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Negative thermal expansion (NTE) is an unusual thermophysical phenomenon and has gained attention as a way of controlling thermal expansion. Here, we report a substantial NTE in fluoroapatite Pb

A combination of $^{19}$F magic angle spinning (MAS) nuclear magnetic resonance (NMR) and density functional theory (DFT) were used to study the ordering of F atoms in Pb$_2$Ti$_4$O$_9$F$_2$. This analysis revealed that F atoms predominantly occupy two of the six available inequivalent sites in a ratio of 73:27. DFT-based calculations explained the preference of F occupation on these sites and quantitatively reproduced the experimental occupation ratio, independent of the choice of functional. We concluded that the Pb atom's 6$s^2$ lone pair may play a role ($\sim$0.1 eV/f.u.) in determining the majority and minority F occupation sites with partial density of states and crystal orbital Hamiltonian population analyses applied to the DFT wave functions.

Control of spin alignment in magnetic materials is crucial for developing switching devices. In molecular magnets, magnetic anisotropy can be rationally controlled by varying their ligands that allow tuning of ligand field splitting energy. However, the inherent weak magnetic interaction between spins or spin-cluster results in spin reorientation (SR) occurring only at low temperatures. Here, we show that layered perovskite oxyfluoride Pb3Fe2O5F2 exhibits a SR transition at 380 K, with the magnetic moments changing from perpendicular to parallel to the c-axis. It is found that the SR is caused by a ferroelectric-like phase transition, where the magnetic HOMO-LUMO interaction changes upon the structural transition due to the concerted effect of the heteroleptic FeO5F coordination and the steric effect of Pb. This finding indicates that the design of spin orientation by local coordination environment, which is common in molecular magnets, can be extended to extended oxides by introducing different anions.

Calcined and dispersible titanium-doped hydroxyapatite (Ti-HAp) nanoparticles at different [Ti/(Ca+Ti)] atomic ratios (0.3, 0.4, and 0.5) were prepared using an anti-sintering method. The Ti substitution ratios of the HAp structures in the feed of Ti-HAp preparation were approximately 80%. Ti-HAp nanoparticles were coated on polyethylene terephthalate (PET) sheets through polyacrylic acid graft-polymers. The PET substrate was almost completely covered with monolayer nanoparticles (over 95%). Antibacterial activity of coated Ti-HAp was calculated from the survival ratio of the bacteria, Staphylococcus aureus, after ultraviolet (UV) irradiation at 312 nm and 6.4 mW/cm2 for 30 s. The number of S. aureus on the Ti-HAp coated substrate decreased by 43% compared to those on the original PET and normal HAp coatings as negative controls. The antibacterial activity of Ti-HAp coated substrate was, furthermore, no statistically difference with TiO2 sheet as a positive control.

Thirteen patients with chlorhexidine-silver sulfadiazine-impregnated catheters have experienced serious anaphylactic shock in Japan. These adverse reactions highlight the lack of commercially available catheters impregnated with strong antibacterial chemical agents. A system should be developed that can control both biocompatibility and antibacterial activity.Hydroxyapatite (HAp) is biocompatible with bone and skin tissues. To provide antibacterial activity by using an external physical stimulus, titanium (Ti) ions were doped into the HAp structure. Highly dispersible, Ti-doped HAp (Ti-HAp) nanoparticles suitable as a coating material were developed. In 3 kinds of Ti-HAp [Ti/(Ca + Ti) = 0.05, 0.1, 0.2], the Ti content in the HAp was approximately 70% of that used in the Ti-HAp preparation, as determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). ICP-AES and X-ray diffraction showed Ti ions were well substituted into the HAp lattice. The nanoparticles were almost uniformly coated on a polyethylene (PE) sheet in a near-monolayer with a surface coverage ratio95%. The antibacterial activity of the Ti-HAp nanoparticles containing 7.3% Ti ions and coating the sheet was evaluated by calculating the survival ratio of Pseudomonas aeruginosa on the coated sheet after ultraviolet (UV) irradiation. The Ti-HAp-coated sheet showed a 50% decrease in the number of P. aeruginosa compared with that on an uncoated control PE sheet after UV irradiation for 30 s. Key Messages: A system of biocompatibility and antibacterial activity with an on/off switch controlled by external UV stimulation was developed. The system is expected to be applicable in long-term implanted intravascular catheters.

