The growth of preamorphized silicon layers doped by multiple energy implants of boron, phosphorus, and boron plus phosphorus ions was investigated under irradiation with a 600 keV Kr+ + beam. The target temperature was set in the range 250–450 °C. During irradiation the growth was measured in situ by transient reflectivity. Boron and phosphorus at a concentration of 1 × 1020/cm3 enhance the rate by a factor of 3 and 2, respectively, whilst in compensated samples the rate is still more than a factor of 2 higher than in intrinsic or Ge-doped samples. This growth rate is characterized by an activation energy of 0.32 ± 0.05 eV which is, within the experimental uncertainties, independent of the dopant. The results are tentatively explained in terms of an interaction between generated point defects and impurities that increases the lifetime of defects at the crystal–amorphous interface.

Fine grain, transformation-toughened Al2O3/ZrO2 (tetragonal, 5–30 vol. %) composites can exhibit both large deformation strains (80%) and strain rates (> 0.001 s−1) without tearing, cavitating, or cracking during hot forging at 1500 °C. Deformability increases with ZrO2 content. The Al2O3 grains grow, develop a crystallographic orientation, and form column structures with increasing deformation. The deformation behavior of the composite series primarily depends on the content of the ZrO2 phase. In this regard, two deformation regimes were observed that appear to be separated by the volume fraction where the ZrO2 phase might form a connective network.

Leaching experiments on naturally occurring, metamict betafite and samarskite minerals in a bicarbonate-carbonate solution show strongly enhanced release to the solution of short-lived 228Th relative to its parent isotope 232Th (by a factor of 3 to 6), but only slightly enhanced dissolution (by a factor of 1.2 to 2) of long-lived 234U and 230Th relative to 238U and 232Th, respectively. The betafite (a complex Ca–U–Ti–Nb oxide of the pyrochlore group, A2−mB2X6Y0−1.H2O) and samarskite (a complex Y–Fe–U–Nb oxide with varying stoichiometry between AB O4 and AB2O6) are x-ray and electron diffraction amorphous having experienced doses of 2.2–2.8 × 1017 alpha-decay events/mg (24–31 dpa) and 3.8–4.4 × 1017 alpha-decay events/mg (39–45 dpa), respectively. The isotopic fractionation is attributed to the radiation damage created by the alpha-decay events. Individual alpha-recoil tracks are preserved for some time as disordered regions of higher chemical reactivity in already fully damaged, aperiodic areas that result from the alpha-decay events. The annealing time of the alpha-recoil track within the aperiodic atomic array of the metamict state is calculated to be 29 300 ± 8100 years for samarskite and 42 700 ± 13 700 years for the betafite. These data plus data on an earlier studied betafite sample (annealing time = 2000 ± 1300 years) give an average annealing time of 25 000 ± 21 000 years. The variation in calculated annealing time is due, in part, to post-metamict alteration of the sample, particularly for the betafite. The wider range of values for the betafite is attributed to its greater degree of alteration. These results demonstrate that recoil nuclei of alpha-decay events may be selectively leached from damaged, aperiodic phases, but that these tracks are subject to low-temperature annealing in short periods of time relative to the age of the samples (∼ 500 m.y.). The same phenomena are expected in actinide-containing nuclear waste form glasses.

The fluorinating properties of NF3 and SF6 in heavy-metal fluoride glass processing were investigated between 200 and 1100 °C. Using infrared (IR) absorption spectroscopy the reactions of NF3 with ZrO2 and Al2O3 and the reactions of SF6 with ZrO2, SiO2, and Ni were studied. The reaction of NF3 with zirconia and alumina starts at 300 and 650 °C, respectively (yielding nitrogen oxides, nitrogen oxyfluoride, and presumably the metal fluorides). The reaction of SF6 and zirconia starts at 600 °C, yielding SO2F2. Sulfur hexafluoride and silica yield (above 900 °C) SiF4, SO2F2, and SOF2. Nickel and SF6 react above 700 °C yielding SF4 (and presumably NiF4). The results indicate that both gases are effective in oxide conversion at typical fluoride glass melting temperatures (800–900 °C). In addition NF3 can be used as a low-temperature fluorinating source for both oxide containing fluoride and pure oxide precursors. This offers great advantages over the use of solid NH4HF2, which is typically used and which forms an additional source of contamination.

