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      • KCI등재

        Guide for Processing of Textured Piezoelectric Ceramics Through the Template Grain Growth Method

        ( Temesgen Tadeyos Zate ),( Jeong-woo Sun ),( Nu-ri Ko ),( Hye-lim Yu ),( Woo-jin Choi ),( Jae-ho Jeon ),( Wook Jo ) 한국전기전자재료학회 2023 전기전자재료학회논문지 Vol.36 No.4

        압전 세라믹스는 전기에너지와 기계에너지를 상호 전환할 수 있는 성질을 기반으로 엑츄에이터 및 트렌스듀서 등에 사용되는 핵심 소재이다. 결정배향 성장법(TGG)은 다결정 세라믹스의 압전 특성을 획기적으로 향상시킬 수 있는 방법으로 많은 주목을 받고 있다. 하지만, TGG 방식을 통해 결정립을 배향하는 과정은 여러 단계의 최적화가 필요하기 때문에 입문자에게는 상당히 도전적인 기술이다. 따라서 이 기고문에서는 입문자의 입장에서 TGG를 가장 쉽게 접근할 수 있도록 납작한 모양의 템플릿을 합성하기 위한 용융염 합성기법 및 실제 결정배향을 위한 Tape Casting 과정 나아가 배향도를 향상시키기 위해 주의할 점에 이르기까지 TGG 전반에 대한 내용을 제공하고자 한다. 본 기고문이 TGG 방법에 대한 이해도를 높이고 활용 및 개선하고자 하는 모든 연구자들에게 정보 및 통찰을 제공할 수 있는 기본 참고서가 되기를 희망한다. The templated grain growth (TGG) method has gained significant attention for its ability to produce highly textured piezoelectric ceramics with significantly enhanced performance, making it a promising method for transducer and actuator applications. However, the texturing process using the TGG method requires the optimization of multiple steps, which can be challenging for beginners in this field. Therefore, in this tutorial, we provide an overview of the TGG method mainly based on our previous published works, including its various processing steps such as synthesizing anisotropic-shaped templates with size and size distribution control using the molten salt synthesis technique, tape casting, and identifying key factors for proper alignment of the templates in the target matrix system. Our goal is to provide a resource that can serve as a basic reference for researchers and engineers looking to improve their understanding and utilization of the TGG method for producing textured piezoelectric ceramics.

      • KCI등재

        Development of Textured 0.37PMN-0.29PIN-0.34PT Ceramics- Based Multilayered Actuator for Cost-Effective Replacement of Single Crystal-Based Actuators

        ( Temesgen Tadeyos Zate ),( Jeong-woo Sun ),( Nu-ri Ko ),( Bo-kun Koo ),( Hye-lim Yu ),( Min-soo Kim ),( Woo-jin Choi ),( Soon-jong Jeong ),( Jae-ho Jeon ),( Wook Jo ) 한국전기전자재료학회 2023 전기전자재료학회논문지 Vol.36 No.4

        Multilayered actuators using Pb(Mg<sub>1/3</sub>Nb<sub>2/3</sub>)O<sub>3</sub>-Pb(In<sub>1/2</sub>Nb<sub>1/2</sub>)O<sub>3</sub>-PbTiO<sub>3</sub> (PMN-PIN-PT) crystals have demonstrated excellent properties, but are costly and lack mechanical strength. Textured PMN-PIN-PT ceramics exhibit robust mechanical strength and comparable properties to their single crystals form. However, the development of multilayered actuators using textured PMN-PIN-PT ceramics has not been achieved until now. This study presents the development of a multilayered actuator using textured 0.37PMN-0.29PIN-0.34PT ceramics with an Ag0.9/Pd0.1 inner electrode, co-fired at 950℃. A random 0.37PMN- 0.29PIN-0.34PT ceramics multilayered actuator was also developed for comparison. The multilayered actuator consisted of 9 ceramic layers (36 μm thickness) with an overall actuator thickness of 0.401 mm. The textured and random 0.37PMN-0.29PIN- 0.34PT ceramics-based multilayered actuators achieved displacements of 0.61 μm (0.15% strain) and 0.23 μm (0.057% strain) at a low applied peak voltage of 100 V. These results suggest that the developed multilayered actuator using high-performance textured 0.37PMN-0.29PIN-0.34PT ceramics has the potential to replace expensive single crystal-based actuators costeffectively.

