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Room temperature Raman spectra of BS7T and BS7TM ceramics excited by 532 and 638 nm lasers. The inset shows the XRD pattern of BS7T.
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The structure, valence state, and dielectric properties of (Ba1-xSm
x
)(Ti0.99Mn0.01)O₃ (BSTM) (x = 0.02‒0.07) ceramics prepared via a high temperature (1400 °C/12 h) solid state reaction were investigated. A homogeneous and dense microstructure was observed in all samples. With increasing Sm content, the crystal structure changed from tetragonal (...
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... indicated that the tetragonal-cubic phase transition did not affect the Raman charge effect, as reported in the literature [38]. Figure 6 exhibits room temperature Raman spectra of the representative samples BS7T and BS7TM excited by 532 and 638 nm lasers in the wide wavenumber range 100-5000 cm -1 . BS7T ceramic with a cubic structure (Figure 6 inset) was prepared under the same conditions (1400 °C/12 h) as BSTM ceramics. ...
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... 6 exhibits room temperature Raman spectra of the representative samples BS7T and BS7TM excited by 532 and 638 nm lasers in the wide wavenumber range 100-5000 cm -1 . BS7T ceramic with a cubic structure (Figure 6 inset) was prepared under the same conditions (1400 °C/12 h) as BSTM ceramics. Abnormal Raman spectra excited by the 532 nm laser were observed at a Raman shift > 1000 cm -1 in BS7T and BS7TM. ...
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... 5 shows that the 840 cm −1 band did not change as a function of temperature, and persisted up to 150 • C. It indicated that the tetragonal-cubic phase transition did not affect the Raman charge effect, as reported in the literature [38]. Figure 6 exhibits room temperature Raman spectra of the representative samples BS7T and BS7TM excited by 532 and 638 nm lasers in the wide wavenumber range 100-5000 cm −1 . BS7T ceramic with a cubic structure (Figure 6 inset) was prepared under the same conditions (1400 • C/12 h) as BSTM ceramics. ...
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... 6 exhibits room temperature Raman spectra of the representative samples BS7T and BS7TM excited by 532 and 638 nm lasers in the wide wavenumber range 100-5000 cm −1 . BS7T ceramic with a cubic structure (Figure 6 inset) was prepared under the same conditions (1400 • C/12 h) as BSTM ceramics. Abnormal Raman spectra excited by the 532 nm laser were observed at a Raman shift > 1000 cm −1 in BS7T and BS7TM. ...
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... nm Figure 6. Room temperature Raman spectra of BS7T and BS7TM ceramics excited by 532 and 638 nm lasers. ...
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Citations
... Overall, the single dopant into the BaTiO 3 decreases the dielectric constant while increasing the dopant concentration. While in the case of doping of double dopants [35], for example in (Ba 1 − x Sm x )(Ti 0.99 Mn 0.01 ) O 3 (BSTM) (x = 0.02, 0.04, 0.06, 0.07 mol%), high dielectric permittivity of 16,000 was obtained for the highest dopant concentration of 0.07 and 6000 was found for dopant concentration of 0.02 mol% [36]. In addition, (Ba 1 − x Sm x )(Ti 1 − x Fe x )O 3 with x = 0, 0.0025, 0.0050, 0.0075, 0.01 mol% prepared by solid-state method has also showed an increase in the the dielectric constant of 5580, 6110, 5720, 6210, and 7020 for composition variation from 0, 0.0025, 0.0050, 0.0075, and 0.01 mol%. ...
