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The synthesis of GdFe0.5Cr0.5O3 by sol-gel method was reported, and the cooling process of the sample was studied by Mössbauer spectroscopy. The Mössbauer spectra at room temperature reflect the characteristics of GdFe0.5Cr0.5O3 with orthogonally distorted perovskite structure, indicating that its Fe3+ is a triangular or tetragonal distorted octahedron symmetric structure. With the decrease of temperature, the isomer shift and quadrupole splitting increase. The spectral transition from the doublet state at 250 K to the sextet state at 120 K reflects the magnetic phase transition in this temperature range. The observed magnetic field is a super-transferred hyperfine field (STHF) formed by the superexchange mechanism of oblique antiferromagnetic ordered Cr atoms. [ABSTRACT FROM AUTHOR]

Multiferroic nanocrystalline Bi 1 − x Sr x FeO3 (x = 0 , 0.05, 0.1) samples were synthesized using the sol–gel method and characterized by powder X-ray diffraction, Mössbauer spectroscopy and SQUID system. The small-angle X-ray diffraction analysis showed that the sample underwent phase transition from rhombohedral to pseudo-cubic structure with the enhancement of Sr content. In addition, impurity peaks gradually diminished, indicating that content of impurities of samples reduced. Furthermore, it can be determined that there is only Fe 3 + in all the samples and impurity phase that existed in the samples was Bi 2 5 FeO 4 0 by fitting Mössbauer spectra. It is further confirmed that Bi 1 − x Sr x FeO3 samples were generated by oxygen vacancy equilibrium valence state when Sr 2 + ions replaced Bi 3 + ions. The change of quadrupole splitting indicated that a low concentration of Sr 2 + ions diffused homogeneously in the sample. Magnetization measurement showed that the magnetization of the sample increased gradually with the substitution of Bi 3 + by nonequivalent Sr 2 + ions, which can be ascribed to the decrease of grain size and the increase of oxygen vacancy and specific surface in the samples. [ABSTRACT FROM AUTHOR]

Co0.1Fe0.9S2 nanoparticles were synthesized by solvothermal method and studied by Mössbauer spectroscopy in the cooling process. Magnetic phase transition can be testified by Mössbauer investigation. The spectrum recorded at room temperature consists of a simple quadrupole doublet, the values of isomer shift and quadrupole splitting of doublet increase gradually with the decrease of temperature. However, the spectrum consists of a sextet when the temperature drops further to 25 K, indicating that the sample changed from paramagnetism to ferromagnetism. The magnetic field at low temperature is probably super-transferred field from the magnetically ordered cobalt atoms through a super-exchange mechanism. [ABSTRACT FROM AUTHOR]

• Preparation and pressurization of Prussian blue analogue Cu0.64Mn0.86[Fe(CN)6]⋅nH2O. • Measurement of XRD and Mossbauer spectra of Cu0.64Mn0.86[Fe(CN)6]⋅nH2O. • The sample has a face-centered cubic structure. • As the pressure increases, the metal ion CuII/MnII transfers to the interior of FeIII. The Prussian blue analogue Cu 0.64 Mn 0.86 [Fe(CN) 6 ]⋅nH 2 O was synthesized by coprecipitation method and pressurized to 0 MPa, 1 MPa, 20 MPa, 30 MPa, 40 MPa, respectively. The effect of pressure on its properties was investigated by X-ray diffraction and Mössbauer spectroscopy. According to XRD results, the sample has a face-centered cubic (Fm-3m) structure. As the pressure increases, the lattice parameters become slightly smaller, but no new high-pressure phase is generated. The results of the Mössbauer spectrum show that as the pressure increases, the singlet of Cu 0.64 Mn 0.86 [Fe(CN) 6 ]⋅nH 2 O increases, and the doublet decreases. Its indicate that the pressure-induced charge is transferred from CuII/MnII to FeIII and forms a mixed-valence ferricyanide system. [ABSTRACT FROM AUTHOR]