Europium substitution into intermetallic phases grown in Ca/Zn flux

Replacement of calcium with europium in the phases Ca21Ni2Zn36 and CaNi2Zn3 was attempted to explore the possibility of substitution in metal flux reactions and potential magnetic interactions between closely spaced Eu2+ ions. Limited substitution occurs when Eu is added to the reaction of nickel in a Ca/Zn flux mixture, up to stoichiometries of Eu5.8(3)Ca15.2(3)Ni2Zn36 and Eu0.42(8)Ca0.58(8)Ni2Zn3. Structural characterization and magnetic susceptibility studies on EuxCa21-xNi2Zn36 phases indicate that the Eu and Ca ions do not form an even solid solution on their sites, but instead segregate in separate regions of the crystals. The europium-rich regions of the samples order ferromagnetically, with TC dependent on the size of the clusters. If the concentration of Eu in the flux is raised above 20 mol%, a new compound Eu1.63(1)Ca1.37(1)Ni2Zn3 (Cmcm, a=4.1150(5) A, b=16.948(2) A, c=10.302(1) A, Z=4, R1=0.0396) is produced. - Graphical abstract: Exploration of europium substitution into intermetallic compounds grown in Ca/Zn flux has yielded analogs of EuxCa21-xNi2Zn36 with unusual magnetic properties due to segregation of europium in the crystals; high concentrations of Eu in the flux trigger the growth of Eu1.63(1)Ca1.37(1)Ni2Zn3 with a new structure type.