2 research outputs found
Pressure Effect Studies on the Spin Transition of Microporous 3D Polymer [Fe(pz)Pt(CN)<sub>4</sub>]
Pressure effects
on the spin transition of the three-dimensional (3D) porous coordination
polymer {Fe(pz)[Pt(CN)<sub>4</sub>]} have been investigated in the
interval 10<sup>5</sup> Pa–1.0 GPa through variable-temperature
(10–320 K) magnetic susceptibility measurements and spectroscopic
studies in the visible region at room temperature. These studies have
disclosed a different behavior of the compound under pressure. In
the magnetic experiments, a temperature independent paramagnetic behavior
has been observed under 0.4 GPa. In contrast, at room temperature
and at 0.8 GPa, a complete HS-to-LS transition has been evidenced.
The differences in the magnetic behavior are strongly related with
the porous structure of the compound and its capability to adsorb
the oil used as pressure transmission media in the magnetic experiments
The Multifunctionality of Lanthanum–Strontium Cobaltite Nanopowder: High-Pressure Magnetic Studies and Excellent Electrocatalytic Properties for OER
Simultaneous study of magnetic and electrocatalytic properties
of cobaltites under extreme conditions expands the understanding of
physical and chemical processes proceeding in them with the possibility
of their further practical application. Therefore, La0.6Sr0.4CoO3 (LSCO) nanopowders were synthesized
at different annealing temperatures tann = 850–900 °C, and their multifunctional properties were
studied comprehensively. As tann increases,
the rhombohedral perovskite structure of the LSCO becomes more single-phase,
whereas the average particle size and dispersion grow. Co3+ and Co4+ are the major components. It has been found
that LSCO-900 shows two main Curie temperatures, TC1 and TC2, associated with
a particle size distribution. As pressure P increases,
average ⟨TC1⟩ and ⟨TC2⟩ increase from 253 and 175 K under
ambient pressure to 268 and 180 K under P = 0.8 GPa,
respectively. The increment of ⟨dTC/dP⟩ for the smaller and bigger particles
is sufficiently high and equals 10 and 13 K/GPa, respectively. The
magnetocaloric effect in the LSCO-900 nanopowder demonstrates an extremely
wide peak δTfwhm > 50 K that
can
be used as one of the composite components, expanding its working
temperature window. Moreover, all LSCO samples showed excellent electrocatalytic
performance for the oxygen evolution reaction (OER) process (overpotentials
of only 265–285 mV at a current density of 10 mA cm–2) with minimal η10 for LSCO-900. Based on the experimental
data, it was concluded that the formation of a dense amorphous layer
on the surface of the particles ensures high stability as a catalyst
(at least 24 h) during electrolysis in 1 M KOH electrolyte