10 research outputs found
Enhanced RCP and large inverse magnetocaloric effect of CoFeO nanoparticles synthesized by auto-combustion method
This work focuses on the microstructure, magnetic properties and
magnetocaloric effect of CoFeO (CFO) nanoparticles elaborated by
sol-gel auto combustion method. The XRD investigation indicates that CFO is
crystallized in a cubic spinel structure and the SEM micrograph shows a fine
quasi-spherical with an average grain sizes of 160 nm. The temperature
dependence of the Raman spectra reveals the ferromagnetic to paramagnetic
(FM-PM) transition started from 723 K and the magnetization versus temperature
measurements shows the Curie temperature located at T = 785 K. Large
value of magnetocaloric temperature change of T =11.2 K with a high RCP
of 687.56 J Kg are achieved indirectly via the Maxwell approach making
our CFO nanopowder suitable candidate for both environmentally friendly
magnetic refrigeration and medical applications at ambient temperature
Room-temperature magnetoelectric effect in lead-free multiferroic BaCaTiSnO-CoFeO particulate composites
Multiferroic particulate composites
BaCaTiSnO-CoFeO with (
= 0.1, 0.2, 0.3, 0.4 and 0.5) have been prepared by mechanical mixing of the
calcined and milled individual ferroic phases. X-ray diffraction and Raman
spectroscopy analysis confirmed the formation of both perovskite
BaCaTiSnO (BCTSn) and spinel
CoFeO (CFO) phases without the presence of additional phases. The
morphological properties of the composites were provided by using Field
Emission Scanning Electron Microscopy. The BCTSn-CFO composites exhibit
multiferroic behavior at room temperature, as evidenced by ferroelectric and
ferromagnetic hysteresis loops. The magnetoelectric (ME) coupling was measured
under a magnetic field up to 10 kOe and the maximum ME response found to be 0.1
mV /cm/ Oe for the composition 0.7 BCTSn-0.3 CFO exhibiting a high degree of
pseudo-cubicity and large density
Electrocaloric effect and high energy storage efficiency in lead-free BaCaTiSnO ceramic elaborated by sol-gel method
Structural, dielectric, ferroelectric, energy storage properties, and
electrocaloric effect were studied in lead-free ceramic
BaCaTiSnO (BCTSn) elaborated by sol-gel
method. Phase purity structure was confirmed from X-ray data using Rietveld
refinement analysis which revealed the coexistence of tetragonal (P4mm) and
orthorhombic (Amm2) symmetries at room temperature. Phase transitions were
detected by dielectric and differential scanning calorimetry results. Energy
storage properties were determined from P-E hysteresis, and the electrocaloric
properties were calculated indirectly via the Maxwell approach. The large value
of electrocaloric temperature change of T=0.807 K obtained at a
relatively small field of 30 kV cm and high energy storage efficiency
can make BCTSn ceramic a promising candidate for environmentally friendly
refrigeration and energy storage applications
Magnetoelectric coupling in multiferroic CFO/BCTSn core shell nanofibers elaborated by co-axial electrospinning method
Multiferroic CoFe2O4-Ba0.95Ca0.05Ti0.89Sn0.11O3 core-shell nanofibers
(CFO@BCTSn NFs) were synthesized by a sol-gel co-axial electrospinning
technique. The scanning electron microscope and transmission electron
microscope were used to check nanofibers' core-shell structure/configuration.
X-ray diffraction and a high-resolution transmission electron microscope were
used to confirm the spinel structure of CFO and the perovskite structure of
BCTSn. The magnetic character of the resultant CFO@BCTSn NFs was determined by
SQUID magnetometry. The piezoelectricity was verified using piezo-response
force microscopy, which revealed an entirely covered ferroelectric shell
outline, in accordance with SEM and TEM observations. The magnetoelectric (ME)
coefficient was measured as a function of the applied external DC magnetic
field. The maximum ME coefficient obtained for the CFO@BCTSn NFs was 346 mV
cm-1 Oe-1. The high magnetoelectric coupling suggests that CFO@BCTSn NFs could
be a promising candidate for magnetic field sensor and magnetoelectric device
applications
Enhanced near-ambient temperature energy storage and electrocaloric effect in the lead-free BaTi0.89Sn0.11O3 ceramic synthesized by sol–gel method
International audienceLead-free perovskite materials with high performance have high potential in clean energy storage applications and developments of electrocaloric devices. In this work, we report structural, dielectric, ferroelectric properties, energy storage and electrocaloric effectnear the ambient temperature in barium stannate titanate (BaTi 0.89 Sn 0.11 O 3, BTS 11) ceramic prepared by a sol-gel method. The formation of a single perovskite structure was confirmed using the X-ray diffraction analysis. An average grain size of 18.5µm was found by the mean of the SEM micrograph with a density of 5.91 g/cm 3 .The presence of the multiphase at very near ambient temperature was proved using temperature-dependent micro-Raman measurements and differential scanning calorimetry. The BTS 11 ceramic exhibits a high dielectric constant of 15460and a low dielectric loss (<0.055) with considerable temperature stability. Moreover, a high energy storage density of 122mJ/cm 3 was showed with an efficiency of 79%, and a maximum value of ECE (ΔT) of 0.86 K and finally, an electrocaloric responsivity (ΔT/ΔE) of 0.24 K.mm/kV under the external electricfield of 35 kV/cm near ambient temperature. The enhanced dielectric, ferroelectric and electrocaloric properties in BTS 11 ceramic makes it a great potential candidate for its uses in solid-state cooling technology and high-energy storage applications near ambient temperature
