by 7 publications

(4 citation statements)

References 17 publications

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“…This is indicated by the DOS diagrams calculated for the following model compounds: undoped (Ca 12 Mn 8 O 28 ), La‐doped (Ca 11 LaMn 8 O 28 ), and Y‐doped (Ca 11 YMn 8 O 28 ) shown in Figure 11a,b. The band gap was calculated to be 0.936 eV, which is twice as higher as the DFT computed band gap of 0.384 eV, 56 and closer to the experimental value of 1.29 eV 57 . As shown in the DOS of the undoped Ca 3 Mn 2 O 7 , the conduction band minimum (CBM) consists of Mn‐3d states mainly, explaining the immediate effect of Hubbard U‐correction on the band gap, whereas the valence band maximum (VBM) consists of O‐2p states mostly, with minor contribution only from Mn‐3d states.…”

Section: Resultsmentioning

confidence: 70%

Ca₃Mn₂O₇‐layered perovskites: Effects of La‐ and Y‐doping on phase stability, microstructure, and thermoelectric transport

et al. 2022

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We investigate phase stability, microstructure, and thermoelectric transport of polycrystalline bulk Ca3−xRxMn2O7 samples prepared by standard solid‐state reaction, where R = Y or La and 0 ≤ x ≤ 0.33. Ab‐initio calculations predict that Y‐doping at Ca‐sites should reduce the potential energy barrier for electron transport, as opposed to La‐doping. We find that Y‐doping prompts transformation from Ca3Mn2O7 to Ca2MnO4, whereas La‐doping is accompanied by no phase transformation. La‐doping significantly hinders grain growth, for example, the average grain size decreases from 4.44 ± 0.24 to 1.20 ± 0.03 μm for x = 0 (undoped) and x = 0.33 upon La‐doping, respectively. Electrical conductivity and Seebeck coefficients are measured for the temperature range of 300–1300 K, and analyzed in terms of the small polaron hopping model. We find that Y‐doping reduces the activation energy for conduction compared to La‐doping, for example, 43 and 63 meV, respectively. This suggests that Y reduces the energy barrier for polaron transport, in accordance with computational predictions. This trend is further supported by calculations of selected electronic, structural, and vibrational properties, highlighting the intriguing correlation between electronic transport governed by small polarons and elastic properties, thereby shedding light on charge transport and thermoelectric properties of such layered perovskites.

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Section: Resultsmentioning

confidence: 70%

Ca₃Mn₂O₇‐layered perovskites: Effects of La‐ and Y‐doping on phase stability, microstructure, and thermoelectric transport

et al. 2022

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“…For Fe substituted in Ca 3 Ti 2 O 7 ceramics, its optical band gap decreases from 3.61 to 2.23 eV, which is attributed to the Fe substitution induces disorder and broadens the gap edge of absorption [92]. Meanwhile, the direct band gap with the semiconductor behaviour of Ca 3 (Mn 1−x Ti x ) 2 O 7 was proved using DFT calculations, which indicated that the bandgap increases with the increase in Ti 4+ content, and the introduction of nonmagnetic Ti 4+ ions weakens the magnetism [93]. A small amount of Li substitution in Ca 3 Mn 2 O 7 remarkably decreases oxygen vacancies, which introduces disorder and results in the widening of the band gap [94].…”

Section: Compoundsmentioning

confidence: 97%

Review of experimental progress of hybrid improper ferroelectricity in layered perovskite oxides

Zhang¹,

Liu²,

Chen³

2021

J. Phys. D: Appl. Phys.

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The primary order parameter of hybrid improper ferroelectricity (HIF) is not spontaneous polarisation but nonpolar modes such as oxygen octahedral rotations (OORs), antipolar, or even Jahn–Teller distortions; therefore, the HIF mechanism may be applied as an effective pathway to tune electronic bandgaps, control orbitals, and create multiferroicity. Most of the current experimental research on HIF is focused on layered perovskite oxides; therefore, this review focuses on the recent progress of experimental studies on HIF materials with the Ruddlesden–Popper (R–P) and Dion–Jacobson (D–J) structures. Experimental research on double-layered R–P oxides is included, and the linear relationship between the Curie temperature and tolerance factor has been established. Moreover, the coexistence of polar and weak ferromagnetic phases has been observed in iron-based double-layered R–P oxides at room temperature. The recent discovery of ferroelectricity in A-site cation-ordered triple-layered R–P oxides has significantly expanded the HIF field. HIF has also been confirmed in caesium- and rubidium-based double-layered D–J oxides, and complex OOR modes have been observed in D–J oxides. Although significant progress has been achieved for HIF materials in layered perovskite oxides, extensive research is required to reveal the mysteries of HIF and to create single-phase multiferroics in HIF materials.

