Perovskite related Ruddlesden-Popper Phases

On the present update of the MALT database, the representation of chemical formula for the Ruddelsen-Popper phases, A3B2O7 and A4B3O10, are changed into A1.5BO3.5 and AB0.75O2.25.

1. Main reasons
   
   • This is to keep the same level of the mixing entropy values among Ruddlesden-Popper phases compared with the perovskite phases.
     
   • Consider the mixture of La4Fe3O10 and Sr4Fe3O10 such as (La4Fe3O10)x +(Sr4Fe3O10)y, where x and y is the molar composition in the solid solution.
     The mixing entropy of this particular solution is given as follows;
     Smix/R = ln x + ln y;
   • On the other hand, the entropy given for the new representation scheme 4{(LaFe0.75O2.25)x +(SrFe0.75O2.25)y} can be written as
     
     Smix/R = 4*(ln x + ln y);
     
   • This clearly shows that when a large chemical formula is considered on the formation of ideal solution, the mixing entropy exhibits extremely lower than that given for a small chemical formula.
     
   • Thus, for the Ruddlesden-Popper phase, the chemical formula given by use of the stoichimetric number close to unity.
   
   
2. Target Compounds
   
   1. ABO3 or ABO2.5 dopants in Perovskites
      CaMnO2.5
      CaCrO2.5,       CaCrO3
      CaYO2.5
      SrCoO2,     SrCoO2.5,     SrCoO3
      SrFeO2.5,     SrFeO3
      SrMnO2.5,     SrMnO3
      SrCrO2.5,     SrCrO3
      Sr0.5ZrO2.5
      SrYO2.5
      SrGdO2.5
      La0.667MnO2.5,     La0.667MnO3,     LaMn0.75O3,     LaMnO2.5,     LaMnO3
      La0.667TiO3,     LaTiO3
      La0.667ZrO3
      
      
      
   2. RP214: A2BO4 or A2BO3.5
      La2MnO4.15,     La2MnO4
      Sr2CoO3.5,     Sr2CoO4
      Sr2FeO3.5,     Sr2FeO4
      SmSrCoO4
      LaSrCoO4
      LaSrFeO4
      LaSrMnO4
      
      
      
   3. RP327: A3B2O7 or A3B2O6
      Nd1.5NiO3.5 should be Nd3Ni2O7 c
      Pr1.5NiO3.5 should be Pr3Ni2O7 c
      Ce1.5NiO3.5 should be Ce3Ni2O7 c
      La1.5NiO3.5 should be La3Ni2O7 c
      La1.5CoO3.5 should be La3Co2O7 c
      La1.5FeO3.5 should be La3Fe2O7 c
      La1.5MnO3.5 should be La3Mn2O7 c
      Ca1.5TiO3.5 should be Ca3Ti2O7 c
      Sr1.5FeO3 should be Sr3Fe2O6 c
      Sr1.5FeO3.5 should be Sr3Fe2O7 c
      Sr1.5MnO3.5 should be Sr3Mn2O7 c
      Sr1.5TiO3.5 should be Sr3Ti2O7 c
      Sr1.5ZrO3.5 should be Sr3Zr2O7 c
      LaSr0.5FeO3.5 should be La2SrFe2O7 c
      La0.5SrFeO3.5 should be LaSr2FeO7 c
      LaSr0.5MnO3.5 should be La2SrMn2O7 c
      La0.5SrMnO3.5 should be LaSr2MnO7 c
      
      
      
   4. RP4310: A4B3O10
      
      NdNi0.75O2.5 should be Nd4Ni3O10 c
      NdCo0.75O2.5 should be Nd4Co3O10 c
      PrNi0.75O2.5 should be Pr4Ni3O10 c
      PrCo0.75O2.5 should be Pr4Co3O10 c
      CeNi0.75O2.5 should be Ce4Ni3O10 c
      LaNi0.75O2.5 should be La4Ni3O10 c
      LaCo0.75O2.5 should be La4Co3O10 c
      LaFe0.75O2.5 should be La4Fe3O10 c
      CaTi0.5O2.5 should be Ca4Ti3O10 c
      SrFe0.75O2.5 should be Sr4Fe3O10 c
      SrTi0.75O2.5 should be Sr4Ti3O10 c
      SrZr0.75O2.5 should be Sr4Zr3O10 c
      La0.25Sr0.75Fe0.75O2.5 should be LaSr3Fe3O10 c
      
   
   
3. How to make data format conversion for those compounds?
   
   1. A-site mixing
      
      
      
      
      Fig. 1 Data File Form to convert the data format to create the ideal solution consisting of LaFe0.75O2.25 and SrFe0.75O2.25.
      
      
      
      
   2. Oxygen Nonstoichiometry
      
      
      
      
      Fig. 2 Data File Form to convert the data format to create the ideal solution consisting of SrCoO3, SrCoO2.5 and SrCoO2.
      
      
      
      

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