Sm and Zr co-doped BaTiO3 ceramics were investigated for their microstructure and dielectric characteristics. (Ba1 − xSmx)(Ti0.75Zr0.25)O3−δ (BSTZO) with x = 0.02, 0.04, and 0.06 mol% of ceramic compounds were prepared by solid-state reaction route. The primary objective is to obtain higher dielectric constant with lower dielectric loss in the proposed material composition. The prepared BSTZO and sintered compounds were found to be highly crystalline with a tetragonal perovskite structure. A typical X-ray photoelectron spectroscopy spectra of BSTZO sample with Sm = 0.02 mol% calcined at 1273 K revealed the elemental composition, binding energy, and chemical state of the elements. Oxygen vacancy concentrations evaluated by in situ high-temperature Raman spectroscopy in the temperature range of 301–773 K were found to decrease with increasing Sm³⁺ concentration and the substitution of the lowest concentration of Sm³⁺ (0.02 mol%) in the A site of the BSTZO was found to be higher (VO··\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${V}_{O}^{\cdot \cdot}$$\end{document}= 1.98 × 10²¹ cm⁻³, at 773 K) than that of the other compositions. The measured maximum dielectric constant was found to be 1808, 2010, and 1736 for BSTZO pellet with x= 0.02, 0.04, and 0.06 mol%, respectively in the temperature range of 323–773 K and at frequency of 20 MHz. Among these compounds, (Ba0.96Sm0.04) (Ti0.75Zr0.25)O3−δ has shown high dielectric constant and low loss tangent compared to other compositions.
... Small A1g Raman peaks within the wavenumber range of 830-836 cm −1 were identified as the Co ions incorporated in the Ti site of the BT host lattice. Metal ion inclusion at the Ti-site is confirmed by Raman active modes in this area [40]. A possible explanation for the asymmetric modes at 722 cm −1 is that they result from the superposition of (Ti/Co)O 6 modes. ...
Following the finding of power conversion efficiency above the Shockley–Queisser limit in BaTiO3 (BTO) crystals, ferroelectric oxides have attracted scientific interest in ferroelectric photovoltaics (FPV). However, since ferroelectric oxides have a huge bandgap (>3 eV), progress in this sector is constrained. This paper proposes and demonstrates a new ferroelectric BaTi1−xCoxO3 powder (0 ≤ x ≤ 0.08), abbreviated as BTCx, that exhibited a bandgap decrease with increased Co content. Notably, changing the composition from x = 0.0 to 0.08 caused the system to show a bandgap drop from 3.24 to 2.42 eV. The ideal design with x = 0.08 displayed an abnormal PV response. Raman spectroscopy measurements were used to investigate the cause of the bandgap decrease, and density functional theory was used to interpret the analyzed results. According to our findings, Co2+ doping and oxygen octahedral distortions enhance bandgap reduction. This research sheds light on how bandgap tuning developed and laid the way for investigating novel low-bandgap ferroelectric materials for developing next-generation photovoltaic applications.
... The peak positions of the BT co-doped powders slightly shift to the left and the lower angles, especially (200) and (211) [41][42][43]. Furthermore, an increase in the dopants concentration enhances the lattice parameter [18,44]. Ho-Mn co-doping leads to the secondary phases formation, including the pyrochlore phase (Ho 2 Ti 2 O 7 ) and HoTiO 3 . ...
Co-doped barium titanate (BT) piezoceramics are applied in advanced energy harvesting systems. In the present study, Ba1-2xHo2xTi1-xMnxO3 (x=0, 0.02, 0.04, and 0.06) were produced via the sol-gel-assisted solid state co-doping technique followed by microwave and conventional heating. In the current investigation, the synthesizing and phase characterization, allotropic transition, morphological examination, elemental analysis and dielectric-piezoelectric responses were investigated by X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC) and Thermo-Gravimetric Analysis (TGA), Field-Emission Scanning Electron Microscope (FESEM), Energy-Dispersive x-ray Spectroscopy (EDS), Mapping analysis and inductance-Capacitance-Resistance meter (LCR meter) techniques, respectively. The XRD pattern and DSC/ TGA outcomes demonstrated that tetragonal BT phases without minor BaCO3 secondary phases are synthesized properly, and that the negligible unsolicited BaCO3 phases are thoroughly calcined by a microwave at 900℃. Doping resulted in an increase in tetragonality (c/a) of 0.19%, 0.15%, and 0.04%, respectively, compared to the pure calcined BT. Additionally, the crystallite size of BT decreased significantly by 59%, 58%, and 52%, respectively. The results revealed that the microwave-sintered samples have higher purity, drastic delicate and finer grain size distribution, and superior tetragonal-ity with respect to the conventionally sintered furnace samples. Furthermore, the piezoelectric constant for the microwave sintered and the conventionally sintered samples with the same value of x=0.04 were 390 and 370 (pC/N), respectively, which established that the sintering method has satisfactory affection (approximately 6%) on the piezo function of the samples. Eventually, the prepared samples which had 0, 2, 4, and 6 % moles of Ho3+-Mn2+ cations and were sintered by a microwave compared to the similar specimens fabricated by the furnace had superior dielectric constants of 2.6, 1.1, 2.2 and 2.9 times, respectively.
