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Porous hollow silica spheres were synthesized using silk fibroin spheres as novel single sacrificial template via a sol-gel route and their in vitro biocompatibility and drug delivery property were evaluated. TEM observation showed that silica spheres had a hollow cavity and a porous shell, while BET measurement showed that they had the pore size of 22 nm and specific surface area of 45 m 2 /g. FT-IR spectrum showed that silica spheres contained Si O Si bonds. After exposure to Hela cells, MTT assay indicated that silica spheres were in vitro biocompatible. It was found that silica spheres not only supported adsorption of tetracycline hydrochloride (TH, one of the representative antibiotics) with adsorption efficiency of 17.4%, but also exhibited a sustained release behavior for TH. The TH-loaded silica spheres showed antibacterial property to inhibit the growth of two representative bacteria: Escherichia coli and Staphylococcus aureus , indicating that the released TH was biologically active.

Zinc/malic acid (Zn/MA) carboxylate gels were synthesized by adding a NaOH solution to solutions containing ZnCl2 and MA at room temperature, without adding a NH4OH solution. Glassy hydrogels with the transparency of 20.0–88.2% and with high viscosity were produced by a polymerization reaction in which the carboxyl and hydroxyl groups of MA were directly chelated by zinc ions. The gelation occurred in a narrow pH range as well as a narrow zinc concentrations range at 0.5 mol/l MA concentration. The Raman spectra showed that a new Raman line appeared at 881 cm−1 and we assigned it to the Zn–O–Zn vibration, and a red shift of the carboxyl and hydroxyl groups of MA. Rheological measurement showed the highest values of the storage and loss modulus when pH of the solution was raised to 7.0, and that the increase in the zinc ion concentration increased the storage and loss modulus increased due to the greater density of chelation. The linear correlation of log (G∗) and log (ω) indicated that the glassy hydrogels had a gel-like three-dimensional network.

Ca(II) containing porous hybrids of gelatin and 3-(glycidoxypropyl)trimethoxysilane (GPSM) were prepared using a sol–gel process, post-gelation soaking, and freeze-drying. The porosity and pore size of the hybrids could be well controlled by the freezing temperature and the pH value of the soaking solution. The pore characteristics were related to the structure change during the soaking treatment. A second soaking of the porous hybrids introduced a binary-pore distribution. The rate of biodegradation in a trishydroxymethylaminomethane (Tris) buffer solution decreased with an increased GPSM content. A bone-like apatite layer was able to form in the Ca(II) containing porous gelatin–siloxane hybrids upon soaking in a stimulated body fluid (Kokubo recipe). These hybrid materials are proposed to find application as novel bioactive and biodegradable scaffolds in bone tissue engineering.

X-ray photoelectron (XPS) and 29Si magic angle spinning (MAS)-NMR spectroscopy have been used to examine the chemical states of fluorine, oxygen, silicon and lead atoms in the glasses of composition x PbF 2 ·(100−y−x) PbO ·y SiO 2 (x=0,5,10,15,20,30 mol%, y=30,50,60 mol%). The analysis of the F 1s spectra indicated that Pb2+ and F− ions are preferentially located among the Si–O skeleton forming ionic Pb–F clusters. The fraction of the bridging (BO) and non-bridging oxygen (NBO) atoms was derived from the O 1s spectra. The network of the fluorine-containing glasses was concluded to depend on the ratio PbO/SiO2; when the ratio PbO/SiO2 was lower than 0.5, not only Pb atoms but also F atoms play a role as network modifiers, while when the ratio PbO/SiO2 is higher than 1.33, part of Pb atoms plays a role as a glass network former.

