Phase transitions in barium–strontium titanate films on MgO substrates with various orientations

Анохин, А. С.; Razumnaya, A. G.; Yuzyuk, Yu. I.; Golovko, Yu. I.; Мухортов, В. М.

doi:10.1134/s1063783416100048

Cited by 10 publications

(8 citation statements)

References 24 publications

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“…Vibrational spectroscopy methods were used to study the dynamics of phase transitions in various Ba‐doped SrTiO 3 samples prepared in different forms, such as, single crystals and ceramics [ 15,16 ] and films and superlattices on different substrates. [ 17–21 ] It was shown that the soft mode, which is a characteristic of displacive structural phase transitions, is active only in the ferroelectric phase. The soft‐mode behavior allows to determine the Curie temperature ( T C ).…”

Section: Introductionmentioning

confidence: 99%

Crystal Structure and the Spectral Response of the Ba‐Doped SrTiO₃ Incipient Ferroelectrics

Linnik

Luk’yanchuk

Mikheykin

et al. 2021

Physica Status Solidi (b)

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The crystal structure and lattice dynamics of quantum paraelectric BaxSr1−xTiO3 (x = 0, 0.01, 0.02) solid solutions are studied using X‐ray diffraction (XRD), Raman and terahertz‐infrared (THz‐IR) spectroscopies in a temperature range of 4–300 K. XRD and Raman spectroscopy reveal the cubic‐to‐tetragonal nonpolar structural phase transition at about 100 K. At the same time, Raman spectra manifest the presence of polar modes, TO2 and TO4, normally prohibited in paraelectric phase. Emergence of these modes indicates the appearance of the polar nanoregions in a broad temperature range. The modes become more intensive at low temperatures, and temperature dependence of their intensities on cooling reveals the kink‐like change of the slope from flat to steep, indicating on activation of polar nanoregions. The transmission THz‐IR spectra show that squared frequency of the polar TO1 soft mode, responsible for ferroelectric transition, follows Cochran's behavior at high temperatures. However, at low temperatures, it doesn't vanish at extrapolated Curie temperature but saturates, demonstrating the plateau feature below 20 K. This behavior, coherent with known saturation of the dielectric constant, indicates that transition to ferroelectric phase in BaxSr1−xTiO3 is suppressed by quantum fluctuations and the system stays in quantum paraelectric state at very low temperatures.

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Section: Introductionmentioning

confidence: 99%

Crystal Structure and the Spectral Response of the Ba‐Doped SrTiO₃ Incipient Ferroelectrics

Linnik

Luk’yanchuk

Mikheykin

et al. 2021

Physica Status Solidi (b)

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“…At the excitation wavelength of 1064 nm, Raman spectrum of (i) BaSrTiO 3 is dominated of an intense Raman line with the maximum at 525 cm −1 ( Figure 3 a) assigned to the A 1 (TO) vibrational mode [ 15 ], while in the case of (ii) the TPU:TPO blend, an intense Raman complex band at 2867–2912 cm −1 accompanied by other lines of low intensity with peaks at 1616, 1436 and 1301 cm −1 is reported. The assignment of the Raman lines of the TPU:TPO blend is shown in Table 1 .…”

Section: Resultsmentioning

confidence: 99%

The Influence of the Ceramic Nanoparticles on the Thermoplastic Polymers Matrix: Their Structural, Optical, and Conductive Properties

et al. 2021

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This paper prepared composites under the free membranes form that are based on thermoplastic polymers of the type of polyurethane (TPU) and polyolefin (TPO), which are blended in the weight ratio of 2:1, and ceramic nanoparticles (CNs) such as BaSrTiO3 and SrTiO3. The structural, optical, and conductive properties of these new composite materials are reported. The X-ray diffraction studies highlight a cubic crystalline structure of these CNs. The main variations in the vibrational properties of the TPU:TPO blend induced by CNs consist of the following: (i) the increase in the intensity of the Raman line of 1616 cm−1; (ii) the down-shift of the IR band from 800 to 791 cm−1; (iii) the change of the ratio between the absorbance of IR bands localized in the spectral range 950–1200 cm−1; and (iv) the decrease in the absorbance of the IR band from 1221 cm−1. All these variations were correlated with a preferential adsorption of thermoplastic polymers on the CNs surface. A photoluminescence (PL) quenching process of thermoplastic polymers is demonstrated to occur in the presence of CNs. The anisotropic PL measurements have highlighted a change in the angle of the binding of the TPU:TPO blend, which varies from 23.7° to ≈49.3° and ≈53.4°, when the concentration of BaSrTiO3 and SrTiO3 CNs, respectively, is changed from 0 to 25 wt. %. Using dielectric spectroscopy, two mechanisms are invoked to take place in the case of the composites based on TPU:TPO blends and CNs, i.e., one regarding the type of the electrical conduction and another specifying the dielectric–dipolar relaxation processes.

