Effect of different heat treatment annealing and substitution of lanthanum (La) with yttrium (Y) In La(Fe,Si)13 compounds

The cubic NaZn₁₃-type LaFe₁₃-xSix based compounds have been studied systematically and have become one of the most interesting systems for exploring large magnetocaloric effects, MCE. Its magnetic properties are strongly doping dependent and provides many advantages compared to other as magnetic materials for magnetic refrigerator application. For the sample preparation, the study of ball milling treatment and properties in La(FeSi)₁₃ compound from raw materials of Lanthanum (La), Iron(Fe) and Silicon (Si) as refrigerant for magnetic refrigeration system have been conducted intensively. The compounds underwent the pellet press process. For the structural properties investigation, LaFe₁₁.₅Si₁.₅ compounds were annealed at two different heat treatment which are 1323 K for 14 days and 1523 K for 4 hour. The powder Xray diffraction shows that high temperature annealing increase the main structure and decrease the impurity (α-Fe and LaFeSi). Rietveld refinement results indicate that the lattice parameter has increased at the high temperature annealing because of more cubic NaZn13 is formed at higher temperature. In an effort to explore the effect of La substitution by Y in NaZn₁₃-type La₁₋ₓYₓFe₁₁.₅Si₁.₅ (x=0, 0.05, 0.1, 0.3) compound, the structural and magnetic properties of the heat treatment have been studied systematically. The permittivity measurements found that, for La₁₋ₓYₓFe₁₁.₅Si₁.₅ at Y=0.05, it shows high value of resistivity while at Y= 0.3 it has the lowest value of tan delta. On mechanical perspective,iii the highest storage modulus and static stress are at Y=0.3 which are 3.8x Pa and 2.72x N/ respectively.