Reactions between Pd and GaAs have been studied using bulk-diffusion couples of Pd (∼0.6 mm thick) /GaAs and thin-film Pd (50 and 160 nm)/GaAs samples. The sequence of phase formation at 600°C between bulk Pd and GaAs was established. Initial formation of the solution phase μ and the ternary phase T does not represent the stable configuration. The stable configuration is GaAs |∊|Λ|γ|ν|Pd and is termed the diffusion path between GaAs and Pd. The sequence of phase formation for the bulk-diffusion couples is similar at 500°C. Phase formation for the thin-film Pd/GaAs specimens was studied at 180,220,250,300,350,400,450,600, and 1000°C for various annealing times. The sequence of phase formation obtained from the thin-film experiments is rationalized readily from the known ternary phase equilibria of Ga–Pd–As and the results from the bulk-diffusion couples of Pd/GaAs. The thin-film results reported in the literature are likewise rationalized. The diffusion path concept provides a useful guide in understanding the phase formation in Pd–GaAs interface or any other M-GaAs interface. This information is important in designing a uniform, stable contact for the metallization of GaAs.

The mechanical deflection of cantilever microbeams is presented as a new technique for testing the mechanical properties of thin films. Single-layer microbeams of Au and SiO2 have been fabricated using conventional silicon micromachining techniques. Typical thickness, width, and length dimensions of the beams are 1.0,20, and 30 μm, respectively. The beams are mechanically deflected by a Nanoindenter, a submicron indentation instrument that continuously monitors load and deflection. Using simple beam theory and the load-deflection data, the Young's moduli and the yield strengths of thin-film materials that comprise the beams are determined. The measured mechanical properties are compared to those obtained by indenting similar thin films supported by their substrate.

The 29Si chemical shielding parameters derived from 29Si nuclear magnetic resonance (NMR) spectra of 25 silicides of Group IVB, VB, VIB, VIIB, and VIII metals are presented. The isotropic shifts of these silicides span the range from −1650 to + 925 ppm, relative to TMS, and have shielding anisotropies −250 to + 335 ppm; these extremes are approximately ten times as large as those of organosilicon and silicon oxide compounds. For silicides of Ti, Zr, Nb, Ta, Cr, Mo, W, Rh, Ni, Pd, Pt, and Cu, the chemical shielding interaction is sufficiently larger than the extraneous spectral broadening to allow detection of multiple phases owing to different crystal structures and local differences in stoichiometry. The potential to detect multiple phases in silicides of Hf, V, Mn, Fe, Ru, and Co is less owing to smaller differences in isotropic shifts and/or broadening that overwhelms the chemical shielding information. However, it is possible that the broadening is not an inherent property of these silicides, but rather, suggests the presence of structural defects in these particular samples.

Electrical conductivity and thermoelectric power have been measured for a series of MnZn ferrites as functions of the oxygen partial pressure under high-temperature equilibrium conditions. The isothermal variation of both properties was successfully correlated to the onset of phase transitions at characteristic Po2's. The ferrite 0.482MnO-0.518Fe2O3 was examined in some detail to locate the stability fields of the metallic alloy of iron and manganese, manganowustite, the spinel ferrite, and the hematitelike phase, and to extract the appropriate free-energy data. The results confirmed by x-ray diffraction are in satisfactory agreement with literature data.

