Materials Literature
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Loral Infrared & Imaging Systems is developing low cost, high performance, uncooled infrared imaging products for both military and commercial applications. These products are based on the microbolometer technology, a silicon micromachined sensor which combines the wafer level silicon processing with a device structur…
A new bias-enhanced nucleation method of forming highly oriented diamond on Si(100) is reported using an alternating current bias source. The percentage of aligned particles via alternating current bias-enhanced nucleation (ac BEN) was greater than 50%. This is compared to less than 10% highly oriented particles when…
Hydrogen-free diamond-like carbon (DLC) films were deposited by the layer-by-layer technique using plasma enhanced chemical vapor deposition (PECVD), i.e., the alternative deposition of thin DLC layer and subsequent CF4 plasma exposure on its surface. The hydrogen-free DLC could be grown on the Si wafer by repeated de…
Bulk samples of La2−2xCa1+2xMn2O7 with the layered Sr3Ti2O7-type perovskite structure have been successfully synthesized and investigated with respect to their magnetic and electrical properties. It is found that La2−2xCa1+2xMn2O7 (x=0.25) is a metallic ferromagnet with a magnetic transition temperature Tc of 215 K. T…
SBRC has developed a high-quality 320 X 240 room- temperature infrared FPA that operates in the 8 - 14 micrometers spectral band. The FPA is based upon the silicon microbolometer technology that has been licensed from Honeywell. This monolithic uncooled FPA utilizes a novel BiCMOS readout circuit that provides high se…
Bulk silicon micromachined IR bolometer detectors operating at room temperature are presented. These devices are based on VO<SUB>2</SUB> films typically exhibiting a thermal coefficient of resistance of the order of -3%/ degree(s)C. Detector sizes are 50 micrometers X 50 micrometers and 100 micrometers X 100 micromete…
Up to third-generation metallodendrimers can be constructed by a repetitive sequence of reactions with building blocks that contain two coordinatively unsaturated Pd centers (“pie” shape) and one labile, coordinating cyano group (▴, see representation below). The key steps of assembly are the displacement of the chlor…
Detailed theoretical studies of the temperature dependence of EPR g-factor for the MgO: crystal have been made by considering both the static contribution due to the thermal expansion of crystal and the vibrational contributions due to the electron - phonon (including the acoustic and optical phonons) interaction. The…
We report measurements of the low-frequency optical response in epitaxial thin films of La0.67Ca0.33MnO3 in the temperature range covering both the ferromagnetic metallic state and the paramagnetic insulating state. We observe a bolometric optical response in fully oxygenated films of the above composition as well as…
A characteristic length scale of the structure of a thixotropic colloidal clay suspension of discotic texture was demonstrated by static light scattering. The length scale, of the order of a micron, corresponds to a fractal dimension that increases from 1 to 1.8 close to a critical volume fraction. Simultaneously, the…
Chen has recently shown how the response matrix of a two-phase composite can be written as linear combinations of products of the component matrices. We elaborate on Chen's expansions by deriving them in a different way, which a. shows them in a different light, and b. permits us to generalize them further. As an appl…
The stability of the $A$-type antiferromagnetic order and canted magnetic structure of LaMn${\mathrm{O}}_{3}$ perovskite is explained in the itinerant-electron picture based on the local-spin-density approximation. We demonstrate the crucial role of the observed lattice distortion which strongly affects the magnetocry…
A new route to the successful arc-discharge synthesis of pure boron nitride (BN) nanotubes is presented. The carbon-free plasma is established between ${\mathrm{HfB}}_{2}$ electrodes in a nitrogen atmosphere. This technique leads to the formation of BN nanotubes with very few layers including single- and double-layer…
Abstract Although there are no fundamental factors hindering the development of nanoscale structures, there is a growing realization that “engineering down” approaches, in other words a reduction in the size of structures generated by lithographic techniques below the present lower limit of roughly 1 μm, may become im…
A magnetic strip with rectangular cross section and infinite extension in the third, easy direction is used as a vehicle to explore numerical micromagnetic algorithms. The manifold of (meta-)stable domain wall solutions is calculated as a function of the thickness of the strip and of the relative strength of the magne…
Polycrystalline Cr2O3 films are prepared by normal pressure chemical vapour deposition (CVD), and electrical and optical properties of the films are investigated. The films are transparent from 800 to 1000 nm wavelength, and absorbing for wavelengths shorter than 800 nm. The optical band gap energy is Eopt = 2.98 to 3…
Copper oxide thin films were prepared by reactive rf magnetron sputtering of a pure copper target in an oxygen-argon atmosphere. The phases of the deposited films strongly depend on the oxygen content in the sputtering gas. X-ray diffraction studies show that by controlling the oxygen partial pressure single phase Cu2…
Changes in microstructure induced by heat treatments between 1000 and 1500 °C in Si3N4 based glasses and ceramics were characterized using x-ray diffraction and Raman scattering. The presence of free silicon appears to be a common feature of these families of materials. Si precipitates were observed by transmission el…
CdTe nanocrystals embedded in a sodium borosilicate matrix, obtained by a sol-gel process, present a wurtzite (hexagonal) structure. Low-temperature photoluminescence and absorption spectra are measured for samples containing bulklike nanocrystals large enough to suppress confinement effects. Thus, the fundamental fre…
A non-separation approach to determine the spark-processed porous silicon thermal parameters is presented. This thermal characterization was performed through application of the photoacoustic technique, in combination with compositional models for spark-processed porous silicon samples. The thermal parameters obtained…