Variational Analysis of Nanoproperties

Cobalt Zinc Ferrite is an accessible magnetic material that, when doped with a rare earth element, becomes an attractive candidate for magneto caloric applications. One application that is deemed attractive is a magneto-caloric pump for refrigeration systems. The fact that this pump would not require mechanical parts would imply a reduction in maintenance costs. In this work a statistical experimental design was used to study the effect of the contents of Gadolinium (Gd) and Sodium Hydroxide (NaOH) on different physical properties of Cobalt-Zinc Ferrite nanoparticles. In particular, the objectives were a low demagnetization temperature, a high magnetization level, a low coercivity value and a high pyromagnetic coefficient. The experimental results indicated that only coercivity could be manipulated with the variation of NaOH and Gd, which in turn meant that this property could be minimized without statistically affecting the rest of the properties.

 Along with the results of the previously mentioned experiment, the analyses of a series of presumed scenarios involving conflict between the different objectives are presented here. A conflict between objectives would imply, for example, that varying Gd in a certain direction would decrease coercivity (a desired effect) but at the same time it would increase the demagnetization temperature (an undesired effect). Considering multiple objectives in conflict entails a special type of optimization procedure called Multiple Criteria Optimization. Having the capability to deal with this kind of situations will enhance the decision-making associated to future experiments that involve tailoring multiple nanoproperties already planned within our research group.