The properties of ZrO 2 co-stabilized by CeO 2 and TiO 2 ceramic bulks were investigated for potential thermal barrier coating (TBC) applications. Results showed that the (Ce 0.15 Ti x )Zr 0.85-x O7 (x = 0.05, 0.10, 0.15) compositions with single tetragonal phase were more stable than the traditional 8YSZ at 1573 K. These compositions also showed a large thermal expansion coefficient (TEC) and a high fracture toughness, which were comparable to those of YSZ. However, the phase stability, fracture toughness and sintering resistance of the CeO 2 -TiO 2 -ZrO 2 system showed a decline tendency with the increase of TiO 2 content. The TEC of the ceramic bulks decreased with increase of TiO 2 content as well because the crystal energy was enhanced with increasing substitution of Zr 4+ by smaller Ti 4+ . The (Ce 0.15 Ti 0.05 )Zr 0.8 O 2 had the best comprehensive properties among the (Ce 0.15 Ti x )Zr 0.85-x O 2 compositions as well as a low thermal conductivity . Therefore, it can be explored as a TBC candidate material for high-temperature applications.
Ti-related oxide ceramics often exhibit excellent microwave dielectric properties and are widely applied in the microwave communication field. However, their microwave dielectric properties are often influenced by unstable defects, which are caused by the relatively low oxygen partial pressure at high sintering temperatures . In this work, Al 2 O 3 was introduced to improve the defect structures of the 0.85CeO 2 -0.15TiO 2 ceramics. According to the XPS pattern and AC conductivity analysis, Al 2 O 3 doping could stabilize the valence state of Ti but increase the oxygen vacancy concentration. Q × f first increased and then decreased as the Al 2 O 3 content increased. The highest Q × f value of 54361 GHz was obtained for the CTA0.015 sample sintered at 1275 °C, as well as the ε r of 29.41 and τ f of +7.8 ppm/°C. Finally, the CTA0.015 sample was used to prepare a microstrip antenna via the screen-printing process, which exhibited a good temperature-independent resonant frequency and indicated good application prospects.
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