... The tetragonal crystal structure of both the samples can also be confirmed from the presence of the split diffraction peaks regarding (002) and (200) set of planes. 37 The crystallite size, lattice parameters, and c/a ratio were also measured from the diffraction patterns of the both the materials using formulae mentioned in our previous studies. 38,39 The average crystallite size was found to get bigger from 24.38 to 30.57 ...
Current study depicts an exclusive technique to detect fluoride ions in water using a cost-effective self-powered sensing device using nanostructured Mn doped BaTiO3 as detecting element. The device is powered by a piezoelectric nanogenerator (PENG), whose substrate was modified by addition of Mn doped BaTiO3 nanomaterial and carbon nanotubes as fillers to generate high PENG output voltage sufficient for driving the fluoride detector. A highest voltage of 43.6 volt and current of 1.23 mA was achieved by the modified PENG substrate. This substrate was then connected as the input to the fluoride detection film via rectified voltage divider circuit. The device was found to detect fluorides in water mixed at different concentrations, with the highest sensor response 32.69, and limit of detection as low as 1.18 mM. This work enlightens a unique method to detect fluoride in a very efficient and inexpensive way.
... Hence, codoping notably prevents the formation of the hexagonal phase and lowers the number of oxygen vacancies. On the other hand, elements of the codopant act as a donor and acceptor dopant at a compensated concentration [48,[87][88][89][90][91][92][93][94][95][96]. ...
Due to the growing demand of energy and wastage of energy, there exists an interest of storing energy so that it could be utilized efficiently. Capacitors are materials designed for such an application. Ferroelectric materials are known for their application as capacitors. Of such materials, perovskites are the preferable classes of materials that have been used as capacitors. Barium strontium titanate nanomaterial is a member of perovskites which encompasses a smaller dielectric loss, elevated dielectric constant, and good thermal stability. Research studies also clarified that incorporating dopants into a barium strontium titanate nanomaterial of high dielectric materials including metal/metal oxides enhances their efficiency and effectiveness. Moreover, multielement doping or codoping has shown better dielectric properties as compared to the unidoping of BST. In this review, barium strontium titanate capacitors codoped with more than one metal/metal oxides have been studied most of which have shown that the codoped barium strontium titanate materials possess improved and sufficient dielectric properties to be utilized as capacitors. We believe that this work will have of its own contribution on understanding the doped barium strontium titanate nanomaterial by clarifying the most probable and detail reasons behind the enhancement of dielectric properties of codoped barium strontium titanate nanomaterials.
... Stabilization of the h-phase was attributed to the Jahn-Teller distortion of TiO 6 octahedra by Mn 3+ (d 4 ) ions [12], whereas, in another study, the opposite effect was reported where B-site Mn 3+ -doping was found to favor the formation of tetragonal and orthorhombic phases [13]. In B-site, Mn 3+ -doped BaTiO 3 , A-site donor dopants like La 3+ , Pr 3+ , and Sm 3+ ions have been reported to stabilize the t-phase due to the reduction of Mn 3+ to Mn 2+ [14][15][16]. In the case of A-site, Nd 3+ co-doping, defect complexes of the type [2Nd • Ba − Mn �� Ti ] have been reported to suppress h-phase formation [17]. ...
This study reports, for the first time, the possibility of exploitation of the defect chemistry to suppress the hexagonal phase formation in donor–acceptor co-doped BaTiO3. Systematic Raman and electron paramagnetic resonance spectroscopic investigations have been carried out to understand the mechanism responsible for the suppression of hexagonal phase in Lanthanum and manganese co-doped BaTiO3. Stabilization of the perovskite phase is related to the donor/acceptor ratio and the doping mechanism. Suppression of the hexagonal phase is found to be facile in barium-deficient compositions, whereas in titanium-deficient compositions, coexistence of cubic and hexagonal phase is observed at [La3+] ≥ 0.02. However, in highly B-site acceptor-doped compositions, [Mn3+] ≥ 0.01, h-phase stabilization occurs irrespective of donor/acceptor ratio in both barium- and titanium-deficient compositions. This has opened up a new pathway for the synthesis of hexagonal phase-free donor–acceptor co-doped BaTiO3.