Background: Thirteen patients with chlorhexidine-silver sulfadiazine-impregnated catheters have experienced serious anaphylactic shock in Japan. These adverse reactions highlight the lack of commercially available catheters impregnated with strong antibacterial chemical agents. A system should be developed that can control both biocompatibility and antibacterial activity. Summary: Hydroxyapatite (HAp) is biocompatible with bone and skin tissues. To provide antibacterial activity by using an external physical stimulus, titanium (Ti) ions were doped into the HAp structure. Highly dispersible, Ti-doped HAp (Ti-HAp) nanoparticles suitable as a coating material were developed. In 3 kinds of Ti-HAp [Ti/(Ca + Ti) = 0.05, 0.1, 0.2], the Ti content in the HAp was approximately 70% of that used in the Ti-HAp preparation, as determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). ICP-AES and X-ray diffraction showed Ti ions were well substituted into the HAp lattice. The nanoparticles were almost uniformly coated on a polyethylene (PE) sheet in a near-monolayer with a surface coverage ratio >95%. The antibacterial activity of the Ti-HAp nanoparticles containing 7.3% Ti ions and coating the sheet was evaluated by calculating the survival ratio of Pseudomonas aeruginosa on the coated sheet after ultraviolet (UV) irradiation. The Ti-HAp-coated sheet showed a 50% decrease in the number of P. aeruginosa compared with that on an uncoated control PE sheet after UV irradiation for 30 s. Key Messages: A system of biocompatibility and antibacterial activity with an on/off switch controlled by external UV stimulation was developed. The system is expected to be applicable in long-term implanted intravascular catheters.

The patterned titania gel film fabricated by UV-irradiation through a mask and leaching was anodized by direct current electrolysis or pulse electrolysis. The patterning prepared through the two electrolyses was quite contrasted in that masking part and unmasking part was anodized in direct electrolysis and in pulse electrolysis, respectively. In addition, the oxide film thickness obtained using pulse electrolysis was thinner than that using direct current electrolysis. Thus, a combination of the photopatterning and pulse electrolysis made it possible to fabricate hydroxyapatite (HAp)-fixed and thinner titanium oxide film with fine pattern on titanium plate.

Tantalum nitrides and oxynitrides, such as Ta 3 N 5 and TaON, respectively, have exhibited promising properties as red and yellow pigments that do not contain toxic heavy metals. We have developed a process for preparing nitrides or oxynitrides that involves the vacuum-calcination of a precursor material obtained by reaction between a metal halide and liquid NH 3 . Herein, we describe the synthetic conditions of the liquid NH 3 process that affects the color, and thus the color characteristics of resulting pigments. Reaction and post-reaction treatment conditions were adjusted to attain the desired red color ; specifically, a powder with a color index of L * = a * = 33.11 and b * = 30.53 was obtained by the liquid NH 3 process using 0.5 eq of NH 2 OH-HCl (relative to TaCl 5 ) as the oxygen source, and calcination of the precursor at 973 K under vacuum, followed by recalcination at 673 K for 60 min under air.

Fabrication of a new ball-shaped titanium material for vertebral compression fracture treatment has been studied using micro-arc oxidation in an electrolyte containing hydroxyapatite (HAp). To prevent microstructural disturbance on the surface, ethanol was used as a co-solvent. The material thus obtained was found to have high porosity with many micropores, fixed HAp particles on the surface, and elasticity comparable to cancellous bone. Furthermore, it was demonstrated that the materials have osteoconductivity and the elasticity was kept under cycled stress. These indicate that they can be new bone filling materials for percutaneous vertebroplasty (PV).

Nanometer-sized TiO(2) island structure on the platy hydroxyapatite nanocrystals (HAp) has been accomplished by two-step emulsion process. At the first step, platy HAp nanocrystals, of which size was in the range of 70-200 nm after heat-treatment at 1078 K for 1 h, were prepared using the W/O emulsion system. Before the second step, HAp nanocrystals were immersed in NaH(2)PO(4) solution for the formation of hydroxyl group on their surface. In the following, titanium tetraisopropoxide reacted with the hydroxyl group of HAp surface to form TiO(2) nanoparticles on the surface of HAp nanocrystals, which were dispersed in the micrometer-sized methanol droplets of polyethylene cetylether-cyclohexane mixture (methanol/oil emulsion). The resulting hydroxyapatite nanocrystals loaded with TiO(2) nanoparticles showed the high photocatalytic activity comparing to the commercial TiO(2) catalyst.

La₂O₃-TiO₂-SiO₂ glass, a type that could not obtained so far by the conventional melting method, was prepared successfully using a sol-gel process. Glass derived with the sol-gel process has compositions of 5La₂O₃-5TiO₂-90SiO₂, 5La₂O₃-10TiO₂-85SiO₂, and 5La₂O₃-20TiO₂-75SiO₂. The UV-visible absorption edge of all glass compositions was below 400 ㎚. The measured density is in the range of 2.55-2.89, and was nearly identical to the calculated density and the refractive index of the glasses derived from the sol-gel ranges from 1.545 to 1.645. The molar additive coefficient of TiO₂ measured in this ternary system is lower than the calculated value, while the value of La₂O₃ is higher.

