Synergistic optimization of rheological, mechanical, and microwave dielectric properties of DLP 3D printed La2Zr2O7 ceramics via MgO addition

Pyrochlore-type zirconates, particularly lanthanum zirconate (La 2 Zr 2 O 7 , LZO) is a promising candidate for microwave applications, yet processing challenges remain. In this study, LZO- x MgO ( x  = 0–8 wt%) composite ceramics were successfully synthesized via Digital Light Processing (DLP) vat photopolymerization. Rheological analysis revealed that MgO functions as an effective solid dispersant, reducing slurry viscosity from 3500 to 850 mPa·s while improving photocuring through refractive-index matching. Characterization results indicate that a certain amount of MgO (2–4 wt%) effectively inhibits abnormal grain growth through a grain-boundary pinning mechanism, leading to a homogenized microstructure. Mechanical performance was notably enhanced, the 4 wt% MgO sample exhibited a peak flexural strength of 303.5 MPa. Crucially, the microwave dielectric properties improved substantially: the product of quality factor and resonant frequency ( Q × f , where Q = 1/tan δ and tan δ is the dielectric loss) increased from 3000 to 11,000 GHz. Additionally, the temperature coefficient of resonant frequency ( τ f ) was effectively tuned from –31 to approximately –10 ppm/°C. However, excessive MgO (8 wt%) leads to phase agglomeration and the reappearance of abnormal grains, which degrades the overall performance. Overall, 2–4 wt% MgO achieves an optimal balance of processability, strength, and dielectric performance.