TY - JOUR

T1 - Investigation of the Structure of Highly Dispersed NiO–SiO2 Catalyst Features Using X-Ray Analysis of the Atomic Pair Distribution Function

AU - Mikhnenko, M. D.

AU - Cherepanova, S. V.

AU - Shmakov, A. N.

AU - Alekseeva, M. V.

AU - Kukushkin, R. G.

AU - Yakovlev, V. A.

AU - Pakharukova, V. P.

AU - Bulavchenko, O. A.

PY - 2024/6

Y1 - 2024/6

N2 - In this work, NiO and NiO–SiO2 are studied using X-ray diffraction and the method of atomic-pair radial distribution. Using X-ray phase analysis, it is determined that the sizes of NiO particles have a coherent-scattering region of more than 100 nm, while the NiO–SiO2 sample has particle sizes of about 2–3 nm. However, full-profile simulation using the Rietveld method does not allow one to describe the effects observed during diffraction: asymmetry of the peaks, the appearance of an additional shoulder of peak 111 in the region of small angles; therefore, the method of atomic-pair radial distribution is used to analyze the structure. When simulating the experimental curve of the atomic-pair radial distribution, 3 different models are used: pure NiO, a mixture of NiO and Ni2SiO4, as well as a modified NiO model with Si embedded into the crystal lattice. The latter model is created based on the assumption of the incorporation of silicon into the NiO structure, as can be evidenced by the X-ray diffraction data. According to the results of simulation of the curve of the atomic-pair radial distribution, it is the latter model that provides the best description of the observed effects: a significantly increased unit-cell parameter in comparison with the sample without the addition of SiO2, as well as decreased cation–oxygen distances in the structure while the distances between cations are increased.

AB - In this work, NiO and NiO–SiO2 are studied using X-ray diffraction and the method of atomic-pair radial distribution. Using X-ray phase analysis, it is determined that the sizes of NiO particles have a coherent-scattering region of more than 100 nm, while the NiO–SiO2 sample has particle sizes of about 2–3 nm. However, full-profile simulation using the Rietveld method does not allow one to describe the effects observed during diffraction: asymmetry of the peaks, the appearance of an additional shoulder of peak 111 in the region of small angles; therefore, the method of atomic-pair radial distribution is used to analyze the structure. When simulating the experimental curve of the atomic-pair radial distribution, 3 different models are used: pure NiO, a mixture of NiO and Ni2SiO4, as well as a modified NiO model with Si embedded into the crystal lattice. The latter model is created based on the assumption of the incorporation of silicon into the NiO structure, as can be evidenced by the X-ray diffraction data. According to the results of simulation of the curve of the atomic-pair radial distribution, it is the latter model that provides the best description of the observed effects: a significantly increased unit-cell parameter in comparison with the sample without the addition of SiO2, as well as decreased cation–oxygen distances in the structure while the distances between cations are increased.

KW - defects

KW - diffraction

KW - method of atomic-pair radial distribution

KW - nickel oxide

KW - simulation

KW - structure

KW - synchrotron radiation

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85198621853&origin=inward&txGid=a60444e5722323728c445ff50e001388

UR - https://www.mendeley.com/catalogue/66690832-42f5-30ee-a7c6-b59081bb53b2/

U2 - 10.1134/S1027451024700241

DO - 10.1134/S1027451024700241

M3 - Article

VL - 18

SP - 641

EP - 647

JO - Journal of Surface Investigation

JF - Journal of Surface Investigation

SN - 1027-4510

IS - 3

ER -