31P magic-angle-spinning (MAS) NMR spectra were measured for several oxides, such as Al2O3, SiO2, TiO2 and Ta2O5 which were treated with TaCl5-free H2O2 solutions and TaCl5-containing H2O2 solutions and soaked in a simulated body fluid (Kokubo solution; pH=7.4) for 7 days. The chemical states of phosphate anions deposited on these oxides were determined. A 31P MAS-NMR peak at a chemical shift ca. 3 ppm was observed in the spectra of Ta2O5 and for the other oxides when they were treated with the TaCl5-containing H2O2 solution. Without the treatment with the TaCl5-containing H2O2 solution no 31P MAS-NMR peaks were observed in the spectra of the oxides. The 31P chemical shift, ca. 3 ppm, indicated that orthophosphate anions, PO43− as found in hydroxyapatite and a cortical bone (rabbit) were adsorbed on the oxides. The surface of Ta2O5 particles and the oxides treated with the TaCl5-containing H2O2 solution induced the deposition of apatite. We concluded that the surface Ta(V) species supported on the oxides induced a bone-like apatite nucleus, even though the base oxides did not deposit apatite.

Wavelet analysis of X-ray diffraction patterns was made for structures of silica glasses manufactured by electrical fusion, oxy-hydrogen flame fusion of quartz powder, and flame hydrolysis of SiCl4. The analysis indicates that their structures were not affected by the manufacture methods. It is believed that there is a thermodynamically most favoured or unique structure for glass in an intermediate range up to a few nm. It is expected that amorphography (in analogy to crystallography for crystal) for glass will emerge as a new branch of science. According to our statistical crystallite model, glass structure could be determined by the crystallography of corresponding crystals and the damping with interatomic distance for the crystalline regularity.

X-ray photoelectron spectra of R2OTeO2 (R: Li, Na, K, Rb and Cs) glasses were measured, using a fresh surface fractured in an ultra high vacuum (≈ 7 × 10−8 Pa) and irradiated with a monochromatic Al K α X-ray (hv = 1486.6 eV). The O ls photoelectron spectra showed only a single Gaussian-Lorentzian peak and the peak shifted toward smaller binding energy with increase in Lewis basicity of oxide ions in the glasses. Two peaks attributed to BO and NBO were not observed. In the near valence band spectra for the lithium tellurite glasses, the spectral profile gradually became similar to that of a Li2TeO3 crystal with increase in Li2O content up to 30 mol% Li2O. This variation of the profile is correlated to the change in the coordination structure of the tellurium atoms (TeO4 trigonal bipyramids → TeO3 trigonal pyramids) with the addition of the alkali oxides.

Sr 2 TiSi 2 O 8 films oriented in polar direction ( c -axis) were prepared by surface crystallization of a glass 33.3SrO · 16.7TiO 2 · 50SiO 2 (in mol%) promoted by ultrasonic surface treatment with aqueous suspensions of Sr 2 TiSi 2 O 8 and subsequent heat treatment with high heating rates. The effects of heating rates and suspension particles and media on the orientation were investigated. The thickness of the oriented films was controllable by the heating time and temperature. The resultant transparent films/glass was found to exhibit second harmonic generation, and the tensor components of the second order optical non-linearity were estimated.

Extended X-ray absorption fine structure (EXAFS) near the Ge K-edge in glasses of the GeO 2 TeO 2 system was measured. The results were analyzed with both the GeO 4 GeO 6 two-shell model and the GeO 4 single-shell model. Since the two-shell model gave a better fit of the measured EXAFS it was concluded that the germanate anomaly should be interpreted by the convention, namely, the formation of GeO 6 units. The fraction of the GeO 6 units decreased from 0.46 to 0.266 as the GeO 2 content increased from 12 to 68 mol%.

Amorphous tungsten trioxide thin films were prepared using a rf magnetron sputtering method. The relation between structure and electrochromic properties was investigated. At the macroscopic level, the films had dense structures. From Raman spectroscopic and X-ray radial distribution analyses, it was deduced that the networks were basically formed by three-, four- and six-membered rings of corner-sharing WO6 octahedra, and in the films with low O/W atomic ratios many edge-sharing units were present. It was also found that the films with high O/W ratios showed good electrochromic properties, which were closely related to the six-membered rings.

Oxy-fluoride glasses in the GeO 2 PbOPbF 2 system were prepared and their structure investigated using vibrational spectra, X-ray diffraction and Raman spectra methods. Structural models were constructed by molecular dynamics simulations. In the models obtained, glass networks were formed by GeO 4 tetrahedra and Ge(O,F) 5 and Ge(O,F) 6 polyhedra. Lead entered the networks at PbFPb in the models with high Pb/Ge ratio. The presence of germanium with high coordination numbers of 5 and 6 was supported by radial distribution analyses. GeO bonds in GeO 4 tetrahedra seemed to give bands between 650 and 850 cm −1 (non-bridging oxygen) and between 450 and 650, and between 850 and 950 cm −1 (bridging oxygen). GeO and GeF in Ge(O,F) n ( n > 4) were supposed to contribute the bands observed between 350 and 550 cm −1 in the Raman spectra.

Surface crystallization of 25Li2O·20Nb2O5·55TeO2 (in mol%) glass was investigated. A few phases including LiNbO3 were precipitated on as-polished glass surfaces, while the crystallization of LiNbO3 was stimulated due to the ultrasonic surface treatment with an aqueous suspension of LiNbO3. A layer containing LiNbO3 single crystalline phase was prepared when the glass was treated at a relatively low temperature and short period after the ultrasonic treatment. The onset temperature of surface crystallization of the glass was reduced due to the ultrasonic surface treatment.

Coordination changes of Te(+ IV) atoms were derived from Raman and X-ray photoelectron spectra of the binary tellurite glasses containing Li, Na, Ba and Zn. A structure model consistent with the experimental results was proposed. In this model, TeO4 units were converted mainly to O22Te=O and O12Te(=O) O− in the range of lower atomic ratio O/Te, and the rate of increase of TeO3/TeO4 decreased in the range of higher O/Te because of the equilibrium TeO42 ↔ O22TeO. The increase in the fraction of non-bridging oxygen atoms and three-coordinated Te(+ IV) atoms was confirmed by X-ray photoelectron spectra. The fraction of non-bridging oxygen estimated from X-ray photoelectron spectra agreed well with that from the Raman spectra and the model.

Iridium (III) ethoxide and hydrogen hexachloroiridate (IV) films were formed on glass substrates by drop-and-spread and dip-coating procedures, and heat treated to IrO 2 films. Effect of additives such as ethylene glycol, H 2 O, and HNO 3 on the microstructure of the heated films was studied as well as that of drying and heating schedules. Preciptation of metallic Ir found for several films was correlated to the high electronegativity of Ir.

New photochromic glasses in the system Al-Cd-O-F, Al-Cd-Pb-O-F and Al-Cd-Pb-O were obtained. 27 Al nuclear magnetic resonance spectra confirmed that both Al(4) tetrahedra and Al(6) octahedra coexisted in the glasses containing fluoride ions and the number of the latter increased, accompanied by an increase of the fraction of Al-F bonds, with increasing atomic ratio F/O. However, most fluorine is coordinated with the Al(6) octahedra. Photo-induced absorption decayed slowly, accompanied by luminescence, and its half-life period was about 10 h at room temperature in the dark. The possible color centers are discussed on the basis of electron spin resonance spectra

TeK-edge spectra were measured for binary glasses of compositions 0.16B 2 O 3 · 0.84TeO 2 and 0.301B 2 O 3 · 0.699TeO 2 . Te O bond length and coordination number of Te atoms were analyzed to be very similar to those of paratellurite. Within errors of measurement, all the Te atoms were four-coordinated and TeO + 3 units were absent in the glasses. It was concluded that some other mechanism should be present to compensate for a negative charge on four-coordinated boron atoms in the glasses.

Two types of glasses in the ternary Alf 3 BaF 2 CaF 2 system were prepared under different cooling rates to investigate their network structure. It is suggested that the network is constructed from (AlF 5 ) 2− chains and (AlF 6 ) 3− isolated units and many isolated units are present in the rapidly cooled glass from radial distribution analyses. Molecular dynamics simulations were carried out to reproduce the difference in the glass network. The models showed good agreement with the observed RDF and Raman spectrum, but an exact structural difference in the network could not be obtained. However, it is suggested that chains with branches may be formed when the melt is slowly cooled.

