Lead-free multiferroic particulate composites of Ni0.83Co 0.15Cu0.02Fe1.9O4-δ-Na 0.5Bi0.5TiO3 (NCCF-NBT) ceramics are synthesized by spark plasma sintering in conjunction with high-energy ball milling. The exhibition of ferromagnetic and ferroelectric characteristics demonstrates that these materials are multiferroic in nature. Magnetic measurements indicate that the composites exhibit an excellent combination of saturation magnetization and coercivity at room temperature. In addition, they have a large magnetoelectric voltage sensitivity, which is up to 663 mV cm -1 Oe-1 under a magnetic field of 5 kOe for the 0.5NCCF-0.5NBT composite. © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Budaraju Srinivasa Murty

Department of Metallurgical and Materials Engineering

Ball milling

Ferromagnetic materials

Nickel

Sodium

Spark plasma sintering

FERROELECTRIC CHARACTERISTICS

HIGH-ENERGY BALL MILLING

Magnetoelectric properties

MAGNETOELECTRIC VOLTAGE

MAGNETOSTRICTIVE MATERIAL

multiferroics

PARTICULATE COMPOSITES

Room temperature

Ferroelectric materials

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IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

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IIT Madras

Scripta Materialia

Ba0.8Pb0.2TiO3 nanocrystalline ferroelectric ceramics were prepared by high-energy ball mill followed by spark plasma sintering and conventional sintering techniques. Sintering behavior, microstructure, dielectric properties, and ferroelectric properties were investigated by XRD, SEM, dielectric spectrometer, and ferroelectric P-E loop tracer. It was found that the densification process was greatly enhanced during SPS. The sintering temperature was 673 K (400 °C) lower and the microstructure was much finer than that of conventionally sintered ceramics, and dense compacts with a higher density of over 99 pct were obtained. The average grain size in the conventionally sintered samples is up to about 200 nm, while that in the spark plasma sintered prepared sample is only about 100 nm. The room temperature and transition temperature dielectric constant of spark plasma-sintered samples is higher than that of the conventionally sintered sample. There is a noticeable difference in processing time between conventional sintering and spark plasma sintering, and the latter offers potential advantage in time saving also. © 2016, The Minerals, Metals & Materials Society and ASM International.

Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science

Conventional and Spark Plasma Sintered Ba0.8Pb0.2TiO3 Nano Ceramics: Structural, Dielectric, and Ferroelectric Properties

Multiferroic composites of x Ni0.5Zn0.5Fe1.9O4-δ-(1-x) Na0.5Bi0.5TiO3 (x NZF-(1-x) NBT, where x=0.05, 0.15 and 0.25 mol fraction) were synthesized by spark plasma sintering (SPS) in conjunction with high-energy ball milling. The presence of NZF and NBT phases in the composites was confirmed by X-ray diffraction. The dielectric constant was studied as a function of frequency (0.5 kHz to 1 MHz) and temperature (30-500 °C). It was found that the 0.25 NZF-0.75 NBT composite possessed the most promising dielectric properties with its dielectric constant being 5-10 times higher than those for the other two composites in the full range of frequency. The magnetic and ferroelectric properties were examined at room temperature and all composite samples exhibited both pronounced ferromagnetic and ferroelectric characteristics. A maximum ME voltage coefficient of ∼870 μV/cm Oe was obtained at the magnetic field of ∼1.25 kOe for the 0.25 NZF-0.75 NBT composite, which was well comparable with the ME output for the lead-containing NZF-PZT composites. © 2015 Elsevier Ltd and Techna Group S.r.l.

Ceramics International

Multiferroic properties of lead-free Ni0.5Zn0.5Fe1.9O4-δ-Na0.5Bi0.5TiO3 composites synthesized by spark plasma sintering

Lead-free multiferroic ceramic composites of x Ni0.93Co0.02Mn0.05Fe1.95O4-(1-x) Na0.5Bi0.5TiO3 (x NCMF-(1-x) NBT, where x=0.1, 0.2, 0.3, 0.4 and 0.5 mol fraction) were synthesized by spark plasma sintering (SPS) in conjunction with high-energy ball milling. The phases, dielectric, piezoelectric, ferroelectric, magnetic and magnetoelectric properties of the composites were analyzed. The composites were composed of a mixture of spinel and perovskite phases. All the composite samples exhibited both apparent ferroelectric and ferromagnetic characteristics as well as considerable magnetoelectric (ME) effects. The maximum value of the ME voltage coefficient of the composites was quite high, being up to ~670 mV cm-1 Oe-1 for the 0.5 NCMF-0.5 NBT composite. Overall, the synthesized composites were promising in terms of electrical, magnetic and magnetoelectric properties, indicating that the SPS is a promising method of fabricating ME composite materials. © 2015 Elsevier B.V.All rights reserved.

