In this study, crednerite CuMnO 2 nanostructures were prepared using a hydrothermal method at 100 °C with various amounts of NaOH mineralizator. Obtained nanostructured crednerite CuMnO 2 with monoclinic structure (space group C 2/ m ) exhibits two morphologies: nanobelts with lengths of 1–1.5 nm and thickness of 15–25 nm, and nanoplates with diameters of 50–70 nm. Comparative analyses of the prepared samples reveal a close relationship between morphological and physical properties of nanostructured CuMnO 2 . A low NaOH concentration promotes elongated crystal growth along the c-axis, resulting in nanobelt-shaped morphology. A strong base solution, on the other hand, promotes the formation of nanoplates. The different morphologies of nanostructured CuMnO 2 have different spectroscopic and magnetic properties. The Raman active A 1g mode at 637 cm −1 and a modified Curie-Weiss behavior characterize the nanobelt-shaped sample. This phase has two magnetic phase transitions: ferromagnetic at 9.2 K and antiferromagnetic at 42 K. The nanoplate-shaped sample, on the other hand, exhibits typical behavior as reported in the literature, namely the Raman active A 1g mode at 688 cm −1 and low-dimensional magnetism with antiferromagnetic ordering below 62 K. The variation in magnetic properties is presumably due to partial oxidation of Cu 1+ /Cu 2+ and Mn 3+ /Mn 4+ , as well as a change in Mn 3+ spin states from low-spin in nanobelt-shaped samples to high-spin in nanoplate-shaped samples. Both morphological and preferred crystal growth of nanostructured CuMnO2 can be tuned utilizing suitable amounts of NaOH mineralizator in the growth solution. A pure CuMnO2 phase of monoclinic structure has been prepared in the form of nanobelts with lengths up to 1.5 mm or nanoplates possessing 50–70 nm in diameter. The physical properties measurements imply distinct behaviour amongst these samples.The CuMnO2 nano-belts exhibit a Raman peak at a lower Raman number compared to that of the nanoplates. The nanobelt sample has been shown to be undergone two successive magnetic phase transitions: antiferromagnetically at 42 K and ferromagnetically at 9.2 K. The nanoplate samples have exhibited low-dimensional magnetic behaviour. The variation in the magnetic properties can be ascribed to the partial oxidation of Cu1+/Cu2+ and Mn3+/Mn4+. The variation of spin states of the Mn ions can be correlated with the change in the morphologies, i.e., from a low-spin state in the belt-shaped sample to a high-spin state in the plate-shaped samples. • Both morphological and preferred crystal growth of nanostructured CuMnO2 and then their physical properties can be tuned utilizing suitable amounts of NaOH mineralizator in the growth solution. Remarkably, a nanobelt CuMnO2 has been obtained for the first time. • Our experiments divulge that a pure CuMnO2 phase of monoclinic structure can been prepared in the form of nano-belts with lengths up to 1.5 mm or nanoplates possessing 50–70 nm in diameter. • The physical properties measurements imply distinct behaviour amongst these samples. The CuMnO2 nano-belts exhibits Raman peak at a lower Raman number compared to that of the nanoplates. • Regarding to the magnetic characteristics, the nanobelt samples have shown to be undergone into two successive magnetic phase transitions: antiferromagnetically at 42 K and ferromagnetically at 9.2 K. • The variation in the magnetic properties can be ascribed to the partial oxidation of Cu 1+ /Cu2+ and Mn 3+ /Mn4+. Remarkably, the variation of spin states of the Mn ions can be correlated with the change in the morphologies, i.e., from low-spin state in the belt-shaped sample to high-spin state in the plate-shaped samples.
Read full abstract
Jan 1, 2023
Е.В Еремин + 3
Open Access
