MDPI - Publisher of Open Access Journals

11 pages, 597 KiB

Open AccessArticle

Magnetic Field Effect on the Electric and Dielectric Properties of the Linear Magnetoelectric Compound Co₄Nb₂O₉

by Iliana N. Apostolova, Angel T. Apostolov and Julia M. Wesselinowa

Materials 2024, 17(23), 5719; https://doi.org/10.3390/ma17235719 - 22 Nov 2024

Cited by 1 | Viewed by 822

Using Green’s function theory and a microscopic model, the multiferroic properties of

{Co}_{4} {Nb}_{2} O_{9}

are investigated theoretically. There are some discrepancies in the discussion of the electric and dielectric behavior of CNO with and without external magnetic fields. We [...] Read more.

Using Green’s function theory and a microscopic model, the multiferroic properties of

{Co}_{4} {Nb}_{2} O_{9}

are investigated theoretically. There are some discrepancies in the discussion of the electric and dielectric behavior of CNO with and without external magnetic fields. We try to clarify them. It is observed that the polarization and the dielectric constant do not show a peak at the antiferromagnetic phase transition temperature

T_{N}

without an external magnetic field h. But applying h, there appears a peak around the Neel temperature

T_{N}

, which increases with increasing h and then shifts to lower temperatures. The magneto-dielectric coefficient MD

(T, h)

is also calculated. Moreover, the magnetization rises with an increasing external electric field below the Neel temperature. This shows strong magnetoelectric coupling in

{Co}_{4} {Nb}_{2} O_{9}

. The obtained results are compared with the existing experimental data. There is a good qualitative agreement. Full article

(This article belongs to the Special Issue Piezoelectrics and Ferroelectrics for End Users)

► Show Figures

Figure 1

11 pages, 1526 KiB

Open AccessArticle

Transition-Layer Implantation for Improving Magnetoelectric Response in Co-fired Laminated Composite

by Sheng Liu, Sihua Liao, Hongxiang Zou, Bo Qin and Lianwen Deng

Magnetochemistry 2023, 9(2), 50; https://doi.org/10.3390/magnetochemistry9020050 - 5 Feb 2023

Viewed by 1796

Abstract

Magnetoelectric (ME) laminated composites with strong ME coupling are becoming increasingly prevalent in the electron device field. In this paper, an enhancement of the ME coupling effect via transition-layer implantation for co-fired lead-free laminated composite (80Bi_0.5Na_0.5TiO₃-20Bi_0.5K_0.5TiO₃)/(Ni_0.8Zn_0.2)Fe₂O₄ (BNKT/NZFO) was demonstrated. A transition layer composed of particulate ME composite 0.5BNKT-0.5NZFO was introduced between the BNKT piezoelectric layer and the NZFO magnetostrictive layer, effectively connecting the two-phase interface and strengthening interface stress transfer. In particular, an optimal ME voltage coefficients (α_ME) of 144 mV/(cm·Oe) at 1 kHz and 1.05 V/(cm·Oe) at the resonant frequency in the composite was achieved, with a layer thickness ratio (BNKT:0.5BNKT-0.5NZFO:NZFO) of 3:1:6. The static elastic model was used to determine strong interface coupling. A large magnetodielectric (MD) response of 3.95% was found under a magnetic field excitation of 4 kOe. These results demonstrate that transition-layer implantation provides a new path to enhance the ME response in co-fired laminated composite, which can play an important role in developing magnetic field-tuned electronic devices. Full article

(This article belongs to the Special Issue Functional Magnetic Materials: From Design to Application)

► Show Figures

Figure 1

14 pages, 27336 KiB

Open AccessArticle

Antiferroelectrics and Magnetoresistance in La_0.5Sr_0.5Fe₁₂O₁₉ Multiferroic System

by Jia-Hang Yin, Guo-Long Tan and Cong-Cong Duan

Materials 2023, 16(2), 492; https://doi.org/10.3390/ma16020492 - 4 Jan 2023

Cited by 1 | Viewed by 1703

Abstract

The appearance of antiferroelectrics (AFE) in the ferrimagnetism (FM) system would give birth to a new type of multiferroic candidate, which is significant to the development of novel devices for energy storage. Here we demonstrate the realization of full antiferroelectrics in a magnetic La_0.5Sr_0.5Fe₁₂O₁₉ system (AFE+FM), which also presents a strong magnetodielectric response (MD) and magnetoresistance (MR) effect. The antiferroelectric phase was achieved at room temperature by replacing 0.5 Sr²⁺ ions with 0.5 La²⁺ ions in the SrFe₁₂O₁₉ compound, whose phase transition temperature of ferroelectrics (FE) to antiferroelectrics was brought down from 174 °C to −141 °C, while the temperature of antiferroelectrics converting to paraelectrics (PE) shifts from 490 °C to 234 °C after the substitution. The fully separated double P-E hysteresis loops reveal the antiferroelectrics in La_0.5Sr_0.5Fe₁₂O₁₉ ceramics. The magnitude of exerting magnetic field enables us to control the generation of spin current, which induces MD and MR effects. A 1.1T magnetic field induces a large spin current of 15.6 n A in La_0.5Sr_0.5Fe₁₂O₁₉ ceramics, lifts up dielectric constants by 540%, and lowers the resistance by −89%. The magnetic performance remains as usual. The multiple functions in one single phase allow us to develop novel intelligent devices. Full article

