Linear and Nonlinear Dielectric Ceramics for High-Power Energy Storage Capacitor Applications

Peddigari, Mahesh,Palneedi, Haribabu,Hwang, Geon-Tae,Ryu, Jungho The Korean Ceramic Society 2019 한국세라믹학회지 Vol.56 No.1

Dielectric materials with inherently high power densities and fast discharge rates are particularly suitable for pulsed power capacitors. The ongoing multifaceted efforts on developing these capacitors are focused on improving their energy density and storage efficiency, as well as ensuring their reliable operation over long periods, including under harsh environments. This review article summarizes the studies that have been conducted to date on the development of high-performance dielectric ceramics for employment in pulsed power capacitors. The energy storage characteristics of various lead-based and lead-free ceramics belonging to linear and nonlinear dielectrics are discussed. Various strategies such as mechanical confinement, self-confinement, core-shell structuring, glass incorporation, chemical modifications, and special sintering routes have been adopted to tailor the electrical properties and energy storage performances of dielectric ceramics. In addition, this review article highlights the challenges and opportunities associated with the development of pulsed power capacitors.

Boosting the Recoverable Energy Density of Lead-Free Ferroelectric Ceramic Thick Films through Artificially Induced Quasi-Relaxor Behavior

Peddigari, Mahesh,Palneedi, Haribabu,Hwang, Geon-Tae,Lim, Kyung Won,Kim, Ga-Yeon,Jeong, Dae-Yong,Ryu, Jungho American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.24

<P>Dielectric ceramic film capacitors, which store energy in the form of electric polarization, are promising for miniature pulsed power electronic device applications. For a superior energy storage performance of the capacitors, large recoverable energy density, along with high efficiency, high power density, fast charge/discharge rate, and good thermal/fatigue stability, is desired. Herein, we present highly dense lead-free 0.942[Na<SUB>0.535</SUB>K<SUB>0.480</SUB>NbO<SUB>3</SUB>]-0.058LiNbO<SUB>3</SUB> (KNNLN) ferroelectric ceramic thick films (∼5 μm) demonstrating remarkable energy storage performance. The nanocrystalline KNNLN thick film fabricated by aerosol deposition (AD) process and annealed at 600 °C displayed a quasi-relaxor ferroelectric behavior, which is in contrast to the typical ferroelectric nature of the KNNLN ceramic in its bulk form. The AD film exhibited a large recoverable energy density of 23.4 J/cm<SUP>3</SUP>, with an efficiency of over 70% under the electric field of 1400 kV/cm. Besides, an ultrahigh power density of 38.8 MW/cm<SUP>3</SUP> together with a fast discharge speed of 0.45 μs, good fatigue endurance (up to 10<SUP>6</SUP> cycles), and thermal stability in a wide temperature range of 20-160 °C was also observed. Using the AD process, we could make a highly dense microstructure of the film containing nano-sized grains, which gave rise to the quasi-relaxor ferroelectric characteristics and the remarkable energy storage properties.</P> [FIG OMISSION]</BR>

Impact of User Ratings on Mobile Apps Due Fault and Change Proneness in API

Rohith Peddigari 사단법인 미래융합기술연구학회 2015 아시아태평양융합연구교류논문지 Vol.1 No.2

An Application Programming Interface (API) is a set of protocols used for building a software. The mobile application (apps) market is growing very fast with the number of mobile apps increasing at a rapid rate in the recent few years. It is natural that users’ tend to use the apps that are less prone to bugs, crashes etc. which demands the developers to create a reliable app in order to sustain in the competent mobile application market. In this paper we study about how the fault-proneness and change-proneness of APIs used have a direct impact on the users’ ratings of the mobile apps. It is no surprise that the apps whose API’s are less prone to faults and changes receive higher ratings than the ones in which the frequency of the faults and changes are relatively higher.

Lead-free piezoelectric materials and composites for high power density energy harvesting

Maurya, Deepam,Peddigari, Mahesh,Kang, Min-Gyu,Geng, Liwei D.,Sharpes, Nathan,Annapureddy, Venkateswarlu,Palneedi, Haribabu,Sriramdas, Rammohan,Yan, Yongke,Song, Hyun-Cheol,Wang, Yu U.,Ryu, Jungho,Pri Published for the Materials Research Society by th 2018 Journal of materials research Vol.33 No.16

<▼1><B>Abstract</B><P/></▼1><▼2><P>In the emerging era of Internet of Things (IoT), power sources for wireless sensor nodes in conjunction with efficient and secure wireless data transfer are required. Energy harvesting technologies are promising solution toward meeting the requirements for sustainable power sources for the IoT. In this review, we focus on approaches for harvesting stray vibrations and magnetic field due to their abundance in the environment. Piezoelectric materials and piezoelectric-magnetostrictive [magnetoelectric (ME)] composites can be used to harvest vibration and magnetic field, respectively. Currently, such harvesters use modified lead zirconate titanate (or lead-based) piezoelectric materials and ME composites. However, environmental concerns and government regulations require the development of a suitable lead-free replacement for lead-based piezoelectric materials. In the past decade, several lead-free piezoelectric compositions have been developed and demonstrated with promising piezoelectric response. This paper reviews the significant results reported on lead-free piezoelectric materials with respect to high-density energy harvesting, covering novel processing techniques for improving the piezoelectric response and temperature stability. The review of the state-of-the-art studies on vibration and magnetic field harvesting is provided and the results are used to discuss various strategies for designing high-performance energy harvesting devices.</P></▼2>

