Investigation on structure, dielectric and magnetic properties of the four-layer Aurivillius phase Pb1-Bi3.5+Nd0.5Ti4-Mn O15 prepared via molten salt method

Structure-property relationships in the lanthanide-substituted PbBi2Nb2O9 Aurivillius phase synthesized by the molten salt method

“…The substitution of larger La 3+ results in a longer Nb-O bond and thereby lowered bond strength, shifting the vibration modes to lower wavenumbers of 565 and 813 cm −1 . Conversely, the substitution of smaller Nd 3+ results in shifts toward higher wavenumbers of 579 and 826 cm −1 , since the Nb-O bond is shorter and results in higher bond strength [21]. We note that the IR spectra do not show sulfate vibration modes around 970-995 cm −1 , which indicates that the salts used as the reaction media do not react with the products.…”

“…7 shows the temperature dependence of the dielectric constant and dielectric loss of pelletized samples measured in the range 50 kHz to 1 MHz, which best reflects the intrinsic polarizability [35]. The density of the pellets was determined as 7.73 g/cm 3 , 7.57 g/cm 3 , and 7.64 g/cm 3 for PBNO, PBNO-La, and PBNO-Nd respectively, which in each case is greater than 93% of the theoretical density and indicates that the molten salt method produces dense grains [21]. A single dielectric peak is observed for all the samples, which corresponds to the phase transition from the ferroelectric to paraelectric phase (T c ).…”

“…This change in the degree of orthorhombicity can also be expected to affect the ferroelectric properties, as discussed further below. Additionally, the main XRD peaks slightly shift toward lower 2θ for PBNO-La and toward higher 2θ for PBNO-Nd, corresponding to changes in the lattice parameters [21]. Rietveld refinement of the NPD data was performed to investigate the structural parameters in detail.…”

Structural transformation in Mn-substituted Sr2Bi2Ta2TiO12 Aurivillius phase synthesized by hydrothermal method: A comparative study and dielectric properties

“…6 depicts the temperature dependence of the dielectric constant (ϵ) and dielectric loss (tan δ) at a frequency range of 50 kHz-300 kHz. The dielectric properties of the samples were investigated for high frequencies, since this best reflects the intrinsic polarizability being correlated to the structural properties of the sample [17]. The magnitude of ϵ for SBTTO initially decreases with an increase in temperature, and then significantly increases above 350 • C, indicating that the sample becomes more conductive.…”

“…Besides, the substitution of B-site cations with various ionic radii potentially enhances the structural distortion in BO 6 octahedra, thus improving its ferroelectricity [15,16]. The substitution of the Mn 3+ cation (d 4 ) for the higher valence state cation (Nb 5+ or Ti 4+ ) in the B-site cation was reported to improve the dielectric properties since it is compensated by the increase in Bi 3+ contents to maintain the charge neutrality [8,17]. Therefore, the substitution of Mn 3+ for Ti 4+ in the Sr 2 Bi 2 Ta 2 TiO 12 is expected to improve the ferroelectricity and raise the magnetization, which is especially useful for data storage applications.…”