Low-temperature Mossbauer studies of the phase composition and structural stability of iron (III) oxide/hydroxide nanocomposite
In article present the results of low-temperature Mossbauer studies of iron (III) oxide/hydroxide nanocomposite synthesized by the method of deposition. Based on these studies, the composition of the synthesized composite was revealed. The nanodispersed composite with a specific surface 280 m2/g is a hematite in the weakly disordered crystalline state (CSR 10 nm), and a lepidocrocite in the X-ray amorphous state (particles size 3-4 nm). The relative integral intensity of the Zeeman sextet, which corresponds to the magnetically ordered phase of hematite, is practically unchanged and is about 17%. The tendency to divide the magnetically ordered component into two sextets, which differ in quadrupole splitting QS= –0.21 mm/s and QS= 0.21 mm/s, respectively, is observed starting from a temperature of 190 K. As a result of annealing of the synthesized material at a temperature of 200°C, a slight redistribution (≈ 5%) of the content of paramagnetic and magnetically ordered components was recorded, which indicates the structural stability of the nanoparticles of the lepidocrocite γ-FeOOH phase at this temperature. Increase of annealing temperatures to 500oC leads to the predicted course of the phase transition γ-FеООH ® α-Fе2О3. The mechanism of growth of hematite crystallites during sintering due to fixation side faces of larger α-Fe2O3 phase of nanoparticles of the γ-FeOOH phase with simultaneous transformation of their crystal structure to side faces of larger α-Fe2O3 phase particles is presented.
K. Kucio, B. Charmas, V. Sydorchuk, S. Khalameida, O. Khyzhun, Applied Catalysis A: General . 603, 117767 (2020) https://doi.org/10.1016/j.apcata.2020.117767.
L.S. Kaykan , J.S. Mazurenko, N.V. Ostapovych , A.K. Sijo, N.Ya. Ivanichok, J. Nano- Electron. Phys. 12, No 4, 04008-1 (2020) https://doi.org/10.21272/jnep.12(4).04008.
Z. Cheng, A.L.K. Tan, Y. Tao, D. Shan, K E Ting, X.J. Yin, International Journal of Photoenergy. 2012, 1 (2012) https://doi.org/10.1155/2012/608298.
V. Kotsyubynsky, B. Ostafiychuk, V.Moklyak, A. Hrubiak, Solid State Phenomena. 230, 120 (2015) https://doi.org/10.4028/www.scientific.net/SSP.230.120.
I.A. Ryizhak, O.P. Krivoruchko, R.A. Buyanov, L.M. Kefeli, A.A. Ostankovich, Kinetika i kataliz. 10, 377 (1969).
R.A. Buyanov, O.P. Krivoruchko, I.A. Ryizhak. Kinetika i kataliz. 13, 470 (1972).
O.P. Krivoruchko, R.A. Buyanov, B.P. Zolotovskii, A.A. Ostan'kovich. Russ Chem Bull 23, 1384 (1974) https://doi.org/10.1007/BF00929635.
Mars Mineral Spectroscopy Database. URL: https://www.mtholyoke.edu/courses/mdyar/database/index.shtml?group= mixe s&species=mix1
B. K. Ostafijchuk, V. S.Bushkova, V.V. Moklyak, R.V. Ilnitsky, Ukrainian Journal of Physics 60, No 12, 1234 (2015) (DOI: 10.15407/ujpe60.12.1234).