Modifications of structural, dielectric and ferroelectric properties induced by porosity in BaTiO3 ceramics with phase coexistence

Padurariu, Leontin; Curecheriu, Lavinia; Ciomaga, Cristina-Elena; Airimioaei, Mirela; Horchidan, Nadejda; Cioclea, Cipriana; Lukacs, Vlad Alexandru; Stirbu, Radu-Stefan; Mitoşeriu, Liliana

doi:10.1016/j.jallcom.2021.161699

Cited by 16 publications

(23 citation statements)

References 57 publications

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“…All diffraction peaks can be indexed based on polycrystalline orthorhombic BaTiO 3 (01–081–2197) with the space group Amm2. Unlike our previous papers [ 20 , 21 ], in which porosity induced structural changes, in this case, all the ceramics are in the orthorhombic phase at room temperature with a small variation in peak ratio (022)/(200) from 1.39 to 1.14 when porosity decreased from 21% to 2%.…”

Section: Resultscontrasting

confidence: 60%

Role of Density and Grain Size on the Electrocaloric Effect in Ba0.90Ca0.10TiO3 Ceramics

et al. 2022

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Pure perovskite Ba0.90Ca0.10TiO3 ceramics, with a relative density of between 79 and 98% and grain sizes larger than 1 µm, were prepared by solid-state reaction. The dielectric and electrocaloric properties were investigated and discussed considering the density and grain size of the samples. Room temperature impedance measurements show good dielectric properties for all ceramics with relative permittivity between 800 and 1100 and losses of <5%. Polarization vs. E loops indicates regular variation with increasing sintering temperature (grain size and density), an increase in loop area, and remanent and saturation polarization (from Psat = 7.2 µC/cm2 to Psat = 16 µC/cm2). The largest electrocaloric effect was 1.67 K for ceramic with GS = 3 µm at 363 K and electrocaloric responsivity (ζ) was 0.56 K mm/kV. These values are larger than in the case of other similar materials; thus, Ba0.90Ca0.10TiO3 ceramics with a density larger than 90% and grain sizes of a few µms are suitable materials for electrocaloric devices.

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Section: Resultscontrasting

confidence: 60%

Role of Density and Grain Size on the Electrocaloric Effect in Ba0.90Ca0.10TiO3 Ceramics

et al. 2022

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“…In the case of uniaxial pressing, irrespective of the concentrations of spherical polymeric addition shown in Figure 1 a, one can observe that in the ceramic microstructures the resulting pores after burning out the polymeric additive have the tendency to be rather elongated ( Figure 1 b) than spherical [ 6 ]. A slightly elongated shape of the pores is also generated when using isostatic pressing.…”

Section: Resultsmentioning

confidence: 99%

“…The mixed powders have been coldly pressed at 150 MPa (uniaxially or isostatic) and then, the green ceramics have been densified by applying a pressureless multi-step thermal treatment to ensure the combustion of polymeric particles, the complete gas elimination before closing the ceramic pores and complete sintering, as described in detail in ref. [ 6 ]. The surface ceramic morphology has been examined in fresh ceramic fractures by high resolution scanning electronic microscopy (SEM) with a Carl Zeiss System NEON40EsB.…”

Section: Methodsmentioning

confidence: 99%

“…and by their deformability during the pressing step [ 5 ]. In a previous work [ 6 ], BaTiO 3 ceramics with variable relative porosity levels (in the range of 8% to 26%) produced by using Poly(methyl methacrylate) (PMMA) spherical inclusions as sacrificial phase, have been analyzed. These ceramics were obtained by sintering of uniaxially pressed mixtures of oxide and polymeric powders.…”

Section: Introductionmentioning

confidence: 99%

“…This might be the cause of a tendency of the pores to elongate along the axis of the cylindrical sample, as observed in ref. [ 6 ]. This represented the starting point of the idea of studying the deformation of the soft inclusions in a bulk matrix, while applying pressure and observing how those deformations might induce anisotropy, if any.…”

Section: Introductionmentioning

confidence: 99%

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Mesoscale Models for Describing the Formation of Anisotropic Porosity and Strain-Stress Distributions during the Pressing Step in Electroceramics

et al. 2022

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Porous ceramics are often produced by using pyrolisable additives to generate porosity during the sintering step. The examination of the experimental microstructures of the resulted porous ceramics revealed certain levels of anisotropy, even if the original soft additives used as pore forming agents were spherical. The paper shows that anisotropic porosity may result in ceramics when using equiaxed soft polymeric additives for generating porosity, due to the deformation of soft inclusions during the pressing step. It has been found, by means of analytical and numerical calculations, that uniaxial pressing of a mixture of solid particles with contrasting mechanical properties (hard/soft) generates modifications in the shape of the soft phase. As a result, anisotropic shape distribution of the soft inclusions in the green ceramic body and elongated porosity in the final ceramic product are obtained. The elongated pores are statistically oriented with the major axes perpendicular to the pressing direction and will generate anisotropy-related functional properties. Analytical calculations indicate the deformation of a single soft inclusion inside a continuum solid. Further, by finite element simulations performed in 2D planes along the transversal and radial directions of the pressing axis, a bimodal angular distribution of the long axes of the soft inclusions has been found.

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Phase Equilibrium in Solid Solutions of BaTiO3 Doped with Eu3+ and Gd3+

Martínez López,

Pérez Labra,

Barrientos Hernández

et al. 2024

The Minerals, Metals &Amp; Materials Series

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Modifications of structural, dielectric and ferroelectric properties induced by porosity in BaTiO3 ceramics with phase coexistence

Cited by 16 publications

References 57 publications

Role of Density and Grain Size on the Electrocaloric Effect in Ba0.90Ca0.10TiO3 Ceramics

Role of Density and Grain Size on the Electrocaloric Effect in Ba0.90Ca0.10TiO3 Ceramics

Mesoscale Models for Describing the Formation of Anisotropic Porosity and Strain-Stress Distributions during the Pressing Step in Electroceramics

Phase Equilibrium in Solid Solutions of BaTiO3 Doped with Eu3+ and Gd3+

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