Structural, optical and mechanical properties of Y2Ti2O7 single crystal

Suganya, M.; Ganesan, K.; Vijayakumar, P.; Gill, Amirdha Sher; Ramaseshan, R.; Ganesamoorthy, S.

doi:10.1016/j.scriptamat.2020.06.016

Cited by 20 publications

(12 citation statements)

References 27 publications

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“…The optical band gap of the YTO is determined to be ∼4.93 eV from extrapolation of the linear part of the [ f ( R ∞ )hν] n plot based on the direct transition ( n = 2), as presented in the Figure c inset. This value is larger than that of any previously reported optical band gap values of YTO, which vary from 3.12, 3.44, and 3.50 to 4.32 eV . The difference between the obtained results can be reasonable.…”

Section: Resultscontrasting

confidence: 76%

Charge Transfer-Triggered Bi³⁺Near-Infrared Emission in Y₂Ti₂O₇for Dual-Mode Temperature Sensing

Wang

Jahanbazi

Wei

et al. 2022

ACS Appl. Mater. Interfaces

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Trivalent bismuth is a popular main group ion showing versatile luminescent behaviors in a broad spectral range from ultraviolet to visible, but barely in the near-infrared (NIR) region. In this study, we have observed unexpected NIR emission at ∼744 nm in a Bi3+-doped pyrochlore, Y2Ti2O7 (YTOB). Our first-principles electronic structure calculation and analysis of the Bi local structure via extended X-ray absorption fine structure indicate that only Bi3+ species appears in YTOB and it has a similar local environment to that of Y3+. The NIR emission is assigned to a Ti4+ → Bi3+ metal-to-metal charge transfer process. Moreover, we have demonstrated dual-mode luminescence thermometry based on the luminescence intensity ratio (LIR) and lifetime (τ) in 0.5% Bi3+ and 0.5% Pr3+ co-doped Y2Ti2O7 (YTOB0.5P0.5). It exhibits high thermometric sensitivity simultaneously in the cryogenic temperature range from 78 to 298 K based on τ of the NIR emission of Bi3+ at 748 nm and in the temperature range of 278–378 K based on the LIR of Bi3+ to Pr3+ emissions (I 748/I 615). As a novel LIR-τ dual-mode thermometric material over a wide temperature range, the maximum relative sensitivities of the YTOB0.5P0.5 reach 3.53% K–1 at 298 K from the τ mode and 3.52% K–1 at 318 K based on the LIR mode. The dual-mode luminescence thermometry with high responsivity from our Bi3+-based pyrochlore Y2Ti2O7 phosphor opens a new avenue for more luminescent materials toward multi-mode thermometry applied in complex temperature-sensing conditions.

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Section: Resultscontrasting

confidence: 76%

Charge Transfer-Triggered Bi³⁺Near-Infrared Emission in Y₂Ti₂O₇for Dual-Mode Temperature Sensing

Wang

Jahanbazi

Wei

et al. 2022

ACS Appl. Mater. Interfaces

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“…An on-site Coulomb correction with effective Hubbard parameter U eff = 5.4 eV was applied to Ti 3d electrons. This value is calculated based on the liner response method developed by Cococcioni et al The calculated band gap was found to be in good agreement with experimental values − (Table and Supporting Information Figure S1).…”

Section: Calculation Methodssupporting

confidence: 61%

Cooperative Oxide-Ion Transport in Pyrochlore Y₂Ti₂O₇: A First-Principles Molecular Dynamics Study

et al. 2021

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We developed a mapping approach for analyzing time-series data of local structural units based on the Voronoi–Dirichlet partition to quantify the defect states and oxide-ion migration mechanism in pyrochlore Y2Ti2O7 (space group: Fd3̅m) observed during first-principles molecular dynamics simulations. Defect states are classified into three types: a Frenkel pair, a single vacancy, and a split vacancy. Although the energetically most favorable defect type is a split vacancy at low temperatures, split and single vacancies are found to be equally favorable at high temperatures. Oxide-ion migration occurs by a two-step cooperative mechanism via a split vacancy. Climbing-image nudged elastic band calculations show the energy barrier for the cooperative diffusion mechanism (0.65 eV) to be substantially less than that of a simple stepwise mechanism (0.96 eV). This lower-energy barrier is comparable to experimental activation energies of oxide-ion diffusion in Y2Ti2O7 reported in the literature, making this previously unrecognized cooperative mechanism the most likely candidate for enabling oxide-ion transport in the titanate pyrochlore.

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“…Previous crystallographic analysis on the stoichiometric end members Y 2 Ti 2 O 7 , 43 Bi 2 Ti 2 O 7 , 44 and Ho 2 Ti 2 O 7 24 indicate the cubic Fd 3̄ m structure at room temperature. After successfully synthesizing compounds in the Bi 2− x RE x Ti 2 O 7 (RE = Y 3+ [ x = 0.5, 1.0, and 2.0], Ho 3+ [ x = 0.5, 1.5, and 2.0]) series, average structural analysis against neutron and X-ray scattering indicates the Fd 3̄ m structure is a good description of the data at room temperature and 2 K, with R w values at or less than 10% for all samples.…”

Section: Resultsmentioning

confidence: 97%

Compositional influence of local and long-range polarity in the frustrated pyrochlore system Bi_2−xRE_xTi₂O₇(RE = Y³⁺,Ho³⁺)

et al. 2022

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Structural, optical and mechanical properties of Y2Ti2O7 single crystal

Cited by 20 publications

References 27 publications

Charge Transfer-Triggered Bi³⁺Near-Infrared Emission in Y₂Ti₂O₇for Dual-Mode Temperature Sensing

Charge Transfer-Triggered Bi³⁺Near-Infrared Emission in Y₂Ti₂O₇for Dual-Mode Temperature Sensing

Cooperative Oxide-Ion Transport in Pyrochlore Y₂Ti₂O₇: A First-Principles Molecular Dynamics Study

Compositional influence of local and long-range polarity in the frustrated pyrochlore system Bi_2−xRE_xTi₂O₇(RE = Y³⁺,Ho³⁺)

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Structural, optical and mechanical properties of Y2Ti2O7 single crystal

Cited by 20 publications

References 27 publications

Charge Transfer-Triggered Bi3+Near-Infrared Emission in Y2Ti2O7for Dual-Mode Temperature Sensing

Charge Transfer-Triggered Bi3+Near-Infrared Emission in Y2Ti2O7for Dual-Mode Temperature Sensing

Cooperative Oxide-Ion Transport in Pyrochlore Y2Ti2O7: A First-Principles Molecular Dynamics Study

Compositional influence of local and long-range polarity in the frustrated pyrochlore system Bi2−xRExTi2O7(RE = Y3+,Ho3+)

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Charge Transfer-Triggered Bi³⁺Near-Infrared Emission in Y₂Ti₂O₇for Dual-Mode Temperature Sensing

Charge Transfer-Triggered Bi³⁺Near-Infrared Emission in Y₂Ti₂O₇for Dual-Mode Temperature Sensing

Cooperative Oxide-Ion Transport in Pyrochlore Y₂Ti₂O₇: A First-Principles Molecular Dynamics Study

Compositional influence of local and long-range polarity in the frustrated pyrochlore system Bi_2−xRE_xTi₂O₇(RE = Y³⁺,Ho³⁺)