Comparison of synthesis and spark plasma sintering of YAG nano particles by variation of pH and precipitator agent. Issue 18 (15th December 2018)

• Record Type: Journal Article
• Authors: Rahmani, Mahsa; Mirzaee, Omid; Tajally, Mohammad; Loghman-Estarki, Mohammad Reza
• Is Part Of: Ceramics international. Volume 44:Issue 18(2018)
• Page Start: 23215
• Page End: 23225
• Publication Date: 2018-12-15
• Subjects: YAG -- Precipitator agent -- SPS -- PH; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2018.07.130
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Yttrium aluminum garnet ceramics with a wide range of technological and industrial applications have attracted great attention owing to their remarkable mechanical, thermal and optical features. The properties of transparent or translucent YAG ceramics with wide-ranging applications notably depend on the features of the starting particles which is directly affected by synthesis conditions. In this study, yttrium aluminum garnet precursors (YAG) were obtained by reverse co-precipitation method from a mix solution of aluminum and yttrium nitrates using ammonium hydrogen carbonate (AHC) and ammonia water (AW) solutions as precipitator agents. The effect of pH on the chemical composition and phase analysis of the precursors synthesized by different precipitants was explored, leading to the formation of precursors with the proper stoichiometric ratio of YAG phase. The phase evaluation process, thermal behavior, microstructures and other characteristics were compared for the two precipitants by ICP, XRD, FTIR, TG-DTA, BET, FESEM, TEM and EDX analysis. The results revealed that unlike AW, using AHC as precipitant at high pH values caused deviation from the YAG stoichiometric ratio. In the pH value of 7, both precipitants produced homogenous precipitates and pure YAG at a calcination temperature of 900 °C while the powders obtained by AHC exhibited more dispersity and fewer aggregates. Sub-micron-grained YAG ceramics were obtained by SPS method at 1380 °C for 10 min using amorphous nano particles without adding any sintering aids. Compared with ceramics produced using synthesized powders by AW, the ceramic of co-precipitated powders by AHC showed higher density (99.9%) and transparency (33% at 680 nm and 50% at 1100 nm).