Search Results - (Author, Cooperation:P. K. Davies)
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1Latest Papers from Table of Contents or Articles in PressI. Grinberg ; D. V. West ; M. Torres ; G. Gou ; D. M. Stein ; L. Wu ; G. Chen ; E. M. Gallo ; A. R. Akbashev ; P. K. Davies ; J. E. Spanier ; A. M. Rappe
Nature Publishing Group (NPG)
Published 2013Staff ViewPublication Date: 2013-11-12Publisher: Nature Publishing Group (NPG)Print ISSN: 0028-0836Electronic ISSN: 1476-4687Topics: BiologyChemistry and PharmacologyMedicineNatural Sciences in GeneralPhysicsPublished by: -
2Articles: DFG German National LicensesStaff View
ISSN: 1551-2916Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision MechanicsPhysicsNotes: The hexagonal perovskite, Ba8ZnTa6O24, was prepared in single-phase form and was found to be a stable secondary phase, formed as a result of the loss of ZnO from Ba(Zn1/3Ta2/3)O3 microwave dielectrics. The experimental and calculated X-ray patterns of Ba8ZnTa6O24 indicate it is isostructural with Ba8Ta6NiO24 with an 8H (cchc)2 close-packed BaO3 stacking sequence and the lattice parameters, a=10.0825(14), c=19.0587(38)Å. High-density ceramics of Ba8ZnTa6O24 could be prepared at temperatures considerably lower (1400°C) than those used to sinter pure Ba(Zn1/3Ta2/3)O3, and exhibit very good microwave dielectric properties with ɛ=30.5, Qf=62 300, and τf=+36 ppm/°C at 8.9 GHz.Type of Medium: Electronic ResourceURL: -
3Articles: DFG German National LicensesStaff View
ISSN: 1476-4687Source: Nature Archives 1869 - 2009Topics: BiologyChemistry and PharmacologyMedicineNatural Sciences in GeneralPhysicsNotes: [Auszug] In both olivine and spinel structures tetrahedral TO4 groups are isolated. Intermediate phases so far observed show a transition from olivine to low-pressure spinelloids (phase 1 and phase 2) having triple groups of corner-shared tetrahedra (T3O10). Phase 1 crystallizes in aluminate-rich samples. ...Type of Medium: Electronic ResourceURL: -
4Articles: DFG German National LicensesSynthesis and dielectric properties of pyrochlore solid solutions in the Bi2O3-ZnO-Nb2O5-TiO2 systemStaff View
ISSN: 1573-4803Source: Springer Online Journal Archives 1860-2000Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision MechanicsNotes: Abstract Phase studies of solid solutions based on (Bi1.5Zn0.5)(Ti1.5Nb0.5)O7 revealed extended regions of pyrochlore formation in the Bi2O3-ZnO-TiO2-Nb2O5 system. At room temperature and 1 MHz (Bi1.5Zn0.5)(Ti1.5Nb0.5)O7 has a high permittivity (κ′ = 200), low dielectric loss (tanδ 〈 1·10−4) and a temperature coefficient of the permittivity, τκ, = −1300 ppm/K. Pyrochlore solid solutions based on (Bi1.5Zn0.5)(Ti1.5Nb0.5)O7 can be formed with (Bi2−xZnx)(Ti2− x Nbx)O7 (0.35 ≤ x ≤ 1.0) and with (Bi1.5 Zn0.5−y/3Ti1.5+yNb0.5−2y/3) O7 (−1.5 ≤ y ≤ 0.75). Investigations of the dielectric characteristics showed that the high temperature dependence of the permittivity of (Bi1.5 Zn0.5)(Ti1.5Nb0.5)O7 can be significantly modified by changing the composition of the pyrochlore within these regions of solid solubility. Below room temperature several of these compositions also exhibit a diffuse frequency dependent maximum in their permittivity characteristic of a transition to a relaxor type ferroelectric state. A third region of high permittivity pyrochlores with (Bi1.5+2zZn0.25−z Ti2.25−z)O7 (0.0 ≤ z 〈 0.15) was also identified in the Bi2O3-ZnO-TiO2 sub system.Type of Medium: Electronic ResourceURL: