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  • 1
    Electronic Resource
    Electronic Resource
    Laser-induced heating of nanocrystals embedded in glass matrices (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 5963-5966 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Laser-induced heating of nanocrystals embedded in silicate glass matrices has been studied by photoluminescence and Raman scattering. No nonequilibrium optical phonons were found both for cw and 150-ps-long laser pulses in contrast to bulk samples. The measured laser-induced temperature rise in one sample where the nanocrystal radii are ∼5 nm was found to be in quantitative agreement with a nonlinear theory proposed by Lax for bulk semiconductors. However, in another sample where the nanocrystal radii are only 3 nm, the observed temperature rise at high laser powers was significantly higher than the theoretical prediction. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363592
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  • 2
    Electronic Resource
    Electronic Resource
    Composition-structure relationships for multisource evaporated CuGaSe2 thin films (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 4903-4908 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: X-ray diffraction (XRD) analysis of doublet formation and peak shifts were used to observe the compositional dependence of the order–disorder transition in polycrystalline CuGaSe2 thin films deposited by multisource evaporation. Cu-poor material had a strong tendency to disorder as evidenced by the simultaneous presence of both the chalcopyrite and sphalerite phases. Stoichiometric and Cu-rich material contained only the tetragonal phase as observed by XRD. Comparison of Cu-poor XRD patterns with theoretical calculations reflecting probable defect chemistries (VCu, GaCu, VSe) suggests an interesting microstructure. The absence of higher index group (iii) reflections, notably the (103) and (211) peaks, in chalcopyrite material suggest that the tetragonal phase maintains a near-stoichiometric composition. Overall Cu-poor film compositions may therefore be obtained by adjustment within the cubic phase which implies compositional segregation between the phases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342439
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis of nanocrystalline gallium nitride in silica aerogels (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 3230-3232 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Nanocrystals of gallium nitride were synthesized in silica aerogel host matrices by pyrolysis of dimeric dimethylgallium-diphenylamide precursor sequestered in the nanometer scale aerogel pores. Powder x-ray diffraction (XRD) and selected area electron-diffraction results verify the formation of hexagonal gallium nitride material in the aerogels, and Scherrer-broadening analysis of the XRD data indicate the gallium nitride particle size is ∼20 nm. Transmission electron microscopy results show that the gallium nitride nanoparticles have diameters between 10 and 40 nm with an average diameter of 23 nm. The synthesis parameters for the gallium nitride nanocrystals in the aerogel hosts are discussed. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.118019
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  • 4
    Electronic Resource
    Electronic Resource
    Resonance Raman studies of the ground and lowest electronic excited state in CdS nanocrystals (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 8432-8442 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The size dependence of the resonance Raman spectrum of CdS nanocrystals ranging in size from 10 to 70 A(ring) radius has been studied. We find that while the lowest electronic excited state is coupled strongly to the lattice, this coupling decreases as the nanocrystal size is decreased. We demonstrate that the lifetime of the initially prepared excited state can influence the apparent strength of electron-vibration coupling. Absolute resonance Raman cross section measurements can be used to determine the value of the excited state lifetime, thus removing this parameter. The coupling to the lattice, while less in nanocrystals than in the bulk, is still greater than what is predicted assuming an infinite confining potential. The width of the observed LO mode broadens with decreasing size, indicating that the resonance Raman process is intrinsically multimode in its nature. The frequency of the observed longitudinal optic (LO) mode has a very weak dependence on size, in contrast to results obtained from multiple quantum well systems. The temperature dependence of the frequency and linewidth of the observed LO mode is similar to the bulk and indicates that the LO mode decays into acoustic vibrations in 2.5 ps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464501
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  • 5
    Electronic Resource
    Electronic Resource
    Processing and properties of some II–IV–V2 amorphous and crystalline semiconductors (1996)
    Springer
    Applied physics 62 (1996), S. 519-523 
    Details
    ISSN: 1432-0630
    Keywords: 81.05. — t
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Experimental investigations on the preparation, characterization, and properties of several bulk and thin-film ternary alloys based on the chalcopyrite II–IV–V2 semiconductors are presented. Rapid melt solidification in vacuum-sealed fused-silica tubes resulted in amorphous alloy formation in almost all compositions in the system CdGeAs2-CdSiAs2. ZnGeAs2-CdGeAs2 alloys showed very limited tendency toward amorphous phase formation. Phase separation, crystallization and electrical properties were studied for amorphous Cd-Ge-Si-As alloys by thermal analysis, transmission electron microscopy, X-ray diffraction, and Hall measurements. Rapid crystallization resulted in a reversal of conductivity type (p-to-n or vice versa). Crystallized glassy alloys showed room-temperature mobility of 64 cm2/V s, and a hole concentration of 1020 cm−3. The p-to-n change in conductivity type upon amorphous-to-crystal transformation suggests that these alloys can be used to fabricate p-n junction devices by surface crystallization of the amorphous phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01571686
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  • 6
    Electronic Resource
    Electronic Resource
    Processing and properties of some II–IV–V2 amorphous and crystalline semiconductors (1996)
    Springer
    Applied physics 62 (1996), S. 519-523 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 81.05. ; t
