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The objective was to determine if there is a significant difference between rates of non-union of type II and III odontoid fractures in patients with calcium pyrophosphate dihydrate deposition (CPPD) compared with a control population. A 10-year retrospective picture archive and communications system review was performed of 31 CPPD patients and 31 control patients. Imaging studies were reviewed for radiographic or CT evidence of osseous union and complications. There was a significant difference in the rates of non-union between the two groups, with the non-union rate reaching 90.3% in the CPPD group and 32% in the control group. Comparing the degree of displacement and angulation of the two groups did not show a significant difference. The results indicate that odontoid fracture non-union rates are significantly higher in CPPD patients and should be taken into consideration when diagnosing odontoid fractures and deciding on appropriate treatment.

Bound magnetic polarons (BMP's) in $p$-type ${\mathrm{Cu}}_{2}{\mathrm{Mn}}_{0.9}{\mathrm{Zn}}_{0.1}{\mathrm{SnS}}_{4}$ were investigated using magnetization measurements. The magnetization $M$ was studied from 2 to 60 K in magnetic fields up to 55 kOe. The data show the characteristic features of BMP's in the collective regime. In addition, the onset of antiferromagnetic order in the ``matrix'' surrounding the BMP's leads to anomalies in the BMP susceptibility at the N\'eel temperature of the matrix ${T}_{N}=8$ K. Below 15 K the low-field magnetization of the BMP's is quite anisotropic. A detailed analysis of the isothermal magnetization curves, based on Wolff's work but with some additional assumptions, separates the BMP contributions to $M$ from the contribution of the matrix. The analysis gives the spontaneous moment ${m}_{s}$ of a single BMP as a function of temperature $T$, and the concentration $N$ of BMP's. The value ${m}_{s}=143$ Bohr magnetons/BMP at the lowest temperatures is consistent with the expected radius of the hole orbit, of order 10 \AA{}. The observed $T$ dependence of ${m}_{s}$ is compared with theoretical calculations based on a model that assumes that the wave function in the absence of the $p$-$d$ interaction is hydrogenic. The calculated decrease of ${m}_{s}$ with increasing $T$ is somewhat slower than that deduced from the experimental data. The BMP concentration $N$, from an analysis of the magnetization data, is about $2\ifmmode\times\else\texttimes\fi{}{10}^{19}$ BMP/cm${}^{3}$ in all the samples. This $N$ is consistent with the observed hopping conductivity at low temperatures. High-field magnetization data, up to 300 kOe, show the canted-to-paramagnetic phase transition of the matrix. At 1.4 K the transition is near 225 kOe.

The work at Tufts University was partially supported by NSF Grant No. DMR-9219727. The research in Zaragoza was supported by CICYT Grant No. MAT94-0043. The work at Brown University was supported by NSF Grant No. DMR-9221141. The Francis Bitter National Magnet Laboratory was supported by NSF.

A marked increase in the activity of a Pd/TiO 2 catalyst toward the decomposition of salicylic acid was observed compared to that measured for a pure TiO 2 film. The observed difference in activity of Pd/TiO 2 vs pure TiO 2 films was in accordance with predictions made from the Langmuir—Hinshelwood model. This study further confirmed Bard's model that the metal cocatalysts provide additional sites for electron transfer to oxygen.

The single-ion anisotropy constant D of Co 2+ in Cd 1− x Co x S was determined from a magnetization step which was detected using optical Faraday rotation technique. Experiments were performed in a dilution refrigerator at a temperature of approximately 80mK. Analysis of the data gave D / k B = 0.96 ± 0.02 K .

Samples of Nb2O5/TiO2 mixed oxide powders were prepared by the incipient wetness method. The photocatalytic activities of TiO2 based catalysts were evaluated by the degradation of 1,4-dichlorobenzene (DCB). The addition of Nb2O5 to TiO2 greatly increased its photocatalytic activity and also increased the catalyst's surface acidity, as determined by the n-butylamine titration method. A correlation between the maximum photocatalytic activity and the number and strength of acid sites were observed. Consequently, the same structural feature that enhances the adsorption of n-butylamine appears to promote the catalytic activity.

