Modified glycine nitrate procedure synthesis and properties of nanostructured Ca1-xGdxMnO3 (x=0.05; 0.1; 0.15; 0.2)

Abstract

Nanocrystalline manganites Ca1-xGdxMnO3(x=0.05, 0.1, 0.15, 0.2) were synthesized by a modified glycine-nitrate procedure. The subsequent studies were focused on the structural, microstructural and magnetic changes of the starting materials induced by calcination and sintering. Thermal treatments of the green bodies were carried out by conventional sintering method. Phase evolution, lattice parameters, chemical composition and magnetic properties were monitored by Differential thermal analysis (DTA), X-ray diffraction (XRD),Induction coupled Plasma Atomic Emission (ICPES), Scanning electron Microscopy with Energy Dispersive Spectroscopy SEM/EDS and magnetic measurements on Superconducting Quantum Interference Device (Squid).DTA revealed phase transition at ≈918ºC.Chemical analysis has been done by ICPES and EDSwhich confirmed that nominal composition has been attained for all samples. XRD data were analysed by Rietveld refinement which showed that orthorhombic perovskite structure, S.G. Pnma (62), persisted with the change of Gd content, while unit cell parameters depended on the composition. Magnetic measurements show that electron doping by Gd3+ ions substantially changes CaMnO3 antiferromagnetic behavior. After introduction of Gd3+ ions, significant ferromagnetic component appears due to an emergence of double exchange interaction between Mn3+-Mn4+ ions. This resulted in appearance of a low temperature plateau in field cooled magnetization diagram as well as in hysteresis loop with the relatively high coercivity up to 2300 Oe.