X-ray photoelectron spectra (XPS) and infrared spectra were measured for lead-tin oxyfluorophosphate glasses and the bonding state of fluorine atoms was investigated. F 1s XPS had a doublet peak: one of the component peaks at 687.4 eV in binding energy was attributed to the fluorine in PF bonds, and the other at 684.9 eV to the fluorine in ionic MF bonds (M:Pb(II) and Sn(II)). The fraction of the latter increases with increase in the fluorine content.

Extended X-ray absorption fine structure (EXAFS) above the Te K-edge and X-ray diffraction measurements on amorphous SixTe1−x films ( x⋍ 0.1 1 2 -0.9 ) prepared by RF sputtering were carried out to determine the local structure of those alloys. The peak areas corresponding to TeSi and TeTe bonding shown in the Fourier-transformed EXAFS oscillation change monotonically with increasing silicon content. The first peak position of the radial distribution function obtained by X-ray diffraction measurement decreases with increasing silicon concentration. The experimental results are compared with some structural models. A random covalent network (RCN) model seems to be most acceptable for explaining the local structure of amorphous SixTe1-xin the high-Si concentration (x > 0.2).

Molar volumes and optical absorption spectra of Ni2+ ions were measured for sodium and potassium borosilicate glasses of the compositions xR2O·B2O3·rSiO2 (0.01 0.55 for r=1 and 0.6 x for r=2 . In the range x > 0.8 for r=1 and x > 9 for r=2, ROSiO3 and ROBO2 units were created by the alkali addition. Here ROBO2 units were also formed as a result of self-decomposition of RBO4 units. The volume of void associated with a BO4 unit was calculated and compared with the size of sodium and potassium ions. It was shown that sodium ions were small enough to be accommodated in the void whereas potassium ions were too large. This could explain the composition dependence of the molar volume of the sodium and potassium borosilicate glasses in the composition range x

A new method to determine ac conductivity of amorphous Ge using Al-amorphous Ge–SiO2–P+Si tunnel junctions is presented. Frequency dependence of ac conductivity is found to satisfy the power law in the frequency range between 1 and 50 kHz and the density of localized states at the Fermi level is estimated to be ∼ 1.7 × 1020 cm−3 eV−1 which decreases to ∼ 4.5 × 1019 cm−3 eV−1 after annealing at 175°C. Temperature dependence of tunneling conductance of Al-amorphous Ge–SiO2–P+Si junctions is appreciable only near zero bias. Zero bias conductance of the junctions obeys the T − 1 4 law of Mott; the density of localized states obtained from the T − 1 4 law is one order of magnitude smaller than that obtained by ac conductivity measurements, being insensitive to annealing. This behavior of the tunnel junctions differes in many respects from those of Al–Al2O3-amorphous Ge tunnel juntions.

Amorphous silicon films have been prepared by plasma decomposition of silane under magnetic field. The films produced at a high power and a relatively high magnetic field possess refractive indices close to the crystalline value, and exhibit no appreciable infrared absorption due to (SiH 2 )n or SiH 3 bonds. This unique film-structure has been correlated with the high photoconductivity and low density of gap states. The growth kinetics of the film is found to be strongly influenced by magnetic field applied to discharge plasma.

Measurements of high field current have been made on amorphous Ge (a-Ge) films over the temperature range from 100 to 300 K. Non-ohmic conduction in a-Ge occurs at electric fields greater than 1–2 × 104 V/cm. Field dependence of the conductivity has been explained in terms of the enhanced emission probability of carriers from the screened coulombic trap centers. Assuming the optical dielectric constant for a-Ge films, the screening length of the trap centers and the density of states at the Fermi level are estimated to be 12 A and ∼6.1 × 1020 cm−3 eV−1, respectively.