The magnetization of cubic ${\mathrm{Zn}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Fe}}_{\mathit{x}}$Se, with x=0.003 and 0.007, was measured at temperatures 2\ensuremath{\le}T\ensuremath{\lesssim}50 K in magnetic fields H along the [100] and [111] directions. Data for H\ensuremath{\le}55 kOe were taken with a superconducting quantum interference device magnetometer. Other data in fields up to 200 kOe were taken with a vibrating sample magnetometer operating in a Bitter magnet. At the lowest temperatures the magnetization M at high magnetic fields is anisotropic: at a given T and for the same magnitude H of the magnetic field, M for H\ensuremath{\parallel}[100] is larger than for H\ensuremath{\parallel}[111]. The difference between the values of M for these directions reaches a maximum value of 19% at the lowest temperatures and when H\ensuremath{\simeq}150 kOe. As the temperature rises, the anisotropy of the high-field magnetization decreases gradually, becoming very small above 40 K. In low fields (H\ensuremath{\lesssim}10 kOe) the anisotropy is very small at all temperatures. These experimental results are generally in good agreement with theoretical calculations based on crystal field theory and on the assumption that only isolated ${\mathrm{Fe}}^{++}$ ions (singles) contribute to the magnetization. Minor discrepancies between experiment and theory remain, however.

TiO[sub 2] powder samples were calcined at various temperatures and their photocatalytic activity toward the degradation of 1,4-dichlorobenzene was measured. The surface acidity of the sample was also determined by the n-butylamine titration method. A linear relationship between photocatalytic activity and surface acidity was observed for the TiO[sub 2] samples. WO[sub 3]/TiO[sub 2] mixed oxide powders and MoO[sub 3]/TiO[sub 2] greatly enhanced its photocatalytic properties. The addition of WO[sub 3] or MoO[sub 3] to TiO[sub 2] also increased the catalysts' surface acidity, as determined by the n-butylamine titration method. A correlation between the maximum photocatalytic activity and the maximum surface acidity was observed. Whereas acidity may not be the only factor which influences activity, it is certainly an important one. 55 refs., 4 figs., 3 tabs.

Samples of WO3/TiO2 mixed oxide powders were prepared by two methods: (1) the incipient wetness impregnation of an aqueous ammonia solution of H2WO4 onto TiO2 (P25), followed by heat treatment and (2) the ultrasonic nebulization and flame hydrolysis of a mixed isopropanol solution of tungsten(V) pentaethoxide and titanium(IV) tetraisopropoxide. The photocatalytic activities of TiO2-based catalysts were evaluated by the degradation of 1,4-dichlorobenzene (DCB). The addition of WO3 to TiO2 greatly increased its photocatalytic behavior. This may be related to an increase in the transfer of electrons from the TiO2 to the outer system, via the formation of an intermediate W(V) species.

Energy levels resulting from the splitting of the 5 E ground term of the Fe ++ ion in ZnSe were studied by Raman scattering. Data were taken at T =2 K and in magnetic fields B≤10T oriented along the [100], [111] and [110] crystal axes. The observed anisotropy of the energy-level diagram in a magnetic field is reasonably well described by a simple crystal field model.

The addition of MoO[sub 3] to TiO[sub 2] enhanced its photocatalytic properties by 100%. This may be related to an increase in the rate of transfer of electrons from the TiO[sub 2] to the outer system, via the formation of a reduced molybdenum species. Samples of MoO[sub 3]/TiO[sub 2] mixed oxide powders were prepared by two methods: (1) the incipient wetness impregnation of ammonium paramolybdate onto TiO[sub 2] (P25), followed by a heat treatment, and (2) the ultrasonic nebulization and flame hydrolysis of a mixed ethanol solution of molybdenyl acetylacetonate and dipropoxy-titanium-bis(acetylacetonate). The photocatalytic activities of TiO[sub 2] based catalysts were evaluated by the degradation of 1,4-dichlorobenzene (DCB). TiO[sub 2] has promising applications in the treatment of both waste and drinking water.

Silver was deposited on TiO[sub 2] powders (Degussa P25) by the photodecomposition of two different silver salts, AgF and AgNO[sub 3]. The photocatalytic activity of TiO[sub 2] powder samples was evaluated by the degradation of 1,4-dichlorobenzene (DCB). Photodecomposition of AgF on TiO[sub 2] gave higher photocatalytic activity than that of AgNO[sub 3]. The optimum catalytic activity found by the deposition of Ag was comparable to that obtained from Au. It was also observed that the photocatalytic activity of Ag-loaded TiO[sub 2] films was greater than that obtained for pure TiO[sub 2] films. This result is consistent with the results obtained for Ag-deposited TiO[sub 2] powders.

