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20 pages, 5071 KiB

Open AccessArticle

Magnetoelectric Properties of Aurivillius-Layered Perovskites

by Vadla Veenachary, Eskilla Venkata Ramana, Simhachalam Narendra Babu, Venkata Sreenivas Puli, Sujoy Saha, Gopalan Srinivasan, G. Prasad and N. V. Prasad

Crystals 2024, 14(4), 299; https://doi.org/10.3390/cryst14040299 - 22 Mar 2024

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Abstract

In the present work, we have synthesized rare-earth ion modified Bi_4−xRE_xTi₂Fe0_.7Co_0.3O_12−δ (RE = Dy, Sm, La) multiferroic compounds by the conventional solid-state route. Analysis of X-ray diffraction by Rietveld refinement confirmed the [...] Read more.

In the present work, we have synthesized rare-earth ion modified Bi_4−xRE_xTi₂Fe0_.7Co_0.3O_12−δ (RE = Dy, Sm, La) multiferroic compounds by the conventional solid-state route. Analysis of X-ray diffraction by Rietveld refinement confirmed the formation of a polycrystalline orthorhombic phase. The morphological features revealed a non-uniform, randomly oriented, plate-like grain structure. The peaks evident in the Raman spectra closely corresponded to those of orthorhombic Aurivillius phases. Dielectric studies and impedance measurements were carried out. Asymmetric complex impedance spectra suggested the relaxation of charge carriers belonging to the non-Debye type and controlled by a thermally activated process. Temperature-dependent AC conductivity data showed a change of slope in the vicinity of the phase transition temperature of both magnetic and electrical coupling natures. Based on the universal law and its exponent nature, one can suppose that the conduction process is governed by a small polaron hopping mechanism but significant distortion of TiO₆ octahedral. The doping of the A-sites with rare-earth element ions and changes in the concentrations of Fe and Co ions located on the B-sites manifested themselves in saturated magnetic hysteresis loops, indicating competitive interactions between ferroelectric and canted antiferromagnetic spins. The magnetic order in the samples is attributed to pair-wise interactions between adjacent Fe³⁺–O–Fe³⁺, Co^2+/3+–O–Co^3+/2+, and Co^2+/3+–O–Fe³⁺ ions or Dzyaloshinskii–Moriya interactions among magnetic ions in the adjacent sub-lattices. As a result, enhanced magnetoelectric coefficients of 42.4 mV/cm-Oe, 30.3 mV/cm-Oe, and 21.6 mV/cm-Oe for Bi_4−xDy_xTi₂Fe0_.7Co_0.3O_12−δ (DBTFC), Bi_4−xLa_xTi₂Fe0_.7Co_0.3O_12−δ (LBTFC), and Bi_4−xSm_xTi₂Fe0_.7Co_0.3O_12−δ (SBTFC), respectively, have been obtained at lower magnetic fields (<3 kOe). The strong coupling of the Aurivillius compounds observed in this study is beneficial to future multiferroic applications. Full article

(This article belongs to the Special Issue Advanced Ferroelectric, Piezoelectric and Dielectric Ceramics)

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16 pages, 4641 KiB

Open AccessArticle

The Impact of Grain Growth on the Functional Properties in Room-Temperature Powder Aerosol Deposited Free-Standing (Ba,Ca)(Zr,Ti)O₃ Thick Films

by Juliana G. Maier, Tim Fuggerer, Daisuke Urushihara, Alexander Martin, Neamul H. Khansur, Ken-ichi Kakimoto and Kyle G. Webber

Crystals 2024, 14(4), 296; https://doi.org/10.3390/cryst14040296 - 22 Mar 2024

Viewed by 705

Abstract

This study investigates the development of freestanding thick films (FSFs) of lead-free (Ba,Ca)(Zr,Ti)O₃ and the role of grain growth on the electromechanical response. During deposition, room temperature powder aerosol deposition rapidly produces thick films with a nano-grain structure that limits the electromechanical [...] Read more.

