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  • 1
    Electronic Resource
    Electronic Resource
    Origin of line broadening in Co-substituted NiZnCu ferrites (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 6220-6222 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A systematic variation in linewidth with Co concentration at the X band (9.38 GHz) was observed in polycrystalline Co-substituted NiZnCu ferrites. Also, the temperature dependence of the linewidth and complex permeability were measured for two different Co concentrations. The linewidth shows a minimum with Co concentration. The contribution of porosity, magnetic anisotropy, and eddy current to line broadening was calculated. The line broadening due to eddy current was negligible and the line broadening due to porosity and magnetic anisotropy explain well the variation of linewidth with Co concentration. The temperature at which the linewidth increases rapidly increases with Co concentration. This temperature is consistent with the temperature of the second maximum peak in the temperature dependence of permeability. Therefore, the rapid increase in linewidth with temperature is attributed to the rapid increase in magnetocrystalline anisotropy of divalent cobalt ions. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372660
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  • 2
    Electronic Resource
    Electronic Resource
    Domain configuration and crystal structure of Pb(Zn1/3Nb2/3)O3–5%PbTiO3 crystals as a function of the electric-field direction (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 4474-4478 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The domain configuration of 0.95Pb(Zn1/3Nb2/3)O3–0.05PbTiO3 single crystals was investigated as a function of the applied electric-field direction with respect to the crystallographic orientation. A normal ferroelectric domain structure, which was not observable in virgin crystals (not exposed to electric field), appeared upon the electric-field (E-field) induced transition from the relaxor state to the normal ferroelectric state. After E-field was applied along the polar 〈111〉 direction and removed, a band-shaped domain configuration appeared as a result of subsequent depolarization. The depoled 〈111〉 crystal consisted of predominantly (110) domain boundaries, which represents the minimum energy domain state in rhombohedral ferroelectrics. In contrast, crystals must transform into the phase with the symmetry lower than rhombohedral, i.e., monoclinic structure, by an E-field application along 〈001〉. Domain boundaries in 〈001〉 poled crystals were indexed to be (001), being a favorable state for monoclinic ferroelectrics. The dependence of the domain configuration upon the E-field application direction could be explained using the relationship between the mechanical compatibility with respect to the ferroelectric strain and the crystal symmetry of a domain. The residual strain on domain boundaries in 〈001〉 crystals may inhibit crystals to recover the rhombohedral structure, resulting in a monoclinic ferroelectric crystal even upon the removal of the E-field. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1428094
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  • 3
    Electronic Resource
    Electronic Resource
    Phase transitions and dielectric properties in A-site ion substituted (Na1/2Bi1/2)TiO3 ceramics (A=Pb and Sr) (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 4538-4542 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dielectric permittivity of A-site ion substituted (Na1/2Bi1/2)TiO3(A=Pb,Sr) solid solutions has been investigated with the aid of structural analysis. As the addition of PT increased, the first order characteristics of the phase transition appeared. In contrast, additions of ST made the solid solution exhibit relaxor ferroelectrics behavior. Microscopic structural analysis revealed that the dielectric properties were determined by cation ordering which controlled the translational symmetry and domain configuration. In the NBT–PT solid solution, A-site cations were randomly redistributed and macrodomains formed. However, the addition of ST distributed A-site cations with local ordering and divided the domains of NBT into micropolar regions. The contrasting effects of the addition of the Pb and Sr cations on the dielectric properties of NBT are discussed in terms of the polarizability and the tolerance factors as they relate to the perovskite structure. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1435415
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of excess Bi2O3 on the ferroelectric properties of SrBi2Ta2O9 ceramics (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 2825-2829 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this study, the effect of bismuth content on phase-transition behavior, ferroelectric property, and crystal structure of strontium–bismuth–tantalate (SBT) ceramics was explored with the aid of εr(T), ferroelectric hysteresis loop, x-ray diffraction (XRD), and Raman spectroscopy. Both the phase-transition behavior and ferroelectric properties such as spontaneous polarization (Ps) showed a dependence on Bi content. The ferroelectric Curie temperature Tc, was found to decrease with increasing the Bi content and Ps was maximized when 2–3 mol % excess Bi2O3 was added. It was found that Raman spectroscopy and XRD can explain the Bi-content dependence of SBT ceramics. The frequency and the width of the mode below 60 cm−1 in Raman spectra revealed that a site exchange of Sr2+ and Bi3+ ions occurred. The formation of antisite defects was confirmed by the change in the intensity ratio of I(008)/I(105) in the XRD patterns. The calculation of structure factors showed it was also related to antisite defects (SrBi,BiSr). © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1286062
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  • 5
    Electronic Resource
    Electronic Resource
