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The influence of Mg doping on a type of Na0.5Bi0.5TiO3 (NBT)-based ceramic, viz. NaBiTi6O14, has been investigated. NaBi(Ti1−xMgx)6Oy ceramics (x = 0.03, 0.06, 0.09, 0.12) were prepared by a traditional solid-phase method, and the influence of Mg doping on their microstructure, dielectric properties, and ferroelectric performance studied. Scanning electron microscopy (SEM) showed that the doped ceramics had clearer grain boundaries and more uniform grain size than the undoped ceramic. Mg doping enhanced the dielectric properties of the NaBiTi6O14 ceramic, with lower dielectric loss and higher dielectric constant. Z* plots showed that the NaBi(Ti1−xMgx)6Oy ceramics were a kind of dielectric. The activation energy of the ceramics was found to be 1.083 eV, 1.087 eV, 1.086 eV, and 0.861 eV, respectively, confirming their excellent dielectric performance. Ferroelectric hysteresis measurements showed that the NaBi(Ti1−xMgx)6O14−6x ceramics exhibited weak ferroelectric performance with 2Pr values of 0.079 μC cm−2 to 0.195 μC cm−2. The stable behavior of the doped ceramics may enable their application in high-temperature and high-frequency devices. [ABSTRACT FROM AUTHOR]

Lead-free NaBixTi6O12.5+1.5x ceramics (x = 0.98, 0.99, 1.01, 1.02) with a pseudo-perovskite structure were prepared via the traditional solid-phase reaction. The structure, dielectric properties and impedance spectroscopy of the NaBixTi6O12.5+1.5x ceramics were investigated in detail. X-ray diffraction patterns reveal that all of the prepared ceramics have a single phase and the scanning electron microscope confirms the well-growth performance of the ceramics. The dielectric constant and dielectric loss show great stability with a wide temperature range. It can be learned that the resistance, the maximum Debye peak, and the corresponding capacitance simultaneously decrease with increasing temperature by analysing Z* plots. The active energy of the NaBixTi6O12.5+1.5x ceramics (x = 0.98, 0.99, 1.01, 1.02) are respectively 0.67, 0.56, 1.34 and 1.37 eV, meanwhile, there is no phase transition point in 25–750 °C. The results demonstrate that the electrical properties of the NaBixTi6O12.5+1.5x lead-free ceramics can be well tuned by varying the Bi quantity. [ABSTRACT FROM AUTHOR]

K x Na 0.5-x Bi 4.46 Ce 0·04 Ti 4 O 15+y (x = 0, 0.04, 0.08, 0.12, 0.16, 0.20) ceramics were synthesized by solid state reaction. The microstructure and electrical properties of the solid solutions were characterized. It is found that the doping of appropriate amount of K improved the degree of lattice distortion of the material, and the characteristic parameter b/a of lattice distortion obtained the maximum value through structural refinement at x = 0.12. A defect dipole pair (K B i ″ − V o • • ) is formed by adjusting the defects of the material. The polarizability of defects is 4.88 × 10-37F·m2. The formation of defect dipole pairs that deflect towards the direction of spontaneous polarization reduces the difficulty of polarization and improves the piezoelectric properties. Finally, the optimal piezoelectric coefficient (d 33) of NBCT-xK ceramics is 23 pC/N, and the residual polarizability (2 P r) is 4.14 μC/cm2. The values of residual polarization rate (2 P r), piezoelectric coefficient (d 33) and b/a show the same trend, which will gradually decrease when their value increases to a certain extent. The dielectric loss of all samples below 200 °C are lower than 0.01, and the dielectric constant is relatively flat below 400 °C. Moreover, the Curie temperature (T c) of K x Na 0.5-x Bi 4.46 Ce 0·04 Ti 4 O 15+y based ceramics is increased to 686.0 °C, which will enable the ceramics to be used in oilfield logging, aerospace and military fields in high temperature environment. [ABSTRACT FROM AUTHOR]