Synthesis of large single crystals of analcime in a template-free system

Abstract

Analcime (ANA) crystals have wide applications in the field of selective adsorption, nanoelectronics, light gas/hydrocarbon mixture separation, and radioactive element adsorbents. However, many organic templates were necessary to synthesize ANA crystals in previous work, causing significant environmental pollution and high cost. Thus, it is crucial to synthesize single ANA crystals under a simple system without the organic template. Herein, we explore the synthesis of large single ANA crystals (size up to 210 μm) in the template-free system of SiO₂ : 0.274Al₂O₃ : 1.79Na₂O : 190H₂O at 180 °C for 40 h. The absence of expensive organic templates and hydrofluoric acid (HF) dramatically reduces the costs and pollution. This makes the method more conducive to mass production. Meanwhile, we report a series of growth conditions for ANA crystals with different sizes, which is more conducive for the preparation of the required ANA single crystals for different application scenarios.