Effect of CoFe and Co‒Fe‒B Metal Nanogranules in Composite Memristors Based on the LiNbO3 Matrix on Its Structural Features

The structural features of an insulating Li‒Nb‒O film and (Co–Fe–B)х(LiNbO $$_{{3-y}}$$ ) $$_{{100-x}}$$ and (Co–Fe)х(LiNbO $$_{{3-y}}$$ ) $$_{{100-x}}$$ (x ≈ 15–30 at %) nanocomposite samples obtained by ion-beam sputtering of a polycrystalline LiNbO3 target and Co40Fe40B20–LiNbO3 and CoFe–LiNbO3 composite targets, respectively, onto polyimide substrates have been subjected to the Nb K-edge X-ray absorption near-edge spectroscopy (XANES) comparative analysis. It is shown that the structure of local bonds of Nb atoms in the film samples is noticeably different from those in crystalline LiNbO3: the Nb–Nb distance shifts by ~0.9 Å towards lower values, indicating partial reduction of Nb in the form of nanoparticles and the multiphase nature of the system. In the (Co–Fe)х(LiNbO $$_{{3-y}}$$ ) $$_{{100-x}}$$ sample, the environment (bonds) of Nb atoms is independent of x; the insulating matrix has in this case a structure most similar to LiNbO3. Meanwhile, in the (Co–Fe–B)х(LiNbO $$_{{3-y}}$$ ) $$_{{100-x}}$$ sample, consistent changes in the XANES spectra have been observed with increasing х, which indicates a significant local restructuring in the sample. The structural features of the samples have been explained by the catalytic effect of the metallic phase of the nanocomposite on the formation of the insulating matrix during its growth.