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Single phase CuFeO2, CuFe0.96M0.03V0.01O2 (M = Ti, Mn, and Ga), and CuFe0.96V0.04O2 compounds with space group R 3 ¯ m were prepared through a newly developed solid-state technique using annealing under high vacuum. Raman studies demonstrate, for the first time, a minor shift in Ti and Mn-doped samples as well as the Jahn–Teller effect induced distortions around 500 cm−1 along with well-documented peaks of Eg and A1g modes. Mössbauer studies confirm the presence of iron in high spin Fe3+ and quadruple splitting values endorsing the presence of octahedron distortions. An increase in the electrical conductivity at low temperatures is observed due to the enhanced charge doping with minor variations related to local distortions. Low-temperature magnetic studies of pristine and Ti-doped samples demonstrate paramagnetic nature up to 25 K. However, on one hand, the pristine sample shows a sharp rise in magnetization values at low applied fields and on the other side, Ti-doped samples exhibit nearly linear behavior. Dielectric measurements confirm weakening of electrical ordering near the magnetic transition in distorted Ti-doped samples, compared to pure CuFeO2 sample. Level of charges along with its local distortions affected mobility has significant effects on transport and multiferroic nature of these samples. [ABSTRACT FROM AUTHOR]

Magnetic, morphological, and physical properties of Pr0.63La0.37−xSrxMnO3 (xSr = 0.00, 0.05, 0.10, 0.15, 0.20, and 0.30) magnetic nanoparticles have been studied experimentally based on the evolution of the amount of Sr in these systems and by heat treatment. A solid-state reaction method was used to prepare the samples. The microstructure of the samples was determined by scanning electron microscopy. Three sets of Sr-doped manganites of the perovskite family Pr0.63La0.37−xSrxMnO3 nanoparticles were heated at three different temperatures, i.e., 500, 700, and 800 °C. X-ray data showed that all compounds in the cubic space group Fd-3m crystallized. Field-cooled and zero-field-cooled thermomagnetic curves measured at low field and low temperatures showed that systems have different magnetic states, varying from superparamagnetic, ferromagnetic to paramagnetic states, with charge ordering behavior present in some prepared systems. The maximum entropy change of the xSr-800°C = 0.05 sample reached the highest value of refrigerant capacity compared to other systems in a magnetic field with 17.278 J/kg at 1 T and 208.264 J/kg at 7 T. [ABSTRACT FROM AUTHOR]