The effect of BaTiO 3 particle shape on complex permittivity of 0.98MgTiO 3 –0.02BaTiO 3 composite powders at GHz frequencies

Abstract

The effect of BaTiO3 particle shape on the properties of 0.98MgTiO3 − 0.02BaTiO3 composite powders was characterized and analyzed using an indirectly coupled open-ended coaxial cavity resonator at gigahertz frequencies. Elongated micrometre sized BaTiO3 particles were found to have a significantly stronger effect on permittivity when compared to composite powders having micro and nano sized spherical BaTiO3 particles. Inclusion permittivities and dielectric loss tangents of composite powders increased from that of pure MgTiO3 powder, 13.3 and 4.6 × 10-3 , up to 15.7 and 1.7 × 10-2 with needle shaped BaTiO3 particles, respectively. The presented results give valuable information for tailoring the properties of dielectrics which can be utilized in the vast field of electronic component manufacturing.

Tailoring the Shape, Size, Crystal Structure, and Preferential Growth Orientation of BaTiO3 Plates Synthesized through a Topochemical Conversion Process

“…The proper crystal orientation and alignment of the particles are an additional requirement for providing the desired functionality. BaTiO 3 is, due to its outstanding ferroelectric, high dielectric constant, and optical properties, one of the most studied and also commercially used perovskite materials. − Numerous literature reports about BaTiO 3 formation under conventional hydrothermal and solvothermal conditions revealed the difficulties in preparing defined-shaped, nonaggregated nanoparticles when TiO 2 , Na 2 Ti 3 O 7 , K 2 Ti 6 O 13 , TiCl 4 , and Ti-alkoxide were used as the Ti-precursors. − The reason most probably lies in the dissolution–precipitation mechanism and in the similar surface energies of the crystal planes, which hinders the growth of the special crystal planes of BaTiO 3 . In contrast, Bis­(ammonium) lactate titanium dihydroxide (TALH) was recognized as an excellent precursor for the formation of BaTiO 3 and SrTiO 3 nanocubes with a very uniform size distribution. , An ordered arrangement of these nanocubes in thin films and in heterostructure BaTiO 3 /SrTiO 3 superlattices was also already demonstrated. − In addition to nanocubes, anisotropic platelet or rod-shaped BaTiO 3 micro- and nanocrystallites represent an advantage in achieving the optimum properties, on condition that they are properly preferentially aligned.…”