Samples of palladium decomposed onto TiO[sub 2] particles were prepared by two methods: the dispersion of a PdCl[sub 2] solution followed by thermal decomposition, and the photodecomposition of PdCl[sub 2]. The addition of palladium to all samples increased their photocatalytic activity toward the degradation of 1,4-dichlorobenzene. This increase was optimized and compared for these two preparative methods. Palladium was also decomposed onto TiO[sub 2] thin films by the photodecomposition of PdCl[sub 2]. The addition of palladium to the films increased their photocatalytic activity toward the degradation of salicylic acid. 35 refs., 4 figs., 4 tabs.

TiO2 thin films were prepared by spin coating and spray pyrolysis techniques. The observed photocatalytic activity is the same for films prepared by both techniques. The photocatalytic activity increases as film thickness increases but remains constant after the thickness reaches 0.60 μm. These films are shown to be capable of photodecomposing organic impurities in water.

This paper reviews the photocatalytic activity of TiO[sub 2] toward the degradation of organic compounds in aqueous solutions at low concentrations. The photocatalytic activity of both polycrystalline samples and thin films can be related to the method of preparation of the catalyst. The increase in the catalytic activity of TiO[sub 2] when certain metals such as silver, gold, and palladium are deposited on the surface is also discussed. These catalysts have potential use in removing harmful carcinogens from water as well as possible application in reducing the harmful effects of oil spills. 45 refs., 2 figs.

Thin films of zinc sulfide were prepared by ultrasonically spraying a toluene solution of bis(diethyldithiocarbamato)zinc(II) onto silicon, sapphire and gallium arsenide substrates at 460–520 °C. The films prepared on silicon or sapphire were found to have a highly oriented hexagonal structure, while those deposited onto cubic (100) gallium arsenide showed a highly oriented cubic structure. The films were characterized by X-ray diffraction analysis, ellipsometry, scanning electron microscopy, and IR spectroscopy.

Various techniques are described for the preparation of polycrystalline and single crystal samples of transition metal oxides. The importance of “precursors” in facilitating the formation of the desired product is discussed. The various problems encountered in the preparation of pure, homogeneous, uniform materials are related to the characterization of these compounds in order to properly describe their properties.

The various techniques for the low temperature synthesis of transition metal sulfides are discussed. The advantages of methods using precursors which already contain metal sulfur linkages are treated, and the properties of the sulfides produced are compared with those prepared by high temperature methods.

Three useful sulfides, Ni 3 S 2 , Co 9 S 8 , and ZnS, have been prepared by the decomposition of their respective diethyldithiocarbamate complexes. The products were characterized by X-ray diffraction analysis, crystallite size determination, and magnetic susceptibility measurements. The problems associated with organometallic precursors for the synthesis of metal sulfides are discussed and the method is compared with the direct conversion of sulfate salts to sulfides in a controlledH 2 /H 2 S environment.

Samples of Ni(II) on MgAl2O4 and of Ni(II) and La(III) on MgAl2O4 were prepared and characterized by X-ray diffraction, temperature programmed reduction, and magnetic susceptibility. The results are consistent with the octahedral site preference of Ni(II) in the spinel phase. The role of lanthanum is discussed in terms of the formation of a perovskite-phase LaAlO3.

Films of titanium(IV) oxide were deposited on a variety of substrates by a simple nebulization and pyrolysis technique. Good uniformity and adhesion was obtained in all cases. The films showed appreciable photocatalytic activity toward the degradation of salicylic acid. The observed activity was increased by the deposition of elemental gold on the TiO2 films.

Samples of gold decomposed on TiO2 powder were prepared by two methods: the dispersion of a gold chloride solution followed by thermal decomposition, and the photodecomposition of gold chloride. The addition of gold to all samples increased their photocatalytic activity. This increase was optimized and compared for these two preparative methods.