      • KCI등재

        Textured Ceramics for Multilayered Actuator Applications: Challenges, Trends, and Perspectives

        Temesgen Tadeyos Zate,고누리,유혜림,최우진,선정우,전재호,조욱 한국전기전자재료학회 2023 전기전자재료학회논문지 Vol.36 No.3

        Piezoelectric actuators, which utilize piezoelectric crystals or ceramics, are commonly used in precision positioning applications, offering high-speed response and precise control. However, the use of low-performance ceramics and expensive single crystals is limiting their versatile use in the actuator market, necessitating the development of both high-performance and cost-effective piezoelectric materials capable of delivering higher forces and displacements. The use of textured Pb (lead)-based piezoelectric ceramics formed by so-called templated grain growth method has been identified as a promising strategy to address the performance and cost issue. This review article provides insights into recent advances in texturing Pb-based piezoelectric ceramics for improved performance in actuation applications. We discussed the relevant issues in detail focusing on current challenges and emerging trends in the textured piezoelectric ceramics for their reliability and performance in actuator applications. We discussed in detail focusing on current challenges and emerging trends of textured piezoelectric ceramics for their reliability and performance in actuator applications. In conclusion, the article provides an outlook on the future direction of textured piezoelectric ceramics in actuator applications, highlighting the potential for further success in this field.

      • KCI등재

        Understanding thermal depolarization via thermally stimulated depolarization current measurement

        Sun Jeong-Woo,Zate Temesgen Tadeyos,Choi Woo-Jin,Lee Geon-Ju,Lee Sang-Goo,Ryu Jong Eun,Jo Wook 한국세라믹학회 2024 한국세라믹학회지 Vol.61 No.4

        Thermal depolarization in poling-induced piezoelectric materials is defi ned as the disappearance of remanent polarization at a so-called depolarization temperature. A thermally stimulated depolarization current (TSDC) measurement is most widely used for examining depolarization as a function of temperature. TSDC results in the literature commonly show a gradual reduction of polarization even below depolarization temperature (Td). However, no degradation happens when thermal heat treatments are conducted below Td, meaning that the apparent reduction in polarization measured by TSDC is sure to be an artifact. Here, we demonstrate that such artifact is unavoidable during TSDC measurements and propose a method to circumvent it. This strategy was manifested on TSDC data collected from a relaxor ferroelectric Pb(Mg 1/3Nb2/3)O3-PbTiO 3 (PMN-PT) single crystals.

      • KCI등재

        A Brief Review of Some Challenging Issues in Textured Piezoceramics via Templated Grain Growth Method

        유혜림,조욱,Temesgen Tadeyos Zate,고누리,최우진 한국센서학회 2023 센서학회지 Vol.32 No.1

        It is well known that polycrystalline ceramics fabricated via the templated grain growth method along a desired crystallographic direction, generally along [001], exhibits enhanced piezoelectric response. Generally, the piezoelectric properties of textured ceramics depend on the degree of texture, as piezoelectric properties peak in single crystals. Therefore, understanding the relationship between the degree of texture and piezoelectric properties is fundamental. Here, we present state-of-the-art textured piezoceramics by focusing on critical issues such as the quality of templates used for texturing and proper evaluation of the degree of texture analysis. The relationship between the degree of texture and its impact on the properties of textured materials is exclusively defined by the Lotgering factor (L.F.) calculated from the X-ray diffraction profiles. Additionally, we show that L.F. is not a suitable indicator of the degree of texture, contrary to previous interpretations. This statement was further supported by the fact that the true degree of texture can be better quantified by the multiples of random distribution. This argument was justified by comparing the quantitative values of the degree of texture obtained from both methods to those of the piezoelectric charge coefficient of textured and random ceramics.

      • KCI등재

        [100]-Texturing of Barium Titanate Ceramics Using Sodium Bismuth Titanate Templates: Challenges and Insights

        ( Nu-ri Ko ),( Temesgen Tadeyos Zate ),( Wook Jo ) 한국전기전자재료학회 2024 전기전자재료학회논문지 Vol.37 No.3

        This research explores the development of [100]-textured barium titanate (BaTiO<sub>3</sub>, BT) ceramics using sodium bismuth titanate (Na<sub>0.5</sub>Bi<sub>4.5</sub>Ti<sub>4</sub>O<sub>15</sub>, NBiT) templates, aimed at leveraging the inherent high dielectric property of BT. However, the attempted texturing was unsuccessful, primarily due to bismuth diffusion from the NBiT templates into the BT matrix below the sintering temperature, at 1,000℃. Systematical exploration about the cause of the failure is involved and alternative approaches are proposed in detail to overcome the challenge. These findings contribute to the understanding of techniques and conditions for textured ceramic fabrication and highlight the need for further research in this area.