► Show Figures

Figure 1

11 pages, 5235 KiB

Open AccessArticle

Human Body Specific Absorption Rate Reduction Employing a Compact Magneto-Dielectric AMC Structure for 5G Massive-MIMO Applications

by Reza Karimian, Mansoor Dashti Ardakani, Shahrokh Ahmadi and Mona Zaghloul

Eng 2021, 2(4), 501-511; https://doi.org/10.3390/eng2040032 - 4 Nov 2021

Cited by 10 | Viewed by 3415

Abstract

A compact artificial magnetic conductor (AMC) structure for the application of specific absorption rate (SAR) reduction is presented in this paper. A magneto-dielectric (MD) structure as a host of AMC substrate is used to miniaturize the AMC size. The magneto-dielectric has been designed with a low-profile spiral loop in a way to have a high permittivity and permeability for the desired center frequency of 3.5 GHz. Simulation results confirm the zero-degree reflection phase of the proposed AMC unit cell. Moreover, a 70% reduction has been achieved in comparison to the conventional AMC. To validate the simulation results, a prototype of the board is fabricated and measured with a coplanar waveguide (CPW) antenna for the reflection coefficient. The measurement results display an excellent agreement with the simulation ones. A VOXEL model of a human body is utilized to determine the SAR value of the proposed structure. Considering the maximum SAR value for an average of 10 g human tissue, more than 70% SAR reduction is verified for the CPW antenna with the recommended MD-AMC structure compared to a conventional single CPW antenna. Full article

(This article belongs to the Special Issue Feature Papers in Eng)

► Show Figures

Figure 1

12 pages, 5479 KiB

Open AccessFeature PaperArticle

Deciphering the Structural Characterization, Hirshfeld Surface Analysis, Raman Studies, and Temperature-Dependent Magnetodielectric Properties of BiMn₂O₅

by Houda Felhi, Mourad Smari, Saber Mansouri, Jalel Massoudi and Essebti Dhahri

Magnetochemistry 2021, 7(5), 68; https://doi.org/10.3390/magnetochemistry7050068 - 16 May 2021

Cited by 1 | Viewed by 2324

Abstract

We investigate the structural, Hirshfeld surface, magnetic, and magnetodielectric properties of BiMn₂O₅. The sample can be indexed with an orthorhombic phase associated with space group Pbam, with crystallographic parameters a = 7.54946 Å, b = 8.54962 Å and c = 5.753627 Å. The Hirshfeld surface analysis, associated with 2D fingerprint plots, was used to visualize and explore the significant intermolecular interactions in the crystal structure quantitatively. The Raman spectra, measured from 6 to 300 K in a frequency range between 250 and 750 cm⁻¹, exhibit good agreement between the SHELL model calculations and the experimental measurement of the proximity of the phonon frequencies for our sample. Furthermore, magnetic measurements show that BiMn₂O₅ becomes antiferromagnetic below the Néel temperature (T_N)—the temperature above which an antiferromagnetic material becomes paramagnetic (T_N = 31 K). The relaxation at intermediate temperatures (200–300 K) can be attributed to the polar jump process at two charge transfer sites between the Mn³⁺ and Mn⁴⁺ ions, which, in combination with the special arrangement of the Mn³⁺/Mn⁴⁺ ions, is likely to produce the strong intrinsic magnetodielectric effect (MD) in the same temperature range. Full article

(This article belongs to the Special Issue Advanced Materials for Magnetic Cooling)

► Show Figures

Figure 1

14 pages, 5285 KiB

Open AccessArticle

Miniaturized Multi-Port Microstrip Patch Antenna Using Metamaterial for Passive UHF RFID-Tag Sensor Applications

by Jamal Zaid, Abdulhadi E. Abdulhadi and Tayeb A. Denidni

Sensors 2019, 19(9), 1982; https://doi.org/10.3390/s19091982 - 28 Apr 2019

Cited by 17 | Viewed by 6087

Abstract

In this paper, a miniaturized Ultra High Frequency Radio Frequency Identification (UHF-RFID) tag-based sensor antenna using a magneto- dielectric substrate (MDS) for wireless identification and sensor applications is presented. Two models of RFID tag-based sensors are designed, fabricated and measured. The first model uses two RFID tags; both of the tags are incorporated with two RFID chips. A passive sensor is also integrated in one of the proposed tags to serve as a sensor node, while the other tag is used as a reference node. Based on the difference in the minimum power required to activate the reference and sensor nodes, the sensed data (temperature or humidity) can be determined. The magneto-dielectric substrate layer is placed underneath the patch antenna to reduce the size of the proposed sensor by about 75% compared to a conventional RFID tag-based sensor. The magneto-dielectric layer is thin enough to embed in the planer circuit. To reduce the size of the proposed sensor, a multi-port tag for including the reference and sensor node in one antenna is also presented. The proposed RFID tag-based sensors have several features such as small size, they are completely capable for two objectives at the same time and easy to integrate with a planer circuit. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Canada 2018)

► Show Figures

Figure 1

Search Results (6)

Further Information

Guidelines

MDPI Initiatives

Follow MDPI

Saved Queries

Search Filter Reset All

Years

Feature Papers

Subjects

Journals

Article Types

Countries / Regions

Search Results (6)

Further Information

Guidelines

MDPI Initiatives

Follow MDPI