Journal of Magnetism and Magnetic Materials

Magnetoelectric properties of lead-free Ni0.93Co0.02Mn0.05Fe1.95O4-Na0.5Bi0.5TiO3 multiferroic composites synthesized by spark plasma sintering

A combination of mechanical alloying and spark plasma sintering (SPS) was used to process Ba0.9Sr0.1TiO3 (abbreviated as BST) with a high-density and homogeneous microstructure, at a temperature 300°C to 400°C lower than that used in conventional sintering. The SPS technique was employed to prepare dense Ba0.9Sr0.1TiO3 nano-ceramics at different temperatures ranging from 800°C to 1000°C within a very short time. The SPS samples were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, electrical, ferroelectric and piezoelectric property measurements. The dielectric constant both at room temperature and Curie temperature increased with increasing SPS temperature. The coercive field increased continuously with rising SPS temperature, but the spontaneous polarization increased gradually up to 900°C and then decreased considerably with further increases in SPS temperature. In addition, the prepared nano-ceramic exhibited excellent piezoelectric properties. © 2015, The Minerals, Metals & Materials Society.

Journal of Electronic Materials

Spark Plasma Sintering Temperature Effect on Structural, Dielectric and Ferroelectric Properties of Ba0.9Sr0.1TiO3 Nanocrystalline Ceramics

Nanosized Ba0.8Pb0.2TiO3 powders obtained by high energy ball milling were compacted and sintered into nanocrystalline ferroelectric ceramics using spark plasma sintering (SPS). The prepared ceramic samples were characterized by field emission scanning electron microscopy, X-ray diffraction, and electrical property measurements. All the samples show a density over 97% of the theoretical value and an average grain size of ∼60-200 nm depending on the ball milling time. The dielectric data exhibit a ferroelectric-paraelectric phase transition and a maximum relative permittivity of 19,000 at 225 C and 100 kHz at the average grain size of ∼60 nm. The values of the dielectric constants both at room temperature and at the phase transition temperature increase considerably as the average grain size decreases. The remanent polarization and coercive field strength decrease slightly as the average grain size decreases but remain at an acceptable level for ferroelectric applications. © 2013 Elsevier Ltd and Techna Group S.r.l.

Effect of grain size on the electrical properties of high dense BPT nanocrystalline ferroelectric ceramics

The barium lead titanate (Ba0.8Pb0.2TiO3, termed BPT) ferroelectric ceramics were prepared using microwave sintering and spark plasma sintering (SPS) techniques. The formation of single phase was confirmed by X-ray diffraction. The SPS-prepared BPT ceramics exhibited higher density and smaller grain sizes as compared with the microwave-sintered ones. Dielectric and ferroelectric properties were compared between the two-technique-prepared ceramics. It was found that the dielectric constant at room temperature was ∼500 higher for the SPS-prepared sample than for the microwave-sintered one, and ∼6000 higher at Curie transition temperature. The remnant and spontaneous polarization values were ∼2 times larger for the SPS-prepared sample as compared with the microwave-sintered one. On the whole, the promising SPS technique possessed distinguished characteristics of energy-saving, rapid processing and uniform temperature distribution throughout the sample. © 2013 Elsevier B.V. All rights reserved.

Materials Chemistry and Physics

A comparative study of structural and electrical properties of Ba 0.8Pb0.2TiO3 nanocrystalline ceramics prepared by microwave and spark plasma sintering

Multiferroic particulate composites of Ni0.83Co0.15Cu0.02Fe1.9O4-δ - NCCF and lead zirconate titanate (PZT) were prepared conventional ceramic method. The generic formulae x NCCF + (1-x) PZT where x = 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 mole fractions. The presence of two phases in multiferroic was confirmed with XRD technique. The dielectric constant and loss tangent were studied as a function of frequency (100 Hz to 1 M Hz) and temperature (30-500 °C). The piezoelectric coefficient d33 were also studied on these particulate composites. The hysteresis behaviour was studied to understand the magnetic properties such as saturation magnetization (Ms) and magnetic moment (μB). The static magnetoelectric (ME) voltage coefficient was measured as a function of dc magnetic bias field. A high value of ME output (3151 mV/Oe.cm) was obtained in the composite containing 50% highly magnetostrictive ferrite component NCCF - 50% highly piezoelectric ferroelectric component PZT. These multiferroic particulate composites are used as phase shifters, magnetic sensors, cables etc. © 2009 Elsevier B.V. All rights reserved.

Current Applied Physics

Enhanced mangnetoelectric voltage in multiferroic particulate Ni0.83Co0.15Cu0.02Fe1.9O4- δ/PbZr0.52Ti0.48O3 composites - dielectric, piezoelectric and magnetic properties

Journal	Data powered by TypesetScripta Materialia
Publisher	Data powered by TypesetElsevier Ltd
ISSN	13596462
Open Access	No