Lead titanate (PT) ceramics co-doped with 8 to 13 mol% Ni-Nb, by substituting titanium ions, were prepared by conventional ceramic method and the influence of Ni-Nb doping level on their morpho-structural, electromechanical and dielectric properties was investigated. Dense tetragonal PT ceramics were obtained for 8 to 12 mol% Ni-Nb co-doping. Lattice anisotropy decreased from 1.053 to 1.046 with increasing doping level. Large thickness coupling factors of 0.4 were obtained for 8, 11, and 12 mol% Ni-Nb. Large electromechanical anisotropy of 10 was obtained for 8 mol% Ni-Nb. It was found that Ni-Nb co-doping has both softening and hardening effects as a function of donor or acceptor behavior of different amounts of Ni-Nb. For 13 mol% Ni-Nb, segregation of a small amount of a secondary phase occurs, lattice constants and tetragonality significantly decrease and the resulting ceramic becomes very hard.
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Molecules
January 2023
Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Piazzale A. Moro 5, 00185 Rome, Italy.
The hydrogen/deuterium sorption properties of NiTiNb synthesized by the vacuum induction melting technique were measured between 400 and 495 °C for pressure lower than 3 bar. The Sieverts law is valid up to H(D)/M < 0.2 in its ideal form; the absolute values of the hydrogenation/deuteration enthalpy are ΔH(H) = 85 ± 5 kJ/mol and ΔH(D) = 84 ± 4 kJ/mol.
View Article and Find Full Text PDFJ Mol Model
December 2021
Department of Chemical & Materials Engineering, University of Nevada, Reno, Reno, NV, 89557, USA.
The demand for hydrogen is increasing due to commercialization of fuel cells. Palladium (Pd)-based crystalline membranes have been used for separation of hydrogen from a mixture of gases in coal-based power generation process. However, very high cost of Pd has prompted to explore inexpensive alternative alloys.
View Article and Find Full Text PDFMaterials (Basel)
August 2021
Department of Physics, Higher Polytechnic School, Campus Montilivi s/n, University of Girona, 17003 Girona, Spain.
Two nanocrystalline ferromagnetic alloys of the Fe-Co-Nb-B system have been produced by mechanical alloying (MA). Their microstructure, thermal behavior and magnetic response were checked by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and vibrating sample magnetometry (VSM). After 80 h of MA, the alloys were nanostructured (bcc-Fe(Co)-rich phase).
View Article and Find Full Text PDFInt J Mol Sci
February 2015
Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan; E-Mail:
The electronic transport behaviors of (Ni(0.39)Nb(0.25)Zr(0.
View Article and Find Full Text PDFIEEE Trans Ultrason Ferroelectr Freq Control
September 2009
National Institute of Materials Physics, Bucharest-Magurele, Romania.
Lead titanate (PT) ceramics co-doped with 8 to 13 mol% Ni-Nb, by substituting titanium ions, were prepared by conventional ceramic method and the influence of Ni-Nb doping level on their morpho-structural, electromechanical and dielectric properties was investigated. Dense tetragonal PT ceramics were obtained for 8 to 12 mol% Ni-Nb co-doping. Lattice anisotropy decreased from 1.
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