Nitrogen trifluoride (NF3) was recently used by others as a reactive atmosphere during the melting of heavy metal fluoride glasses. This compound fluorinates oxide impurities, dehydrates the melt, and controls the oxidation state of both glassformer and impurity cations. The reaction of NF3 with nickel, silica, platinum, and vitreous carbon between 200 and 1100°C using IR absorption spectroscopy was investigated. This is an important issue, since reaction products (impurities) from the crucible and containment vessel walls may be incorporated in the melt. All materials, except for nickel, reacted below 600°C yielding corresponding fluorides (and oxides in the case of silica). The results indicate that, directly heated, vitreous carbon crucibles are preferred for melting of fluoride glasses in a NF3 atmosphere.

The structure of shock-loaded polycrystalline titanium diboride was examined with transmission electron microscopy. The shock wave from ballistic impact produces prismatic and basal slip in grains favorably oriented with respect to the shock wave. It can be deduced from annealing experiments with the formation of stacking fault hexagons that there is a high concentration of point defects in deformed regions from the motion of dislocation jogs. Weak-beam microscopy shows that the dislocations in TiB2 are dissociated into partial dislocations. The stacking fault energy measured from a screw dislocation in the basal plane was found to be 120 mJ/m2. Widely dissociated dislocations in the shocked sample suggest that residual stresses are present in some regions.

The energy levels of antisite defects at a GaAs/Ge (110) interface are calculated and shown to be essentially unaltered with respect to the GaAs valence band maximum by different choices of the valence band offset.

Extensive experimental investigations have been reported on the ion-induced motion of the interface between the crystalline and amorphous phases of silicon. The crystal grows into the amorphous phase at low ion fluxes and high temperatures. The amorphous phase grows into the crystal at high ion fluxes and low temperatures. The experimental observations are shown to fit a model based on a single defect. The concentration of this defect decays by binary recombination, this is, two of the defects annihilate one another. The model accounts for the linear relationship between interface motion and reciprocal temperature, for the Arrhenius temperature dependence of the flux at which no interface motion occurs, and for the temperature independence of the crossover frequency observed in beam pulsing experiments. The defect on which this model is based has a motion energy of 1.2 eV. Assuming that the same defect is also responsible for thermal recrystallization of the amorphous phase gives a formation energy of 1.5 eV for the defect. The defect is believed to be a dangling bond in the amorphous phase.

Nitrogen molecular ion implantations have been performed in niobium thin films to form B 1-NbN layers with an accelerating voltage of 150 kV up to a dose of 5 × 1017 N2+ ions/cm2 at room temperature. Measurements of superconducting transition temperature (Tc), Auger electron spectroscopy analyses (AES), and x-ray diffraction analyses (XRD) have been carried out as a function of nitrogen dose in order to characterize the implanted layer. It has been found that there are two regions in the dose dependence of Tc; in the low-dose case, Tc decreases from the initial value of 8 K to less than 4.2 K with increasing dose, and in case of the high dose (more than 2.5 × 1017 ions/cm2) it increases rapidly to 11 K and becomes independent of the implantation dose. The XRD patterns indicate the generation of lattice disorder at the low dose, the formation of Nb2N and ∊NbN at the intermediate dose, and the formation of δNbN (B 1 structure) at the high dose; the selective growth of δNbN occurs at the highest dose, in spite of the fact that thermodynamically Nb2N and ∊NbN are equilibrium phases at room temperature and they are formed at the intermediate dose. In conclusion, high-dose nitrogen implantation at room temperature causes the formation of δNbN to increase Tc.

LiNbO3 powders have been prepared by appropriate hydrolysis of lithium and niobium alkoxides using a sol-gel process. Ceramics with pretty high shrinkage coefficients and compactness have been obtained by sintering of the particles at 1075 °C.

