Molten salt assisted growth of lead-free BCZT crystals: effects of synthesis conditions and sintering on structural and electrical properties

An attempt of preparing lead free [(Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃] (BCZT) crystals by molten salt synthesis (MSS) method and the influence of MSS process parameters on the morphology, phase structure, dielectric and ferroelectric properties of BCZT ceramic have been reported in this investigation. A reduction in reaction temperature of 350 °C (1000 °C/4 h in MSS method versus 1350 °C/4 h in conventional solid state method) has been achieved in MSS method. Among various alkali metal salts NaCl–KCl salt mixture has been found most effective in producing phase pure and anisotropic platelet like BCZT crystals. Powder X-ray diffraction pattern and Raman spectra of the BCZT crystals confirm the room temperature tetragonal structure of the BCZT ceramic. Finally, BCZT template prepared by alkali metal salts (Na₂SO₄, NaCl, KCl, NaCl–KCl and NaBr) at 1000 °C/4 h were compacted and sintered at 1450 °C/2 h to achieve pellets with good sintered densities. The crystal structure, microstructural and electrical properties were compared with randomly-oriented BCZT ceramics prepared by conventional solid-state synthesis method, and the results are presented in this paper.