      • Electrochemical supercapacitors of anodized-brass-templated NiO nanostrutured electrodes

        AL-Osta, Ahmed,Jadhav, Vijaykumar V.,Zate, Manohar K.,Mane, Rajaram S.,Hui, K.N.,Han, Sung-Hwan Elsevier 2015 Scripta materialia Vol.99 No.-

        <P>This paper reports the electrochemical synthesis of nickel oxide (NiO) onto a substrate template of anodized-brass (Cu–Zn). Structurally and morphologically all the electrodes, i.e. pristine, anodized and NiO-covered Cu–Zn electrodes, are different from one another. NiO-covered Cu–Zn electrodes were annealed at different temperatures (300–600°C at 100°C intervals) and appear suitable for electrochemical supercapacitors; a wide potential range (0.1–0.6V) and optimum specific capacitance (91.43Fg<SUP>−1</SUP>) are obtained for 400°C in 0.5M NaOH electrolyte at 2mVs<SUP>−1</SUP> scan rate.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

      • Influence of Bi<sup>3+</sup>-doping on the magnetic and Mössbauer properties of spinel cobalt ferrite

        Gore, Shyam K.,Mane, Rajaram S.,Naushad, Mu.,Jadhav, Santosh S.,Zate, Manohar K.,Alothman, Z. A.,Hui, Biz K. N. The Royal Society of Chemistry 2015 Dalton Transactions Vol.44 No.14

        <P>The influence of Bi<SUP>3+</SUP>-doping on the magnetic and Mössbauer properties of cobalt ferrite (CoFe<SUB>2</SUB>O<SUB>4</SUB>), wherein the Fe<SUP>3+</SUP> ions are replaced by the Bi<SUP>3+</SUP> ions to form CoBi<SUB><I>x</I></SUB>Fe<SUB>2−<I>x</I></SUB>O<SUB>4</SUB> ferrites, where <I>x</I> = 0.0, 0.05, 0.1, 0.15 or 0.2, has been investigated. The structural and morphological properties of undoped and doped ferrites, synthesized chemically through a self-igniting sol–gel method, are initially screened using X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy measurements. The changes in magnetic moment of ions, their coupling with neighboring ions and cation exchange interactions are confirmed from the Mössbauer spectroscopy analysis. The effect of Bi<SUP>3+</SUP>-doping on the magnetic properties of CoFe<SUB>2</SUB>O<SUB>4</SUB> ferrite is examined from the vibrating sample magnetometry spectra. Saturation magnetization and coercivity values are increased initially and then decreased, as result of Bi<SUP>3+</SUP>-doping. The obtained results with improved saturation magnetization (from 26.36 to 44.96 emu g<SUP>−1</SUP>), coercivity (from 1457 to 1863 Oe) and remanence magnetization (from 14.48 to 24.63 emu g<SUP>−1</SUP>) on 0.1–0.15 mol Bi<SUP>3+</SUP>-doping of CoBi<SUB><I>x</I></SUB>Fe<SUB>2−<I>x</I></SUB>O<SUB>4</SUB> demonstrate the usefulness for magnetic recording and memory devices.</P> <P>Graphic Abstract</P><P>Bi<SUP>3+</SUP>-doping improves the saturation magnetization, coercivity and the remanence magnetization, which can be applied for magnetic recording and memory devices, of CoFe<SUB>2</SUB>O<SUB>4</SUB> ferrite. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5dt00156k'> </P>

      • KCI등재

        Enhanced polarization retention and softening in [001]-oriented Pb(Mg1/3Nb2/3)-PbTiO3 single crystals through corona poling

        Sun Jeong-Woo,Choi Woo-Jin,Yu Hye-Lim,Lee Sang-Goo,Ryu Jong Eun,Zate Temesgen Tadeyos,Jo Wook 한국세라믹학회 2024 한국세라믹학회지 Vol.61 No.5

        This study investigates the electrical properties of Pb(Mg1/3Nb2/3)-PbTiO3 (PMN-PT) single crystals subjected to corona poling (CorP) compared to direct current poling (DCP) and alternating current poling (ACP) methods. The results revealed the superiority of CorP in terms of polarization retention and softening. The corona-poled sample demonstrated a higher depolarization temperature (Td ~ 100 ℃) than DCP or ACP methods (Td ~ 90 ℃), indicating improved polarization stability at elevated temperatures. Furthermore, lowering of the coercive field (EC) in CorP samples suggests CorP makes the materials electrically softer. These advantages stem from the noncontact nature of the CorP method, which minimizes the risk of localized dielectric breakdown, and ensures a uniform electric field distribution. This work sheds a light on the potential of CorP as a promising technique for enhancing the electrical performance of materials in piezoelectric applications.

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