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10 pages, 3742 KiB

Open AccessArticle

Influence of Powder Milling and Annealing Parameters on the Formation of Cubic Li₇La₃Zr₂O₁₂ Compound

by Dariusz Oleszak, Mirosława Pawlyta and Tomasz Pikula

Materials 2021, 14(24), 7633; https://doi.org/10.3390/ma14247633 - 11 Dec 2021

Cited by 1 | Viewed by 2242

Li-ion batteries are widely used as energy storage devices due to their excellent electrochemical performance. The cubic Li₇La₃Zr₂O₁₂ (c-LLZO) compound is regarded as a promising candidate as a solid-state electrolyte for lithium-ion batteries due to its [...] Read more.

Li-ion batteries are widely used as energy storage devices due to their excellent electrochemical performance. The cubic Li₇La₃Zr₂O₁₂ (c-LLZO) compound is regarded as a promising candidate as a solid-state electrolyte for lithium-ion batteries due to its high bulk Li-ion conductivity, excellent thermal performance, and chemical stability. The standard manufacturing procedure involves the high-temperature and lengthy annealing of powders. However, the formation of the tetragonal modification of LLZO and other undesired side phases results in the deterioration of electrochemical properties. The mechanical milling of precursor powders can enhance the powders’ reactivity and can result in an easier formation of c-LLZO. The aim of this work was to study the influence of selected milling and annealing parameters on c-LLZO compound formation. The starting powders of La(OH)_3, Li₂CO₃, and ZrO₂ were subjected to milling in various ball mills, under different milling conditions. The powders were then annealed at various temperatures for different lengths of times. These studies showed that the phase transformation processes of the powders were not very sensitive to the milling parameters. On the other hand, the final phase composition and microstructure strongly depended on heat treatment conditions. Low temperature annealing (750 °C) for 3 h produced 90% of c-LLZO in the powder structure. Full article

(This article belongs to the Special Issue The Electrophysical Properties of Ceramic Materials)

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14 pages, 12324 KiB

Open AccessFeature PaperArticle

Effect of Chemical Composition on Magnetic and Electrical Properties of Ferroelectromagnetic Ceramic Composites

by Dariusz Bochenek, Przemysław Niemiec and Artur Chrobak

Materials 2021, 14(10), 2488; https://doi.org/10.3390/ma14102488 - 11 May 2021

Cited by 8 | Viewed by 1873

Abstract

In this paper, ferroelectric–ferrimagnetic ceramic composites based on multicomponent PZT-type (PbZr_1−xTi_xO₃-type) material and ferrite material with different percentages in composite compositions were obtained and studied. The ferroelectric component of the composite was a perovskite ceramic material [...] Read more.

In this paper, ferroelectric–ferrimagnetic ceramic composites based on multicomponent PZT-type (PbZr_1−xTi_xO₃-type) material and ferrite material with different percentages in composite compositions were obtained and studied. The ferroelectric component of the composite was a perovskite ceramic material with the chemical formula Pb_0.97Bi_0.02(Zr_0.51Ti_0.49)_0.98(Nb_2/3Mn_1/3)_0.02O₃ (P), whereas the magnetic component was nickel-zinc ferrite with the chemical formula Ni_0.5Zn_0.5Fe₂O₄ (F). The process of sintering the composite compounds was carried out by the free sintering method. Six ferroelectric-ferrimagnetic ceramic P-F composite compounds were designed and obtained with different percentages of its components, i.e., 90/10 (P90-F10), 85/15 (P85-F15), 80/20 (P80-F20), 60/40 (P60-F40), 40/60 (P40-F60), and 20/80 (P20-F80). X-ray diffraction patterns, microstructural, ferroelectric, dielectric, magnetic properties, and DC electrical conductivity of the composite materials were investigated. In this study, two techniques were used to image the microstructure of P-F composite samples: SB (detection of the signals from the secondary and backscattered electron detectors) and BSE (detection of backscattered electrons), which allowed accurate visualization of the presence and distribution of the magnetic and ferroelectric component in the volume of the composite samples. The studies have shown that at room temperature, the ceramic composite samples exhibit good magnetic and electrical properties. The best set of physical properties and performance of composite compositions have ceramic samples with a dominant phase of ferroelectric component and a small amount of the ferrite component (P90-F10). Such a composition retains the high ferroelectric properties of the ferroelectric component in the composite while also acquiring magnetic properties. These properties can be prospectively used in new types of memory and electromagnetic converters. Full article

(This article belongs to the Special Issue The Electrophysical Properties of Ceramic Materials)

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15 pages, 10869 KiB

Open AccessArticle

Mechanochemical Activation and Spark Plasma Sintering of the Lead-Free Ba(Fe_1/2Nb_1/2)O₃ Ceramics

by Dariusz Bochenek, Joanna A. Bartkowska, Lucjan Kozielski and Izabela Szafraniak-Wiza

Materials 2021, 14(9), 2254; https://doi.org/10.3390/ma14092254 - 27 Apr 2021

Cited by 5 | Viewed by 1580

Abstract

This paper investigates the impact of the technological process (Mechanochemical Activation (MA) of the powder in combination with the Spark Plasma Sintering (SPS) method) on the final properties of lead-free Ba(Fe_1/2Nb_1/2)O₃ (BFN) ceramic materials. The BFN powders were [...] Read more.

