Langbeinite phosphosilicates K2-xCsxZr2P2SiO12 (x = 0, 0.5, 1.0, 1.5, 2.0) for cesium encapsulation; synthesis, chemical durability and thermal expansion study

• Published in: Ceramics international Vol. 47; no. 20; pp. 28951 - 28959
• Main Authors: Balaji, Daneshwaran, Kumar, Sathasivam Pratheep
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.10.2021
• Subjects: Cesium leaching; Langbeinite; Phosphosilicate; Thermal expansion; X-ray diffraction; Cesium leaching; X-ray diffraction; Thermal expansion; Phosphosilicate; Langbeinite
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2021.07.055

The volatization of cesium at high temperatures makes its immobilization challenging to the nuclear scientists. Present work reports the feasibility of cesium incorporation into an orthorhombic langbeinite phosphosilicate. The structural flexibility, leachability and thermal expansion of K2-xCsxZr2P2SiO12 (x = 0, 0.5, 1.0, 1.5, 2.0) have been investigated. Powder X-ray results authenticates the accommodation of cesium into a single phasic orthorhombic langbeinite structure up to 29.17 wt %. Morphological study reveals the particle agglomeration and poor crystallinity, and vibrational spectral analysis shows peak broadening and peak shift upon increasing the cesium concentration. The static leach test has been performed on the pellet sample and the normalized leaching of Cs is found to be in the order of 101 g/m2. The average coefficient of thermal expansion for K0.5Cs1.5Zr2P2SiO12 is registered as 7.45 × 10−6/K between 303 and 873 K. Cesium insertion into K2Zr2P2SiO12 displays a large deviation in thermal expansion due to the size effect as observed by several researchers for other phosphate and phosphosilicate members.