We have measured the magnetoreflectance of orthorhombic ${\mathrm{Cu}}_{2}$${\mathrm{Zn}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$${\mathrm{GeS}}_{4}$ with x=0.83, 0.92, and 1.00 at 1.3 K in applied dc magnetic fields B up to 15 T with B applied parallel to crystallographic directions a, b, and c. Exciton splittings as large as \ensuremath{\sim}170 and \ensuremath{\sim}230 meV were observed for light polarization vector E\ensuremath{\parallel}a and E\ensuremath{\parallel}c, respectively. With increasing magnetic field, the average energy of the E\ensuremath{\parallel}a exciton components decreased and that of the E\ensuremath{\parallel}c components increased. Sample geometry did not permit E\ensuremath{\parallel}b measurements. Room-temperature excitions were also observed but their Zeeman splittings were not observed. The excitons are associated with transitions between the conduction and valence bands, which were assumed to be s like and p like, respectively. We have also measured the magnetization of the x=0.92 and 1.00 samples at 1.4 K in applied dc magnetic fields up to 19.5 T with B\ensuremath{\parallel}b. From the optical and magnetization data, we determined the s-d and p-d exchange-constant difference ${\mathit{N}}_{0}$\ensuremath{\alpha}-${\mathit{N}}_{0}$\ensuremath{\beta} where ${\mathit{N}}_{0}$\ensuremath{\alpha} and ${\mathit{N}}_{0}$\ensuremath{\beta} measure the exchange interaction between the ${\mathrm{Mn}}^{2+}$ 3d electrons and the conduction and valence-band electrons, respectively. For x=0.92, we obtained ${\mathit{N}}_{0}$\ensuremath{\alpha}-${\mathit{N}}_{0}$${\mathrm{\ensuremath{\beta}}}_{\mathit{x}}$=0.089\ifmmode\pm\else\textpm\fi{}0.005 eV and ${\mathit{N}}_{0}$\ensuremath{\alpha}-${\mathit{N}}_{0}$${\mathrm{\ensuremath{\beta}}}_{\mathit{z}}$=0.126\ifmmode\pm\else\textpm\fi{}0.007 eV. For x=1.00, we obtained ${\mathit{N}}_{0}$\ensuremath{\alpha}-${\mathit{N}}_{0}$${\mathrm{\ensuremath{\beta}}}_{\mathit{x}}$=0.077\ifmmode\pm\else\textpm\fi{}0.005 eV and ${\mathit{N}}_{0}$\ensuremath{\alpha}-${\mathit{N}}_{0}$${\mathrm{\ensuremath{\beta}}}_{\mathit{z}}$=0.110\ifmmode\pm\else\textpm\fi{}0.007 eV. These values are an order of magnitude smaller than those observed in II-VI diluted magnetic semiconductors.

Titanium(IV) oxide samples were prepared by two techniques, namely, ultrasonic nebulization and flame hydrolysis, and the ultrasonic nebulization and furnace pyrolysis. Titanium(IV) chloride and diisopropoxy-titanium(IV)-bis-(acetylacetonate) were employed for the preparation of titanium(IV) oxide samples. The photocatalytic activities of the prepared samples were evaluated by measuring the degradation of 1,4-dichlorobenzene and compared with that of Degussa P25 titanium(IV) oxide. The ultrasonic nebulization and flame hydrolysis method was more efficient than nebulization and furnace pyrolysis. Products obtained using this method gave photocatalytic activities similar to that of P25.

The effect of polyiodide solution treatment on WSe2−both n and p type−prior to Schottky junction formation, has been studied. The junctions have been characterized mainly by (photo)current/voltage and spectral response measurements. Barrier heights of ≳1 V have been found [Eg(WSe2)∼1.2 eV]. X‐ray photoelectron spectroscopy and Rutherford backscattering analyses of polyiodide‐treated WSe2 show that some iodine species (the nature of which has not been conclusively identified) exists to considerable depths (10−6–10−5 cm) in the WSe2, and that the I uptake is much faster and more extensive on defects (∥c faces) than on the van der Waals (⊥ c) face, if indeed it is adsorbed on the latter at all. Also, the surface charge differs between the two faces for both the nontreated and I‐treated cases. The results are consistent with a passivation mechanism whereby some I species at the defects chemically attack the deposited metal (Au,Al), effectively removing the metal/defect–semiconductor junctions which short the ...

