Open Ceramics (Nov 2020)
Synthesis of new sodium strontium niobates via (emim)OAc ionic liquid and an imidazole:choline chloride deep eutectic solvent
Abstract
The synthesis of sodium strontium niobate phases was explored via an ionic liquid (IL), namely 1-ethyl-3-methylimidazolium acetate ((emim)OAc), and a deep eutectic solvent (DES), viz. Imidazole 7:3 choline chloride. Four different crystal compositions were synthesized, two via the use of the IL and the remaining via DES assisted syntheses. Those synthesized via the use of the IL belong to the class NaxSr1-xNbO3, with X values X < 0.3, and with crystalline structures assumed to be tetragonal with space group P4/mbm (127). For those synthesized with X values 0.26 < X < 0.3, crystalline refinement established unit cell parameters of a = 5.68 Å, c = 4.01 Å, and average volume of = 129.42 Å3; phases with X values 0.14 < X < 0.25, values of a = 5.69, c = 4.01, and average volume of = 129.38 Å3; and those with X values 0.12 < X < 0.14, values of a = 5.69, c = 4.02, and average volume of = 130.19 Å3. Conversely, the crystalline product obtained via DES assisted synthesis is determined to have the chemical formula Na0·1Sr0·9NbO3. Based on results obtained, the crystalline structure is presumed to be orthorhombic, with space group pnnm (58). The dimensions of this unit cell are a = 32.542 Å, b = 5.665 Å, and c = 3.948 Å, and α = β = γ = 90°, with a total volume of 727.974 Å. The characterization of the new crystal compositions was carried out via powder diffraction, SEM, TEM, EDX, ICP-OES and computational refinement.