This paper investigates the impact of the technological process (Mechanochemical Activation (MA) of the powder in combination with the Spark Plasma Sintering (SPS) method) on the final properties of lead-free Ba(Fe_1/2Nb_1/2)O₃ (BFN) ceramic materials. The BFN powders were obtained for different MA duration times (x from 10 to 100 h). The mechanically activated BFN powders were used in the technological process of the BFN ceramics by the SPS method. The measurements of the BFN_xMA ceramic samples included the following analysis: Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometry (EDS), DC electrical conductivity, and dielectric properties. X-ray diffractions (XRD) tests showed the appearance of the perovskite phase of BFN powders after 10 h of milling time. The longer milling time (up 20 h) causes the amount of the perovskite phase to gradually increase, and the diffraction peaks are more clearly visible. Short high energy milling times favor a large heterogeneity of the grain shape and size. Increasing the MA milling time to 40 h significantly improves the microstructure of BFN ceramics sintered in the SPS technology. The microstructure becomes fine-grained with clearly visible grain boundaries and higher grain size uniformity. Temperature measurements of the BFN ceramics show a number of interesting dielectric properties, i.e., high values of electric permittivity, relaxation properties with a diffusion phase transition, as well as negative values of dielectric properties occurring at high temperatures. The high electric permittivity values predestines the BFN_xMA materials for energy storage applications e.g., high energy density batteries, while the negative values of dielectric properties can be used for shield elements against the electromagnetic radiation. Full article

(This article belongs to the Special Issue The Electrophysical Properties of Ceramic Materials)

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13 pages, 7196 KiB

Open AccessArticle

Dielectric and Electrical Properties of BLT Ceramics Modified by Fe Ions

by Beata Wodecka-Dus, Tomasz Goryczka, Małgorzata Adamczyk-Habrajska, Mateusz Bara, Jolanta Dzik and Diana Szalbot

Materials 2020, 13(24), 5623; https://doi.org/10.3390/ma13245623 - 9 Dec 2020

Cited by 8 | Viewed by 1551

Abstract

The solid solution of the perovskite type structure Ba_0.996La_0.004Ti_1−yFe_yO₃ (BLTF) for varying iron content (y = 0.1−0.4 mol.%) was obtained as a result of a solid state reaction using the conventional method. [...] Read more.

The solid solution of the perovskite type structure Ba_0.996La_0.004Ti_1−yFe_yO₃ (BLTF) for varying iron content (y = 0.1−0.4 mol.%) was obtained as a result of a solid state reaction using the conventional method. At room temperature (Tr < T_C), the as-received ceramics reveals a single-phase, tetragonal structure and a P4mm space group. An increase in the iron content causes a slight decrease in the volume of the elementary cell. In addition, this admixture significantly reduces the maximum permittivity value (ε_m) and the shift of the phase transition temperature (T_C) towards lower temperatures. The BLTF solid solution shows a classical phase transition and low values of dielectric loss tangent (tgδ), both at room temperature and in the phase transition area. The Curie–Weiss temperature (T₀) and Curie constant (C) were also determined on the basis of the dielectric measurements results. The analysis of temperature changes in DC conductivity revealed presence of the positive temperature coefficient of resistivity (PTCR) effect in the phase transition area. Full article

(This article belongs to the Special Issue The Electrophysical Properties of Ceramic Materials)

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25 pages, 16145 KiB

Open AccessArticle

Structural and Magneto-Optical Characterization of La, Nd: Y₂O₃ Powders Obtained via a Modified EDTA Sol–Gel Process and HIP-Treated Ceramics

by Andrzej Kruk

Materials 2020, 13(21), 4928; https://doi.org/10.3390/ma13214928 - 2 Nov 2020

Cited by 16 | Viewed by 2031

Abstract

In this study, pure Y₂O₃, La_0.1Y_1.9O₃ and La_0.1Nd_0.12Y_1.78O₃ nanosized powders were successfully synthesized by a modified sol–gel method. Pure and rare-earth ions doped yttria powders were characterized [...] Read more.