Polycrystalline samples of members of the systems (ZnS)1-x(CuMS2)x(M = A1, In or Fe) were prepared by direct combination of the elements. Single crystals have been grown by chemical vapor transport using iodine as the transport agent. They all crystallize with the zinc blende structure. Their IR transmission range is narrower than that observed for pure Zinc Sulfide, but all, except for the ZnS-CuInS2 system, still show good transmission in the long wavelength IR range. The addition of small amounts of I-III-VI2 modifies the hardness and the thermal stability of ZnS. Zinc Sulfide has been studied extensively because it offers a variety of unique device applications. ZnS crystallizes with the cubic zinc blende structure below 1020 C and with the hexagonal wurtzite structure above this phase transition temperature. The ternary chalcogenides, CuMS2(M = A1, Ga, In or Fe) crystallize with the chalcopyrite structure, which is closely related to the cubic zince blende structure. In the chalcopyrite structure, there is an ordering of Cu(I) and M(III) (M = A1, Ga, In Or Fe) which results in a doubling of the c-axis. There have been relatively few studies carried out on the preparation and characterization of solid solutions formed between ZnS and CuMS2(M = A1, Ga, In or Fe).

The magnetization of Cd1-xFexSe, with x=0.025 and 0.027, was measured at 1.2 and 4.2 K in magnetic fields H both parallel and perpendicular to the c-axis. At low fields the parallel magnetization M‖ (for H ‖ c) is larger than M⊥( H ⊥c), but at H=195±30 kOe the magnetic anisotropy reverses. The anisotropy reversal is explained by model calculations for singles (isolated Fe++ ions in the crystal). Some discrepancy between the experimental and theoretical curves exists, however, even when the small contribution of nearest-neighbor pairs is included in the theory.

Ni(II) and Co(II) precursors were reacted with MgO, MgAl 2 O 4 , and γ-Al 2 O 3 . The reaction products were characterized by X-ray analysis, temperature programmed reduction, and magnetic susceptibility, The different stabilizations toward reduction were correlated with the site preference and formal valence state of the transition metal ions.

Layered dichalcogenide semiconductors (LS) are studied intensively for photovoltaic applications. It is generally accepted that the smooth van der Waals face (\ensuremath{\perp}c) is most suitable for this purpose. Recombination centers have been associated with surface steps (exposing \ensuremath{\parallel}c facets) or near-surface dislocations. Efforts to passivate the recombination centers had, until now, only limited success. In contrast to this approach, a method of surface preparation of LS, leading to rough surfaces that exhibit high photoactivity with high reproducibility, is presented. The physical principles underlying this technique are discussed in detail.

The various techniques for the low temperature synthesis of transition metal sulfides are discussed. The advantages of methods using precursors which already contain metal sulfur linkages are treated, and the properties of the sulfides produced are compared with those prepared by high temperature methods.

TiO2 samples were prepared by two procedures and their catalytic activities were compared to samples of commercial TiO2 (P25). The addition of gold to all of these samples increased their photocatalytic activity.

α-Fe2O3 thin films were deposited on silicon substrates by nebulization of a 0.01 M solution of iron acetylacetonate in a 50% methanol/water mixture followed by pyrolysis and annealing in flowing oxygen. The resulting films were characterized by X-ray diffraction, scanning electron microscopy, and their electrical transport behavior. The IR transmission spectrum of α-Fe2O3 recorded from such films agreed with published theoretical analysis based on the crystal structure.

Samples of “cobalt oxide” supported on γ-Al2O3 were prepared from a variety of precursors. The samples were characterized by X-ray analysis, temperature-programmed reduction, and measurement of magnetic susceptibility. Their properties were compared with those of bulk Co3O4 and CoAl2O4 and the observed differences were related to the method of preparation.

A hot tungsten filament reactor was used to deposit diamond films on silicon, copper, and gold substrates. Diamond can be readily nucleated on all three substrates, but the nucleation density is greatly enhanced by prescratching with 0.25-μm diamond paste. Visual examination of photomicrographs of diamond crystallites formed on prescratched silicon substrates indicates that no new nuclei are formed between 1 and 2 hr of deposition. However, new nuclei are formed throughout this period when the substrate is copper or gold. Deposite diamond films adhered to silicon substrates, but could be readily removed from copper and gold substrates.

Films of Y2O3, La2O3, and La2CuO4 were prepared by an ultrasonic nebulization and pyrolysis method using acetylacetonates of the corresponding metals in alcohol solvents as source materials. Homogeneous, uniform films with good adherence have been obtained using this simple technique. As-deposited yttrium and lanthanum oxide films were poorly crystallized. After postannealing in oxygen at higher temperature, they crystallized into cubic and hexagonal phases, respectively. Transparent yttrium and lanthanum oxide films have high electric breakdown voltages. Single phase polycrystalline La2CuO4 thin films were obtained from a source solution with a La:Cu ratio of 2:1.