This study investigates the development of freestanding thick films (FSFs) of lead-free (Ba,Ca)(Zr,Ti)O₃ and the role of grain growth on the electromechanical response. During deposition, room temperature powder aerosol deposition rapidly produces thick films with a nano-grain structure that limits the electromechanical properties. In this study, the films are removed from the substrate using a sacrificial buffering layer to avoid thermal treatment and allow for an initial as-processed state. Following this, FSFs were thermally treated at various annealing temperatures from 800 °C to 1400 °C to induce grain growth, which was characterized with scanning and transmission electron microscopy. X-ray diffraction revealed an increase in the crystallite size consistent with an increase in grain size and a decrease in internal residual stress. The temperature-dependent dielectric behavior and the large-field ferroelectric response were also characterized, revealing significant differences of the FSFs from the bulk properties. Full article

(This article belongs to the Special Issue Advanced Ferroelectric, Piezoelectric and Dielectric Ceramics)

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9 pages, 8051 KiB

Open AccessArticle

Improving the Energy Storage Performance of Barium Titanate-Based Ceramics through the Addition of ZnO-Bi₂O₃-SiO₂ Glass

by Peifeng Xiong, Man Xiao, Zhonghua Yao, Hanxing Liu and Hua Hao

Crystals 2024, 14(3), 242; https://doi.org/10.3390/cryst14030242 - 29 Feb 2024

Viewed by 825

Abstract

Lead-free ceramics with excellent energy storage performance are important for high-power energy storage devices. In this study, 0.9BaTiO₃-0.1Bi(Mg_2/3Nb_1/3)O₃ (BT-BMN) ceramics with x wt% ZnO-Bi₂O₃-SiO₂ (ZBS) (x = 2, [...] Read more.

Lead-free ceramics with excellent energy storage performance are important for high-power energy storage devices. In this study, 0.9BaTiO₃-0.1Bi(Mg_2/3Nb_1/3)O₃ (BT-BMN) ceramics with x wt% ZnO-Bi₂O₃-SiO₂ (ZBS) (x = 2, 4, 6, 8, 10) glass additives were fabricated using the solid-state reaction method. X-ray diffraction (XRD) analysis revealed that the ZBS glass-added ceramics exhibited a perovskite structure, with the maximum relative density achieved at x = 6. The average grain size reduced obviously as the glass additive wt% increased. Also, the dielectric constant decreased and the breakdown strength increased with increases in the glass additives. The optimal energy storage density of 1.39 J/cm³ with an energy storage efficiency of 78.3% was obtained at x = 6 due to high maximum polarization and enhanced breakdown strength. The results demonstrate that this material is a potential candidate for high-pulse-power energy storage devices. Full article

(This article belongs to the Special Issue Advanced Ferroelectric, Piezoelectric and Dielectric Ceramics)

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18 pages, 4769 KiB

Open AccessArticle

Potentials and Limits of PMN-PT and PIN-PMN-PT Single Crystals for Pyroelectric Energy Harvesting

by Mohammed Es-Souni

Crystals 2024, 14(3), 236; https://doi.org/10.3390/cryst14030236 - 28 Feb 2024

Viewed by 727

Abstract

Waste heat is inherent to industrial activities, IT services (e.g., data centers and microprocessors), human mobility, and many other common processes. The power lost each year in this way has been estimated in the 1000 TWh in the EU which, owing to skyrocketing [...] Read more.

Waste heat is inherent to industrial activities, IT services (e.g., data centers and microprocessors), human mobility, and many other common processes. The power lost each year in this way has been estimated in the 1000 TWh in the EU which, owing to skyrocketing energy prices and not least the urgent need for decarbonizing the economy, has engendered tremendous research efforts among scientists and engineers to recover/recycle this waste energy. Beyond established thermal engineering solutions for waste heat, advances in multifunctional materials open new paradigms for waste heat harvesting. Two smart material types are of particular focus and interest at present; these are thermoelectric and pyroelectric materials, which can both transform heat to electrical power, though via different effects. The present paper summarizes our research work on a new class of pyroelectric materials, namely <111> oriented (1 − x)(Pb(Mg_1/3Nb_2/3)O₃–xPbTiO₃ (PMN-PT) and x-Pb(In_1/2 Nb_1/2)O₃-y-Pb(Mg_1/3 Nb_2/3)O₃-(1 − x − y)-PbTiO₃ (PIN-PMN-PT) single crystals that exhibit some of the highest pyroelectric properties ever measured. First, a figure of merit for pyroelectric energy harvesting is derived, followed by a detailed assessment of the properties of the said crystals and how they depend on structure, poling, thickness, and temperature. The properties are further contrasted with those of conventional pyroelectric crystals. It is concluded that the PMN-PT-base single crystals are best suited for harvesting devices with a working temperature range from 40 to 100 °C, which encompasses waste heat generated by data centers and some chemical and industrial processes, affording the highest figure of merit among pyroelectric materials. Full article

