The magnetic and neutron diffraction studies of La1−xSrxMnO3 nanoparticles prepared via molten salt synthesis

•Series of La1−xSrxMnO3 nanoparticles was prepared by novel method in NaNO2 melt.•Lower magnetization and Curie temperature in comparison to sol–gel nanoparticles was observed.•Overdoping of outer shell was indicated by neutron diffraction and cerimetric titration.•Overdoping shifts La0.37Sr0.63MnO3 ground state to a mixture of FM and A-type AFM ordering.

Series of single-phase La1−xSrxMnO3 nanoparticles (x=0.25−0.47) with the size of about 50 nm was prepared in molten NaNO2. TEM evidenced well dispersed particles that are not interconnected by sintering bridges in contrast to traditional products. Interestingly, some reduction of the perovskite cell volume, particularly at higher Sr-contents, was detected by XRD. Moreover, reduced magnetization and decreased Curie temperature in comparison to sol–gel samples were observed. Neutron diffraction analysis of the as-prepared nanoparticles and several comparative samples with x=0.37 indicated that the anomalous behavior of studied particles probably originate in the overdoped outer shell. The overdoping might result from both the surface oxygen chemisorption and from an increased Sr concentration in the shell. By all means, the overdoping would lead to compressive surface stress, driving the x=0.37 ground state toward a mixture of FM and A-type AFM ordering as observed by neutron diffraction.

Graphical abstractLa1−xSrxMnO3 nanoparticles with the size of about 50 nm were prepared by newly established method in molten NaNO2. TEM proved the formation of well-separated particles without sintering bridges, the major advantage over traditional preparation methods.Figure optionsDownload full-size imageDownload as PowerPoint slide