Ceramics

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10 pages, 1483 KiB

Open AccessArticle

Ferroelectric and Piezoelectric Properties of (Mg_1/3Nb_2/3)⁴⁺-Doped Bismuth Sodium Titanate Ceramics

by Yonggang Zhao, Ning Yang, Yi Chen, Xingting Li, Luyao Wang, Peng Wang and Guangzhi Dong

Ceramics 2025, 8(3), 88; https://doi.org/10.3390/ceramics8030088 - 13 Jul 2025

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Lead-free (Bi_1/2Na_1/2)(Ti_1−x(Mg_1/3Nb_2/3)_x)O₃ ceramics were synthesized using the solid-phase method, and the effects of varying (Mg_1/3Nb_2/3)⁴⁺ content, substituting for Ti⁴⁺ ions at the B-site of [...] Read more.

Lead-free (Bi_1/2Na_1/2)(Ti_1−x(Mg_1/3Nb_2/3)_x)O₃ ceramics were synthesized using the solid-phase method, and the effects of varying (Mg_1/3Nb_2/3)⁴⁺ content, substituting for Ti⁴⁺ ions at the B-site of the BNT perovskite lattice, on piezoelectric performance were systematically investigated. The influence of sintering temperature on both piezoelectric and ferroelectric properties was also explored, revealing that sintering temperature significantly affects both the microstructure and the electrical properties of the ceramics. The results indicate that the incorporation of (Mg_1/3Nb_2/3)⁴⁺ significantly enhances the piezoelectric and ferroelectric properties of BNT ceramics. Specifically, a maximum piezoelectric constant of 91 pC/N was achieved at a sintering temperature of 1160 °C and a doping concentration of x = 0.01. By comparing the ferroelectric properties across different doping levels and sintering temperatures, this study provides valuable insights for further design and process optimization of BNT-based piezoelectric materials. Full article

(This article belongs to the Special Issue Advances in Electronic Ceramics, 2nd Edition)

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18 pages, 2148 KiB

Open AccessArticle

Structural and Dielectric Impedance Studies of Mixed Ionic–Electronic Conduction in SrLaFe_1−xMn_xTiO₆ (x = 0, 0.33, 0.67, and 1.0) Double Perovskites

by Abdelrahman A. Elbadawi, Elsammani A. Shokralla, Mohamed A. Siddig, Obaidallah A. Algethami, Abdullah Ahmed Alghamdi and Hassan H. E. Idris

Ceramics 2025, 8(3), 87; https://doi.org/10.3390/ceramics8030087 - 7 Jul 2025

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Abstract

The structural and electrical properties of double perovskite compounds SrLaFe_1−xMn_xTiO_6−δ (x = 0, 0.33, 0.67, and 1.0) were studied using X-ray diffraction (XRD) and dielectric impedance measurements. The reparation of perovskite compounds was successfully achieved through the precursor [...] Read more.

The structural and electrical properties of double perovskite compounds SrLaFe_1−xMn_xTiO_6−δ (x = 0, 0.33, 0.67, and 1.0) were studied using X-ray diffraction (XRD) and dielectric impedance measurements. The reparation of perovskite compounds was successfully achieved through the precursor solid-state reaction in air at 1250 °C. The purity phase and crystal structures of perovskite compounds were determined by means of the standard Rietveld refinement method using the FullProf suite. The best fitting results showed that SrLaFeTiO_6−δ was orthorhombic with space group Pnma, and both SrLaFe_0.67Mn_0.33TiO_6−δ and SrLaFe_0.33Mn_0.67TiO_6−δ were cubic structures with space group Fm3m, while SrLaMnTiO_6−δ was tetragonal with a I/4m space group. The charge density maps obtained for these structures indicated that the compounds show an ionic and mixed ionic–electronic conduction. The dielectric impedance measurements were carried out in the range of 20 Hz to 1 MHz, and the analysis showed that there is more than one relaxation mechanism of Debye type. Doping with Mn was found to reduce the dielectric impedance of the samples, and the major contribution to the dielectric impedance was established to change from a capacitive for SrLaFeTiO_6−δ to a resistive for SrLaMnTiO_6−δ. The fall in values of electrical resistance may be related to the possible occurrence of the double exchange (DEX) mechanism among the Mn ions, provided there is oxygen deficiency in the samples. DC-resistivity measurements revealed that SrLaFeTiO_6−δ was an insulator while SrLaMnTiO_6−δ was showing a semiconductor–metallic transition at ~250 K, which is in support of the DEX interaction. The dielectric impedance of SrLaFe_0.67Mn_0.33TiO_6−δ was found to be similar to that of (La,Sr)(Co,Fe)O_3-δ, the mixed ionic–electronic conductor (MIEC) model. The occurrence of a mixed ionic–electronic state in these compounds may qualify them to be used in free lead solar cells and energy storage technology. Full article

