E-ISSN:2583-9152

Editorial

Glass-Ceramic Dielectrics

Journal of Condensed Matter

2023 Volume 1 Number 1 Jan-Jun
Publisherwww.thecmrs.in

Lead free glass-ceramic dielectrics: A highly potential material for energy storage, photonics and memory applications

Molla A1*
DOI:10.61343/jcm.v1i01.1

1* Atiar Rahaman Molla, Senior Principal Scientist, Csir Central Glass And Ceramic Research Institute, Raja S C Mullick Road Kolkata, West Bengal, India.

To maintain a modern livelihood, huge amount of energy is needed which are primarily sourced from fossil fuels that causes global warming and has become an environmental concern. The use of renewable and sustainable green energy has been increasing day by day which needs efficient devices for storage and supply of energy on demand. Among the energy storage devices, batteries have a high energy storage density and low power output, while capacitors possess relatively lower energy density but are capable of exhibiting a high-power output. Dielectric capacitors show high-power density, ultra-fast charge-discharge rates and higher efficiency which make them indispensable for application in electronic devices. Dielectric materials used in the commercially available capacitors are mostly lead based ferroelectric and anti-ferroelectric ceramics. As lead is toxic and causes havoc environmental concerns, the usage of lead/heavy metal containing materials is being gradually phased out and alternate lead-free high-performance materials are sought after. Due to difficulties in ceramic synthesis technique, uncontrolled grain growth and other defects are created resulting in poor dielectric properties. This article tries to present lead-free anti-ferroelectric glass-ceramics based dielectrics as an emerging material for catering to the future green energy demands. Lead free glass-ceramics based dielectrics are multifunctional materials with huge potentials for ferroelectric random access memory (FRAM) and photonic applications, besides their prospects as a future energy storage material.

Keywords: Anti-ferroelectric glass-ceramics, Dielectric capacitor, Transparent ferroelectric glass-ceramics, Energy Storage Devices, ferroelectric RAM, Photonics, Non-linear optical properties

Corresponding Author How to Cite this Article To Browse
Atiar Rahaman Molla, Senior Principal Scientist, , Csir Central Glass And Ceramic Research Institute, Raja S C Mullick Road Kolkata, West Bengal, India.
Email: 		Molla A, Lead free glass-ceramic dielectrics: A highly potential material for energy storage, photonics and memory applications. J.Con.Ma. 2023;1(1):1-4.
Available From
https://jcm.thecmrs.in/index.php/j/article/view/1

Manuscript Received Review Round 1 Review Round 2 Review Round 3 Accepted
2023-05-10 2023-05-15 2023-05-20 2023-05-25 2023-06-01
Conflict of Interest Funding Ethical Approval Plagiarism X-checker Note
None Yes Nil 20.78%

© 2023by Molla Aand Published by Condensed Matter Research Society. This is an Open Access article licensed under a Creative Commons Attribution 4.0 International License https://creativecommons.org/licenses/by/4.0/ unported [CC BY 4.0].

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Editorial

High energy demands for daily modern life and over-dependence on fossil fuel sources for energy is leading to global warming and environmental pollution. Due to very fast depletion of non-renewable energy sources (coal, gas, oil etc.), alternative, renewable, cheaper and cleaner energy resources, such as solar, wind, nuclear etc. are being harnessed for use by the mankind. This leads to a high demand for devices for effectively storing-absorbing-supplying the electricity as per demands.

Among the energy storage devices, batteries, electrochemical super-capacitors and dielectric capacitors are being used extensively for storing and supplying clean energies. Compared to dielectric capacitors, batteries, fuel cells and super-capacitors demonstrate high energy storage density but lacks high power density which is available with dielectric capacitors. These energy storage devices are employed in a complimentary way depending on the requirements of energy or power for electronic devices.

Dielectric capacitors exhibiting high-power density, faster charge-discharge rates together with their high efficiency makes them indispensable for application in electronic devices, pulsed power supplies and power systems, e.g.: electromagnetic guns, inverter equipment, hybrid electric vehicles, military launch platforms, etc. Commercial capacitors made of polymers and ceramics, show low power density, small discharge currents and a shorter life cycle, limiting their applications. Ceramic materials exhibit large dielectric constant (DC) but possess very weak breakdown strength (BDS) and on the other hand polymers show good BDS but suffer with poor DC. The energy density of a solid-state dielectric material is directly dependent on its DC and BDS following the equation (1). For catering to the needs of miniaturized modern electronic devices and electrical equipment, development of suitable efficient dielectric material is being researched globally. Capacitors are the main components that take a lot of spaces in the electronic appliances and thus it needs to be miniaturized while retaining the same energy storing capacity [1,2].

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The essential requirements for an ideal capacitor material are, it should have (i) high BDS (ii) large saturation polarization (iii) small remnant polarization and (iv) low coercive field. Dielectric materials used for capacitors falls into either of the four categories: linear dielectric (Al2O3, glass), ferroelectrics (BaTiO3, PbTiO3), relaxor ferroelectrics ((Pb,La)(Zr,Ti)O3) and anti-ferroelectrics (PbZrO3). Among these dielectrics, anti-parallel dipolar arrangements in anti-ferroelectric materials lead to a lack of ferroelectric domains at low electric fields and have a negligible dielectric loss, hysteresis loss, and low remnant polarizations due to double hysteresis loops, resulting in high recoverable energy density [3]. A schematic diagram showing Polarization (P) vs. Electric Field (E) hysteresis loops and the energy storage characteristics of an anti-ferroelectric material has been presented in Figure 1.

