Abstract
Structure, morphology and thermal behavior of silver-doped nanoparticles formed in La2(SO4)3 and LaCl3 systems. / O. Lavrynenko. – 2021–2022. – # 21/22. – pp. 167-176. – eng. The formation of structures in systems of lanthanum sulphate and chloride in the presence of silver nitrate was studied by XRD, TG–DTA and SEM/EDS methods. TG–DTA analysis showed the formation of hexagonal structure La(OH)3 and its transformation into an unstable compound of monoclinic lanthanum (oxy)hydroxide in the temperature range 260 – 300°C, dehydroxilation of (oxy)hydroxide’s lattice at temperatures of 420 – 440°C. The subsequent ordering of the lanthanum oxide structure and the destruction of the substances included in the system took place at temperatures of 600 – 830°C and the removing of silver clusters – at 920°C. It is shown that at Т = 400 – 600°С the well-crystallized powders formation of lanthanum oxide La2O3 (space group P3m1 corresponds to a trigonal system) takes place, which includes elements of cubic phases La2O3 (space group Ia3) and LaO (space group F) in its structure. The presence of silver cations in the systems during the calcination process leads to their reduction on the surface of lanthanum oxide clusters. Morphological study indicates the heterogeneity of the powders and the distortion of the (hexagonal) shape of lanthanum oxide crystals to spherical that is typical for lanthanum chloride systems. In addition to the main elements (oxygen, lanthanum and silver if present in the system) the composition of the powders contains the elements that make up the anions of the initial salts (sulphur, chlorine, nitrogen), as well as the residual elements (sodium and potassium) of additional substances. Tab. 1, Fig. 3, Ref. 16.