Influence of temperature and oxygen pressure on the stability of barium or strontium doped neodymium manganites

Abstract

In this work neodymium manganites, Nd1-xAxMnO3±δ, doped with Ba or Sr (where x = 0.15 and 0.25) were obtained by ceramic technology at 1250 °C. In order to obtain materials with stable thermal and electrical properties, their structure and physicochemical properties were studied depending on the dopant type and its concentration. It was established that the manganites doped with strontium (for x = 0.15 and 0.25) and barium (for x = 0.15) have the Jahn-Teller distortion of the structure, but it was not observed for the sample Nd0.75A0.25MnO3±δ. The sequence of phase transformations was studied under conditions of reduced oxygen pressure in gaseous phase using thermal analysis in combination with XRD. The influence of temperature and oxygen pressure on the stability limit of the manganites was investigated. The studied manganites remain stable in the range of partial oxygen pressures PO2 from 0.21 to 10−14 atm at 800 °C. An increasing in the dopant concentration leads to the increase of manganite electrical conductivity without decreasing the thermal stability limit. © 2020 University of Novi Sad, Faculty of Technology. All rights reserved.