A series of cement paste and mortar specimens containing waste ceramic insulator and blast- furnace slag was made. The compressive strength and the acid resistance of these materials are investigated here. Among 18 specimens of cement paste, only two showed a compressive strength less than the standard specified for the sulfuric acid-proof mortar. These tests show that the waste ceramic insulator powder can be added by approximately 0.4 parts by weight in the powder materials of cement paste, and the waste ceramic insulator aggregate can be added by two-thirds by weight in the materials of mortar. The acid resistance was tested by immersing the specimens in 5% sulfuric acid. The reaction layer formation of specimens is affected by the immersion time, temperature, and compounding ratio of the materials. The results show that adding the waste ceramic insulator controls the dilatability of the reaction layer of cement paste and mortar.

Anodization of aluminum plate followed by the electrodeposition of Ag or Au has yielded the metal nanorod-incorporated porous aluminum oxide film (NR/AO). This 2-step electrochemical method enabled us to arbitrarily control the aspect ratio of the nanorods by changing the electrodeposition time. The Ag- and Au-NR/AO exhibited clear light-incident-angle dependent color variation, the so-called flip-flop phenomenon. This was achieved by the synergy of the interference wave of AO and the surface plasmon absorption of the NRs. Further, the color was finely tunable by variation of their aspect ratio.

A composite consisting of titanium dioxide (TiO2) particle, the surface of which was modified with amino groups, and a silicone substrate through covalent bonding at their interface was developed, and antibacterial and cell adhesion activities of the composite were evaluated. The density of the amino groups on the TiO2 particle surface was controlled by the reaction time of the modification reaction. The degradation rate of CH3CHO in the presence of the TiO2 particles under UV irradiation decreased with an increase in the amino group density on the TiO2 surface. On the other hand, the number of L929 cells adhering on the TiO2/silicone composite increased with an increase in the amino group density. From the above two results, the optimum density of amino groups for both photoreactivity and cell adhesiveness was estimated to be 2.0-4.0 molecules/nm2. The optimum amino group-modified TiO2/silicone composite sheet (amino group density, 3.0 molecules/nm2) showed an effective antibacterial activity for Escherichia coli bacteria under UV irradiation.

Repeated electrodeposition of gold and silver on anodized aluminum plate yielded Au-Ag alternate nanowires in the geometrically anisotropic pores of the anodic oxidation films with mean diameter 10 nm and depth 10 mum, respectively. The absorption maximum wavelengths in the visible region resulting from the transverse surface plasmon resonances of Au and Ag nanorods are invariant with their growth. Consequently, the color of the anodized aluminum was simply tuned in a wide range, which is impossible to attain in each monometallic system.

AuAg alloy nanowires in the geometrically anisotropic pores of the aluminum anodic oxidation films with a mean diameter of 10nm and depth of 10μm were successfully prepared by the electrodeposition of gold and silver under the bath voltage of 6V AC in a cyanide-free bath (Ag2SO4-HAuBr4-(NH4)2S2O3). The aspect ratio of the alloy nanowires was controlled by changing the electrodeposition time. The maximum position of absorption band due to the transverse surface plasmon resonances of AuAg alloy nanowires shifts to a longer wavelength with an increase of the composition of Au. The color and shading of the anodized aluminum deposited with alloy nanowires were simply tuned in a wide range.

Anatase-brookite composite nanocrystals have successfully been synthesized at 50 degrees C using a simple liquid-phase process. The photocatalytic activity of the sample for the gas-phase oxidation of CH3CHO is 5.4 times greater than that of a single-phase anatase sample with comparable crystallite size and surface area. Electron energy loss spectra suggest that this high activity results from junction between anatase and brookite crystals.

TiO2 materials with a hierarchical meso/macropore organization were fabricated by using titanium dioxide nanoparticles and starch gel templates. Starch sponges with high internal macroporosities were prepared by freezing and thawing of starch gels and were then infiltrated with colloidal suspensions of titania nanoparticles and air-dried to produce TiO2-starch foams with pores up to 200 μ m across depending on the starch concentration and the TiO2 loading. The TiO2 nanoparticles were deposited as coherent layers on the thin walls of the starch framework, which was removed by calcination without significant disruption of the TiO2 framework. The three dimensional macroporous structures of TiO2-starch sponge composite and TiO2 sponge induced extremely high photocatalytic activity.