(This article belongs to the Special Issue Advances in Electronic Ceramics, 2nd Edition)

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11 pages, 2553 KiB

Open AccessArticle

Effect of Ni²⁺ Doping on the Crystal Structure and Properties of LiAl₅O₈ Low-Permittivity Microwave Dielectric Ceramics

by Xuekai Lan, Huatao Tang, Bairui Chen and Bin Tian

Ceramics 2025, 8(3), 85; https://doi.org/10.3390/ceramics8030085 - 4 Jul 2025

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Abstract

Low-permittivity microwave dielectric ceramics are essential for high-frequency communication and radar systems, as they minimize signal delay and interference, thereby enabling compact and high-performance devices. In this study, LiAl_5−xNi_xO_8−0.5x (x = 0.1–0.5) ceramics were synthesized [...] Read more.

Low-permittivity microwave dielectric ceramics are essential for high-frequency communication and radar systems, as they minimize signal delay and interference, thereby enabling compact and high-performance devices. In this study, LiAl_5−xNi_xO_8−0.5x (x = 0.1–0.5) ceramics were synthesized via a solid-state reaction method to investigate the effects of Ni²⁺ substitution on crystal structure, microstructure, and dielectric properties. X-ray diffraction and Rietveld refinement reveal a phase transition from the P4₃32 to the Fd

\bar{3}

m spinel structure at x ≈ 0.3, accompanied by a systematic increase in the lattice parameter (7.909–7.975 Å), attributed to the larger ionic radius of Ni²⁺ compared to Al³⁺. SEM analysis confirms dense microstructures with relative densities exceeding 95% and grain size increases from less than 1 μm at x = 0.1 to approximately 2 μm at x = 0.5. Dielectric measurements show a decrease in permittivity (ε_r) from 8.24 to 7.77 and in quality factor (Q × f) from 34,605 GHz to 20,529 GHz with increasing Ni content, while the temperature coefficient of the resonant frequency (τ_f) shifts negatively from −44.8 to −69.1 ppm/°C. Impedance spectroscopy indicates increased conduction losses and reduced activation energy with higher Ni²⁺ concentrations. Full article

(This article belongs to the Special Issue Advances in Electronic Ceramics, 2nd Edition)

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11 pages, 998 KiB

Open AccessArticle

Study on the Absorbing Properties of V-Doped MoS₂

by Jiang Zou and Quan Xie

Ceramics 2025, 8(3), 84; https://doi.org/10.3390/ceramics8030084 - 2 Jul 2025

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Abstract

This study employed a hydrothermal method to prepare V-doped MoS₂. The influence of varying filler ratios (30 wt%, 40 wt%, 50 wt%) on its absorption properties was analyzed. For annealing studies, a precursor powder with a 40 wt% filler ratio was [...] Read more.

This study employed a hydrothermal method to prepare V-doped MoS₂. The influence of varying filler ratios (30 wt%, 40 wt%, 50 wt%) on its absorption properties was analyzed. For annealing studies, a precursor powder with a 40 wt% filler ratio was heat-treated at 600 °C for 2 h. The results obtained through characterization and testing indicate that the unannealed 40 wt% filler sample demonstrates superior absorption performance, with minimum reflection loss (RL_min) of −32.24 dB, an effective absorption bandwidth (EAB) of 4.40 GHz, and 99.9% electromagnetic (EM) wave attenuation. However, upon subjecting the sample with a 40 wt% filling ratio to annealing treatment, a notable decrease in impedance matching degree was observed, and regions with impedance matching values close to 1 were no longer present. Consequently, it can be concluded that at a filling ratio of 40 wt%, the sample’s excellent attenuation coefficient in conjunction with its good impedance matching collectively contribute to its superior comprehensive absorption performance. Full article

