We are proud to highlight an exciting achievement by our valued partners, the A.B. Nalbandyan Institute (NAL) and the Spanish National Research Council (CSIC), within the framework of the BEETHOVEN project.
Their recent research paper, “Thermally driven rock-salt to spinel transition in high-entropy (CoFeMnNiZn)xOy oxides: Effects on magnetic and mechanical properties”, has been successfully published in the Chemical Engineering Journal.
Authored by, Hasmik Kirakosyan, Ani Sargsyan, Yeva Grigoryan, AlexT. Sheardy, Khachatur Manukyan, Marieta Zakaryan, Harutyun Gyulasaryan, Adrian Quesada, Cecilia Granados-Miralles, Sofiya Aydinyan, Suren Kharatyan, the paper can be accessed via the following DOI: https://doi.org/10.1016/j.cej.2025.168976
Below, you will find the abstract of the publication.
Abstract:
High-entropy (CoFeMnNiZn)xOy oxides with rock-salt and spinel structures were synthesized by a one-step solution combustion synthesis method employing metal nitrates as oxidizers and glycine as fuel. Two distinct combustion regimes were established by adjusting the fuel-to-oxidizer ratio. Fuel-lean conditions favored the formation of a single-phase rock-salt (CoFeMnNiZn)O, whereas fuel-rich conditions led to the formation of spinel (CoFeMnNiZn)3O4 through the re-oxidation of reduced intermediate phases. Thermal analysis and spark plasma sintering (SPS) revealed a reversible transformation between the rock-salt and spinel structures driven by the redox environment, i.e. oxygen uptake and release processes. SPS enabled densification up to ~97 % of the theoretical density and promoted grain growth while preserving nanoscale crystallinity, which is important for structural reversibility. The structural evolution was tracked using X-ray diffraction, Raman spectroscopy, and electron microscopy. Entropy calculations confirmed the high-entropy character of both phases. The sample retaining partial spinel content showed higher hardness and magnetization, while the fully transformed counterpart exhibited higher coercivity. These insights offer a tunable platform for designing functional high-entropy oxides with broad technological relevance.