Change of crystallinity and optical transmittance of K2Ni(SO4)2·6H2O single crystal by heat treatment

• Published in: Inorganic chemistry communications Vol. 170; p. 113402
• Main Authors: Abdulwahab, A.M., Gaffar, M.A., Abu El-Fadl, A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-12-2024
• Subjects: Crystallinity; Heat treatment; Optical transmittance; Potassium nickel sulfate hexahydrate; Ultraviolet light filter; Optical transmittance; Potassium nickel sulfate hexahydrate; Heat treatment; Crystallinity; Ultraviolet light filter
• ISSN: 1387-7003
• DOI: 10.1016/j.inoche.2024.113402

[Display omitted]
•Potassium nickel sulfate hexahydrate (KNISH) single crystal was grown at 309 K.•Heat treatment to 383 K converts the crystalline KNISH to amorphous KNIS.•The amorphous anhydrous KNIS transforms to crystalline state above 629 K.•The optical transmittance changes slightly by heat treatment from 296 K to 338 K.•Heat treatment under 370 K does not affect the efficiency of KNISH as UV filter.
Potassium nickel sulfate hexahydrate (KNISH) was prepared and grown as single crystal from the supersaturated aqueous solution at 309 K using slow evaporation method. Thermal measurements were achieved for the prepared crystal. The dehydration process, structural phase transitions and melting point of the obtained material were detected. Crystal structure and optical transmittance of KNISH crystal were studied through heat treatment. At 370 K, the dehydration process started to convert KNISH to the anhydrous phase KNIS and the crystallinity decreased gradually until the material became totally amorphous at 383 K. The anhydrous KNIS stayed at the amorphous state from 383 K to 629 K where it transformed again to the crystalline state with different structure. The heat treatment under dehydration temperature did not affect the efficiency of KNISH crystal for using as ultraviolet light filter and sensor. Above dehydration temperature, the obtained anhydrous phase KNIS is not suitable for these applications.