Inelastic Light Scattering Near the Ferroelectric Phase-Transition Point in Bismuth Vanadate Crystals

Avakyants, L. P.; Chervyakov, А. V.; Горелик, В. С.; Sverbil, P. P.

doi:10.1023/b:jorr.0000049086.09037.b3

Cited by 14 publications

(13 citation statements)

References 25 publications

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“…Considering the sample thickness, we can approximate the speed of sound to be 1.4 ± 0.2 × 10 3 m s −1 . Sound velocities have been reported for a BiVO 4 single crystal as a function of propagation directions and range from 1.6 to 4.9 × 10 3 m s −1 at room temperature, 47 in good agreement with our data. There is minimal temperature dependence to the sound velocity over the temperature range studied, which suggests that no phase transition or metal-to-insulator transition occurs.…”

Section: Resultssupporting

confidence: 91%

Physical Origins of the Transient Absorption Spectra and Dynamics in Thin-Film Semiconductors: The Case of BiVO₄

et al. 2018

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Transient absorption (TA) spectroscopy is uniquely suited for understanding kinetic processes initiated by light over vast ranges of time. In combination with white light probes, the recorded differential absorption spectra can contain spectroscopic signatures characteristic of specific charge carrier population densities. However, disentangling the often-complex and convoluted spectra is made challenging without robust analysis methods relating the underlying physical mechanisms to the spectral components. In this work, we address the origin of the transient spectra of a model system of emerging solar energy harvesting materials using a monoclinic BiVO 4 thin film. Using ground-state optical properties of the semiconductor, we find the main derivative-like spectral response to be related to shifting and broadening of oscillators, rather than specific carrier-related transitions. However, by using the Drude optical model of free carriers, we also identify the transient response related to freehole density. Importantly, sample heating from the optical pumping, which begins at ∼10 ps and plateaus by ∼200 ps, dominates the overall spectral response at longer times. On the basis of a physical model of the spectral response, a kinetic model is developed that describes the pump power dependence of the free-hole density, as well as the temporal evolution of the spectral changes associated with shifting and broadening of oscillators. First-principles density functional theory calculations are used to rationalize experimental measurements. This comprehensive approach to analyzing and modeling the TA spectra offers a generalizable basis for understanding the complex pump−probe data, reveals thermal heating artifacts that are frequently erroneously assigned to long-lived photocarriers, and offers a path to eliminating ambiguity in analysis of photocarrier dynamics in solid-state systems.

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Section: Resultssupporting

confidence: 91%

Physical Origins of the Transient Absorption Spectra and Dynamics in Thin-Film Semiconductors: The Case of BiVO₄

et al. 2018

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“…We include the wavenumbers and symmetries yielded by the ab-initio calculations performed with the hybrid functional HSE06, as well as the results corresponding to the single crystal study reported in Ref. 34. The B 1 g , B 2 g and A 1…”

Section: Mode Characterizactionmentioning

confidence: 99%

“…23 It appears that the monoclinic symmetry of the fergusonite phase is the result of a distortion of the tetragonal symmetry of the scheelite phase 23,24 by a ferroelastic instability. 25 Opposite to other orthovanadates, a second order phase transition from the fergusonite to the scheelite phase is observed either at high pressure [26][27][28] [1.4(1) GPa] or high temperature 23,[28][29][30][31][32][33][34][35] [525(3) K]. Another approach to stabilize the tetragonal scheelite phase is appropriate doping of the sample.…”

Section: Introductionmentioning

confidence: 99%

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Phase transition systematics in BiVO4 by means of high-pressure–high-temperature Raman experiments

et al. 2018

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We report here high pressure-high temperature Raman experiments performed on BiV O4. We have characterized the fergusonite and scheelite phases (powder and single crystal samples) and the zircon polymorph (nano powder). The experimental results are supported by ab-initio calculations, which in addition provide the vibrational patterns. The temperature and pressure behavior of the fergusonite lattice modes reflects the distortions associated with the ferroelastic instability. The linear coefficients of the zircon phase are in sharp contrast with the behavior observed in the fergusonite phase. The boundary of the fergusonite to scheelite second order phase transition is given by T F −Sch (K) = −166(8)P (GP a) + 528(5). The zircon to scheelite, irreversible, first order phase transition takes place at T Z−Sch (K) = −107(8)P (GP a) + 690(10). We found evidence of additional structural changes around 15.7 GP a, which in the downstroke were found to be not reversible. We have analyzed the anharmonic contribution to the wavenumber shift in fergusonite using an order parameter. The introduction of a critical temperature depending both on temperature and pressure allows description of the results of all the experiments in a unified way.

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“…Avakyants et al [74] have reported the Raman spectra of single-crystal BiVO4. They found eight external modes (62,130 Figure 10a is the comparison of Fourier-transformed power spectra of the oscillation component measured at 550 and 610 nm with the Raman spectrum of a single crystal.…”

Section: Bivomentioning

confidence: 99%

Applications of Time‐Domain Spectroscopy to Electron–Phonon Coupling Dynamics at Surfaces

Matsumoto

2014

The Chemical Record

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Photochemistry is one of the most important branches in chemistry to promote and control chemical reactions. In particular, there has been growing interest in photoinduced processes at solid surfaces and interfaces with liquids such as water for developing efficient solar energy conversion. For example, photoinduced charge transfer between adsorbates and semiconductor substrates at the surfaces of metal oxides induced by photogenerated holes and electrons is a core process in photovoltaics and photocatalysis. In these photoinduced processes, electron-phonon coupling plays a central role. This paper describes how time-domain spectroscopy is applied to elucidate electron-phonon coupling dynamics at metal and semiconductor surfaces. Because nuclear dynamics induced by electronic excitation through electron-phonon coupling take place in the femtosecond time domain, the pump-and-probe method with ultrashort pulses used in time-domain spectroscopy is a natural choice for elucidating the electron-phonon coupling at metal and semiconductor surfaces. Starting with a phenomenological theory of coherent phonons generated by impulsive electronic excitation, this paper describes a couple of illustrative examples of the applications of linear and nonlinear time-domain spectroscopy to a simple adsorption system, alkali metal on Cu(111), and more complex photocatalyst systems.

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Inelastic Light Scattering Near the Ferroelectric Phase-Transition Point in Bismuth Vanadate Crystals

Cited by 14 publications

References 25 publications

Physical Origins of the Transient Absorption Spectra and Dynamics in Thin-Film Semiconductors: The Case of BiVO₄

Physical Origins of the Transient Absorption Spectra and Dynamics in Thin-Film Semiconductors: The Case of BiVO₄

Phase transition systematics in BiVO4 by means of high-pressure–high-temperature Raman experiments

Applications of Time‐Domain Spectroscopy to Electron–Phonon Coupling Dynamics at Surfaces

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Inelastic Light Scattering Near the Ferroelectric Phase-Transition Point in Bismuth Vanadate Crystals

Cited by 14 publications

References 25 publications

Physical Origins of the Transient Absorption Spectra and Dynamics in Thin-Film Semiconductors: The Case of BiVO4

Physical Origins of the Transient Absorption Spectra and Dynamics in Thin-Film Semiconductors: The Case of BiVO4

Phase transition systematics in BiVO4 by means of high-pressure–high-temperature Raman experiments

Applications of Time‐Domain Spectroscopy to Electron–Phonon Coupling Dynamics at Surfaces

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Product

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Physical Origins of the Transient Absorption Spectra and Dynamics in Thin-Film Semiconductors: The Case of BiVO₄

Physical Origins of the Transient Absorption Spectra and Dynamics in Thin-Film Semiconductors: The Case of BiVO₄