Papers by Keyword: Perovskite Structure

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Authors: Francesca Zurlo, Elisabetta di Bartolomeo, A. d’Epifanio, Valeria Felice, Isabella Natali Sora, S. Licoccia
Abstract: A “cobalt free” cathode material with stoichiometric composition La0.8Sr0.2Fe0.8Cu0.2O3 (LSFCu) was specifically developed for La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM) electrolyte. The chemical stability with LSGM electrolyte was investigated by structural and morphological analysis. The electrochemical properties of LSFCu dense pellets were investigated in the temperature range 600–750°C by electrochemical impedance spectroscopy (EIS). LSFCu/LSGM/LSFCu symmetrical cells were prepared and Area Specific Resistance (ASR) values, directly depending on the rate limiting step of the oxygen reduction reaction, were evaluated. Fuel cells were prepared using LSFCu as cathode material on LSGM pellet and electrochemical tests were performed and compared to similar fuel cells prepared by using commercial La0.6Sr0.4Fe0.8Co0.2O3(LSFCo). The maximum current density and power density recorded for LSFCu and LSFCo were comparable demonstrating that Cu can be used as substitutes Co.
Authors: Piotr Dulian, Wojciech Bąk, Krystyna Wieczoek-Ciurowa, Czesław Kajtoch
Abstract: This paper considers the mechanochemical synthesis of advanced electroceramic material with a perovskite structure as well as this method as an effective way for modifying the properties of BaTiO3 by substitution of foreign ions. Dielectric properties mainly para-ferroelectric phase transitions in Ba1-xSrxTiO3 solid solutions (0.0 x 0.6) are presented.
Authors: N. Sankara Subramanian, K. Kathiresan
Abstract: Lead zirconium titanate thinfilms have been prepared by the cost effective spin coating method on glass and stainless steel substrate with the following optimized coating parameters, (1) Coating period of the sol - 4th to 5th day, (2) Spin rate – 2500 rpm, (3) Spin time – 10 Sec, (4) Number of coating – 8, (5) Heat treatment temperature - 450 °C and (6) Heat treatment duration – 8 Sec. The developed PZT thinfilms are annealed between the temperature 200 oC and 1000 oC. The XRD profile of all the PZT thinfilms annealed at different temperatures confirm polycrystalline perovskite structure with preferred orientation along (110) plane. The thermal conductivity measurement of the PZT thinfilm samples annealed at different temperatures illustrates a non linear decline with the increase in annealing temperature. The sheet resistance and resistivity measurement of the PZT specimen show a maximum value of 15.6 MΩ/ and 13.7 x 10-6 Ω-cm, for the PZT thinfilm annealed at the temperature 1000 oC. Hardness of the PZT thinfilms annealed at different temperatures is measured in the Vickers scale. A maximum hardness of 740 VHN and a minimum hardness of 220 VHN is observed for the PZT thinfilm annealed at the temperature 1000 °C and 300 °C respectively. The 2D and 3D AFM micrograph of the PZT thinfilm annealed at 1000 °C illustrates fine grain growth, smooth and uniform surface pattern with large number of grain boundaries.
Authors: Ling Peng, Qi Bin Liu
Abstract: o improve the electrical properties of PSZT piezoelectric ceramics, a ceramic powder Pb0.94Sr0.06(Zr0.52Ti0.48)O3 (PSZT) with Nb2O5 was designed. The power was prepared by solid state sintering. The surface structure of sample was characterized using SEM, and the crystal structure of the sample was examined by XRD. The capacitance and dielectric loss of sample was measured by Tonghui Electronics TH2618 capacitor tester. The result of microstructure and electrical properties show that Nb2O5 inhibit crystal growth when the contents of Nb2O5 is less than 0.5.wt%, but excessive Nb2O5 cause pyrochlore phase producing while the contents of Nb2O5 more than 0.5wt.% . The excellent piezoelectric properties are achieved in the ceramics with 0.5wt.% Nb2O5:εr=1504,tanδ=0.0065,d33=336pC/N, kp=0.562.
Authors: Imran Nazir Qureshi, Muhammad Shahid, A. Nusair Khan
Abstract: Yttria stabilized zirconia thermal barrier coating (TBC) along with CoNiCrAlY bondcoat was deposited using air plasma spray on Inconel-X750 superalloy. The coated samples were exposed at 9500C in a mixture of Na2SO4 and V2O5. The exposed specimens were investigated using XRD and SEM. The formation of spinel and perovskite structures was revealed at the interface of topcoat and the bondcoat. XRD analyses of the samples confirmed phase transformation of the tetragonal zirconia into monoclinic zirconia and yttrium vanadate.
Authors: Ke Lan Yan, Run Hua Fan, Min Chen, Kai Sun, Xu Ai Wang, Qing Hou, Chuan Bing Cheng
Abstract: The phase structure, and electrical and magnetic properties of La0.7Sr0.3MnO3 (LSMO)-x Ag (x is the mole ratio, x=0, 0.3, 0.5) composite were investigated. It is found that the sample with x=0 is single phase; the samples with x=0.3 and 0.5 present three phase composite structure of the manganese oxide and Ag. With the increasing of Ag content, the grain size of the samples increases and the grain boundaries transition from fully faceted to partially faceted. The permittivity of spectrum (10 MHz - 1 GHz) and the theoretical simulation reveal that the plasma frequency fp increase with Ag content, due to the increasing of free electron concentration, which is further supported by the enhancement of conductivity. While for the permeability (μr'), the μr' decrease with the increasing of Ag content at low frequency range (f < 20 MHz), while at the relative high frequency range (f > 300 MHz), the μr' increased with Ag content. Therefore, the introduction of elemental Ag resulted in a higher μr' at the relative high frequency range.
Authors: Masaaki Ichiki, Lulu Zhang, Zhen Yang, Tsuyoshi Ikehara, Ryutaro Maeda
Authors: Masaaki Ichiki, Harumi Furue, Ryosuke Kogo, Yasushi Morikawa, Kazuhiro Nonaka, Takeshi Kobayashi, Chiaki Endo, Ryutaro Maeda
Authors: Katsuyoshi Kakinuma, Hiroshi Yamamura, Tooru Atake
Abstract: We have discovered a high oxide ion conductor within the perovskite-type (Ba1-x-ySrxLay)InO2.5+y/2 solid-solution system. The system was derived from brownmillerite-type Ba2In2O5, which possessed a ordered oxide ion vacancies. When we doped La3+ into the Ba site, the vacancy changed to a disordered state. The oxide ion conductivity increased with the amount of doped La3+, reaching a maximum value of 0.12 (S/cm) at 800 oC in (Ba0.3Sr0.2La0.5)InO2.75, a level exceeding that of yttria-stabilized zirconia. The oxide ion conductivity of this system was strongly dependent on the unit cell free volume, which appears to be the key parameter governing oxide ion mobility.
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