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“…Moreover, the antiferromagnetic (AFM) Neel temperature of La‐doped Ca 3 Mn 2 O 7 was enhanced from 100 to 130 K, 13 and weak ferromagnetism has been introduced successfully in the G‐type AFM (G‐AFM) Ca 3 Mn 2 O 7 by Li doping 14 . In addition, more works analyzed the electronic configuration, optical, dielectric, and other properties of Ca 3 Mn 2 O 7 by the first‐principles calculations 15–17 . However, previous studies were mainly focused on the A‐site doping to realize the transformation from antiferromagnetism to ferromagnetism in Ca 3 Mn 2 O 7 , but the B‐site doping was rarely studied.…”

Section: Introductionmentioning

confidence: 99%

“…14 In addition, more works analyzed the electronic configuration, optical, dielectric, and other properties of Ca 3 Mn 2 O 7 by the first-principles calculations. [15][16][17] However, previous studies were mainly focused on the A-site doping to realize the transformation from antiferromagnetism to ferromagnetism in Ca 3 Mn 2 O 7 , but the B-site doping was rarely studied.…”

Section: Introductionmentioning

confidence: 99%

Enhanced magnetism in Ru‐doped hybrid improper perovskite Ca₃Mn₂O₇ via experimental and first‐principles study

Yuan

Zhang

et al. 2022

J Am Ceram Soc.

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The quasi‐2D Ruddlesden–Popper layered perovskites with single‐phase multiferroicity have attracted much attention in recent magnetoelectric memory applications. We have systematically investigated the optical and magnetic properties of Ru‐doped hybrid improper perovskite Ca3Mn2O7 both experimentally and using first‐principles calculations. The Ca3RuxMn2−xO7 (x = 0, 0.02, 0.06, 0.10) powders were successfully synthesized using the sol–gel method. Ru doping enhanced the ferromagnetism of Ca3Mn2O7. The quasi‐2D antiferromagnetic (AFM) fluctuation effect was observed in Ca3Mn2O7 and in certain doped samples. We also found that the optical bandgaps of the doped samples were reduced after doping, agreeing with the results of the first‐principles calculations. Infrared absorption spectra indicated the distortion of the Mn–O bonds was possibly due to the Jahn–Teller effect. To analyze the electronic structures and to understand the detailed atomic contributions of magnetic moments, the Crystal Orbital Hamilton Population (COHP) and Integrated COHP of the (Mn,Ru)O6 octahedra were also calculated. The Ru‐doped materials with the coexistence of ferromagnetic and AFM orderings are expected to be excellent candidates for magnetoelectric devices.

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The electronic structure and optical properties of Ca₃(Mn1−xTi_x)₂O₇from first-principle calculations

Cited by 7 publications

References 17 publications

Ca₃Mn₂O₇‐layered perovskites: Effects of La‐ and Y‐doping on phase stability, microstructure, and thermoelectric transport

Ca₃Mn₂O₇‐layered perovskites: Effects of La‐ and Y‐doping on phase stability, microstructure, and thermoelectric transport

Review of experimental progress of hybrid improper ferroelectricity in layered perovskite oxides

Enhanced magnetism in Ru‐doped hybrid improper perovskite Ca₃Mn₂O₇ via experimental and first‐principles study

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The electronic structure and optical properties of Ca3(Mn1−xTix)2O7from first-principle calculations

Cited by 7 publications

References 17 publications

Ca3Mn2O7‐layered perovskites: Effects of La‐ and Y‐doping on phase stability, microstructure, and thermoelectric transport

Ca3Mn2O7‐layered perovskites: Effects of La‐ and Y‐doping on phase stability, microstructure, and thermoelectric transport

Review of experimental progress of hybrid improper ferroelectricity in layered perovskite oxides

Enhanced magnetism in Ru‐doped hybrid improper perovskite Ca3Mn2O7 via experimental and first‐principles study

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The electronic structure and optical properties of Ca₃(Mn1−xTi_x)₂O₇from first-principle calculations

Ca₃Mn₂O₇‐layered perovskites: Effects of La‐ and Y‐doping on phase stability, microstructure, and thermoelectric transport

Ca₃Mn₂O₇‐layered perovskites: Effects of La‐ and Y‐doping on phase stability, microstructure, and thermoelectric transport

Enhanced magnetism in Ru‐doped hybrid improper perovskite Ca₃Mn₂O₇ via experimental and first‐principles study