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  • 1
    Electronic Resource
    Electronic Resource
    Effect of neodymium (Nd) doping on the dielectric and ferroelectric characteristics of sol-gel derived lead zirconate titanate (53/47) thin films (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 2975-2984 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The results of the studies on the effect of rare earth Nd doping on the phase formation behavior and electrical properties of sol-gel derived Pb1.05(Zr0.53Ti0.47)O3 (PZT) thin films are presented. The perovskite phase is obtained up to 5 at. % doping and beyond that pyrochlore phase was found to coexist with the perovskite phase in all the films. The transition temperature of undoped lead zirconate titanate (PZT) film was found to be reduced with Nd doping. The Nd doped films also exhibited typical relaxor-type behavior and a diffuse phase transition, similar to that observed in relaxor materials. The introduction of Nd into the PZT lattice probably introduces disorder in the B site of ABO3 lattice, which causes the observed dielectric relaxation. Efforts were made to isolate the irreversible component contributions in low field dielectric and high field polarization switching behavior. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1391416
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  • 2
    Electronic Resource
    Electronic Resource
    Sol–gel derived grain oriented barium strontium titanate thin films for phase shifter applications (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 896-903 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In the present work process methodology was optimized to synthesize oriented barium strontium titanate (BST) (50/50) and (60/40) thin films on strontium titanate (100) and lanthanum aluminate (LAO) (100) substrates by using the chemical solution deposition technique. These films were characterized in terms of their phase formation behavior and structural growth characteristics using x-ray diffraction and atomic force microscopy. A tentative mechanism of the epitaxial growth has been proposed. Films were also characterized in terms of their dielectric properties. The high tunability and low dielectric loss of these films make them attractive for fabricating tunable dielectric devices. Accordingly, we have fabricated eight element coupled microstrip phase shifters and tested them in terms of their degree of phase shift and insertion loss characteristics. An insertion loss of 8.435 dB, phase shift in the order of 320° (2.6–14.5 V/μm) and κ factor (phase shift/dB of loss) of about 38.0°/dB was achieved in BST (60/40) films deposited on LAO (100) substrate which is comparable to the films grown by other film deposition techniques reported in the literature. The microstructure of the sol–gel derived films show surface porosity which may be responsible for the low dielectric strength of these films. Presently, we are studying the sintering mechanism and kinetics of these films in order to improve the density which is believed to further improve the phase shift and lower insertion loss to result in an improved tunability. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1378811
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  • 3
    Electronic Resource
    Electronic Resource
    Controlled micro oxidation of CdTe surface by laser irradiation: A micro-spectroscopic study (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 477-481 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A small area of CdTe single crystal within a spot of ≤2 μm diameter has been oxygenated under ambient conditions using 514.5 nm radiation from Ar+ laser. The oxygenation could be monitored using laser Raman spectroscopy, and it has been established that the asymmetric TeO2−3 ion is formed on the surface. The significance of the process for basic material science and technological applications in electronic and optoelectronic devices has been emphasized. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362779
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  • 4
    Electronic Resource
    Electronic Resource
    Temperature dependent Raman scattering in KTiOPO4 and KTiOAsO4 single crystals (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 3235-3240 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The longitudinal (LO) and transverse (TO) A1 vibrational modes have been measured between 30 and 1200 cm−1 as a function of temperature (30–1240 K) for both KTiOPO4 (KTP) and KTiOAsO4 (KTA). KTP and KTA exhibit an obviously different Raman spectra in the frequency region 400–650 cm−1 (with respect to KTA). This middle-frequency difference is attributed to the substitution ions in XO4 group (X=P or As) modifing the force constant of crystal. The relative intensities of the low-frequency bands increase dramatically with increasing temperature due to high mobility of K+ ion. There is no typical soft-mode like behavior in the measured frequency range. A higher symmetric structure taking place above Tc has been confirmed by the disappearance of the A1g(LO) stretching modes of TiO6 group. Comparison of each frequency belonging to the symmetry A1, A2, B1, and B2 measured along the [110] phonon direction shows complex difference. The vibrational frequencies of various symmetries were also obtained. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361270
