Plasma augmented structural and electrical properties of half doped neodymium strontium manganites

The reduction in resistivity and modification of the thermoelectric power of perovskite oxides is in continuous demand because of its large scale industrial applications. Currently, electron or ion beam irradiations are the most preferred methods employed to improve its properties. The quantum of improvement achieved with these methods is appreciable, however, it involves intriguing technicalities in the production of the beams. Plasma is a natural medium with the presence of both electrons and ions that can be easily produced using the glow discharge technique. In this work, the effect of oxygen plasma exposure on the structural properties, electrical resistivity, and thermopower of Nd_0.5Sr_0.5MnO₃ manganites is investigated. Powdered Nd_0.5Sr_0.5MnO₃ manganites samples are prepared using the solid-state reaction method. It is found that plasma exposure has changed the lattice parameters thereby varying the cell volume, which are not normally seen in the case of electron beam exposure. Further, the electrical resistivity is observed to decrease significantly after plasma exposure that changed the transport properties. It is also observed that plasma exposure decreases the absolute value of thermopower at low temperatures but increases it at high temperatures. (paper)