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Keywords:

  • X-ray diffraction;
  • dielectric permittivity;
  • phase transitions;
  • piezoelectrics;
  • ferroelectrics;
  • BaTiO3

Structural and dielectric investigations were carried out on a perovskite lead-free (Ba1−xCax)(Zr0.05Ti0.95)O3 ferroelectric ceramic for x = 0.03, 0.05, 0.08, 0.10, 0.12 and 0.15. The room-temperature structural analysis reveals a crossover from orthorhombic to tetragonal crystal structure near x = 0.10. A coexistence of tetragonal (P4mm) and orthorhombic (Pmm2) structure is observed in the composition range 0.05 ≤x≤ 0.10. The fraction of tetragonal phase increases from 27% for x = 0.05 to 71% for x = 0.10. The dielectric measurements show that the tetragonal to orthorhombic and rhombohedral to orthorhombic transition temperatures decrease with an increase in Ca2+ content, while the cubic to tetragonal transition temperature remains the same. It is also shown that for the tetragonal to orthorhombic transition a phase coexistence occurs over a temperature range of about 18 K. The coexistence range covers room temperature for intermediate compositions: x = 0.05, 0.08 and 0.10. Therefore, higher dielectric and piezoelectric properties are observed in these compositions.