(This article belongs to the Special Issue Advances in Electronic Ceramics, 2nd Edition)

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9 pages, 15356 KiB

Open AccessArticle

Fabrication and Properties of ITTO Segments for Cylindrical Targets by Pressureless Oxygen Atmosphere Sintering Method

by Jiwen Xu, Fangzhou Wu, Yuan Yao, Ling Yang, Guisheng Zhu and Huarui Xu

Ceramics 2025, 8(2), 75; https://doi.org/10.3390/ceramics8020075 - 18 Jun 2025

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Abstract

Cylindrical targets have a high utilization rate, but are difficult to manufacture. A large hollow ITTO segment with thin walls was prepared by cold isostatic pressure and two-stage sintering. The fabrication process yielded a segment with an outer diameter of 153 mm, an [...] Read more.

Cylindrical targets have a high utilization rate, but are difficult to manufacture. A large hollow ITTO segment with thin walls was prepared by cold isostatic pressure and two-stage sintering. The fabrication process yielded a segment with an outer diameter of 153 mm, an inner diameter of 135 mm, and a length of 700 mm, indicating a length to thickness ratio of up to 78. The dense and uniform green bodies ensure the achievement of high density and uniformity of the sintered body throughout its volume. The segment exhibited a high relative density of about 99.5% and a low resistivity of below 3.4 × 10⁻⁴ Ω·cm. The density and resistivity illustrate a minimal inhomogeneity along the length of the segment. The segment exhibits a cubic bixbyite phase and is characterized by densely packed fine grains with an average size of several microns. Therefore, these results establish a substantial foundation for the large-scale production of cylindrical ITTO segments. Full article

(This article belongs to the Special Issue Advances in Electronic Ceramics, 2nd Edition)

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11 pages, 1806 KiB

Open AccessArticle

Enhanced Electrical Property and Thermal Stability in Lead-Free BNT–BT–BF Ceramics

by Kangle Zhou, Enxiang Hou, Yanfeng Qu, Yan Mu and Junjun Wang

Ceramics 2025, 8(2), 70; https://doi.org/10.3390/ceramics8020070 - 7 Jun 2025

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Abstract

The synergistic combination of outstanding electrical properties and exceptional thermal stability holds significant implications for advancing piezoelectric ceramic applications. In this work, lead-free ((1−x)(0.94Bi_0.5Na_0.5TiO₃-0.06BaTiO₃)-xBiFeO₃ (x = 0.08, 0.10, 0.12)) ceramics were synthesized using a [...] Read more.

The synergistic combination of outstanding electrical properties and exceptional thermal stability holds significant implications for advancing piezoelectric ceramic applications. In this work, lead-free ((1−x)(0.94Bi_0.5Na_0.5TiO₃-0.06BaTiO₃)-xBiFeO₃ (x = 0.08, 0.10, 0.12)) ceramics were synthesized using a conventional solid-state method, with systematic investigation of phase evolution, microstructural characteristics, and their coupled effects on electromechanical performance and thermal stability. Rietveld refinement analysis revealed a rhombohedral–tetragonal (R–T) phase coexistence, where the tetragonal phase fraction maximized at x = 0.10. This structural optimization enabled the simultaneous enhancement of piezoelectricity and thermal resilience. The x = 0.10 composition achieved recorded values of d₃₃ = 132 pC/N, g₃₃ = 26.11 × 10⁻³ Vm/N, and a depolarization temperature T_d = 105 °C. These findings establish BiFeO₃ doping as a dual-functional strategy for developing high-performance lead-free ceramics. Full article

(This article belongs to the Special Issue Advances in Electronic Ceramics, 2nd Edition)

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19 pages, 6066 KiB

Open AccessArticle

Pseudocapacitive Behavior of Protonic Niobate Nanowires in Aqueous Acidic Electrolyte

by Adilar Gonçalves dos Santos Júnior, Jessica Gotardi, Edna Jerusa Pacheco Sampaio, Cristiano Campos Araújo, Gabriel Luiz Rasch, Antonio Marcos Helgueira de Andrade, Roberto Hübler, Andrés Cuña Suárez and Célia de Fraga Malfatti

