Novel amorphous precursor densification to transparent Nd:Y₂O₃ Ceramics

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• 作者：Rekha Mann ; ^{mann_rekha@lastec.drdo.in} ; Kiranmala Laishram ; Sheikh Ashfaq Ahmed ; Neelam Malhan
• 关键词：Nd ; Yttria ; Microwave gel combustion ; Precursor sintering ; Transparent ceramic
• 刊名：Ceramics International
• 出版年：2012
• 期刊代码：13_02728842
• 类别：ms
• 出版时间：July, 2012
• 卷：38
• 期：5
• 页码：4131-4135
• 文件大小：643 K

摘要

A novel approach of neodymium ion doped yttrium oxide (Nd:Y₂O₃) amorphous precursor compaction and sintering is being reported for the first time. Precursor of 2 at.%Nd³⁺ doped Y₂O₃ was synthesized by gelation of sol of yttrium and neodymium nitrates with l-alanine at 80 掳C for 16 h followed by gel combustion in microwave. A part of microwave precursor was heat treated at 700 掳C for 5 h to give the partially crystalline Nd:Y₂O₃ amorphous precursor. Thermogravimetric analysis (TGA) of partially crystalline amorphous precursor of Nd:Y₂O₃ gave 8.5%total weight loss indicating removal of maximum organics. X-Ray diffraction (XRD) showed broad peaks indicating incomplete crystallization of cubic Nd:Y₂O₃. Morphology was found to be close to spherical with particles in size range 17-19 nm by TEM. Another part of microwave precursor on calcination at 1000 掳C for 3 h led to formation of fully crystalline Nd:Y₂O₃ with particles in size range of 35-85 nm. Both partially crystalline amorphous precursor and fully crystalline Nd:Y₂O₃ were compacted at 400 MPa by cold isostatic press and sintered at 1750 掳C for 10 h under vacuum (10^鈭? mbar). The partially crystalline Nd:Y₂O₃ amorphous precursor densified to 99%with 65%transmission at 2500 nm (0.5 mm thickness) compared to 96%densification with 34%transmission for fully crystalline Nd:Y₂O₃ without any sintering aids. Retention of cubic phase purity of Y₂O₃ was observed in both the ceramic pellets post sintering by XRD. Good grain fusion with grain growth to 鈮? 渭m was observed by scanning electron microscope (SEM) for partially crystalline Nd:Y₂O₃ amorphous precursor. Thus partially crystalline Nd:Y₂O₃ amorphous precursor nanopowders, with homogeneous close to spherical fine particles and high reactivity due to ionic mobility of amorphous phase, led to better densification.