In this study, pure Y₂O₃, La_0.1Y_1.9O₃ and La_0.1Nd_0.12Y_1.78O₃ nanosized powders were successfully synthesized by a modified sol–gel method. Pure and rare-earth ions doped yttria powders were characterized by X-ray diffraction, scanning electron microscopy and Brunauer–Emmett–Teller methods. The powders were sintered by the hot isostatic pressing process. The highest in-line transmittance of 56% was obtained at 800 nm and increased in the IR region. The influence of the lanthanum and neodymium ions on the physicochemical properties of yttria were discussed. The La-Nd-doped material exhibited a Verdet constant over 4000 deg/T·m at 400 nm and low thermal dependence. An interesting evolution of the Verdet constant across the absorption band with high resolution was studied. A study of the optical and magneto-optical properties of yttria doped with Nd³⁺ and La³⁺ is discussed in this paper. Full article

(This article belongs to the Special Issue The Electrophysical Properties of Ceramic Materials)

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12 pages, 2475 KiB

Open AccessArticle

Dielectric Tunability Properties in (110)-Oriented Epitaxial 0.5Ba(Ti_0.8Zr_0.2)O₃-0.5(Ba_0.7Ca_0.3)TiO₃ Thin Films Prepared by PLD Method

by Bing Luo, Yiwen Xu, Fuzeng Zhang, Tingting Wang and Yingbang Yao

Materials 2020, 13(21), 4771; https://doi.org/10.3390/ma13214771 - 26 Oct 2020

Cited by 7 | Viewed by 1803

Abstract

Epitaxial 0.5Ba(Ti_0.8Zr_0.2)O₃-0.5(Ba_0.7Ca_0.3)TiO₃ (BZT-BCT) thin films with single-crystal perovskite structure have been grown by pulsed laser deposition (PLD) on the (110) SrRuO₃/SrTiO₃ substrates. Temperature-dependent dielectric measurements show obvious characteristics of [...] Read more.

Epitaxial 0.5Ba(Ti_0.8Zr_0.2)O₃-0.5(Ba_0.7Ca_0.3)TiO₃ (BZT-BCT) thin films with single-crystal perovskite structure have been grown by pulsed laser deposition (PLD) on the (110) SrRuO₃/SrTiO₃ substrates. Temperature-dependent dielectric measurements show obvious characteristics of a diffused phase transition. Typical P-E hysteresis loops with a distinct ferroelectric imprint phenomenon are observed in these BZT-BCT thin films with a remnant polarization of 2.0 μC/cm² and coercive field of 187 kV/cm. Small leakage currents (<1 × 10⁻⁶ A/cm²) are obtained in these thin films under an electrical field of 240 MV/m. These BZT-BCT thin films have shown large dielectric tunability values ranging from 75.8% to 85.7%, under a wide temperature range from 200 K to 330 K and a frequency range between 100 Hz and 100 kHz, which shows their good temperature and frequency stability. Such excellent dielectric tunability properties in these (110)-oriented BZT-BCT thin films promise their great potentials in practical phase shifter applications. Full article

(This article belongs to the Special Issue The Electrophysical Properties of Ceramic Materials)

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19 pages, 6675 KiB

Open AccessArticle

The Effect of Mixed Doping on the Microstructure and Electrophysical Parameters of the Multicomponent PZT-Type Ceramics

by Dariusz Bochenek, Przemysław Niemiec and Grzegorz Dercz

Materials 2020, 13(8), 1996; https://doi.org/10.3390/ma13081996 - 24 Apr 2020

Cited by 12 | Viewed by 2804

Abstract

This work shows the influence of admixture on the basic properties of the multicomponent PbZr_1−xTi_xO₃ (PZT)-type ceramics. It presents the results of four compositions of PZT-type material with the general chemical formula, Pb_0.99M_0.01((Zr_0.49 [...] Read more.