... The Raman spectra of Fe and Mn doped BTO, Ba 1Àx Fe x Ti 1Ày Mn y O 3 are studied by Rajan et al. 13 Verma et al. 14 performed Raman studies of pure and Fe doped BTO nanorods and nanowires. The lattice dynamics investigation of different transition behaviors of cubic BTO and SrTiO 3 by first-principles calculations are performed by Xie et al. 15 The phase transitions in Mn doped BTO are investigated through Raman studies by Madhan et al., 16 Mukherjee et al., 17 and Liu et al. 18 The bandgap E g of ion doped BTO is observed experimentally in Refs. 17 and 19-23 and theoretically in Ref. 24 using first-principles calculations. ...
... For example, for Dy, it is x ¼ 0:025, 27 for Sm-0.07, 18 for Nb-0.1, 17 for Eu-0.5, 26 and for La-0.02 33 and 0.04. 37 The phonon energy is reduced with the increase in the Mn dopants, whereas it is enhanced with the increase in the Fe ones, for J d . ...
We have calculated the phonon energy and damping of ω0=264cm−1 in Fe, Mn, and Dy doped BaTiO3 using a microscopic model. By doping with Fe ions, the phonon energy ω and damping γ show anomalies at the two phase transition temperatures. ω increases whereas γ decreases with the increase in the magnetic field and the kink at TCfm vanishes. ω and TCfe decrease or increase with the increase in Mn or Fe dopants, respectively. TCfe and ω of ω0=718cm−1 decrease with the increase in Dy ion doping on the Ba site. γ is enhanced for all three ions. The changes in the phonon properties by ion doping are due to the different strain caused by the different ionic radii of the host and doping ions. The effects of Fe, Mn, and Sm doping on the bandgap energy are also discussed.
... Therefore, this generation of new charge carriers may lead to an increase in the value of the dielectric constant. The existence of oxygen vacancies, which are created as a result of the sample being sintered at a higher temperature for a longer period, is an extrinsic parameter that is associated with space charge polarization, contributing to this high value of the dielectric constant [35][36][37]. Figure 7b displays the variation in the dissipation factor (tanδ) against frequency for YBMZO ceramic. It is defined as the ratio of energy dissipation to energy storage by the sample and its variation with applied field frequency (i.e. ...
In the present communication, the composition of barium and zirconium modified YMnO3 ceramic, i.e. Y0.95Ba0.05Mn0.95Zr0.05O3, has been synthesized using the solid-state reaction method, and emphasis has been made to observe the variations on structural, optical, electrical, and ferroelectric properties of the prepared ceramic. The primary structural analysis has been verified by the X-ray diffraction technique. XRD patterns revealed that the sample has been crystallized in a hexagonal geometry with P63cm space group symmetry. Further, Rietveld’s refinement of Y0.95Ba0.05Mn0.95Zr0.05O3 ceramic has been done to support the results of XRD. The lattice parameters are increased, while the average crystallite size is decreased with Ba2+ and Zr4+ doping. A detailed study of the optical property of the prepared sample was done using the UV-DRS method. The optical energy band gap of the sample is found to be ~ 1.534 eV, while the Urbach’s energy is found to be ~ 0.169 eV. The dielectric constant and dielectric loss of the ceramic show the dispersion due to Maxwell–Wagner’s type of interfacial polarization. Moreover, the given ceramic sample reveals the enhanced value of the dielectric constant. The complex modulus measurement revealed that the transport phenomenon in this ceramic indicates the relaxation mechanism of the non-Debye’s type. The complex impedance study of the given ceramic has been done to explore the grain and grain boundaries contribution, which are in sequence the controlling factors for the electrical properties of the given material. The ceramic sample with an enhanced dielectric constant may be appropriate for device applications.
