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Luminescent and structural properties of [M.sub.1-x][Ce.sub.x][F.sub.2+x] (M = Ca, Sr, Ba, 0.15 < x < 0.35) single crystals were studied. It was found that the solid solutions have fluorite crystal structure with the lattice constant noticeably different from that of MF2 crystal. A partial deficiency in the fluorine positions as well as excessive fluorine in interstitial sites was revealed. Crystal lattice modification does not strongly affect the basic absorption and emission properties as compared with weakly Ce-doped [MF.sub.2]. The spectral-kinetic parameters of solid solutions luminescence are similar to those of [Ce.sup.3+] ion in perturbed site in Ce[F.sub.3] lattice. Low light yield of mixed compounds is connected with the small Stokes shift and reabsorption. The probable model of perturbed [Ce.sup.3+] center in [M.sub.1-x][Ce.sub.x][F.sub.2+x] crystals assumes the presence of interstitial fluorine in the nearest or next nearest neighborhood of the cerium ion. Index Terms--Luminescence, radiation damage.

Over 25 1-[cm.sup.3] CdZnTe crystals produced using the Traveling Heater Method at Redlen Technologies have been characterized. The charge carrier mobility and lifetime, and charge carrier transport uniformity of each crystal were measured using alpha particles. Some of the crystals were made into coplanar-grid detectors and their performance characterized using 662 keV gamma rays. The average electron mobility-lifetime product for these crystals was found to be a factor of about five times greater than that measured from crystals obtained over the last decade from two other commercial crystal growers. The coplanar-grid detectors produced from the material typically achieved an energy resolution at 662 keV near 2% FWHM when operated at room temperature. This is comparable to the best coplanar-grid detectors commercially produced today. Index Terms--CdZnTe detectors, gamma-ray spectroscopy detectors, charge carrier lifetime, charge carrier mobility.

Ordered FePt film is attractive for its very high perpendicular anisotropy. In the present study, we report different texture formation and mechanisms of ordering FePt films on MgO (100) single crystal (A) substrates and MgO (200) polycrystalline film formed on Si[O.sub.2]/Si (B) substrates with and without Si[O.sub.2] addition. Films with structure of [[0.24 nm Pt/0.25 nm Fe/0.21 nm Si[O.sub.2].sub.15] were deposited on 600[degrees]C substrates and subsequently treated by rapid thermal annealing. In the as-deposited state, FePt grain size was smaller and its degree of ordering was lower on substrate (B) than substrate (A) regardless of Si[O.sub.2] addition. Upon annealing, grain growth was more significant on substrate (A) than on substrate (B), and degree of ordering kept nearly constant. However, in the case of Si[O.sub.2] addition, upon annealing, grain growth was more significant on substrate (B) than substrate (A), and the ordering parameter increased on both substrates (A) and (B). This indicates ordering reaction is dominated by phase separation of Mg,O or MgO incorporated in FePt grains of the as-deposited states during the short time rapid annealing treatments. Different texture formation and grain size difference in the two different substrates will be discussed together with the mechanism of ordering in FePt films. Index Terms--FePt, MgO substrates, ordering mechanism, Si[O.sub.2] addition.

Fe top layers with a thickness [t.sub.Fe] between 1 and 15 nm were deposited on textured FePt(001)/Pt(001)/Cr(002) layers to study the associated exchange coupling effect and their switching behaviors. The deposition of a Fe layer does not change the crystalline structure of the FePt layer. Microstructural analysis reveals that the Fe(200) texture is formed epitaxially on the FePt(001) surface. When [t.sub.Fe] = 1 nm, the remanent coercivity ([H.sub.cr]) remains the same as that without a Fe top layer. The lack of reversible magnetization reveals that the Fe layer is thinner than the critical thickness; the strong coupling force throughout the whole Fe layer facilitates the cooperatively magnetic rotation of Fe and FePt layers. Significant exchange spring was observed in the sample with [t.sub.Fe] = 3 and 5 nm, reducing Her by 14% and 43% (the maximum reduction), respectively. The results are consistent with the theoretical prediction. As [t.sub.Fe] was increased up to 8 and 12 nm, the exchange spring effect disappeared. Although the two films exhibited similarly reduced Her values of about 1.5 kOe, the reduction of Her is caused by the tilt of the magnetic moments rather than the exchange spring. This incline of the moments is caused by the weakened exchange coupling and the complex domain structure. The magnetic reversal was further examined by measuring the variation in longitudinal and transverse magnetizations during magnetic field sweeping. The results suggest that at [t.sub.Fe] = 1 and 3 nm, the reversal occurs cooperatively in a single direction. As [t.sub.Fe] is increased to 5 and 8 nm, the moments switch randomly, in a manner that may be related to the increase in the density of the domain wall, observed by MFM. This work demonstrates the feasibility of reducing coercivity through exchange-spring mechanism and provides information on detailed magnetic reversal mechanism in perpendicular exchange coupled FePt. Index Terms--Exchange coupling, FePt thin films, magnetic reversal behaviors, perpendicular recording.