This work shows the influence of admixture on the basic properties of the multicomponent PbZr_1−xTi_xO₃ (PZT)-type ceramics. It presents the results of four compositions of PZT-type material with the general chemical formula, Pb_0.99M_0.01((Zr_0.49Ti_0.51)_0.95Mn_0.021Sb_0.016W_0.013)_0.9975O₃, where, in the M position, a donor admixture was introduced, i.e., samarium (Sm³⁺), gadolinium (Gd³⁺), dysprosium (Dy³⁺) or lanthanum (La³⁺). The compositions of the PZT-type ceramics were obtained through the classic ceramic method, as a result of the synthesis of simple oxides. The X-ray diffraction (XRD) pattern studies showed that the obtained multicomponent PZT materials have a tetragonal structure with a P4mm point group. The microstructure of the obtained compositions is characterized by a well crystallized grain, with clearly visible grain boundaries. The composition with the admixture of lanthanum has the highest uniformity of fine grain microstructure, which positively affects its final dielectric and piezoelectric properties. In the multicomponent PZT-type ceramic, materials utilize the mixed (acceptor and donor) doping of the main compound. This dopiong method has a positive effect on the set of the electrophysical parameters of ceramic materials. Donor dopants W⁶⁺ (at positions B) and M³⁺ = Sm³⁺, Gd³⁺, Dy³⁺, and La³⁺ (at positions A) increase the dielectric and piezoelectric properties, while the acceptor dopant Sb³⁺ (at positions B) increases the time and temperature stability of the electrophysical parameters. In addition, the suitable selection of the set of admixtures improved the sinterability of the ceramic samples, as well as resulted in obtaining the required material with good piezoelectric parameters for the poling process. This research confirms that all ceramic compositions have a set of parameters suitable for applications in micromechatronics, for example, as actuators, piezoelectric transducers, and precision microswitches. Full article

(This article belongs to the Special Issue The Electrophysical Properties of Ceramic Materials)

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8 pages, 2292 KiB

Open AccessFeature PaperArticle

A Large Piezoelectric Strain Recorded in BCT Ceramics Obtained by a Modified Pechini Method

by Lucjan Kozielski, Agnieszka Wilk, Mirosław M. Bućko and Juras Banys

Materials 2020, 13(7), 1620; https://doi.org/10.3390/ma13071620 - 1 Apr 2020

Cited by 3 | Viewed by 2405

Abstract

There is a strong need in the industry to develop lead-free piezoelectrics for sensors and actuators. Although these materials have become an important component of many electronic devices, it is very important for the industry to decarbonise ceramic technology, especially through the introduction [...] Read more.

There is a strong need in the industry to develop lead-free piezoelectrics for sensors and actuators. Although these materials have become an important component of many electronic devices, it is very important for the industry to decarbonise ceramic technology, especially through the introduction of modern sintering technologies. Among the many piezoelectric compounds available, Calcium Barium Titanate (BCT) have been widely investigated because of its similar performance to lead-containing Lead Titanate Zirconate (PZT). In this paper, a modified Pechini method for obtaining ceramic Ba_0.9Ca_0.1TiO₃ nano-powders is described. Deviation from the established procedure resulted in the precipitation of the solution or obtaining of a low-quality (poorly crystallized) product with numerous impurities. The samples of BCT materials were examined to find their ideal microstructures and structures; these factors were confirmed by their outstanding X-ray diffraction spectra and high piezoelectric constant values that are comparable to commercial lead-containing materials. Full article

(This article belongs to the Special Issue The Electrophysical Properties of Ceramic Materials)

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13 pages, 10021 KiB

Open AccessArticle

Dielectric and Impedance Studies of (Ba,Ca)TiO₃ Ceramics Obtained from Mechanically Synthesized Powders

by Kamil Feliksik, Lucjan Kozielski, Izabela Szafraniak-Wiza, Tomasz Goryczka and Małgorzata Adamczyk-Habrajska

Materials 2019, 12(24), 4036; https://doi.org/10.3390/ma12244036 - 4 Dec 2019

Cited by 6 | Viewed by 2262

Abstract

Mechanochemical synthesis offers unique possibility of perovskite phase formation at ambient conditions that is very attractive (simplifies production, allows strict stoichiometry control and brings economic benefits). In this work the mechanochemical synthesis has been used for preparation ofBa_1−xCa_xTiO₃ [...] Read more.

Mechanochemical synthesis offers unique possibility of perovskite phase formation at ambient conditions that is very attractive (simplifies production, allows strict stoichiometry control and brings economic benefits). In this work the mechanochemical synthesis has been used for preparation ofBa_1−xCa_xTiO₃ (0.2 ≤ x ≤ 0.3) powders from simple oxides. The 20 h milled powders have been uniaxially pressed and sintered in order to get the ceramic samples. The sample morphologies have been observed by scanning electron microscopy. Dielectric and impedance studies have been performed on ceramics. The obtained results indicate that the two mechanism of doping occurred. The first one is observed for the lower calcium concentration (below 0.3) and consists of the introduction of calcium ion into the A site of the perovskite structure. The second one is observed for the higher calcium concentration (equal 0.3). In this case the calcium ions partially occupies the B site in the perovskite structure. Both cases have different influence on the final properties of the ceramics because they induce different defects. Full article

(This article belongs to the Special Issue The Electrophysical Properties of Ceramic Materials)

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