Infrared absorption, laser Raman scattering as well as X-ray induced ESR spectra have been measured for lithium fluoroborate and chloroborate glasses. For the glasses with an identical Li 2 O/B 2 O 3 ratio, the chloroborate glasses showed vibrational spectra similar to those observed in the halide free borate glasses, while the fluoroborate glasses showed different ones. ESR spectra confirmed that Cl 2 - radical is formed in the chloroborate glasses upon the X-ray irradiation, but F 2 - radical has not been detected for the fluoroborate glasses even at 77 K. It is concluded that F is covalently bonded to B, but Cl is just present in interstitial sites in the borate glass as a free ion.

In order to characterize a few series of network type glasses in the systems of borate, borosilicate and aluminosilicate from a view point of macroscopic model, correlations between the lattice energy, bulk modulus K and ion-pair volume Vip has been studied. The aluminosilicate glasses with the ratio Al/R = 1 show a relation KVip4=constant due to the alkali ions R being filled in the silica-like network. Such filling effect is also found for the sodium borate glasses with the ratio Na2O/B2O2>0.33 constructed by sufficiently strengthened borate network as well as in the borosilicates with varied atomic ratio R/B. For a series of the borosilicate glasses with R/B=1 and different in SiO2 content the K vs. Vip plots in log-log scale compose a line of slope −4/3. On the basis of the total amount of the bridging bond per network forming cation, the difference in the K-V plots between the aluminosilicate and borosilicate is attributed to the borate group formation in the latter glasses.

Structural inhomogeneities of μc-Si:H in the range 20≈500 A are observed for the first time by small angle X-ray scattering. Inhomogeneous distributions of bonded hydrogen in the amorphous tissue are suggested to be a possible origin of the SAXS yield. Such inhomogeneities can be reduced when the average grain size and volume fraction of microcrystallites are simultaneously increased.

The spaces in glass networks to be occupied by network modifying (NWM) cations are defined as “voids”, being distinguished from interstitial sites for network forming (NWF) cations. The volumes of the voids were evaluated as those of the largest spheres to be accomodated in them for several high-cristobalite (h-c) type networks using silica glass as the reference material. The sizes of the alkali ions were compared with those of the voids in SiO 2 , GeO 2 , alkali disilicate, germanosilicate and some other assumed glasses.

The DC conductivity, F1s X-ray photoelectron spectra (XPS), Al Kα fluorescence spectra (XFS) and Raman spectra have been studied for the glasses in the systems B2O3PbOPbF2 and B2O3PbOPbF2AlF3. The conductivity increases by several orders of magnitude and the activation energy decreases linearly with the PbF2 content for both the ternary and the quaternary glasses. Such a change has been proposed to be due to the contribution of F− ions to the conduction. The F1s XPS study shows the presence of three kinds of F− ions, such as those bonded to B, Al and Pb atoms in the glasses. The decrease in the conductivity upon the addition of AlF3 is attributed to the formation of AlF bonds. The Raman and Al Kα XFS study shows that the glasses are comprised of discrete and polymerized three-coordinated borate units and six-coordinated Al atoms.

The annealing-induced changes in optical properties of hydrogenated amorphous silicon deposited at a high deposition-rate were investigated. The photoluminescence intensity increased, while optical gap increased slightly when the sample was annealed up to 400°C. The silicon hydrogen bonding configuration varied with annealing in a completely different manner from that of low-rate films. The mode of atomic stacking in high-rate as-deposited films appears to deviate appreciably from that in low-rate ones.

The predominant hydrogen-bonding configuration in high-rate a-Si : H film changes monotonically from the SiH configuration to the SiH2 configuration with decreasing deposition rate due to the dilution of silane with hydrogen. However, the change of the parameters (ESR spin density, optical absorption coefficient at 1.25 eV and PL intensity) related to the structural disorder is not monotonous and this change is not corresponding to the simple change of the hydrogen-bonding configuration observed in the IR measurements. These results seem to be consistently explained on the basis of the two-phase model suggested by Ueda et al. for the high-rate films.