Investigation of Ceramic Materials using Temperature-dependent XRD
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The study focused on verifying the phase purity and crystal structure of Pb (1-x) LaxTi (1-x) Al x O 3 samples within the range of 0≤x≤0.25, which were synthesized through the sol-gel process. Synchrotron x-ray powder diffraction was employed for confirmation. The investigation included temperature-dependent XRD to explore the structural transition from a tetragonal to cubic phase. The primary aim of this research was to assess the impact of the newly synthesized Pb (1- x ) La x Ti (1-x) Al x O 3 compounds (0≤x≤0.25) in terms of their structural, vibrational, dielectric, and ferroelectric properties. Notably, the incorporation of La/Al into PbTiO 3 allowed for easy processing of the samples into ceramic form while retaining their ferroelectric functionalities. This is particularly significant as the pure PbTiO 3 , with its high non-centrosymmetric tetragonal lattice strain (c/a ∼ 1.064), is unsuitable for use in ceramics for ferroelectric and piezoelectric applications.
Figure 1. Synchrotron-based temperature dependent XRD for x =0.09 composition
The successful synthesis of Pb(1-x)LaxTi(1-x)AlxO3 ceramics within the specified composition range (0≤x≤0.25) was achieved through the effective application of the sol-gel process on synthesized powders. To examine the structural transition from a tetragonal to cubic phase, temperature-dependent X-ray diffraction (XRD) analysis was conducted. In the XRD study of the composition with x=0.09 [Fig.1a], a notable separation of two peaks (001) and ( 100) at lower temperatures was observed, indicative of a tetragonal phase. As the temperature rose, these peaks gradually fused into a singular peak at 573 K, signifying a transformation to a cubic phase (Fig. 1b). Similar temperature-dependent trends were noted for other peaks associated with the tetragonal to cubic phase transition. Furthermore, a temperature-dependent dielectric study provided confirmation of the phase transition from a tetragonal to a cubic structure.
Reference:
Yadav AK, Verma A, Kumar S, Srihari V, Sinha AK, Reddy VR, et al. Investigation of la and Al substitution on the spontaneous polarization and lattice dynamics of the Pb(1-x)LaxTi(1-x)AlxO3 ceramics . J Appl Phys 2018;123. https://doi.org/10.1063/1.5017765.