Abstract In this study, we present a comprehensive investigation of Zn₁₋ₓ₋ᵧCoₓPdᵧO with x , y values of (0.00, 0.00), (0.03, 0.00), and (0.03, 0.03). ZnO doped and co-doped with Co 2 ⁺ and Pd 2 ⁺ was synthesized by the solid-state reaction method to explore the structural and magnetic effects of controlled doping, with particular emphasis on how Pd influences the spin dynamics and local environment of Co 2 ⁺ ions under external mechanical pressure (686 ± 20 MPa) applied using a hydraulic press. X-ray diffraction (XRD) confirmed the wurtzite structure of the samples and enabled the evaluation of lattice parameter variations due to dopant incorporation. The estimated microstrain increased under pressure, from 0.54(5) × 10⁻ 3 to 2.22(6) × 10⁻ 3 for the Co-doped sample, and from 0.47(2) × 10⁻ 3 to 1.18(7) × 10⁻ 3 for the Co–Pd codoped sample. Scanning electron microscopy (SEM) revealed pressure-induced agglomeration and a slight increase in particle size for the Co-doped samples, from 2.01(14) to 2.14(12) μ m, while a reduction was observed for the Co–Pd codoped samples. Raman spectroscopy identified vibrational modes consistent with non-axial lattice distortions in the basal plane. Electron Paramagnetic Resonance (EPR) spectra recorded at X-band showed clear modifications in line shape and intensity upon pressure application, indicating changes in the local crystal field and enhanced spin interactions. Overall, the results demonstrate that Co 2 ⁺ ions act as local probes sensitive to both chemical doping and applied pressure, offering valuable insight into the interplay between structural distortions and spin dynamics under external stress.
Zipa-Romero et al. (Wed,) studied this question.