    Charged defects and ferroelectricity in (1−x)PbZrO3−x(Na1/2Bi1/2)TiO3 solid solution (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 368-371 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The crystal structure, dielectric/ferroelectric properties, and domain configuration of (1−x) PbZrO3−x(Na1/2Bi1/2)TiO3 solid solution with 0.14≤x≤0.4 were investigated using x-ray powder diffraction, D-E hysteresis, εr(T) measurements, and transmission electron microscopy. A sluggish transition from normal ferroelectric to relaxor state was observed as a function of composition. With an increasing amount of (Na1/2Bi1/2)TiO3, this transition was accompanied by changes in crystal structure (rhombohedral to pseudocubic), domain size and morphology (normal micron-size domain to polar nanodomain), and thermal phase transition behavior (normal ferroelectric transition to diffuse transition behavior with polarization relaxation). For intermediate compositions (i.e., x=0.25) between normal ferroelectric (x=0.16) and relaxor (x=0.4), a spontaneous relaxor-to-normal ferroelectric transition occurred at 80 °C in the εr(T) curve. It is suggested that this transition originates from the introduction of charged defects such as NaPb′ and BiPb•, resulting in the disturbance of long-range interactions among polar ordered BO6-octahedra and short-range structural order of charged defects (i.e., NaPb′−BiPb•). © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369457
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  • 6
    Electronic Resource
    Electronic Resource
    Microwave Dielectric Properties of Low-Fired Ba5Nb4O15 (2002)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 85 (2002), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of B2O3 on the sintering temperature and microwave dielectric properties of Ba5Nb4O15 has been investigated using X-ray powder diffraction, scanning electron microscopy, and a network analyzer. Interactions between Ba5Nb4O15 and B2O3 led to formation of second phases, BaNb2O6 and BaB2O4. The addition of B2O3 to Ba5Nb4O15 resulted in lowering the sintering temperature from 1400° to 925°C. Low-fired Ba5Nb4O15 could be interpreted by measuring changes in the quality factor (Q×f), the relative dielectric constant (ɛr), and the temperature coefficient of resonant frequency (τf) as a function of B2O3 additions. More importantly, the formation of BaNb2O6 provided temperature compensation. The microwave dielectric properties of low-fired Ba5Nb4O15 had good dielectric properties: Q×f= 18700 GHz, ɛr= 39, and τf= 0 ppm/°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2002.tb00525.x
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  • 7
    Electronic Resource
    Electronic Resource
    Roles of Ba/Ti Ratios in the Dielectric Properties of BaTiO3 Ceramics (2001)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 84 (2001), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of the Ba/Ti ratio on microstructure, dielectric/ferroelectric properties, and domain width was studied using optical microscopy, ɛ(T) curves, D–E hysteresis, and transmission electron microscopy. Although Ti-excess samples showed abnormal grain growth and a decrease of room-temperature permittivity due to a liquid phase at grain boundaries, its ferroelectric properties were similar to those of stoichiometric BaTiO3 ceramics. However, in Ba-excess samples, an increase of permittivity and ferroelectric properties different from those of stoichiometry were found. Changes in domain width and ferroelectric transition behavior indicated that the variation of dielectric properties was related to the internal stress. It is proposed that this internal stress originated from differences in the thermal expansion coefficient between the matrix and the second phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2001.tb00949.x
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  • 8
    Electronic Resource
    Electronic Resource
    Contribution of Structure to Temperature Dependence of Resonant Frequency in the (1 −x)La(Zn1/2Ti1/2)O3·xATiO3 (A = Ca, Sr) System (2001)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 84 (2001), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The crystal structure and microwave dielectric properties of the (1 −x) La(Zn1/2Ti1/2)O3·xSrTiO3 and (1 −x)La(Zn1/2Ti1/2)O3·xCaTiO3 system were investigated. X-ray powder diffraction showed that cation ordering disappeared atx〉 0.3 for both systems. However, infrared spectra demonstrated that short-range cation ordering could exist atx= 0.4. Permittivity and the temperature coefficient of the resonant frequency (τf) of both systems exhibited nonmonotonic variations with composition. Both systems exhibited a τf of zero at the same composition of x= 0.5 although the τf of SrTiO3 was about two times larger than that of CaTiO3. The behavior of the permittivity and τf were described by the tilting of oxygen octahedra and cation ordering. The relation between τf and cation ordering of La(Zn1/2Ti1/2)O3 was discussed in conjunction with the experimental results on metal halides. It is suggested that cation ordering induced a negative τf and suppressed the increase of permittivity for compositions between x= 0 to x= 0.5 for (1 −x)La(Zn1/2Ti1/2)O3·xSrTiO3 and (1 −x)La(Zn1/2Ti1/2)O3·xCaTiO3 systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2001.tb00737.x
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  • 9
    Electronic Resource
    Electronic Resource
    Preparation and Dielectric Properties of Low-Temperature-Sinterable (Zr0.8Sn0.2)TiO4 Powder (1998)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 81 (1998), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Low-temperature-sinterable (Zr0.8Sn0.2)TiO4 powders were prepared using 3 mol% Zn(NO3)2 additive and then compared with powders prepared using 3 mol% ZnO additive and no additives. Sintering at 1200°C for 2 h produced a dielectric ceramic with ρ= 98.6% of theoretical density (TD), ɛr= 38.4, Q×f (GHz) = 42000, and τf=−1 ppm/°C. Sintering at 1250°C resulted in an excellent dielectric with ρ= 99% of TD, epsilonr= 40.9, Q×f (GHz) = 49000, and τf=−2 ppm/°C. Scanning electron microscopy showed a microstructure with grains measuring 0.5 to 1 μm, and transmission electron microscopy revealed secondary phase in the grain boundaries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1998.tb02470.x
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  • 10
    Electronic Resource
    Electronic Resource
    Interaction of BiNbO4-Based Low-Firing Ceramics with Silver Electrodes (1998)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 81 (1998), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Several commercial silver electrode pastes have been evaluated for use with BiNbO4-based low-firing ceramics. After electrode application and subsequent cofiring, the electrode pattern on the ceramic was no longer visible. A bismuth-rich second phase was present at the electrode/BiNbO4 interface, and silver was detected in the second phase. Systematic X-ray diffractometry analysis of the mixtures between different silver pastes and doped/undoped BiNbO4 revealed an interaction between the silver and the BiNbO4. This reaction was responsible for the disappearance of the silver electrode patterns.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1998.tb02737.x
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