We studied the effects of medium microstructure on the switching field (SF) and its distribution (SFD). Specifically, quasi-single crystalline and polycrystalline Co/Pt based multilayers, chosen for its high perpendicular anisotropy and high exchange coupling, have been prepared via sputtering technique. The quasi-single crystalline was achieved by utilizing an Ag underlayer. Using electron-beam lithography, films were patterned into arrays of small islands, ranging from 1 [micro]m to 0.050 [micro]m (= 50 nm) in size. The hysteresis loop for the both types of film, as unpatterned, showed similar anisotropy field and coercivity whereas, as patterned, the quasi-single crystalline samples consistently exhibited a higher SF than that of the polycrystalline samples. However, the interpretation on the SFD was rather complex. Additionally, a critical size where remanent magnetization changes a multi domain to a single domain state appeared to be notably smaller for the polycrystalline samples than that for the quasi-single crystal samples, suggesting a different nucleation volume in the films. Index Terms--Co/Pt multilayers, medium microstructure, switching field (SF), switching field distribution (SFD).

The dynamic behavior of a mixed spin-l/2 and spin-3/2 Ising model with a crystal-field interaction in the presence of a time-varying magnetic field on alternate layers of hexagonal lattice is studied by using the Glauber-type stochastic dynamics. We study time variations of the average magnetizations in order to find the phases in the systems, and the temperature dependence of the dynamic sublattice magnetizations and total magnetization to obtain the dynamic phase transition (DPT) points and dynamic compensation points, respectively, as well as to characterize the nature (continuous and discontinuous) of transitions. Dynamic phase diagrams are also calculated for both DPT points and dynamic compensation effects. According to values of Hamiltonian parameters, besides the paramagnetic (p), antiferromagnetic (af) and antiferrimagnetic (i) fundamental phases, the af + p, i + p and i + af mixed phases, and the compensation temperature or P- and L-types behavior in the Neel classification nomenclature exist in the system. Index Terms--Compensation, magnetic field effects, magnetic materials, magnetic recording.

Hot-pressed [Nd.sub.13.5][Fe.sub.77][Si.sub.1][B.sub.8] alloy compacts with various grain sizes ranging from approximately 50 nm to 200 nm were prepared using melt-spun material. The compacts were then subjected to die-upsetting. The effect of grain size in the hot- pressed compact on the texture in die-upset magnet was investigated. The effect of die-upset temperature on the texture in die-upset magnet was also investigated. Texture in the die-upset [Nd.sub.13.5][Fe.sub.77][Si.sub.1][B.sub.8] alloy samples decreased with increasing the grain size in the hot-pressed compact before the die-upsetting. This dependence of texture on the initial grain size could be explained by the unique texture formation mechanism of a stress-induced preferential grain growth via dissolution and precipitation. Texture of the die-upset sample was also influenced by the die-upsetting temperature. The samples die-upset at 700[degrees]C and 900[degrees]C had poorer texture compared to the samples die-upset at the temperature range of 750[degrees]C-850[degrees]C. The poor texture in the sample die-upset at lower temperature of 700[degrees]C was attributed to the less dissolution of the unfavorable [Nd.sub.2][Fe.sub.14]B grains and low fluidity of the liquid Nd-rich grain boundary phase. The poor texture in the sample die-upset at higher temperature of 900[degrees]C was explained by the reduced elastic modulus and the excessive grain growth of the [Nd.sub.2][Fe.sub.14]B grains. Index Terms--Hard magnetic materials, magnetic materials, magnets, permanent magnets.