(This article belongs to the Special Issue Advanced Ferroelectric, Piezoelectric and Dielectric Ceramics)

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8 pages, 7628 KiB

Open AccessArticle

High-Permittivity and Bias-Voltage-Insensitive (Ba,Sr,Ca)TiO₃·0.03(Bi₂O₃·3TiO₂) Ceramics with Y5U Specification

by Wei Li, Zhonghua Yao, Hua Hao, Minghe Cao and Hanxing Liu

Crystals 2023, 13(12), 1627; https://doi.org/10.3390/cryst13121627 - 23 Nov 2023

Viewed by 607

Abstract

Class II ceramics are a material with high permittivity but low reliability of their capacitance and bias voltage due to high the temperature sensitivity of their dielectric permittivity. In this work, a BST-based (Ba_0.9−xSr_xCa_0.1)TiO₃·0.03(Bi₂ [...] Read more.

Class II ceramics are a material with high permittivity but low reliability of their capacitance and bias voltage due to high the temperature sensitivity of their dielectric permittivity. In this work, a BST-based (Ba_0.9−xSr_xCa_0.1)TiO₃·0.03(Bi₂O₃·3TiO₂) (x = 0.2, 0.25, 0.3, 0.35, 0.4) composition with Y5U characteristics was investigated through compositional control to develop high-permittivity and voltage-stable ceramic compositions. Sr doping can increase the breakdown strength (E_b) but decreases the Curie temperature (T_c). The composition at x = 0.3 can obtain optimal comprehensive electrical properties, with high permittivity of 4206, low dielectric loss of ~0.009, and moderate breakdown strength (E_b) of 77.6 kV/cm, which meets Y5U specifications. Typically, a low bias-voltage dependence of capacitance is confirmed with a variation rate of 7.64% under 20 kV/cm. This strategy provides a promising candidate for high-permittivity Class II ceramic dielectrics that can be used in this field. Full article

(This article belongs to the Special Issue Advanced Ferroelectric, Piezoelectric and Dielectric Ceramics)

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11 pages, 2983 KiB

Open AccessArticle

Evolution Characteristics of Electric Field-Related Properties in Polymorphic Piezoceramics with Temperature-Impelled Phase Transition

by Chunlin Zhao, Haopeng Feng, Yanli Huang, Xiao Wu, Min Gao, Tengfei Lin and Cong Lin

Crystals 2023, 13(9), 1324; https://doi.org/10.3390/cryst13091324 - 30 Aug 2023

Viewed by 709

Abstract

In this work, to systematically investigate the evolution characteristics of electrical properties in polymorphic piezoceramics, the Ba(Ti_0.92Zr_0.08)O₃ ceramics are selected as a paradigm that possesses all the general phase structures above room temperature. It is found that the [...] Read more.

In this work, to systematically investigate the evolution characteristics of electrical properties in polymorphic piezoceramics, the Ba(Ti_0.92Zr_0.08)O₃ ceramics are selected as a paradigm that possesses all the general phase structures above room temperature. It is found that the evolution of electrical properties with temperature change can be divided into three stages based on phase structure transforming: high ferroelectric and stable strain properties at R and R-O, high ferroelectric and enhanced strain/converse piezoelectric properties at O, O-T, and T phase, and the rapidly decreased ferroelectric and strain properties in T-C and C phase. However, the ferroelectric and strain properties all increase with rising electric field and their evolution can be divided into two parts based on phase structures. The high property and slow increase rate are present at R, R-O, O, and O-T, while the poor property but a high increase rate is present around T-C. Similar results can be found in the evolution of electrostrictive property. Finally, the highest d₃₃* of ~1240 pm/V and Q₃₃ of ~0.053 m⁴/C² are obtained at O-T due to the high ferroelectricity but easy domain switching. This work affords important guidance for the property optimization of polymorphic piezoceramics. Full article