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  • 5
    Electronic Resource
    Electronic Resource
    Micro-Raman and infrared reflectivity spectra of YBa2Cu3O7−δ deposited on LaAlO3 and stainless steel/inconel substrates (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 1108-1113 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The motivation for this article has been to try to understand the relative phenomenological differences between the behavior of the films of the high-temperature superconductors like YBa2Cu3O7−δ deposited on (a) relatively insulating substrates (like LaAlO3) through sputtering technique and (b) highly metallic substrates (like stainless steel and inconel) through laser ablation method. It is observed that the most prominent Raman bands on LaAlO3 substrate falling near 337, 440, and 503 cm−1 have half widths (defined as the full width at half the maximum intensity) of 22, 42, and 38 cm−1, respectively. The half width gets nearly doubled on the metallic substrates. These results have been attributed to the metal-superconductor interfacial interactions. Further, infrared reflectance measurements and the Kramers–Kronig analysis of the spectra reveal a large difference in the conductivity of the film on LaAlO3 compared to the films on metallic substrates. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360344
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  • 6
    Electronic Resource
    Electronic Resource
    Raman study of the network disorder in sputtered and glow discharge a-Si:H films (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 5120-5125 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have carried out a comprehensive study of the Raman spectra of a-Si:H films produced by the glow discharge (GD) and radio frequency sputtering (RFS) deposition techniques. The results show that the short-range disorder (bond-angle deviation), as measured by the width of the TO band (ΓTO), is larger in RFS than in GD a-Si:H films. The intermediate-range disorder (dihedral angle deviation), as measured by the ratio of the intensity of the TA band to that of the TO band (ITA/ITO), is generally larger in RFS than in GD a-Si:H films. However, while the ITA/ITO values of RFS films remain relatively close to those of GD films when the interior is probed, the near surface of RFS films shows much larger values evidencing the existence of a significant disorder gradient along the growth axis. Together, these results indicate that the network order and homogeneity of RFS amorphous silicon is lower than those of GD for substrate temperatures that produce the hydrogenated material. These structural differences are interpreted in terms of the differences between the two film growth processes and are believed to be the reason for the poorer transport properties of RFS a-Si:H films. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359743
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  • 7
    Electronic Resource
    Electronic Resource
    Raman spectroscopy and x-ray diffraction of PbTiO3 thin film (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 1920-1925 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A PbTiO3 thin film prepared on silicon substrate by sol-gel technique has been studied by micro-Raman spectroscopy and x-ray diffraction (XRD). The spectra, in comparison to the single crystal work, show high background in the low frequency region and Raman lines are broader, thus revealing the polycrystalline nature of the film. The frequencies of the Raman bands in the film are clearly shifted to lower frequencies compared to the corresponding ones in the single crystal or powder forms. This phenomenon is similar to the hydrostatic pressure effect on the Raman lines of PbTiO3 single crystal. The film, therefore, has grains under stress. This stress is caused by nonequilibrium defects and diffusion at the interface. Measurements at different film positions showed variations in the frequency and width of the Raman bands which are associated with the stress and grain size inhomogeneities. The measured shift in the Raman frequencies suggests grain sizes ≤1 μm. XRD indicates grain size of around 22 nm and an average stress around 1.3 GPa, which was determined using the measured shift for the c-lattice constant. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360229
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  • 8
    Electronic Resource
    Electronic Resource