Effects of Thickness Ratio in Piezoelectric/Elastic Cantilever Structure on the Piezoelectric Energy Harvesting Performance

Ga-Yeon Kim,Mahesh Peddigari,Kyung-Won Lim,Geon-Tae Hwang,Woon-Ha Yoon,HongSoo Choi,이정우,류정호 대한금속·재료학회 2019 ELECTRONIC MATERIALS LETTERS Vol.15 No.1

The energy harvesting by utilizing the piezoelectric eff ect for the conversion of oscillatory mechanical energy to usefulelectrical energy has been promising for self-powered devices. The output power can be controlled by designing the sizeand shape of the constituents of the harvester. This study demonstrates the eff ect of Ti plate (elastic layer) thickness on theresonant frequency, neutral axis position, vibration amplitude and energy harvesting performance of the cantilever structuredpiezoelectric energy harvester (PEH). Here, the each harvester had the same dimensions of piezoelectric layer and the sameproof mass position at the end of the cantilever while it had the diff erent elastic layer thicknesses (70–300 μm). The analysisrevealed that the output power showed the opposite trend in vibration amplitude with varying the elastic layer thickness. Among all of the PEHs, the confi guration with the largest elastic layer thickness (300 μm) exhibited a maximum output powerof 48 μW at 76 Hz under 0.2 g acceleration, despite of the smallest vibration amplitude and the highest resonant frequency. The outcomes suggest that the thickness ratio of the piezoelectric and elastic layers should be optimized to realize the bestharvesting performance.

PMN-PZT/Ni 자기-전기 복합체에서 단결정 압전 모드에 따른 자기장 감도 특성

박소정 ( Sojeong Park ),( Mahesh Peddigari ),류정호 ( Jungho Ryu ) 한국센서학회 2020 센서학회지 Vol.29 No.1

Magnetoelectric (ME) composites were designed using the PMN-PZT single crystal and Ni foils; the properties and magnetic-field sensitivities of ME composites with different piezoelectric vibration modes (i.e., 31, 32, and 36 modes that depend on the crystal orientation of the single crystal) were compared. In the off-resonance condition, the ME coupling properties of the ME composites with the 32 and 36 piezoelectric vibration modes were better than those of the ME composites with the 31 piezoelectric vibration mode. However, in the resonance condition, the ME coupling properties of the ME composites were almost similar, irrespective of the piezoelectric vibration mode. Additionally, in the off-resonance condition (at 1 kHz), the magnetic-field sensitivity of the ME composites with the 36 piezoelectric vibration mode was up to 2 nT and those of the ME composites with the 31 and 32 piezoelectric vibration modes were up to 5 nT. These magnetic-field sensitivities are similar to those offered by conventional high-sensitivity magnetic-field sensors; the potential of the proposed sensor to replace costly and bulky high-sensitivity magnetic field sensors is significant.

Energy storage characteristics of {001} oriented Pb(Zr_0.52Ti_0.48)O₃ thin film grown by chemical solution deposition

Lim, Kyung-Won,Peddigari, Mahesh,Annapureddy, Ventateswarlu,Hwang, Geon-Tae,Choi, Jong-Jin,Kim, Ga-Yeon,Yi, Sam Nyung,Ryu, Jungho Elsevier 2018 THIN SOLID FILMS - Vol.660 No.-

<P><B>Abstract</B></P> <P>Capacitors with high energy density and high discharging rate have been attracting attention for electric vehicles and military applications, in which the rapid discharge of large amounts of electric energy is required. Since ferroelectric thin film of perovskite structure has different polarization characteristics according to its crystallographic orientation, the charged energy density can be tailored. In this study, we investigated the effect of the crystallographic orientation of Pb(Zr<SUB>0.52</SUB>Ti<SUB>0.48</SUB>)O<SUB>3</SUB> (PZT) thin films grown by chemical solution deposition on the energy storage capability and discharging rate. The {001} and randomly oriented PZT thin films were prepared and their dielectric and ferroelectric properties, stored energy densities, and discharging rates were characterized. The storage energy density of {001}-oriented film was found to be superior to that of other films, while its efficiency was nearly the same. It is believed that {001} oriented PZT thin film has potential for use in high performance capacitors with large energy density.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly {001}-oriented ferroelectric PZT thin film grown by chemical solution deposition </LI> <LI> Energy storage density of the {001}-oriented PZT film reached 8.4 J/cm<SUP>3</SUP> at 80 MV/m </LI> <LI> Discharge time of the {001}-oriented PZT film was 4.1 μs at 27 MV/m </LI> </UL> </P>

A high output magneto-mechano-triboelectric generator enabled by accelerated water-soluble nano-bullets for powering a wireless indoor positioning system

