J. Mater. Sci. Technol. ›› 2024, Vol. 189: 13-24.DOI: 10.1016/j.jmst.2023.11.064

• Research Article • Previous Articles     Next Articles

Cuboidal vs equiaxed: The role of nanopowder assembly during BaTiO3 ceramic pressing step

Vlad Alexandru Lukacsa,*, Radu Stirbua, Oana Andreea Conduracheb, Lavinia Petronela Curecheriua, Mirela Airimioaeic, Cristina Elena Ciomagad, George Stoiane, Gabriel Caruntuf, Liliana Mitoseriua,*, Maria Teresa Buscagliag   

  1. aDielectrics, Ferroelectrics & Multiferroics Group, Faculty of Physics, “Al. I. Cuza” University of Iasi, 11 Carol I Bv., 700506 Iasi, Romania;
    bElectronic Ceramics Department, Jozef Stefan Institute, Ljubljana 1000, Slovenia;
    cFaculty of Chemistry, “Al. I. Cuza” University of Iasi, 11 Carol I Bv., 700506 Iasi, Romania;
    dDepartment of Exact and Natural Sciences, Institute of Interdisciplinary Research, “Al. I. Cuza” University of Iasi, 11 Carol I Bv., 700506 Iasi, Romania;
    eNational Institute of Research and Development for Technical Physics, 700050 Iasi, Romania;
    fDepartement of Chemistry & Biochemistry, Central Michigan University, Mount Pleasant, MI 48859, United States;
    gInstitute of Condensed Matter Chemistry and Technologies for Energy, CNR, Via de Marini 6, 16149 Genoa, Italy
  • Received:2023-07-31 Revised:2023-11-04 Accepted:2023-11-21 Published:2024-08-01 Online:2024-01-17
  • Contact: *E-mail addresses: . vlad.lukacs@uaic.ro (V.A. Lukacs), lmtsr@uaic.ro (L. Mitoseriu)

Abstract: The functional properties of BaTiO3 ceramics, produced by using the same pressing/sintering strategy from nanopowders with two distinct morphologies (cuboidal/equiaxed nanoparticles) and similar particle sizes, are comparatively investigated. The sintered ceramics exhibit similar nanoscale structures, with faceted crystalline grains and crystalline inclusions, clean grain boundaries and well-defined 90° lamellar domains extending in some entire grains or finer nanodomains inside grain regions. The differences in the functional behavior originating from the different nanopowder morphology are described in terms of the nanoparticle assembly during the pressing step. The numerically simulated green body densification indicated a more efficient assembly resulting in higher density for the cubic particles (0.90 vs. 0.84 relative density) and a more homogeneous pore distribution in the spherical-derived ones. As a result of the higher density after sintering, the functional properties are enhanced in cuboid-originated ceramics. For comparison, the ceramic produced from cubic nanoparticles sintered at T1/T2 = 1250/800 °C shows higher permittivity (room temperature value of ∼2100 - cubic vs. ∼1700 - rounded), enhanced ferroelectric characteristics (cubic: Ps = 8.57 μC cm-2, Pr = 0.95 μC cm-2, and Ec = 2.3 kV cm-1, with respect to Ps = 6.06 μC cm-2, Pr = 0.4 μC cm-2, and Ec = 1.4 kV cm-1, for spherical - derived ones, measured at Emax = 29.3 kV cm-1) and a stronger dc-field dependence of their permittivity of ∼12 % (cubic) vs. only ∼2 % (spherical), for a dc-applied field in the range of -15 kV cm-1 < Edc < 15 kV cm-1. In contrast, the spherical particles-derived ceramics contain fewer defects and have a more homogeneous and finer porosity distribution in the ceramic volume and consequently, they are more stable and sustain larger field applications in comparison with the cubic-derived counterparts.

Key words: Electroceramics, Pressing, Morphology, Compaction, BaTiO3