    Influence of Precursor Solutions on the Ferroelectric Properties of Sol-Gel-Derived Lanthanum-Modified Lead Titanate (PLT) Thin Films (2004)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 87 (2004), 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: Precursor chemistry was found to have a dominant effect on the electrical properties of sol-gel-derived Pb0.85La0.15TiO3 (PLT15) thin films prepared using different precursor sources for lanthanum, namely, lanthanum acetate dissolved in acetic acid (LAA) and lanthanum 2-methoxyethoxide in 2-methoxyethanol (LMM). The LMM-derived PLT15 films had lower dielectric constants (KLMM= 394, KLAA= 548, measured at 100 kHz, applying 500 mV oscillation voltage), poorer polarization hysteresis characteristics, and higher leakage current densities (JLMM∼ 1.5 × 10−7 A/cm2, JLAA∼ 2 × 10−9 A/cm2, measured at 10 kV/cm field). Differential thermal analysis (DTA) and thermogravimetric analysis (TGA) measurements in conjunction with Fourier transformed infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses indicate that better removal of C–O moieties are the key step to yield improved electrical properties in these films. Possibly, C–O moieties reduce the metallic oxides to their corresponding metals and the presence of the metallic constituent(s) (e.g., lead), in turn deteriorate the electrical properties. In line with these postulations it was found that, when the pyrolysis temperature is increased from 450° to 550°C, the organic contents of LMM-derived films are reduced and their electrical properties are indeed comparable to that of the LAA-derived films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1551-2916.2004.00384.x
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  • 9
    Electronic Resource
    Electronic Resource
    Structural and electrical characteristics of Pb0.90La0.15TiO3 thin films on different bottom electrodes (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 5637-5643 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pb0.90La0.15TiO3 (PLT15) thin films were deposited by the sol-gel method on Pt, Pt/Si, and RuO2 on Si and Pt/Si bottom electrodes. X-ray diffraction, micro-Raman spectroscopy, and atomic force microscopy techniques were used for structural characterization of these films. PLT15 films on different electrodes showed good surface morphology with dense and uniform microstructure. PLT15 films on solution derived RuO2 bottom electrodes show (100) preferred orientation of growth and result in larger crystallites. Films deposited on a Pt bottom electrode show sharp and intense Raman features indicating better crystallinity and insignificant film–electrode interactions. PLT15 film on a Pt bottom electrode exhibited higher dielectric constant (1300 at 100 kHz) and high values of Pm and Pr, 68 and 46 μC/cm2, respectively, compared to other electrodes. Films on a RuO2 bottom electrode showed relatively inferior dielectric and ferroelectric properties. The ac field dependence of dielectric permittivity at subswitching fields was fitted using the Rayleigh law. It was found that ∼22% of the total measured permittivity was due to irreversible domain wall displacement for the films on a Pt electrode. The reversible polarization components estimated from the capacitance–voltage (C–V) and quasistatic hysteresis measurements showed that Prev/Psat at Vmax for the case of Pt/Si (24%), was larger than that of Pt (11%) bottom electrodes. The observed results were correlated with the domain wall pinning at the disturbed film–electrode interface. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1365062
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  • 10
    Electronic Resource
    Electronic Resource
    Micro-Raman scattering and dielectric investigations of phase transition behavior in the BaTiO3–BaZrO3 system (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 8085-8091 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this study, the phase transition behavior of the BaTiO3–BaZrO3 system was studied using micro-Raman scattering and dielectric measurement techniques. BaZrxTi1−xO3 ceramics were prepared for x=0.00, 0.05, 0.08, 0.15, 0.20, and 1.00 compositions using a solid-state reaction technique. A single-phase perovskite structure of the ceramics was identified by the x-ray diffraction technique. The basic phase transition temperatures in these compositions were studied in the temperature range of 70–575 K. The tetragonal to cubic transition temperature was found to decrease with increasing Zr content. The orthorhombic to tetragonal transition temperature that increases with an initial increase in Zr content merges with the tetragonal–cubic transition for x≥0.15 compositions. Raman spectra of rhombohedral and orthorhombic phases could not be distinguished. Excellent agreement between the crystallographic transition temperatures obtained by both techniques suggested that Zr substituted octahedra were uniformly distributed in the material without introducing any mechanical stress. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1369399
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