Lim, Kyung-Won,Peddigari, Mahesh,Park, Chan Hee,Lee, Ha Young,Min, Yuho,Kim, Jong-Woo,Ahn, Cheol-Woo,Choi, Jong-Jin,Hahn, Byung-Dong,Choi, Joon-Hwan,Park, Dong-Soo,Hong, Jae-Keun,Yeom, Jong-Taek,Yoon, The Royal Society of Chemistry 2019 ENERGY AND ENVIRONMENTAL SCIENCE Vol.12 No.2

<P>A high-performance magneto-mechano-triboelectric nanogenerator (MMTEG) was demonstrated by introducing accelerated water-soluble nano-bullet modified nanostructures to convert a gentle magnetic field into electric energy for powering an indoor wireless positioning system. NaCl salt nanoparticles were accelerated by an aerosol deposition (AD) process to collide on a perfluoroalkoxy (PFA) film with a high kinetic energy for the formation of a complicated nanomorphology on the triboelectric active surface. Under an alternating current (AC) magnetic field of 7 Oe, the MMTEG generated an open-circuit peak-to-peak voltage (<I>V</I>pp) and a short-circuit current of 708 V and 277 μA, respectively. The harvesting device also presented a maximum peak power of 21.8 mW as well as a continuous AC output power of 4.8 mW (4.8 mJ per second). A self-powered indoor IoT positioning system was constructed by integrating the MMTEG, a power managing circuit, a storage element, and an IoT Bluetooth beacon. The electric energy from the MMTEG device enabled continuous operation of a beacon device, and we successfully confirmed the accurate location of the installed wireless positioning system, subsequently resulting in transmission of our indoor position to the main monitoring computer. Lastly, the MMTEG generated an open-circuit <I>V</I>pp and a short-circuit current of 330 V and 23 μA, respectively, near a 60 Hz power cable connected to home appliances, which were large enough to turn on 108 blue light emitting diodes (LEDs).</P>

High Energy Storage Properties and Electrical Field Stability of Energy Efficiency of (Pb0.89La0.11)(Zr0.70Ti0.30)0.9725O3 Relaxor Ferroelectric Ceramics

Ajeet Kumar,So Hyeon Kim,Mahesh Peddigari,Dong-Hyuk Jeong,Geon-Tae Hwang,Jungho Ryu 대한금속·재료학회 2019 ELECTRONIC MATERIALS LETTERS Vol.15 No.3

In this study, electric energy storage properties of (Pb 0.89 La 0.11 )(Zr 0.70 Ti 0.30 ) 0.9725 O 3 (PLZT 11/70/30) relaxor ceramics wereinvestigated. XRD pattern and SEM image confi rms the perovskite phase and dense structure without any secondary phasesand pores, respectively. Room temperature dielectric constant was found to be high (~ 3520) with low dielectric loss (~ 0.03). Dielectric constant changes with temperature confi rm the relaxor ferroelectric behaviour of PLZT ceramics. Diff erentparameters such as degree of deviation ( ΔT m ) from the Curie–Weiss law, the diff useness of the phase transition ( ΔT diff ) anddegree of diff useness ( γ ), which are related to the relaxor nature of ferroelectrics were calculated. With the remarkably slimpolarization versus electric fi eld hysteresis loops even at high applied electric fi eld, high energy storage of 0.85 J/cm 3 andvery high energy storage effi ciency of 92.9% were obtained from the PLZT ceramics. These values suggest that the PLZT11/70/30 composition can be used for the pulse driving energy storage applications.

Dielectric, Ferroelectric, Energy Storage, and Pyroelectric Properties of Mn-Doped (Pb_0.93La_0.07)(Zr_0.82Ti_0.18)O₃ Anti-Ferroelectric Ceramics

Kumar, Ajeet,Yoon, Jang Yuel,Thakre, Atul,Peddigari, Mahesh,Jeong, Dae-Yong,Kong, Young-Min,Ryu, Jungho The Korean Ceramic Society 2019 한국세라믹학회지 Vol.56 No.4

In this study, the dielectric and polarization properties of manganese (Mn% = 0.0, 0.1, 0.2, 0.5) doped (Pb_0.93La_0.07)(Zr_0.82Ti_0.18)O₃ (PLZT 7/82/18) anti-ferroelectric ceramics were studied for energy storage capacitor and pyroelectric applications. A systematic investigation demonstrated that the electric properties of PLZT 7/82/18 ceramics are affected significantly by the Mn-doping content. A maximum dielectric constant of ~ 2,128 at 1 kHz was found for 0.1% Mn-doped PLZT ceramics with a low dielectric loss of 0.018. The bipolar polarization versus electric field (P-E) hysteresis loops were traced for all compositions showing a typical anti-ferroelectric nature. The breakdown field was found to decrease with Mn-doping. The energy storage density and efficiency were found to be 460 J/㎤ and ~ 63%, respectively, for 0.2% Mn-doped PLZT ceramics. The pyroelectric coefficient of PLZT ceramics shows an increase based on the amount of Mn-doping.