The reactions of metal layers with their silicon substrates resulting in the formation of various silicides are considered generally not only as phenomena common to all diffusion couples where new phases are formed, but also as typical of all transitions from two to three phases. The conditions under which such transitions will display the same characteristics as encountered in the usual one-to-two phase transitions (condensation, crystallization, boiling) are analyzed by comparison to the classical theory of nucleation. Because of the lack of knowledge about the exact values of the relevant parameters, the discussion is carried out mostly in descriptive thermodynamic terms. Although nucleation effects are analyzed in general terms, the main focus of attention is a class of reactions where nucleation dominates the formation of a new phase; a salient feature of these reactions is the absence of any equilibrium temperature, although the nucleation temperatures are relatively well defined within narrow limits. Nucleation effects are correlated to such material characteristics as the stability of the nucleated phases, and to such kinetic characteristics as the sequence of phase formation. The modification of the energy levels of the different phases brought about by stress, ion bombardment, or the replacement of usual phases by metastable ones, are considered with respect to their effect on nucleation processes. The nearly total absence of literature references to nucleation in metal-metal diffusion couples is discussed with respect to some specific aspects of the metal-silicon reactions.

The melt self-quenching technique has been used to examine the metastable solid solution extension of mullite formed from rapidly solidified Al2O3.SiO2 melts. Increasing melt cooling rates were seen to increase the Al2O3 content of mullite, decrease the amount of mullite precipitating, and decrease the melt compositional range over which mullite forms. The maximum mullite Al2O3 content achieved was 77.3 mol % for cooling rates between 103 and 105 K/s. The highest Al2O3 content mullite also exhibited very similar ao and bo lattice parameters indicating a structure close to tetragonal symmetry (equilibrium mullite is orthorhombic).

Analysis of Ti-containing heterogeneities in a hot-pressed Al2O3 has revealed changes in microstructure caused by oxidation that provide some insight regarding the effects of Ti on local grain growth. The most consistent hypothesis is that Ti4+ in solution compensates the Mg2+ ion taken into solution from the MgO additive, probably by forming dipoles, and negates the effect of Mg2+ on grain boundary drag.

An ultra high vacuum system has been designed and constructed for the purpose of depositing high-quality oxide films on well-characterized crystal surfaces at low temperatures. In particular, aluminum phosphorus oxide films have been deposited on both In P and Ge surfaces for the purpose of device application. Electrical measurements of metal-oxide-semiconductor structures show much improved interfacial properties with little or no hysteresis.

Hydration reactions and their rates have been studied qualitatively in CaO-and P2O5-rich compositional regions of the system CaO–SiO2-P2O5-H2O. Using aqueous solutions of Ca (NO3)2–4H2O, Ludox, and H3PO4 as starting materials, amorphous powders made by the sol-gel process were reacted with water. Some “curing” reactions were carried out at several temperatures: room temperature, 90 °C, and under hydrothermal conditions. Some glasses in the phosphate-rich region of the system were also made and hydrated. The hydration products are OH–Ap [OH–Ap = Ca10(PO4)6-(OH)2], Ca(OH)2 [CH = Ca(OH)2],C–S–H crystalline, C–S–P–H (C = CaO,S = SiO2,P = P2O5,H = H2O) crystalline, C–S–H gel, C–S–P–H gel, Ca(H2PO4)2·H2O, and CaHPO4. All phases have been identified and characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray analysis (EDAX). The reactivities of the precursor materials and the compositional-structural nature of the hydration products formed are discussed. Some new compositions for “cementlike behavior” have been discovered.

Bond counting, and calculations of entropy, bond, and bond angle strain have been used to evaluate the relative stability of diamond and graphite on various substrates for conditions that normally stabilize the graphite structure in bulk. Pseudomorphic and many metallic substrates that bond to carbon when clean are found to stabilize the diamond phase; others stabilize the graphite phase. If the relative thermodynamic stability governs the kinetics of growth under film deposition conditions, then an interesting prediction of the present research is that growth of diamond on {100} surfaces should proceed by formation of surface monolayers that alternately have graphite and diamond bonding configurations, and with the graphite monolayer converting to a diamond configuration when it becomes subsurface. The latter mode of growth should not occur in an atomic hydrogen atmosphere, nor should it occur on {111} surfaces.