Combustion-synthesized ultrafine SrTiO3 nanocrystals with low-temperature sintering and multifunctional properties for LTCC applications

Nanocrystalline SrTiO 3 was synthesized using a single-step modified combustion process, producing phase-pure perovskite powder suitable for low-temperature ceramic processing. Remarkably, the material achieved a high relative density of 99.2% at a sintering temperature of only 890 °C , without the use of any sintering additives. Structural analysis by X-ray diffraction confirmed a cubic perovskite phase with an average crystallite size of 16 nm , which was consistent with the TEM observations showing uniformly distributed nanoparticles with clear lattice fringes, indicating high crystallinity. XPS analysis verified the expected oxidation states of Ti 4+ and Sr 2+ and revealed oxygen-vacancy-related components in the O 1s spectrum, correlating well with the material’s optical behavior. The optical band gap was determined to be 3.07 eV, and the strong blue photoluminescence emission originated from vacancy-induced defect states within the TiO 6 octahedra. Thermal stability assessed through DTA–TGA showed no significant weight loss up to 900 °C , confirming robust thermochemical behavior. The sintered ceramics exhibited a dielectric constant of εᵣ ≈ 50, a loss factor of tan δ ≈ 0.3 at 5 MHz , and a low temperature coefficient of permittivity (T CK ≈ 0.505 ppm °/C ). The combination of nanoscale features, excellent densification at reduced temperature, oxygen-vacancy-driven luminescence, and favorable dielectric properties highlights nanocrystalline SrTiO 3 as a strong candidate for advanced LTCC (Low-Temperature Co-fired Ceramic) devices.