In the last few decades, lead-based materials such as lead lanthanum zirconium titanate (Pb,La) (Zr,Ti)O3, PLZT) have been the main stay anti-ferroelectric materials, however, with increasing environmental concerns (to comply with RoHs regulations) that calls for the development of lead-free dielectric materials for capacitors [4]. Moreover, ceramic materials have the disadvantages of particle coarsening and aggregation that occurs during sintering process which sometimes lead to inferior microstructures and defects (pores, cracks etc.) that interfere with their poling process resulting in high dielectric losses and degradation in BDS, causing a significant drop in the energy storage density, thus limiting their applications.

The difficulties in ceramic fabrication process (sintering) can be overcome by adopting glass-ceramics (GCs) synthesis route which is a melt quenching followed by ceramization heat-treatment technique for generation of desired crystalline phases in the glass matrix [5]. Advantages in this technique includes, high speed fabrication, pore-free which impart these materials with higher dielectric breakdown strengths; the possibility of tailoring the properties of GCs by varying the volume fraction of the active phase (anti-ferroelectric crystals) dispersed in the glass matrix to increase dielectric constant enormously to a few orders of magnitude [6]. Generally, glasses possess high dielectric breakdown strength but show very low permittivity (~4-6) that demands for usage of high voltages for storing the energy


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in a glass based dielectric medium. This limitation can be overcome by growth of anti-ferroelectric (AFE)/ferroelectric/paraelectric crystals within the glasses to enhance their dielectric properties. With fabrication of such lead-free AFE/ferroelectric/paraelectric GCs, the dielectric permittivity and breakdown strength of the material can be improved simultaneously and a significant amount of energy can be stored using the material at low electric field voltages which will be vital for the future of a clean energy landscape. Particularly for AFE GCs, because of their higher dielectric constant, higher breakdown strength together with low loss due to minimum remnant polarization makes the energy storage density higher in case of glass-ceramic which is envisaged as a highly potential material for energy storage applications [7]. For example, lead free glass-ceramics containing anti-ferroelectric NaNbO3 (sodium niobate), KNbO3 (potassium niobate), LiNbO3 (lithium niobate), AgNbO3 (silver niobate) crystals etc. possessing high saturation polarization (Ps), high DC and low dielectric loss and low remnant polarization (Pr) are highly promising for energy storage applications. Due to advancement in GCs synthesis techniques over the years, it is now possible to produce nano-crystalline transparent ferroelectric glass-ceramics (TFGC) which further expands its applications in the photonics, such as for optical amplification, switching, sensors, transducers, actuators, etc, as structural anisotropy in such materials gives rise to a host of nonlinear optical properties like, electro-optic effect, harmonic generation, and photo-refraction etc.

Ferroelectric RAM (FRAM) is a non-volatile memory technology that uses a ferroelectric material to store data. The key requirement for the material used in FRAM is that it exhibits ferroelectric properties which can be polarized and retain its polarization even after the electric field is removed. The most commonly used material for FRAM is lead zirconate titanate (PZT), due to its desirable ferroelectric properties, including high remnant polarization, low coercive field, and good fatigue endurance [8]. However, PZT has some limitations, such as high processing temperatures, compatibility issues with complementary metal-oxide-semiconductor (CMOS) technology, and environmental concerns due to the presence of lead. Researchers may like to explore the alternative and potential lead-free

materials like, BiFeO3, BaTiO3, SrTiO3, HfO2 to overcome these limitations with glass-ceramics synthesis route for memory applications. A schematic diagram is shown in Fig. 2, exhibiting high remnant polarization (Pr) in a hysteresis loop of a typical ferroelectric material suitable for FRAM applications.

The demand for next-generation efficient energy storage systems in modern miniaturized electronic components can be met with anti-ferroelectric glass–ceramic based dielectric materials that can provide high power, higher energy density, ultrafast charge-discharge speeds, high-temperature stability, stable frequency in an environment friendly way. However, extensive research needs to be conducted in this area to realize its true potential. Glass-ceramics based dielectrics have huge potential for photonic applications because of their transparency and several non-linear properties, however, researchers need to explore the alternative materials with useful properties to understand their true potential. It's important to note that the choice of material for FRAM depends on various factors, including performance requirements, processing compatibility, scalability, and environmental considerations. On-going research and development in the field may lead to the discovery and adoption of new materials for FRAM in the future, where glass-ceramics can play a vital role.

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Figure 1: Polarisation vs Electric field (P-E) hysteresis loops and energy storage characteristics of a typical anti-ferroelectric material


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Figure 2: Polarisation vs Electric field (P-E) hysteresis loop of a typical ferroelectric material

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4. Jing Gao, Lei Zhao, Qing Liu, Xuping Wang, Shujun Zhang, Jing-Feng Li “Antiferroelectric-ferroelectric phase transition in lead-free AgNbO3 ceramics for energy storage applications”, Vol. 101, Issue 12, 2018 5443-5450.

5. Chakrabarti A., Menon S., Tarafder A., and Molla A. R., “Glass–ceramics: A Potential Material for Energy Storage and Photonic Applications”, In: K Annapurna and A R Molla (ed) “Glasses and Glass-Ceramics: Advanced Processing and Applications” 2022 vol 178 chapter 10, 265-297.

6. Chakrabarti A., Molla A. R., “Synthesis of Eu2O3 doped BaO-TiO2-GeO2 based glass-ceramics: Crystallization kinetics, optical and electrical properties”, Elsevier 2018 B.V. 0022-3093.

7. Chauhan A., Patel S., Vaish R., and Chris R. Bowen, “Anti-Ferroelectric Ceramics for High Energy Density Capacitors”, Materials 2015, 8, 8009–8031.

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