Films of anatase were prepared on silicon and silica supports by ultrasonic nebulization of an ethanol solution of titanium acetylacetonate followed by pyrolysis and annealing in oxygen at 380°C. The transformation to rutile occurred in the temperature range 800–950°C without degradation of the film quality. TiO 2 films could be slightly reduced to TiO 2−x at 500°C in an atmosphere of pure hydrogen and further reduction, giving increased conductivity, occurs at elevated temperature. These films were comparable in quality to those prepared by more elaborate techniques.

Chromium (III) oxide films of 2000A thickness were deposited on n-type silicon wafers by a novel spray pyrolysis method. Different spray solutions, all containing a chromium acetylacetonate complex, gave different rates of film deposition. IR spectroscopy of these films confirmed them to be α-Cr 2 O 3 . The deposited films of α-Cr 2 O 3 were found to be homogeneous and uniform with breakdown potentials in excess of 20 V. The characteristics of films prepared from different spray solutions are compared and discussed.

Various techniques are described for the preparation of polycrystalline and single crystal samples of transition metal oxides. The importance of “precursors” in facilitating the formation of the desired product is discussed. The various problems encountered in the preparation of pure, homogeneous, uniform materials are related to the characterization of these compounds in order to properly describe their properties.

Semimagnetic semiconductors are a class of doped II–VI compounds which are of interest in the study of magnetic interactions. Samples of iron-doped ZnS, ZnSe, and CdS were prepared by the direct combination of the elements. Magnetic measurements indicate that the antiferromagnetic interactions of the iron in the zinc systems are greater than those observed in the cadmium chalcogenides. Single crystals of iron-doped zinc chalcogenides were grown by chemical vapor transport. Their IR transmission was measured and the iron concentration for maximum hardness was determined.

Zirconium oxide films were deposited on silicon substrates by nebulizing alcohol solutions of zirconium acetylacetonate followed by pyrolysis and annealing of the oxide film in flowing oxygen for 30 minutes. The homogeneous uniform films obtained showed comparable properties to those reported from more elaborate procedures. The simplicity of this technique of ultrasonic nebulization and pyrolysis is of interest because of the commercial desirability of zirconium oxide films.

Magnetization steps (MSTs) were observed in Zn1-xCoxSe and Zn1-xCoxS using temperatures T < 1 K, steady magnetic fields up to 200 kOe, and pulsed fields up to ∼400 kOe. Unlike the MSTs observed earlier in other materials, these MSTs are due to pairs of distant-neighbor spins rather than to pairs of nearest-neighbor spins. For Zn1-xCoxSe the results give a second-neighbor exchange constant J2/kB = −3.04±0.1 K, and suggest a third-neighbor exchange constant J3/kB ≌ −0.8 K. An exchange constant J/kB = −2.25±0.2 K observed in Zn1-xCoxS is either J2 or J3.

Samples of Cu x Pd 1− x O were prepared by codecomposition of the nitrates. Single-phase products were obtained for x ≦ 0.15. The presence of Cu(II) in D 2 h symmetry coordination has been confirmed by magnetic susceptibility and ESR spectra. The results are discussed, compared with those of the system Cu x Mg 1− x O, and interpreted in terms of the Cu(II) coordination symmetry and the electron orbitals.

Samples of cobalt-doped ZnS, ZnSe, CdS, and CdSe were prepared by the direct combination of the elements. The limit of solubility of cobalt in these systems was established. Magnetic measurements indicate that the antiferromagnetic interactions of the cobalt in the zinc systems were greater than those observed in the cadmium chalcogenides. Single crystals of cobalt-doped zinc chalcogenides were grown by chemical vapor transport. Their IR transmission was measured and the cobalt concentration for maximum hardness was determined.

A simple spray pyrolysis technique has been applied to the formation of dense, homogeneous gallium(III) oxide thin films on both silicon and silica substrates. The high quality of these films has been established by transmission electron microscopy, x-ray diffraction, optical spectra, and current-voltage measurements.

Alumina thin films of 2000 A were deposited on n-type silicon wafers by a novel spray pyrolysis method. The spray solution contained an aluminum acetylacetonate complex which was characterized by NMR techniques. The deposited films of Al2O3 were homogeneous, uniform, dense and had breakdown potentials of greater than 10 V.