The [La.sub.0.8][Ca.sub.0.2][Mn.sub.0.99][sup.57][Fe.sub.0.01][O.sub.3] sample was prepared by sol-gel method. The crystallographic and magnetic properties of [La.sub.0.8][Ca.sub.0.2][Mn.sub.0.99][sup.57][Fe.sub.0.01][O.sub.3] have been studied using x-ray diffraction (XRD), vibrating sample magnetometer (VSM) and Mossbauer spectroscopy measurements. The crystal structure of [La.sub.0.8][Ca.sub.0.2][Mn.sub.0.99][sup.57][Fe.sub.0.01][O.sub.3] was found to be orthorhombic (Pnma) structure with lattice constants [a.sub.o] = 5.486 [Angstrom], [b.sub.o] = 7.761 [Angstrom], and [c.sub.o] = 5.510 [Angstrom] at room temperature. The Curie temperature ([T.sub.c]) is determined to be 160 K by zero field coolded (ZFC) magnetization curve under 5 kOe applied field. The maximum value of magnetic entropy changes, [absolute value of [DELTA][S.sub.M]] is 1.25 J/kg x K at 157 K under 13 kOe applied field. Mossbauer spectrum at 4.2 K was fitted with two independent magnetic components of the magnetic hyperfine fields [H.sub.f,1] = 526 kOe and [H.sub.f,2] = 501 kOe. Mossbauer spectra show that the two well-resolved sextets show nearly equal intensities between them without any external fields. This unusual phenomenon provides direct evidence of the two-phase character of the metallic state in the mixed valence state of [La.sub.0.8][Ca.sub.0.2][Mn.sub.0.99][sup.57][Fe.sub.0.01][O.sub.3] powder. Index Terms--[La.sub.0.8][Ca.sub.0.2][Mn.sub.0.99][sup.57][Fe.sub.0.01][O.sub.3], magnetic refrigeration, magnetocaloric effect, Mossbauer spectra, sol-gel method.

Angular dependence of Gilbert's damping constant [alpha] for Ni-Fe(001) single-crystal thin films were investigated by employing Q-band (35 GHz) and X-band (9 GHz) ferromagnetic resonance analysis in terms of the specimen's crystal structure. The [alpha] for 10-nm-thick specimen had constant values of 0.006, which were estimated by the Q-band ferromagnetic resonance (FMR) spectra, when the spectra were measured with changing external field directions in the film plane and out of plane. The [alpha] for the Ni-Fe specimens did not depend on the crystal directions. The [alpha] values estimated by X-band FMR spectra were in good agreement with those by Q-band FMR spectra, when the magnetization of the specimens was saturated at the X-band resonance field. The [alpha] values were overestimated, when the magnetization was not saturated and the specimens had multidomain structures at the resonance field. Index Terms--Ferromagnetic resonance (FMR), Gilbert's damping constant, permalloy, Q-band, X-band.

Co epitaxial thin films were prepared on single-crystal MgO substrates of (100), (110), and (111) planes heated at 300[degrees]C by ultra high vacuum molecular beam epitaxy. The film crystal structure varies depending on the substrate orientation. On MgO(100) substrate, a Co(11[bar.2]0) epitaxial bi-crystalline film with an hcp structure is obtained. A Co(110) single-crystal film with an fcc structure is formed on MgO(110) substrate, whereas a Co(0001) single-crystal film with an hcp structure is grown on MgO(111) substrate. Co film growth on MgO substrates follows the Volmer-Weber mode. The in-plane magnetization properties reflect the magnetocrystalline anisotropy of bulk hcp-Co or fcc-Co crystal. The Gilbert's damping constants of these 40-nm-thick epitaxial Co films are determined. Index Terms--Co thin film, epitaxial growth, FMR, single-crystal substrate.

Heusler alloys with nickel rich nominal composition [Ni.sub.2+x][Mn.sub.1-x]Ga (x = 0.16 - 0.26) were prepared by arc- melting and subsequent homogenization by annealing. A large magnetic entropy change around room temperature was observed in the alloy where martensite-austenite structural and ferro-para magnetic transition temperatures almost coincide with each other. It also shows large hysteresis in the magnetization isothermals. A sharp peak in the specific heat versus temperature curve indicates a first-order transition at the temperature of large entropy change. Index Terms--Austenite phase, Heusler alloys, magnetocaloric effect, martensite phase.

