sciencedirect: Influence of AC fields and electrical conduction mechanisms on the flash-onset temperature: Electronic (BiFeO3) vs. ionic conductors (8YSZ)

 

Ceramics International

Volume 49, Issue 9, Part B, 1 May 2023, Pages 14834-14843

Influence of AC fields and electrical conduction mechanisms on the flash-onset temperature: Electronic (BiFeO₃) vs. ionic conductors (8YSZ)

Sandra Molina-Molina a, Antonio Perej´on a,b,**, Luis A. P´erez-Maqueda a,***, Pedro E. S´anchez-Jim´enez a,b,*

^a

Instituto de Ciencia de Materiales de Sevilla, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla, Calle Américo Vespucio 49, Sevilla, 41092, Spain

^b

Departamento de Química Inorgánica, Facultad de Química, Universidad de Sevilla, Sevilla, 41012, Spain

Received 27 February 2022, Revised 21 June 2022, Accepted 22 June 2022, Available online 1 July 2022, Version of Record 22 March 2023.

 

Abstract

This work aims to clarify the influence of AC (up to 50 kHz) vs DC fields on the flash-onset temperature, emphasizing the role of the electrical conduction mechanism. BiFeO₃ (BFO) is used as an example of electronic conductor while 8-mol % Yttria-stabilized zirconia (8YSZ) is used as an example of ionic conductor. For 8YSZ, a frequency dependence of the flash-onset temperature and flash-induced heating is observed. This is consistent with the different contributions found in the total electrical response of 8YSZ as characterized by impedance spectroscopy measurements. Estimations based on the blackbody radiation model suggest that 8YSZ samples attain higher temperatures under AC fields due to a more efficient heating. Moreover, a noticeable decrease in the activation energy for the electrical conduction after the flash is triggered is attributed to electronic conduction. Meanwhile, the lack of frequency response and insensitiveness to the type of electrical field found in the case of BFO can be attributed to its mainly electronic bulk conduction.

 

https://www.sciencedirect.com/science/article/pii/S0272884222022763

sciencedirect: Flash sintering improves magnetic properties of spinel zinc ferrite

 

Scripta Materialia

Volume 236, November 2023, 115681

Flash sintering improves magnetic properties of spinel zinc ferrite

Soumyadeep Sur, Parmanand Kumar Tyagi, Shikhar Krishn Jha

Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India

Received 11 June 2023, Revised 20 July 2023, Accepted 22 July 2023, Available online 28 July 2023, Version of Record 28 July 2023.

 

Abstract

We report on a simple protocol for one step synthesis and sintering of single-phase magnetic spinel ZnFe₂O₄ zinc ferrite (ZFO) using an electric field assisted sintering. The resultant materials show improved saturation magnetization and higher coercivity compared to conventionally sintered ferrite. The changes in properties have been attributed to generation of non-thermal lattice defects when processed under electric field. Instead of using the high temperatures (>1000 °C) and extended dwell periods (> 4 h) required by the traditional sintering processes, this method permits sintering of ZFO at a furnace temperature of only 950 °C in just a minute by applying a minimal field of 25 Vcm⁻¹. This magnetic material with decreased coercivity and increased saturation magnetization will improve the efficiency of solenoids, transformer/inductor cores, microwave devices and magnetic shields.

 

https://www.sciencedirect.com/science/article/pii/S1359646223004049

sciencedirect: Flash sintering of complex shapes

Applied Materials Today
Volume 26, March 2022, 101293

Flash sintering of complex shapes

Charles Manière a b 1 2, Geuntak Lee a 1, Eugene A. Olevsky a 1

a    Powder Technology Laboratory, San Diego State University, San Diego, United States of America

b    Normandie Univ, ENSICAEN, UNICAEN, CNRS, CRISMAT, Caen, France

Received 1 September 2021, Revised 16 November 2021, Accepted 24 November 2021, Available online 7 December 2021, Version of Record 7 December 2021.

 

Highlights

• •
  Flash spark plasma sintering scalability.
• •
  Interface method for spark plasma complex shaping.
• •
  Flash sintering of complex shapes.

