Understanding the Dependence of Nanoparticles Magnetothermal Properties on Their Size for Hyperthermia Applications: A Case Study for La-Sr Manganites.

Magnetic oxides are promising materials for alternative health diagnoses and treatments. The aim of this work is to understand the dependence of the heating power with the nanoparticle (NP) mean size, for the manganite composition LaSrMnO (LSMO)-the one with maximum critical temperature for the whole La/Sr ratio of the series. We have prepared four different samples, each one annealed at different temperatures, in order to produce different mean NP sizes, ranging from 26 nm up to 106 nm.

Anomalous acoustic phonons as the physical mechanism behind the adiabatic barocaloric effect on graphene.

A graphene sheet is able to either heat up or cool down due to a mechanical strain: this is the adiabatic barocaloric effect. In order to understand the physical mechanism behind this effect, we have explored the adiabatic temperature change of the graphene and, for this purpose, we considered two contributions to the total entropy: a lattice entropy (depending on the transversal, longitudinal and anomalous out-of-plane acoustic phonons) and a strain entropy. We found that the adiabatic barocaloric effect only depends on the strain energy and the anomalous acoustic phonons, without terms due to the transversal and longitudinal acoustic phonons.

Barocaloric effect on graphene.

We describe how mechanical strain is able to control the flow of heat on a graphene sheet, since this material can either absorb or expel heat from/to a thermal reservoir, depending on the strain energy. In a similar fashion as the magneto- and electro-caloric effects, the present case considers the fact that a mechanical strain produces a pseudo-magnetic field that, on its turn, is responsible for the barocaloric effect. This result pushes graphene to the list of multicaloric materials.

Hydrothermal synthesis, crystal structure, and magnetic properties of a new inorganic vanadium(III) phosphate with a chain structure.

A new vanadium(III) phosphate, Na3V(OH)(HPO4)(PO4), has been synthesized by using mild hydrothermal conditions under autogeneous pressure. This material represents a very rare example of sodium vanadium(III) phosphate with a chain structure. The crystal structure has been determined by refinement of powder X-ray diffraction data, starting from the atomic coordinates of an isotypic compound, Na3Al(OH)(HPO4)(PO4), which was obtained under high temperature and high pressure.