We have studied room-temperature ferromagnetism (RTFM) in [Sn.sub.1-x][Co.sub.x][O.sub.2] powders and films fabricated by the sol-gel method. Our X-ray diffraction, high-resolution transmission microscopy, and X-ray photoelectron spectroscopy results show that all the samples have a pure rutile structure, and Co ions have a chemical valence of 2+. In addition, the magnetic moment per Co ion drops rapidly with the increase of Co content. Interestingly, [Sn.sub.1-x][Co.sub.x][O.sub.2] films spin-coated on a Si (111) substrate have much larger magnetic moment than powder samples, because film samples have larger domain volumes, which may induce stronger long-range magnetic exchange coupling. Index Terms--Crystal size, doping, ellipsometry, ferromagnetic materials, hysteresis.

Atomic-scale simulations have been employed to predict the site solution preference of [Bi.sup.3+] activator cations in a series of [RE.sub.2][O.sub.3] scintillators with the bixbyite crystal structure (Ia[bar.3]), where RE denotes a 3+ cation ranging in size from [Sc.sup.3+] to [La.sup.3+]. There are two crystallographically unique cation sites in the bixbyite structure, in Wyckoff notation referred to as the 24d and 8b site. It is expected that the spectroscopic properties of an activator cation residing on the 24d site will be different from the same activator cation residing on the 8b site, due to the distinct symmetries ([C.sub.2] and [S.sub.6] respectively) of these two sites. Previous studies have revealed two different [Bi.sup.3+] emissions in [Y.sub.2][O.sub.3] corresponding to [Bi.sup.3+] cations occupying both lattice 24d and 8b sites. By predicting the energy difference of the [Bi.sup.3+] solution on the 24d and 8b sites, we are able to predict the distribution of [Bi.sup.3+] in a range of bixbyite compounds. Index Terms--Atomistic simulation, defect chemistry, rare earth compounds, scintillators.

A novel approach to find the effective electric and magnetic parameters of finite periodic structures is proposed. The method uses the reflection coefficients at the interface between a homogenous half-space and the periodic structure of different thicknesses. The reflection data are then approximated by complex exponentials, from which one can deduce the wavenumber, and the effective electric and magnetic properties of the equivalent structure by a simple comparison to the geometrical series representation of the generalized reflection from a homogenous slab. Since the effective parameters are for the homogenous equivalent of the periodic structure, the results obtained are expected to be independent of the number of unit cells used in the longitudinal direction. Although the proposed method is quite versatile and applicable to any finite periodic structure, photonic crystals and metamaterials with metallic inclusions have been used to demonstrate the application of the method in this paper. Index Terms--Effective constitutive parameters, homogenization, metamaterials, photonic crystals.

Dielectric properties of low-density polyethylene (LDPE) blended with metallocene catalyzed polyethylene (MPE) to 1, 3, 5 wt% of the latter are reported. It was found that the 1 wt% MPE blend had the lowest volume resistivity, the highest direct current (DC) breakdown strength and the least accumulated space charge. The crystalline morphology of the blends was studied through differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and small-angle light scattering (SALS) measurements. It was found that blending increased the percentage crystallinity, decreased the spherulite size and caused the formation of imperfect spherulites, i.e. spherulites containing defects and impurities in their crystalline phases, and thus fewer impurities and defects on their boundaries. The improvement in dielectric properties of the blends, especially the 1 wt% MPE blend, is attributed to the increase in crystallinity and the formation of imperfect spherulites. Index Terms--polyethylene, blend, dielectric properties, crystalline morphology.

Optimized one-dimensional (1-D) magnetophotonic crystals greatly increase the sensitivity of magnetooptical sensors, which are widely used in magnetooptical imaging to observe the magnetic domain patterns in magnetic materials, to observe the vortex states in superconductors, to detect small bits in magnetooptical recording media, to visualize defects in ferromagnetic objects, and to measure the value and spatial distribution of stray magnetic fields. This paper examines the properties of such devices operating in the optimized reflection (doubled Faraday rotation) mode and discusses the use of 1-D magnetophotonic crystals as sensors. Index Terms--Magnetic domains, magnetic photonic crystals, magnetooptical magnetic field sensors.