Abstract

Flash (ultra-rapid) sintering of powder materials is a Multiphysics phenomenon which has a potential for the quasi-instantaneous fabrication of various components. However, the intrinsic instability of flash sintering makes it difficult to apply to complex shapes and large specimens. Here, we circumvent this problem by the use of an interface-controlled approach to impose stable and very fast heating to large powder samples which become fully dense in a matter of seconds. The Multiphysics simulation demonstrated that an electric-thermal-mechanical confinement of the specimen allows a very efficient (and selective) heating and sintering of the powder specimen with a homogeneous microstructure and a substantial reduction of the grain growth. Our results indicate that the ultra-rapid sintering of large and complex shape samples is possible.

 https://www.sciencedirect.com/science/article/pii/S2352940721003565

sciencedirect: A novel Multi‐Phase Flash Sintering (MPFS) technique for 3D complex‐shaped ceramics

 Applied Materials Today 26 (2022) 101274

A novel Multi-Phase Flash Sintering (MPFS) technique for 3D complex-shaped ceramics

Sandra Molina-Molina a,1, Eva Gil-González a,b,1,∗, Francisco José Durán-Olivencia c,
José Manuel Valverde d, Antonio Perejón a,e, Pedro E. Sánchez-Jiménez a,e,∗,
Luis A. Pérez-Maqueda a,∗

Highlights

• •
  First demonstration of enhanced flash sintering by a rotating electric field.
• •
  Larger power densities allow for reduced sintering temperatures.
• •
  A wide variety of ceramics can be more efficiently sintered by MPFS.
• •
  Homogeneous sintering is attainable even for complex-shaped specimens.

Abstract

This work demonstrates the first proof-of-concept of Multi-Phase Flash Sintering (MPFS). This novel technique essentially consists of applying a rotating electric field to the sample by means of a multi-phase voltage source as furnace temperature increases. Several ceramic materials with different types of electrical conductivities are sintered within seconds at furnace temperatures much lower than those used for traditional DC flash sintering due to the higher power densities administered by a multi-phase power supply. Thus, ceramic materials are flashed at relatively lower applied voltages which minimizes undesired phenomena such as localization and preferential current pathways. Furthermore, MPFS allows diverse electrode configurations to promote a more uniform electric field distribution, enhancing the sintering of 3D complex-shaped specimens. MPFS could be a true breakthrough in materials processing, as 3D complex-shaped specimens are homogeneously sintered at reduced temperatures, while keeping all the advantages of conventional flash sintering.

https://www.sciencedirect.com/science/article/pii/S2352940721003371

Ceramics International: Expanding the scope of multiphase-flash sintering: Multi-dogbone configurations and reactive processes

 

Ceramics International

Volume 50, Issue 14, 15 July 2024, Pages 25210-25215

 

 

Expanding the scope of multiphase-flash sintering: Multi-dogbone configurations and reactive processes

A.F. Manchón-Gordón a
, S. Molina-Molina a, A. Perejón a b, A. Alcalde-Conejo a, P.E. Sánchez-Jiménez a b, L.A. Pérez-Maqueda a

a
    Instituto de Ciencia de Materiales de Sevilla, ICMSE CSIC-Universidad de Sevilla, C. Américo Vespucio 49, Sevilla, 41092, Spain

b
    Departamento de Química Inorgánica, Facultad de Química, Universidad de Sevilla, 41012, Sevilla, Spain

Received 1 March 2024, Revised 5 April 2024, Accepted 19 April 2024, Available online 20 April 2024, Version of Record 3 June 2024.

 

Abstract

In this work, we have expanded the possibilities of the multiphase-flash sintering (MPFS) technique by investigating several configurations that involve multiple dogbone specimens (ranging from 1 to 3) and multiple phases (also ranging from 1 to 3). Unlike the traditional MPFS approach using complex 3D or cylindrical samples, this new method allows for a direct comparison with the established conventional flash sintering technique. Our experimental results with dense 8-mol% Yttria-stabilized zirconia demonstrate a significant reduction in the onset temperature as the number of phases and dogbones increases. Building on these findings, we achieved the preparation of pure bulk specimens of SrFe₁₂O₁₉ for the first time through reactive multiphase-flash sintering.