... Previous studies showed that the XRD patterns of the undoped BaTiO3 have a single peak at 45 corresponding to (002) Miller index when it is in the cubic phase. It offers a peak splitting at 45 corresponding to (002) and (020) peaks for the tetragonal phase [13][14]. Indication of pseudo-cubic perovskite structure in the tetragonal phase was also observed in previous studies of BaTiO3 based ceramics [15]. ...
... The smoothest peak was observed for the co-doped samples. The intensity of the major peak increases with Ce and Mn's addition, which indicates better crystallization of the samples [14]. From the major peaks lattice parameters, a were calculated by using the Nelson-Riley method using the equation ...
Undoped, Cerium (Ce) doped, Manganese (Mn) doped and Ce-Mn co-doped Barium Titanate (BaTiO 3) with the general formula Ba 1-x Ce x Mn y Ti 1-y O 3 (where x = 0.00, 0.01, 0.02, 0.03, y = 0.00; x = 0.00, y =0.01, 0.02, 0.03; and x = y = 0.01, 0.02,0.03) were synthesized by solid-state reaction method and sintered at 1200 C for 4 hr with an aim to study their structural and electrical properties. The grain size of the samples has been estimated using the Scanning Electron Microscopy (SEM). The X-ray Diffraction (XRD) analysis indicates that the structure of the Ce-doped and Ce-Mn co-doped BaTiO 3 is cubic. However, the undoped BaTiO 3 and Mn-doped BaTiO 3 confirmed the tetragonal-cubic mixed phases. With the change of doping concentrations, the positions of different peaks shifted slightly. The lattice parameter varied irregularly with increasing doping concentration because of Mn's changeable valency. EDX spectra confirmed the presence of Ba, Ti, Ce, and Mn contents in the co-doped samples with stoichiometric ratio. Crystallinity is observed to be clearly increased when Ce-Mn is co-doped in BaTiO 3. J-V characteristic curves indicate transition from conducting to semiconducting nature for the doped and co-doped samples with the increase in temperature. The dielectric constant of the samples increases up to 4500 with the doping concentration. The higher values of dielectric constant are observed for the 2% Mn-doped and 1% Ce-Mn co-doped samples compared to the other undoped samples. For the undoped and Mn-doped samples, constant dielectric values increase with temperature but decrease for the Ce-doped and Ce-Mn co-doped samples. It is inferred that co-doping of BaTiO 3 with Ce and Mn would be beneficial and economical for its applications.
... As the Co, Fe, or Ni ions incorporate in the Ti site of the BNBT host lattice, small A 1 g Raman peaks were detected within the wavenumber range of 832-835 cm − 1 , as shown in Fig. 4b-d. Raman active modes in this region confirm the incorporation of metal ions at the Ti-site [53]. The broad bands observed in the BNBT-M spectra (Fig. 4b-d), resulting from the overlapping of different modes, were unconvoluted and compared to theoretical and experimental results reported in the literature ( Table 2). ...
A wide bandgap is one of the greatest issues that restrain the photoelectric application of classical ferroelectric oxides in the visible spectrum. Typical approaches to reduce their bandgap, as well as to tune other physical properties (dielectric, piezoelectric …), is to use specific dopants. This work reports the variation by doping of the structural and optical bandgap properties of the Ba0.92Bi0.04Na0.04Ti0.96M0.04O3 (BNBT-M); (M = Ni, Fe, Co) ceramics. Structural refinement shows that all samples are crystallized with a tetragonal phase with a P4mm space group. Detailed analysis of the bond lengths, bond angles, octahedral distortions demonstrates the cooperative effect induced by the Co, Fe, and Ni doping. UV–Vis absorption spectra showed a decrease in the bandgap and increased absorption for longer wavelengths, induced by transitions metal (TM) ions doping. The bandgap narrowing is attributed to the development of new M − O bonds and states in the electronic structure, as the TM ions are incorporated on the Ti site, with simultaneous oxygen vacancies creation. The formation of oxygen vacancies via metal ions doping in BNBT was proven by ESR study. The present investigation can provide useful insight into the understanding and ferroelectrics bandgap tuning for visible-light photovoltaic applications.
