Synthesis and densification of Gd2Zr2O7 nanograin ceramics prepared by field assisted sintering technique

- Gd2Zr2O7 nanocrystalline powders with an average crystallite size of 5.9 nm can be obtained by a non-aqueous gel-combustion method.
- Gd2Zr2O7 nanograin ceramics with high relative densities were successfully fabricated at relatively low temperatures by FAST sintering.
- The densification and grain growth in the sintering process were divided into three stages.
- Nanograin ceramics have comparatively high hardness compared with sample sintered at 1500 °C for 72 h in furnace.

For Gd2Zr2O7, nanograin ceramics with high relative densities (95%-97.4%) and small average grain sizes (61 nm - 82 nm) were successfully fabricated for the first time using field assisted sintering technique (FAST), also known as spark plasma sintering (SPS) method, in which nanopowders with an average crystallite size of 5.9 nm were synthesized via a non-aqueous gel-combustion method. Temperature was varied over a broad range to investigate its influence on the densification mechanism, microstructure evolution and hardness. The results revealed that both relative density and grain size increase with the increase of sintering temperature. The densification processes were divided to three stages. 1250 °C-1300 °C is the most suitable temperature range to fabricate dense Gd2Zr2O7 nanograin ceramics with comparatively high hardness by FAST.

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