Strontium Manganese Dioxide
Strontium Manganese Oxide
Introduction
The ternary inter oxide SrMnO3 was first characterized by XRD by Negas and Roth []. This perovskite type inter oxide crystallizes in the hexagonal form with the space group P63/mmC(194). This inter oxide is of considerable interest to materials scientists owing to its ability to accommodate a high degree of anion vacancies, crystal structure and its high Neel Temperature (TN). It also exhibits polymorphism with two different cubic and hexagonal structures. The value of TN was reported to be 350 K by Chamberland et al [ ] corresponding to anti ferromagnetic ordering. However, Battle et al [ ] concluded TN to be 278 ± 5 K from Massbauer and neutron diffraction studies on 57Fe doped SrMnO3 which value of TN was expected to be little different from that for undoped one. The variation of electrical conductivity with oxygen stoichiometry and the correlation of high temperature stability with structure were also reported by Battle et al [ ] besides others [ , ]. The results of this synthesis and XRD characterization as well as measurement of SrO activities in this inter oxide at higher temperatures under 1 atmosphere of oxygen are also presented here. An attempt to thermodynamically characterized the product of hydrogen reduction of SrMnO3 using a 15YSZ based emf method is also described.
2.Experimental
2.1. Materials
Mn3O4 ( purity better than 99.99%,Aldrich, USA) and SrCO3 ( better than 99.9%, IDPL India) were the main starting materials. Reagent grade ethylene glycol ( better than 99.91%, Aldrich, USA), citric acid (better than 99.8%, Merck India), and nitric acid ( better than 99%, Fischer, India ) were used for the hybrid polymeric gel cum combustion route. Better than 99.99% pure SrF2 (Aldrich) and 15YSZ ( purity better than 99.8% and density greaer than 98% theoretical, Yamori, Japan) were used for the preparation of electrolyte as well as for use as an electrochemical catalyst in the electrodes.
2.2.
Introduction
The ternary inter oxide SrMnO3 was first characterized by XRD by Negas and Roth []. This perovskite type inter oxide crystallizes in the hexagonal form with the space group P63/mmC(194). This inter oxide is of considerable interest to materials scientists owing to its ability to accommodate a high degree of anion vacancies, crystal structure and its high Neel Temperature (TN). It also exhibits polymorphism with two different cubic and hexagonal structures. The value of TN was reported to be 350 K by Chamberland et al [ ] corresponding to anti ferromagnetic ordering. However, Battle et al [ ] concluded TN to be 278 ± 5 K from Massbauer and neutron diffraction studies on 57Fe doped SrMnO3 which value of TN was expected to be little different from that for undoped one. The variation of electrical conductivity with oxygen stoichiometry and the correlation of high temperature stability with structure were also reported by Battle et al [ ] besides others [ , ]. The results of this synthesis and XRD characterization as well as measurement of SrO activities in this inter oxide at higher temperatures under 1 atmosphere of oxygen are also presented here. An attempt to thermodynamically characterized the product of hydrogen reduction of SrMnO3 using a 15YSZ based emf method is also described.
2.Experimental
2.1. Materials
Mn3O4 ( purity better than 99.99%,Aldrich, USA) and SrCO3 ( better than 99.9%, IDPL India) were the main starting materials. Reagent grade ethylene glycol ( better than 99.91%, Aldrich, USA), citric acid (better than 99.8%, Merck India), and nitric acid ( better than 99%, Fischer, India ) were used for the hybrid polymeric gel cum combustion route. Better than 99.99% pure SrF2 (Aldrich) and 15YSZ ( purity better than 99.8% and density greaer than 98% theoretical, Yamori, Japan) were used for the preparation of electrolyte as well as for use as an electrochemical catalyst in the electrodes.
2.2.