We successfully developed a high-precision wafer alignment and bonding system for the fabrication of a variety of 3-D nanostructures. To control the wafer positions with high accuracy during the wafer-bonding process, we improved upon a design of the conventional mask-alignment stage. A stress sensor was incorporated to measure the load between the two wafers. In addition, the parallelism of the wafers was monitored by an optical interferometry system. To determine alignment errors in both the x and y directions simultaneously, we devised an alignment method consisting of crossed vernier scales. We demonstrated that the new alignment and bonding system allowed us to realize precise 3-D photonic crystals with the alignment inaccuracy of < 100 nm at most, and we show that the best experimental error achieved to date was < 25 nm. As this system has the benefit of more readily and intuitively determining the absolute positions of the two wafers, it can be applied to the fabrication of a wide variety of nanoscale multilayer devices. [2007-0018] Index Terms--Microassembly, micromachining, nanostructure, nanotechnology, periodic structure, photonic crystal, wafer bonding, 3-D integration.

The impact of the probability density function (PDF) of a quartz on the frequency versus temperature curve (FTC) is studied for a fundamental mode AT cut crystal and four different ways of specifying the FTC and the resulting PDF are discussed.

The reversible ferroelectric-ferroelectric transition of morphotropic relaxor-ferroelectric lead zinc niobate-lead titanate and lead magnesium niobate-lead titanate single crystals as accessed by the mechanical compression is presented. Implications of the observation for sound projectors are presented.

Study is conducted to show that thickness-twist modes in a plate of polarized ceramics or 6-mm crystals can be used as the operating modes of a piezoelectric generator for converting mechanical energy of shear motions into electrical energy. An exact solution is obtained for the finite plate generator, which is a relatively rare example in piezoelectricity.

A unique technique to calculate the piezoelastic properties of multidomain single crystals from the single-domain constants is described .The technique, which consists of both considering the wall as a very thin layer with specific properties and defining new electrical conditions across the lattice media, allows special boundary conditions at the interface separating the two domains to be taken into account.

Three-dimensional periodic structures of synthetic opals and various inverse opals with interconnected regular array of nano-scale voids in which liquids and liquid crystals can be infiltrated have been prepared for the study of liquids and liquid crystals confined in nano-scale spaces. One-dimensional periodic structure containing a defect layer in which liquids and liquid crystals can be introduced have also been prepared by the multi-layered Si[O.sub.2] and Ti[O.sub.2] stacks. These three-dimensional and one-dimensional periodic structures containing liquids and liquid crystals exhibited novel properties as tunable photonic crystals. Utilizing these phenomena a simple apparatus to evaluate the refractive index of liquids precisely have been proposed, with which sorts of dielectric liquids can be distinguished. Kerr effect and non-linear optical effects of liquids contained in the defect layer of the one-dimensional systems have also been discussed. When the opals and inverse opals contain liquid crystals, the transmission dip and reflection peak wavelengths can be tuned by applied field. The response characteristics are different for opals and inverse opals, which can he interpreted by taking the interaction of liquid crystal molecules with the inner surface of the void into consideration. Utilizing one-dimensional systems containing liquid crystals in the defect layer a ultra-fast switching of a laser light and also in systems containing liquid crystals and fluorescent dyes a voltage tunable lasing in the wide spectral range have been demonstrated. Index Terms--Liquids, liquid crystals, periodic structures, carbon, electrooptic effects, nanostructures, photonic crystals.

The true congruent composition for LiTaO(sub 3) single crystals was determined by measuring the velocities of leaky surface acoustic waves (LSAWs) with the line-focus-beam ultrasonic material characterization (LFB-UMC) system for two 42-degree Y X-LiTaO(sub 3) crystal ingots. The results showed that the distribution of melt and crystal compositions within and among the crystals varied largely with the material composition.

There are many interesting properties for the propagation of the electromagnetic waves in a two-dimensional (2-D) pillar-type photonic-crystal (PC) single straight waveguide structure with nonlinear medium properties. We propose a new frequency converter constructed with a 2-D pillar-type PC waveguide structure by utilizing both nonlinear properties and a compound waveguide structure. To simulate this new PC device with a nonlinear medium, we also explain how to treat nonlinearity with the condensed node spatial network method, which is a numerical means of simulating electromagnetic fields in three-dimensional space and the time domain like the finite-difference time-domain method. Index Terms--Condensed node spatial network method (CN-SNM), frequency conversion, nonlinear medium, phase difference, photonic-crystal (PC) waveguide.