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract.  Experimental investigations on the preparation, characterization, and properties of several bulk and thin-film ternary alloys based on the chalcopyrite II–IV–V2 semiconductors are presented. Rapid melt solidification in vacuum-sealed fused-silica tubes resulted in amorphous alloy formation in almost all compositions in the system CdGeAs2–CdSiAs2. ZnGeAs2–CdGeAs2 alloys showed very limited tendency toward amorphous phase formation. Phase separation, crystallization and electrical properties were studied for amorphous Cd–Ge–Si–As alloys by thermal analysis, transmission electron microscopy, X-ray diffraction, and Hall measurements. Rapid crystallization resulted in a reversal of conductivity type (p-to-n or vice versa). Crystallized glassy alloys showed room-temperature mobility of 64 cm2/V s, and a hole concentration of 1020 cm-3. The p-to-n change in conductivity type upon amorphous-to-crystal transformation suggests that these alloys can be used to fabricate p–n junction devices by surface crystallization of the amorphous phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01571686
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  • 7
    Electronic Resource
    Electronic Resource
    Microanalyses of chemically etched thin film alumina-ferrite interfaces (1989)
    Springer
    Journal of materials science 24 (1989), S. 1169-1176 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Thin films of aluminium oxide were deposited on ferrite (Ni x Zn1−x Fe2O4) substrates by r.f. sputtering. The sputtered alumina films were not easily etched by hot phosphoric acid unlike readily etchable films prepared by physical deposition techniques. Microanalytical characterization of unetched films, partially etched films and interfacial regions was conducted to identify the microscopic features responsible for reluctant film etchability. The post-etched films were categorized as easily, partially and un-etchable (EE, PE and U respectively) and were examined using optical microscopy, SEM, XRD, EDS, XPS, AES, and TEM/STEM. TEM examination of cross-sections of partially etchable films revealed a non-uniform crystalline phase at the film-substrate interface. Electron diffraction data identified the phase asη-alumina although AES and EDS results suggest that the interfacial phase also contained some iron. The occurrence and orientation of theη-alumina phase was shown to depend on the orientation of the grains of the ferrite substrate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02397044
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  • 8
    Electronic Resource
    Electronic Resource
    Microanalyses of chemically etched thin film alumina-ferrite interfaces (1989)
    Springer
    Journal of materials science 24 (1989), S. 1169-1176 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Thin films of aluminium oxide were deposited on ferrite (Ni x Zn1−x Fe2O4) substrates by r.f. sputtering. The sputtered alumina films were not easily etched by hot phosphoric acid unlike readily etchable films prepared by physical deposition techniques. Microanalytical characterization of unetched films, partially etched films and interfacial regions was conducted to identify the microscopic features responsible for reluctant film etchability. The post-etched films were categorized as easily, partially and un-etchable (EE, PE and U respectively) and were examined using optical microscopy, SEM, XRD, EDS, XPS, AES, and TEM/STEM. TEM examination of cross-sections of partially etchable films revealed a non-uniform crystalline phase at the film-substrate interface. Electron diffraction data identified the phase asη-alumina although AES and EDS results suggest that the interfacial phase also contained some iron. The occurrence and orientation of theη-alumina phase was shown to depend on the orientation of the grains of the ferrite substrate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00553139
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  • 9
    Electronic Resource
    Electronic Resource
    Rare-earth chalcogenides — an emerging class of optical materials (1994)
    Springer
    Journal of materials science 29 (1994), S. 1135-1158 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Sulphide compounds belong to the family of chalcogenides and are well known for their optical and electronic properties. They possess good optical properties because of their ability to transmit into the infrared (IR) region. Several sulphide glasses are known to exist which exhibit far infrared transmission and are also useful semiconductors. In recent years, there has been an increasing interest in IR materials to be used on surveillance equipment. This led to the identification of several new crystalline sulphide materials which can transmit very far into the IR region (up to a wavelength of 14 Μm). Crystalline and amorphous rare-earth sulphides emerged as a new class of materials, which possess several unique optical and electronic properties. This paper reviews the status of these rare-earth sulphide amorphous and polycrystalline materials, the techniques used to process these materials and discusses their structure, thermal, mechanical and optical properties. Conventional and emergent novel chemical processing techniques that are used for synthesizing these materials are reviewed in detail. The use of metallorganic precursors and the modification of their chemistry to tailor the composition of the final ceramic are illustrated. The potential of these chemical techniques and their advantages over the conventional solid state techniques used for processing sulphide ceramics is discussed, particularly in light of their successful applications in processing novel electronic and optical oxide ceramics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00975057
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  • 10
    Electronic Resource
    Electronic Resource
    Microwave induced plasma processing of nuclear waste calcines (1991)
    Springer
    Journal of materials science 26 (1991), S. 155-162 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Microwave induced plasma processing was used to sinter synthetic Idaho Chemical Processing Plant (ICPP) alumina and zirconia based high level nuclear waste calcines in a nitrogen atmosphere. The microwave densification behaviour of these nuclear waste calcines was observed parallel with identification of the phases formed after sintering. Sintered densities of 〉 3.20 g cm−3 were obtained within 10 min of microwave sintering of pure calcines. Glass frit containing calcines showed lower sintering densities (〈 2.0 g cm−3) due to reactions between the frit and volatile substances in both zirconia based and alumina based calcines; prior removal of frit volatiles increased the sintered density. Phases formed in the microwave sintered calcines were identified by X-ray diffraction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00576046
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