Ceramics 2025, 8(2), 59; https://doi.org/10.3390/ceramics8020059 - 20 May 2025

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Abstract

Niobium-based oxides are being increasingly evaluated as materials for energy storage applications. Additionally, the use of these oxides as cathodes in aqueous electrolytes has shown promise. Based on this, the pseudocapacitive behavior of protonic niobate nanowires in an aqueous acidic electrolyte (1 M [...] Read more.

Niobium-based oxides are being increasingly evaluated as materials for energy storage applications. Additionally, the use of these oxides as cathodes in aqueous electrolytes has shown promise. Based on this, the pseudocapacitive behavior of protonic niobate nanowires in an aqueous acidic electrolyte (1 M H₂SO₄) was evaluated for the first time. The material was obtained in two simple sequential steps. First, hydrothermal synthesis resulted in sodium niobate; second was ionic exchange (in two concentrations of 2 M and 0.1 M HNO₃), where the protonic niobate was obtained. The resulting protonic niobate was characterized by FEG-SEM, the results demonstrated that the morphology of the oxide was concentration-dependent in the ionic exchange step, and EDS analysis was used to validate the procedure. Using DRX, Raman spectroscopy, and FTIR analysis, the transformation of sodium niobate to protonic niobate was evidenced. The electrochemical tests demonstrated that the protonic niobate presented pseudocapacitive behavior when employed as the cathode in 1 M H₂SO₄, and the ionic exchange in 2 M HNO₃ promoted a better specific capacitance, reaching 119.8 mF·cm⁻² at a 1 mA·cm⁻² current density. Full article

(This article belongs to the Special Issue Advances in Electronic Ceramics, 2nd Edition)

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17 pages, 5229 KiB

Open AccessArticle

CuNb₂O₆ Particles Obtained via Solid-State Reaction and Application as Electrocatalyst for Oxygen Evolution Reaction

by Kívia F. G. de Araújo, Cleber S. Lourenço, Vitor M. S. F. Souza, Matheus D. da Silva, Gabriel D. S. Vasconcelos, Maria J. S. Lima, Jakeline R. D. Santos, Kelly C. Gomes, Francisco J. A. Loureiro, Marco A. Morales and Uílame U. Gomes

Ceramics 2025, 8(2), 55; https://doi.org/10.3390/ceramics8020055 - 13 May 2025

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Abstract

Copper niobate (CuNb₂O₆) is an important compound due to its low cost and polymorphism, presenting monoclinic and orthorhombic phases, which leads to unique physical–chemical properties. The electrochemical performance of efficient electrocatalysts for the oxygen evolution reaction (OER) is of [...] Read more.

Copper niobate (CuNb₂O₆) is an important compound due to its low cost and polymorphism, presenting monoclinic and orthorhombic phases, which leads to unique physical–chemical properties. The electrochemical performance of efficient electrocatalysts for the oxygen evolution reaction (OER) is of importance in order to produce hydrogen gas from water. In this context, this work reports the synthesis of CuNb₂O₆ particles by high-energy milling for 5 and 10 h, and subsequent thermal treatment at 900 °C for 3 h. The samples were characterized by XRD, XRF, FESEM, RAMAN, UV–Vis, and FT-IR techniques, and were applied as electrocatalysts for the OER. The samples had both monoclinic and orthorhombic crystalline phases. The band gaps were in the range of 1.92 to 2.06 eV. In the application for the OER, the particles obtained by 5 and 10 h of milling exhibited overpotentials of 476 and 347 mV vs. RHE at 10 mA cm⁻², respectively. In chronopotentiometry experiments for 15 h, the samples exhibited excellent chemical stability. The electrochemical performance of the sample milled for 10 h showed superior performance (347 mV vs. RHE) when compared with electrocatalysts of the same type, demonstrating that the methodology used to synthesize the samples is promising for energy applications. Full article

(This article belongs to the Special Issue Advances in Electronic Ceramics, 2nd Edition)

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