(This article belongs to the Special Issue Advanced Ferroelectric, Piezoelectric and Dielectric Ceramics)

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Review

Jump to: Research

24 pages, 7486 KiB

Open AccessReview

Recent Novel Fabrication Techniques for Proton-Conducting Solid Oxide Fuel Cells

by Mengyang Yu, Qiuxia Feng, Zhipeng Liu, Peng Zhang, Xuefeng Zhu and Shenglong Mu

Crystals 2024, 14(3), 225; https://doi.org/10.3390/cryst14030225 - 26 Feb 2024

Viewed by 952

Abstract

Research has been conducted on solid oxide fuel cells (SOFCs) for their fuel flexibility, modularity, high efficiency, and power density. However, the high working temperature leads to the deterioration of materials and increased operating costs. Considering the high protonic conductivity and low activation [...] Read more.

Research has been conducted on solid oxide fuel cells (SOFCs) for their fuel flexibility, modularity, high efficiency, and power density. However, the high working temperature leads to the deterioration of materials and increased operating costs. Considering the high protonic conductivity and low activation energy, the proton conducting SOFC, i.e., the protonic ceramic fuel cell (PCFC), working at a low temperature, has been wildly investigated. The PCFC is a promising state-of-the-art electrochemical energy conversion system for ecological energy; it is characterized by near zero carbon emissions and high efficiency, and it is environment-friendly. The PCFC can be applied for the direct conversion of various renewable fuels into electricity at intermediate temperatures (400–650 °C). The construction of the PCFC directly affect its properties; therefore, manufacturing technology is the crucial factor that determines the performance. As a thinner electrolyte layer will lead to a lower polarization resistance, a uniformly constructed and crack-free layer which can perfectly bond to electrodes with a large effective area is challenging to achieve. In this work, different fabrication methods are investigated, and their effect on the overall performance of PCFCs is evaluated. This article reviews the recent preparation methods of PCFCs, including common methods, 3D printing methods, and other advanced methods, with summarized respective features, and their testing and characterization results. Full article

(This article belongs to the Special Issue Advanced Ferroelectric, Piezoelectric and Dielectric Ceramics)

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21 pages, 3643 KiB

Open AccessReview

Performance of LiTaO₃ Crystals and Thin Films and Their Application

by Xuefeng Xiao, Shuaijie Liang, Jiashun Si, Qingyan Xu, Huan Zhang, Lingling Ma, Cui Yang and Xuefeng Zhang

Crystals 2023, 13(8), 1233; https://doi.org/10.3390/cryst13081233 - 10 Aug 2023

Cited by 4 | Viewed by 1959

Abstract

Lithium tantalate (LiTaO₃, or LT) crystal is widely used in optical applications, infrared detection, and acoustic surface wave devices because of its excellent piezoelectric, pyroelectric, and nonlinear optical properties. In this paper, we discuss the defect structure of LT; the preparation [...] Read more.

Lithium tantalate (LiTaO₃, or LT) crystal is widely used in optical applications, infrared detection, and acoustic surface wave devices because of its excellent piezoelectric, pyroelectric, and nonlinear optical properties. In this paper, we discuss the defect structure of LT; the preparation method for LT; the influence of doping on LT; and LT’s application in optical, acoustic, and electrical devices. We mainly analyzed the structure and physical properties of LT crystal, the preparation of LT crystal and LT thin films, the periodic polarization of LT crystal, the reduction of LT wafers, and the application potential of LT crystals in lasers and acoustic surface filters according to the most recent research. We also provide an overview of future research directions for LT in the fields of acoustics, optics, and other fields. The applications of LT in 5G, 6G, SAW filters, nonlinear optical devices, and waveguides are expected to provide additional breakthroughs. Full article

(This article belongs to the Special Issue Advanced Ferroelectric, Piezoelectric and Dielectric Ceramics)

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