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  • 1
    Electronic Resource
    Electronic Resource
    Processing, microstructure, and electric properties of buried resistors in low-temperature co-fired ceramics (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 4175-4182 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electrical properties of ruthenium oxide based devitrifiable resistors embedded within low-temperature co-fired ceramics were investigated from −100 °C to 100 °C. Special attention was given to the processing conditions and their effects on resistance and temperature coefficient of resistance (TCR). Results indicate that within this temperature range the conductance for these buried resistors is limited by tunneling of charge carriers through the thin glass layer between ruthenium oxide particles. A modified version of the tunneling barrier model is proposed to account for the microstructure ripening observed during thermal processing. The model parameters determined from curve fitting show that charging energy (i.e., the energy required for a charge carrier to tunnel through the glass barrier) is strongly dependent on particle size and particle–particle separation between ruthenium oxide grains. Initial coarsening of ruthenium oxide grains was found to reduce the charging energy and lower the resistance. However, when extended ripening occurs, the increase in particle–particle separation increases the charging energy, reduces the tunneling probability and gives rise to a higher resistance. The tradeoff between these two effects results in an optimum microstructure with a minimum resistance and TCR. Furthermore, the TCR of these buried resistors has been shown to be governed by the magnitude of the charging energy. Model parameters determined by our analysis appear to provide quantitative physical interpretations to the microstructural changes in the resistor, which in turn, are controlled by the processing conditions. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1353563
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  • 2
    Electronic Resource
    Electronic Resource
    Structure of the defect perovskite [Pb0.85La0.10]TiO3 between 10 and 1023 K (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 1683-1689 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structure of the defect perovskite [Pb0.85(D'Alembertian)0.05La0.10]TiO3 was investigated by powder neutron and x-ray diffraction and by specific heat measurements made at various temperatures. Refinement of the structure by the Rietveld technique at 10, 200, and 300 K from time-of-flight powder neutron diffraction data revealed no low temperature transitions from the ferroelectric tetragonal (4mm) phase. On average, the oxygen octahedral framework of the parent compound was not distorted by the incorporation of lanthanum and vacancies, and the ratio of cation displacements along the polar axis was comparable to that observed for pure PbTiO3. However, the material showed a large nonuniform strain that increased with decreasing temperature. As a result, the effective coupling between the uniform tetragonal deformation and cation displacement was reduced. X-ray diffraction and specific heat measurements at 298–1023 K indicated that the ferroelectric m3m→4mm transition was nearly tricritical and took place at 565 K. The diffuse nature of the transition was reflected in a temperature-dependent x-ray profile broadening and anomalous excess specific heat that persisted to ≈775 K, close to the phase transition temperature of pure lead titanate. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358858
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  • 3
    Electronic Resource
    Electronic Resource
    A New Metastable Thin-Film Strontium Tantalate Perovskite (1999)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 82 (1999), 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: A novel Sr-Ta-O perovskite phase has been synthesized by a chemical preparation route and crystallized on Pt-coated SiO2/Si substrates at ∼800°C. The phase was isolated as a thin film only (not as a polycrystalline powder) and is likely metastable. SEM, EDS, XRD, EPR, and Raman analyses suggest this phase is cation-deficient, having the formula SrxTaxO3 (x∼ 0.85). X-ray Rietveld analysis indicates the structure to be a simple-cubic perovskite-type lattice; Pm3m space group, a= 3.955(2) Å, V= 61.86 Å3, Z= 1. Electrical property measurements recorded a dielectric constant k of ∼16 with a tan delta of 0.04.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1999.tb02047.x
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  • 4
    Electronic Resource
    Electronic Resource
    Neo-Pentoxide Precursor Synthesis, Solution Preparation, and Electronic Properties of (Ba,Sr)TiO3 Thin Films Derived from a Solution Route (1999)
    Springer
    Journal of sol gel science and technology 16 (1999), S. 47-55 
    Details
    ISSN: 1573-4846
    Keywords: BST ; sol-gel ; thin films ; tunable dielectric
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We have recently isolated the neo-pentoxide (HOCH2CMe3, ONp) derivatives of Ba, Sr, and Ti as Ba4(ONp)8(HONp)6(py)2, Sr5(O)(ONp)8(Solv)5 (Solv = solvent), and Ti2(ONp)8, respectively. The combination of these precursors were found to be readily soluble in a wide range of solvents and thus were excellent candidates for preparation of barium strontium titanate ((Ba,Sr)TiO3 or BST) thin films using spin-cast deposition techniques. The highest quality BST films for this system were generated from ternary mixtures dissolved in either pyridine or pyridine/toluene. By in situ VT-GIXRD analysis it was determined that the perovskite phase of BST was readily formed at 650°C. The electronic properties of films crystallized at 700°C indicated that the thin films (300 nm) possessed a dielectric constant of 120 (tan δ = 0.03) with a tunability of 29% at ±10 V. 300 nm films (700°C) which had been generated from a standard BST solution modified with a novel tridentate ligand, had a higher dielectric constant of 180 and a tunability of 35% at ±10 V. The collective characteristics of these precursors offer an attractive alternative to the more complex, less stable sol-gel precursors currently in use.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008730801392
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  • 5
    Electronic Resource
    Electronic Resource
    Microstructure and Phase Development of Buried Resistors in Low Temperature Co-fired Ceramic (2000)
    Springer
    Journal of electroceramics 5 (2000), S. 217-223 
    Details
    ISSN: 1573-8663
    Keywords: microstructure ; buried resistor ; LTCC ; XRD ; SEM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Embedded resistor circuits have been generated with the use of a Micropen system, Ag conductor paste (DuPont 6142D), a new experimental resistor ink from DuPont (E84005-140), and Low Temperature Co-fired Ceramic (LTCC) green tape (DuPont A951). Sample circuits were processed under varying peak temperature ranges (835°C–875°C) and peak soak times (10 min–720 min). Resistors were characterized by SEM, TEM, EDS, and high-temperature XRD. Results indicate that devitrification of resistor glass phase to Celcian, Hexacelcian, and a Zinc-silicate phase occurred in the firing ranges used (835–875°C) but kinetics of divitrification vary substantially over this temperature range. The resistor material appears structurally and chemically compatible with the LTCC. RuO2 grains do not significantly react with the devitrifying matrix material during processing. RuO2 grains coarsen significantly with extended time and temperature and the electrical properties appear to be strongly affected by the change in RuO2 grain size.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026575428178
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