Uniformity of properties of a semiconductor material is one of the important conditions to achieve high spectrometric performance of ionizing radiation detectors. To study uniformity of electrophysical properties of crystals, an original method for acquisition of distributions of local values of a dielectric permittivity [epsilon]' and tangent of a dielectric loss angle tan [[delta].sub.M] in high-resistance semiconductors is offered. The method was approved on [Cd.sub.1-x][Zn.sub.x]Te (x = 0.1 to 0.16) crystals grown by Bridgman method under high pressure of inert gas. Locality and reproducibility of measurements are provided by a special design of a movable electrode, with both the area and the hold-down pressure of the electric contact being unvaried. Differences in [epsilon]' and tan [[delta].sub.M] distributions over the sample's area and an effect of uniform monochromatic illumination at a varied wavelength on these distributions are revealed. The physical nature of revealed irregularities is analyzed with involving results of researching CdZnTe crystals by diverse methods. Index Terms--CdZnTe, crystals, dielectric losses, dielectric measurements, electrodes, electrophysical properties, infrared imaging, semiconductor radiation detectors.

Good-optical-quality KGd(WO4)2 single crystals doped with erbium and ytterbium ions were grown using the top-seeded-solution growth slow-cooling method (TSSG). Spectroscopic characterization of erbium was performed in this host in terms of the polarized optical absorption and luminescence at RT and 6 K.

Amplitude frequency effect of a Y-cut langanite (LGN) and a Y-cut langatate resonator were measured. The frequency shifts from the baseline frequency with 1mA were measured as a function of drive currents up to 28mA and the amplitude frequency shift was effectively measured, which was unaffected by the temperature related frequency changes.

A theory that predicts the efficiency of type-1second-harmonic generation (SHG) with simultaneous spatial and temporal walk-offs and with pump depletion is developed. A comparison between predictions and a numerical solver is also given to validate this theory that provides a useful tool for estimating SHG efficiency with pulsed sources in both nondepletion and depletion regions.

The melting of the vortex lattice in Bi2Sr2CaCu2O8+delta (BSCCO) single crystals has been examined with scanning Hall probe microscopy. Results indicate the presence of a flux solid with good six-fold order below the melting line. Pronounced rotations of the solid due to incommensurability effects are also observed as the field is varied. The peak-to-valley corrugation of the vortex lattice drops abruptly and discontinuously to zero at the melting line.

The effect of the substrate temperature and the deposition rate on the structural and superconducting properties of in-situ grown yttrium barium copper oxide thin (YBCO) films by pulsed laser deposition has been studied. Results indicate that the cubic structure of the YBCO films is formed at low substrate temperatures and high deposition rates. The c-lattice parameter increases while the critical temperature decreases with decreasing substrate temperature and increasing deposition rate.

Tunnelling electron microscopy was used in studying the intra-grain structure and variations in high-angle grain boundaries misorientations in copper oxide superconductors. YBCO samples were prepared through the Liquid Phase Removal Method. Results show that misorientation angles for the platelet and low-angle grain boundaries are between O.5 to 5 degrees. The misorientation is due to the alternation of the misorientation direction and does not go beyond 6 degrees. The misorientation of high-angle boundaries is influenced by the presence of platelet boundaries and low-angle grain boundaries.

Research was conducted to measure the V-I properties of (YBa2Cu3O(sub x) bulk single crystal containing Y2BaCuO(sub x) particles) (QMG) for pulse current and transition of the voltage during the pulse. The two n-values derived for two rods cut out of the same QMG single crystal at 77 K did not coincide. Results indicate that QMG single crystal had some amount of distortion based on its crystalline substructure.

Absorption, emission, excitation and thermoluminescence for pure, Eu- and Ce-doped LiBa[F.sub.3] crystals, both as grown and irradiated, were investigated. High purity of initial crystal was shown to be necessary to reduce the afterglow and decrease the radiation damage level. Doping by Ce or Eu ions could be used to change the spectral and kinetic characteristics. The exciton luminescence and blue afterglow were suppressed in Eu- or Ce-doped crystals. Radiation-induced absorption spectrum was a complex and included more than six overlapping bands. Emission of these color centers appears in the luminescence spectrum.

Raman microscopy was employed in studying the oxygen content and structural defects of three high temperature superconducting YBa2Cu3O7-x thin films grown at various temperatures. C-axis lattice parameter and x-ray peak intensity ratios reveal different levels of cation disorder in the films. The positions of the 115cm-1 and 500cm-1 Raman peaks were found to alter as a function of cation disorder, spatial position and oxygen.