 

https://www.sciencedirect.com/science/article/pii/S027288422401647X

 

Vacuum: Investigation of intense pulsed ion beam generation by a magnetically insulated ion diode at a reduced impedance

 

Vacuum

Volume 217, November 2023, 112496

 

Investigation of intense pulsed ion beam generation by a magnetically insulated ion diode at a reduced impedance

Marat Kaikanov, Dosbol Nauruzbayev, Alshyn Abduvalov, Kanat Baigarin

    Nazarbayev University, Astana, 010000, Kazakhstan

Received 22 March 2023, Revised 9 August 2023, Accepted 10 August 2023, Available online 11 August 2023, Version of Record 14 August 2023.

 

Abstract

The intense pulsed ion beam (IPIB) generation was investigated at reduced impedance of a magnetically insulated ion diode. The main goal of our research was to obtain IPIB with adjustable parameters at low current densities. The diode impedance was varied by the external magnetic field current by setting the delay of the accelerator's trigger relative to the launch of the magnetic field generator. The B-applied ion diode adjustably generated IPIB with a current density in the range from 25 to 4 A/cm². In the matched mode the accelerator generates the ion beam with a current density of about 100 A/cm². Obtained results of the IPIB current density adjustment allows to irradiate samples in a single vacuum cycle without the change of charging voltage of both magnetic field and accelerating voltage generators. Gold films with a thickness of 10 nm deposited on fluorine-doped tin oxide (FTO)/glass substrates were irradiated to demonstrate the applicability of obtained IPIB for irradiation of thin coatings without their deterioration. Single shot of IPIB with current density of 20 A/cm² transformed Au film to spherical micro-particles, while after irradiation at the same fluence with 5 pulses of IPIB with current density of 4 A/cm² Au coating was preserved as a film.

 

 https://www.sciencedirect.com/science/article/pii/S0042207X23006930

Ceramics International: Influence of the atmosphere on the formation of high-entropy oxides within the Co–Cu–Fe–Mg–Mn–Ni–O system via reactive flash sintering

 

Ceramics International

Volume 50, Issue 21, Part B, 1 November 2024, Pages 42276-42285

 

Influence of the atmosphere on the formation of high-entropy oxides within the Co–Cu–Fe–Mg–Mn–Ni–O system via reactive flash sintering

 A.F. Manchón-Gordón a, C. Lobo-Llamas a, S. Molina-Molina a, A. Perejón a b
, P.E. Sánchez-Jiménez a, L.A. Pérez-Maqueda a

a
    Instituto de Ciencia de Materiales de Sevilla, ICMSE CSIC-Universidad de Sevilla, C. Américo Vespucio 49, Sevilla, 41092, Spain

b
    Departamento de Química Inorgánica, Facultad de Química, Universidad de Sevilla, Sevilla, 41012, Spain

Received 8 May 2024, Revised 22 July 2024, Accepted 4 August 2024, Available online 5 August 2024, Version of Record 27 September 2024.

 

Abstract

In this study, the feasibility of preparing quinary equimolar high-entropy oxides within the Co–Cu–Fe–Mg–Mn–Ni–O system was explored using the reactive flash sintering (RFS) technique. Various compositions were tested using this technique under atmosphere pressure, leading to the formation of two primary phases: rock-salt and spinel. Conversely, a new high-entropy oxide was produced as a single-phase material with the composition (Co_0.2,Cu_0.2,Mg_0.2,Mn_0.2,Ni_0.2)O when RFS experiments were conducted in nitrogen atmosphere. The reducing conditions achieved in nitrogen enabled the incorporation of cations with oxidation states different from +2 into the rock-salt lattice, emphasizing the critical role of the processing atmosphere, whether inert or oxidizing, in the formation of high-entropy oxides. The electrical characterization of this material was obtained via impedance spectroscopy, exhibiting a homogeneous response attributed to electronic conduction with a temperature dependence characteristic of disordered systems.

 

https://www.sciencedirect.com/science/article/pii/S0272884224035028