Room-temperature magnetoelectric effect in lead-free multiferroic (1−x) Ba0.95Ca0.05Ti0.89Sn0.11O3-(x)CoFe2O4 particulate composites
Multiferroic particulate composites (1−x) Ba0.95Ca0.05Ti0.89Sn0.11O3-(x)CoFe2O4 with (x = 0.1, 0.2, 0.3, 0.4 and 0.5) have been prepared by mechanical mixing of the calcined and milled individual ferroic phases. X-ray diffraction and Raman spectroscopy analysis confirmed the formation of both perovskite Ba0.95Ca0.05Ti0.89Sn0.11O3 (BCTSn) and spinel CoFe2O4 (CFO) phases without the presence of additional phases. The morphological properties of the composites were provided by using Field Emission Scanning Electron Microscopy. The BCTSn-CFO composites exhibit multiferroic behavior at room temperature, as evidenced by ferroelectric and ferromagnetic hysteresis loops. The magnetoelectric (ME) coupling was measured under a magnetic field up to 10 kOe and the maximum ME response found to be 0.1 mV /cm/ Oe for the composition 0.7 BCTSn-0.3 CFO exhibiting a high degree of pseudo-cubicity and large density
Piezoelectric, magnetic and magnetoelectric properties of a new lead-free multiferroic (1-x) Ba0.95Ca0.05Ti0.89Sn0.11O3—(x) CoFe2O4 particulate composites
International audienceNew multiferroic particulate composites (1-x) Ba0.95Ca0.05Ti0.89Sn0.11O3-(x) CoFe2O4 with (x = 0.1, 0.2, 0.3, 0.4 and 0.5) have been prepared by mechanical mixing of the calcined and milled individual ferroic phases. X-ray diffraction and Raman spectroscopy analysis confirmed the formation of both perovskite Ba0.95Ca0.05Ti0.89Sn0.11O3 (BCTSn) and spinel CoFe2O4 (CFO) phases without the presence of additional phases. The morphological properties of the composites were provided by using field emission scanning electron microscopy. The BCTSn-CFO composites exhibit multiferroic behavior at room temperature, as evidenced by ferroelectric and ferromagnetic hysteresis loops. For all composites, the converse piezoelectric coefficient was calculated and found to decrease from 203 pm.V-1 to 27 pm.V-1 in pure BCTSn. when the CFO content increases. The magnetoelectric (ME) coupling was measured under a magnetic field up to 10 kOe and the maximum ME response found to be 0.1 mV.cm(-1).Oe(-1) for the composition 0.7 BCTSn-0.3 CFO exhibiting a high degree of pseudo-cubicity and large density
Chemical Synthesis of Organo-siloxene 2D Materials from Calcium Di-Silicide: Characterization, Dielectric and Electrochemical Studies
International audienc
Electrocaloric effect and high energy storage efficiency in lead-free Ba0.95Ca0.05Ti0.89Sn0.11O3 ceramic elaborated by sol-gel method
International audienceStructural, dielectric, ferroelectric, energy storage properties, and electrocaloric effect were studied in lead-free ceramic Ba0.95Ca0.05Ti0.89Sn0.11O3 (BCTSn) elaborated by the sol-gel method. Phase purity structure was confirmed from X-ray data using the Rietveld refinement analysis which revealed the coexistence of tetragonal (P4mm) and orthorhombic (Amm2) symmetries at room temperature. Phase transitions were detected by dielectric and differential scanning calorimetry measurements. The energy storage properties were determined from P-E hysteresis, and the electrocaloric properties were calculated indirectly via the Maxwell approach. The large value of electrocaloric temperature change of Delta T = 0.807 K obtained at a relatively small electric field of 30 kV cm(-1), and the high energy storage efficiency can make BCTSn ceramic a promising candidate for environmentally friendly refrigeration and energy storage applications
Impact of Polymeric precursor and Auto-combustion on the Structural, Microstructural, Magnetic, and Magnetocaloric Properties of La0.8Sr0.2MnO3
International audienceIn this work, La0.8Sr0.2MnO3 (LSMO) nanopowders are synthesized using two different methods: Pechini (LSMO-PC) and auto-combustion (LSMO-AC). Nanoparticle sizes, structural, magnetic, and magnetocaloric properties were determined and compared. The X-ray diffraction confirms the coexistence of two phases; rhombohedral symmetry with space group R-3c and orthorhombic symmetry with space group Pbnm, with the rhombohedral phase dominating. The scanning electron microscope images show that LSMO-PC has larger nanoparticle sizes (∼ 495 nm) than LSMO-AC (∼195 nm). The samples exhibit ferromagnetic properties with distinct hysteresis loops and Curie temperatures 340 K and 290 K for LSMO-PC and LSMO-AC respectively. The variation of the magnetic entropy was measured indirectly using the Maxwell approach with increasing magnetic field. For LSMO-PC it reaches a maximum -ΔSM=1.69 J/kg.K at 340 K and ΔH= 5 T. The associated adiabatic temperature change ΔTM is 1.04 K. While LSMO-PC demonstrates superior magnetic and magnetocaloric properties, LSMO-AC displays significant magnetocaloric thermal stability. The obtained values make LSMO-PC and LSMO-AC promising candidates for eco-friendly room-temperature magnetocaloric applications