A series of cation substitution reactions were performed to generate stable and processable YBa2Cu3O7-delta superconductors. Y1-yCayBa1-yLayCu3O7-delta compounds were found to exhibit increased corrosion resistance with increasing levels of substitution. Results reveal that the Y0.6Ca0.4Ba1.6La0.4Cu3O6.96 composition was over 100 time more stable than its YBa2Cu3O6.94 parent compound.

A study was conducted on the deformation-dominated texturing of OPIT-fabricated Bi(Pb)SCCO-2223/Ag composite tapes' superconducting filaments. The inhomogeneous distribution of plastic deformation was found to be related to the texture inhomogeneity of the filament cross section. Microhardness increases and x-ray peak broadening were caused by work hardening due to non-sintered powder plastic deformation.

A study was conducted on the influence of Sm2BaCuO5 addition on the superconducting properties and microstructure of melt-textured-growth YBa2Cu3Oy. Reductions in crystal domain size and plate grains thicknesses were caused by Sm2BaCuO5 addition. Intragrain critical current density increases were also observed. Measured levitation force and force relaxation were then compared for bulks with and without Sm2BaCuO5 addition.

Microstructural studies were conducted on melt-processed Y123 oxide superconductor samples. Results show that the magnetic properties of the samples are significantly affected by oxygenation conditions. The formation mechanisms of dislocation, CuO stacking fault, BaCuO platelet boundary and other defects were analyzed. No defects were seen in trapped Y211 inclusions and Y123 matrix of the samples that were heat-treated in flowing oxygen for different times.

High resolution scanning electron microscopy of filamentary Nb3Sn strands revealed high quality images of Nb3Sn filaments and their grain structure. Image analysis of the micrographs were conducted for a detailed macro- and micro-structural characterization of the filament in terms of shape, size and separation. Results show that grain size and morphology vary within the same filament as well as from filament to filament.

A study was conducted on the influence of cold rolling and wire drawing on the texture development of (Bi,Pb)2Sr2CaCu2Ox (2212) phase and its effects on the subsequent (Bi,Pb)2Sr2Ca2Cu3Oy (2223) phase texture in Ag-clad tapes. The 2212 phase was developed at different stages of deformation through reactions in a mixture of (Bi,Pb)2CuO4 and SrCaCuO3 powders with overall 2223 composition. Results reveal a significant improvement in texture.

PLZT thin films were deposited on single crystal Si substrates using radio frequency magnetron sputtering. An analysis was then conducted on the effects of bottom Pt/Ti electrodes and postannealing on the ferroelectric properties and structures of the thin film crystal. Results show that optimum crystal structures and ferroelectric properties for PLZT thin films can be achieved by using appropriate Ti layer thickness.

Several articles have been reviewed on the scintillation response of NaI(Tl). Those publications which report results obtained with radioactive sources either dispersed throughout the NaI(Tl)-lattice or located inside the wells of NaI(Tl)-crystals match within a [+ or -]0.9% standard deviation of a linear scintillation response between 3 MeV and 3 keV. Several authors who placed their sources outside the crystals measured nonlinear responses of NaI(Tl) with up to [+ or -]7% of standard deviations between 700 and 4.5 keV. The presented analysis suggests that the observed nonlinearity is not an intrinsic effect of NaI(Tl) but could be caused, at least partly, by effects occurring at the radiation entrance surfaces of the crystals. Index Terms - Gamma spectroscopy, inorganic scintillators.

A small amount of phenolphthalein, acting as a nucleating agent, was added to low density polyethylene (LDPE) to modify the size and number of spherulites. The crystalline morphology was observed and analyzed with the aid of a chemical etching method. It was found that the growth of water trees is faster in LDPE samples in which spherulites are larger and the number of the spherulites is lower. In contrast, water trees grow more slowly in other LDPE samples in which spherulites are smaller in size and greater in number. On the other hand, three different kinds of additives, weak electrolyte and hydrophilic or hydrophobic substances, were added to the LDPE materials to investigate the influence of typical spherulite boundary regions on the growth of water trees. It was verified experimentally that during the process of crystallization, these three different additives are rejected and finally settled near the spherulite boundaries. Therefore, three kinds of boundary regions with different characteristics are formed. It has been concluded that hydrophillic boundary regions can strongly inhibit the growth of water trees, while the other two boundary regions (weak electrolyte, hydrophobic) have little influence on the water tree growth.