Influence of Ta and Zr single doping on the properties of sodium yttrium copper titanate ceramics: a multifaceted investigation

The growing demand for high-performance dielectric materials in electronic devices has increased interest in sodium yttrium copper titanate (NYCTO) as a promising alternative to calcium copper titanate, which is limited by its high dielectric loss. This study investigates the effects of Ta and Zr doping on the microstructural, electrical, and optical properties of NYCTO ceramics synthesized using the solid-state method. The single-phase formation of the synthesized compositions was confirmed through X-ray diffraction and Raman spectroscopy. SEM images revealed a slight increase in grain size from 2.24 to 2.98 μm with Ta doping. Ta doping resulted in an increase in the dielectric constant (ε′), while Zr doping notably reduced the dielectric loss (tanδ). The Ta-doped NYCTO achieved the highest dielectric constant of 1.846 × 10⁴ at 20 Hz, while the Zr-doped sample exhibited the lowest dielectric loss of 0.012 at 1 MHz. The high ε′ observed in the system is attributed to the internal barrier layer capacitance (IBLC) effect. Meanwhile, the reduced tanδ in Zr-doped NYCTO over a broad frequency range is attributed to the increased resistance at the grain boundaries as a result of Zr doping. XPS analysis identified Cu⁺ ↔ Cu²⁺ charge hopping as the primary mechanism behind the n-type behavior in NYCTO and NYCTTO ceramics. Overall, this study highlights the role of Ta and Zr dopants in optimizing the dielectric and electrical properties of NYCTO, establishing its potential for advanced electronic applications.