Table 1
Lattice parameters of the (1 – x)Ba0.06(Na1/2Bi1/2)0.94TiO3–xNaNbO3 (0 ⩽ x ⩽ 1) ceramics.
| Parameters / x | 0.00 | 0.05 | 0.10 | 0.25 | 0.50 | 0.75 | 0.90 | 0.95 | 1.00 |
|---|---|---|---|---|---|---|---|---|---|
| a [Å] | 3.9037 | 3.8979 | 3.9033 | 3.9 | 3.898 | 3.935 | 3.909 | 3.933 | 3.95 |
| b [Å] | 3.9037 | 3.8979 | 3.9033 | 3.9 | 3.898 | 3.912 | 3.87 | 3.912 | 3.84 |
| c [Å] | 3.898 | 3.903 | 3.909 | 3.9038 | 3.907 | 3.88 | 3.885 | 3.88 | 3.909 |
| c/a | 0.998 | 1.0013 | 1.0014 | 1.0009 | 1.0023 | 0.9860 | 0.9938 | 0.9865 | 0.9896 |
| Cell volume [Å 3] | 58.86 | 59.29 | 59.56 | 59.38 | 59.36 | 59.7 | 58.74 | 59.7 | 59.34 |
| Crystal system | R / T | R / T | R / T | R / T | R / T / O | O | O | O | O |
Note: T – Tetragonal; O – Orthorhombic and R – Rhombohedral
Fig. 1
(a) XRD patterns of (1 – x)Ba0.06(Na1/2Bi1/2)0.94 TiO3–xNaNbO3 ceramics at room temperature and (b) XRD patterns of (1 – x)Ba0.06(Na1/2Bi1/2)0.94TiO3–xNaNbO3 ceramics in the selected regions of 2θ(45.5° to 48°).
Fig. 2
SEM images of (1 – x)Ba0.06(Na1/2Bi1/2)0.94 TiO3–xNaNbO3 ceramics.
Fig. 3
Raman spectra of (a) Ba0.06(Na1/2Bi1/2)0.94 TiO3 and peaks fitted with Gaussian components, (b) Raman spectra of NaNbO3 can be deconvoluted with Lorentzian components contrary to Ba0.06(Na1/2Bi1/2)0.94TiO3, NaNbO3 requires multiple peaks and (c) shows a change in the Raman spectra with increasing NaNbO3 doping % in Ba0.06(Na1/2Bi1/2)0.94TiO3 matrix.
Fig. 4
Frequency dependence of dielectric constant of (1 – x)Ba0.06(Na1/2Bi1/2)0.94TiO3–xNaNbO3 ceramics at room temperature.
Fig. 5
Temperature dependence of dielectric constant and loss tangent of (1 – x)Ba0.06(Na1/2Bi1/2)0.94TiO3– xNaNbO3 ceramics at different frequencies (a) 1 kHz (b) 10 kHz (c) 100 kHz (d) 1MHz.
Fig. 6
The modified Curie-Weiss plots ln(1/∊–1/∊m) vs. ln(T–Tm) for (1 – x)Ba0.06(Na1/2Bi1/2)0.94 TiO3–xNaNbO3 ceramics for x = 0, x = 0.50, x = 1.0 at 1 kHz.
Table 2
Tolerance factor, average A-and B-site ionic radius of (1 – x)Ba0.06(Na1/2Bi1/2)0.94TiO3–xNaNbO3 ceramics.
| x | Tolerance factor (t) | Average ionic radius of A site [Å] | Average ionic radius of B site [Å] |
|---|---|---|---|
| 0.00 | 0.950 | 1.300 | 0.605 |
| 0.05 | 0.951 | 1.304 | 0.607 |
| 0.10 | 0.952 | 1.309 | 0.609 |
| 0.25 | 0.955 | 1.322 | 0.614 |
| 0.50 | 0.960 | 1.345 | 0.623 |
| 0.75 | 0.965 | 1.367 | 0.631 |
| 0.90 | 0.968 | 1.381 | 0.637 |
| 0.95 | 0.969 | 1.385 | 0.638 |
| 1.00 | 0.970 | 1.390 | 0.640 |