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“…Since the Ba 0.8 Sr 0.2 TiO 3 is an anisotropic material with the point group R3m 35 , the SHG intensity is extremely sensitive to the orientation of the electric field of the incident optical pulse (inset of Fig. 2).…”

Section: Discussionmentioning

confidence: 99%

“…We investigated a prototypical ferroelectric heteroepitaxial (Ba 0.8 Sr 0.2 )TiO 3 [111] thin film (thickness 400 nm) on a centrosymmetric MgO substrate (thickness 580 μm). Ba 0.8 Sr 0.2 TiO 3 film of such composition undergoes a ferroelectric phase transition at T c = 353 K 35 . Moreover, Ba 0.8 Sr 0.2 TiO 3 has several infrared active phonon modes in THz range that can be driven resonantly by THz radiation.…”

Section: Methodsmentioning

confidence: 99%

Transient Second Harmonic Generation Induced by Single Cycle THz pulses in Ba0.8Sr0.2TiO3/MgO

Grishunin

Bilyk

Sherstyuk

et al. 2019

Sci Rep

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The ability to switch ferroics (magnets, ferroelectrics, multiferroics) between two stable bit states is the main principle of modern data storage technology. Due to many new ideas, originating from fundamental research during the last 50 years, this technology has developed in a breath-taking fashion. Ever increasing demands for faster and more energy efficient data storage strongly motivate fundamental studies of dynamics in ferroics triggered by ultrashort stimuli. It has been recently realized that nearly single cycle intense THz pulses and the phenomenon of the second harmonic generation are appealing tools for excitation and detection of poorly understood ultrafast dynamics of electric polarization in ferroelectrics at the picosecond timescale. Here we investigate picosecond dynamics of second harmonic from near-infrared pulse in ferroelectric heterostructure Ba0.8Sr0.2TiO3/MgO triggered by the electric field of a nearly single cycle intense THz pulse. The dynamics of the nonlinear optical signal is characterized by a step and oscillations at the frequency of about 1.67 THz. Although the observations can be mistakenly interpreted as oscillations of the electric polarization at the frequency of the soft mode and switching of the order parameter to another metastable state, here we show that the THz modulation of second harmonic generation in Ba0.8Sr0.2TiO3/MgO has a purely optical origin. The observation can be explained assuming that the THz pulse is a relativistically propagating inhomogeneity which induces center of symmetry breaking and linear birefringence. Our work reveals the role of propagation effects in interpretation of time-resolved non-linear optical experiments and thus it has important implications for experimental studies of ultrafast dynamics in ferroics.

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Phase transitions in barium–strontium titanate films on MgO substrates with various orientations

Cited by 10 publications

References 24 publications

Crystal Structure and the Spectral Response of the Ba‐Doped SrTiO₃ Incipient Ferroelectrics

Crystal Structure and the Spectral Response of the Ba‐Doped SrTiO₃ Incipient Ferroelectrics

The Influence of the Ceramic Nanoparticles on the Thermoplastic Polymers Matrix: Their Structural, Optical, and Conductive Properties

Transient Second Harmonic Generation Induced by Single Cycle THz pulses in Ba0.8Sr0.2TiO3/MgO

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Phase transitions in barium–strontium titanate films on MgO substrates with various orientations

Cited by 10 publications

References 24 publications

Crystal Structure and the Spectral Response of the Ba‐Doped SrTiO3 Incipient Ferroelectrics

Crystal Structure and the Spectral Response of the Ba‐Doped SrTiO3 Incipient Ferroelectrics

The Influence of the Ceramic Nanoparticles on the Thermoplastic Polymers Matrix: Their Structural, Optical, and Conductive Properties

Transient Second Harmonic Generation Induced by Single Cycle THz pulses in Ba0.8Sr0.2TiO3/MgO

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Crystal Structure and the Spectral Response of the Ba‐Doped SrTiO₃ Incipient Ferroelectrics

Crystal Structure and the Spectral Response of the Ba‐Doped SrTiO₃ Incipient Ferroelectrics