The surge of interest in multiferroic materials over the past 15 years has been driven by their fascinating physical properties and huge potential for technological applications such as sensors, microwave devices, energy harvesting, photovoltaic technologies, solid-state refrigeration, data storage recording technologies and multiferroic random access multi-state memories (MFRAM) [1]. Remarkable efforts have been done to develop laminated bi-layer and multilayer multiferroic composites as bulk or thin films. Such structures lead to remarkable magneto-electric coupling coefficients of a few Volts / cm∙Oe because in such configuration the ferroic layer is a “full dielectric” which can be completely polarized in the conventional way [2]. On the other hand in the particulate ceramic composites the requirement for “full dielectric” is no longer applicable, since the ferroic phases are fully separated within the composite. The strengths of particulate ceramic composites are low cost, simple production technology, higher strain mediated magneto-electric coupling (since electric order phase/magnetic phase interface density can be higher) and easy control of electrical and magnetic properties if the ferroelectric phase (generally a perovskite) and the ferromagnetic one (a ferrite with spinel structure) are mixed in a favourable proportion under the percolation threshold of the ferromagnetic phase. A great research effort is in progress to improve the fabrication of PZT–CoFe2O4 (PZT–CF) composites in order to avoid the unwanted reactions, which occur during densification of PZT–CF materials at 1100-1200 °C, and to achieve the electric saturation during the poling. Up to date, by setting a quite-fast sintering, full densification and prevention of unwanted reactions were achieved for the PZT:CF 74:26 composites [3], but the achieving of electric saturation is still a challenging. Further important achieved results were: the understanding that the main cause of reactions is the PbO loss [3]; the proposal of an equation to calculate the PbO loss through XRD analysis, considering the amount of ZrO2 and variation of perovskite's tetragonality [3]; and the ability to design the ceramic process to control the CF grain size distribution, which can be mono- or bi-modal, and overgrowth [3,4]. [1] M. M. Vopson. Crit. Rev. Solid State 4:40 (2015) 223-250 doi:10.1080/10408436.2014.992584 [2] P. Galizia, et al. J. Eur. Ceram. Soc. 36 (2016) 373-380. doi:10.1016/j.jeurceramsoc.2015.07.038 [3] P. Galizia, et al., PZT-cobalt ferrite particulate composites: Densification and lead loss controlled by quite-fast sintering. J. Eur. Ceram. Soc. (2016). doi:10.1016/j.jeurceramsoc.2016.08.025 [4] P. Galizia, et al., Multiple parallel twinning overgrowth in nanostructured dense cobalt ferrite. Mater. Design109 (2016) 19–26. doi:10.1016/j.matdes.2016.07.050

Developed and characterization of PZTN-CFO particulate ceramic composites / Galizia, Pietro; Claudio, Capiani; Carmen, Galassi. - ELETTRONICO. - (2016), pp. 194-194. (Intervento presentato al convegno Materials.it 2016 tenutosi a Aci Castello (Italia) nel December 12 - 16, 2016).

Developed and characterization of PZTN-CFO particulate ceramic composites

GALIZIA, PIETRO;
2016

Abstract

The surge of interest in multiferroic materials over the past 15 years has been driven by their fascinating physical properties and huge potential for technological applications such as sensors, microwave devices, energy harvesting, photovoltaic technologies, solid-state refrigeration, data storage recording technologies and multiferroic random access multi-state memories (MFRAM) [1]. Remarkable efforts have been done to develop laminated bi-layer and multilayer multiferroic composites as bulk or thin films. Such structures lead to remarkable magneto-electric coupling coefficients of a few Volts / cm∙Oe because in such configuration the ferroic layer is a “full dielectric” which can be completely polarized in the conventional way [2]. On the other hand in the particulate ceramic composites the requirement for “full dielectric” is no longer applicable, since the ferroic phases are fully separated within the composite. The strengths of particulate ceramic composites are low cost, simple production technology, higher strain mediated magneto-electric coupling (since electric order phase/magnetic phase interface density can be higher) and easy control of electrical and magnetic properties if the ferroelectric phase (generally a perovskite) and the ferromagnetic one (a ferrite with spinel structure) are mixed in a favourable proportion under the percolation threshold of the ferromagnetic phase. A great research effort is in progress to improve the fabrication of PZT–CoFe2O4 (PZT–CF) composites in order to avoid the unwanted reactions, which occur during densification of PZT–CF materials at 1100-1200 °C, and to achieve the electric saturation during the poling. Up to date, by setting a quite-fast sintering, full densification and prevention of unwanted reactions were achieved for the PZT:CF 74:26 composites [3], but the achieving of electric saturation is still a challenging. Further important achieved results were: the understanding that the main cause of reactions is the PbO loss [3]; the proposal of an equation to calculate the PbO loss through XRD analysis, considering the amount of ZrO2 and variation of perovskite's tetragonality [3]; and the ability to design the ceramic process to control the CF grain size distribution, which can be mono- or bi-modal, and overgrowth [3,4]. [1] M. M. Vopson. Crit. Rev. Solid State 4:40 (2015) 223-250 doi:10.1080/10408436.2014.992584 [2] P. Galizia, et al. J. Eur. Ceram. Soc. 36 (2016) 373-380. doi:10.1016/j.jeurceramsoc.2015.07.038 [3] P. Galizia, et al., PZT-cobalt ferrite particulate composites: Densification and lead loss controlled by quite-fast sintering. J. Eur. Ceram. Soc. (2016). doi:10.1016/j.jeurceramsoc.2016.08.025 [4] P. Galizia, et al., Multiple parallel twinning overgrowth in nanostructured dense cobalt ferrite. Mater. Design109 (2016) 19–26. doi:10.1016/j.matdes.2016.07.050
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/2660984
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