Thick anodic oxide film with high photocatalytic activity was prepared successfully in 1.5 kmol/m 3 H2SO4–0.3 kmol/m 3 H2O2 with 0.03– 0.09 kmol/m 3 H3PO4 in a one-pot process. Increasing H3PO4 concentration in the range of 0–0.3 kmol/m 3 suppressed spark discharge, resulting in a higher anatase-to-rutile ratio and fewer lower-valent titanium oxides in the anodized films. The photocatalytically active films consisted of a mixture of anatase and rutile crystallites with a small amount of Ti 3þ ions, and had very rough surface with a large number of pores with a diameter on the order of micrometers. The film prepared in the 1.5 kmol/m 3 H2SO4–0.3 kmol/m 3 H2O2–0.03 kmol/m 3 H3PO4 dispersed with TiO2 nanoparticles was the most active photocatalytically among the films obtained, and exhibited antibacterial activity.

Inorganic-organic hybrid materials in La2O3-TiO2-SiO2 system were prepared from La(NO3)3, titanium tetraisopropoxide, and silicon alkoxides. Ternary transparent materials prepared from glycidyloxypropyltrimethoxysilane (GPTS) were obtained in a wide composition region (La2O3 ≤ 50 mol%, TiO2 ≤ 40 mol%). Hybrid materials prepared using methyltrimethoxysilane (MTMS) at MTMS/TMOS = 1 were transparent in the composition of La2O3 ≤ 30 mol% and TiO2 ≤ 25 mol%. La(NO3)3 crystallines or TiO2 small particles were precipitated in translucent materials. La2O3 content strongly affected the bulk density compared with TiO2 content. Absorption edge of the hybrid materials was shifted to longer wavelength as TiO2 and La2O3 contents increased. Partial coefficient of refractive index for the three metal oxides increased in the order SiO2 < TiO2 < La2O3 for both hybrid materials.

Nanocomposite films consisting of TiO2 and Zn with thickness of 10–15 μm (TiO2-Zn) have been electrodeposited on steel plates by rapid plating from a ZnSO4-based bath (Id > 10 A dm−2). Upon addition of NH4NO3 to the bath (

Eu2+-doped inorganic-organic hybrid materials, which are potentially suitable for a tunable laser in the near ultra violet and blue region, were prepared through the photoreduction of Eu3+ ions in the materials under the irradiation of the fourth harmonic wave light (266 nm) of the Nd:YAG laser. The hybrid materials doped with Eu3+ ions were prepared from Si(OCH3)4, CH3Si(OCH3)3, EuCl3 and chloropropyltrimethoxysilane (CPTM). After the prehydrolized silica sol was added to the Eu3+-containing solution, Eu3+-doped transparent inorganic-organic hybrid material was obtained by drying at 50°C. The emission peak around 450–475 nm due to the charge transfer transition (5d-4f) of Eu2+ ions increased with the laser irradiation time. Eu3+ ions were effectively photoreduced to Eu2+ ions in pore-free materials prepared at high CPTM to Eu3+ ratios. Eu2+ ions were generated by the photodecomposition of the bond between Eu3+ and Cl (Cl− or Cl(CH2)3 in CPTM).

Anodic oxide film of titanium with photocatalytic activity was successivery prepared by re-anodization of anodized titanium film. Porous anodized plate of titanium are more than 5 μm thick in a mixture of H3PO4, H2SO4 and H2O2 over spark discharging voltage. The glay thick anodized film was photocatalytic inactive regardless of the film consisting of anatase TiO2. Low valent titanium oxides of the thick anodized film were tried to remove by re-anodizing in the mixture of NH4HF2 and H2O2 to sustain photocatalytic activity as low valent titanium oxides deactivate the photocatalytic properties. After re-anodization (second anodization) L* value (lightness) increased. The value depends on re-anodizing condition. Photocatalytic activity was generated by second anodizing. L* value and photocatalytic activity is remarkably changed under second anodizing condition although XRD, GDOES and XPS spectra showed no difference between first and second anodized films. From the results of ESR measurement, the low valent titanium oxides in anodized film were decreased by the second anodizing.

Nanometer-sized spherical hematite single crystals were prepared by heating the precipitate which was synthesized from Fe(OH)(CH3COO)2 and NaOH in alkaline ethanol-water solutions without the deliberate addition of surfactants or adsorbing ligands. Hematite nanocrystals (5–10 nm in diameter) and ferrihydrite (

Micrometer-scale patterning of a sol-gel derived TiO2 film was formed on a titanium plate using photo-irradiation patterning.The patterned TiO2 on a micrometer scale, which had nearly the same design as the TiO2 gel film, was formed at pulsed-current density by anodic oxidation in an alkaline bath under spark discharge.

A titanium plate was anodized in an alkaline electrolytic bath. The anodized film was re-anodized under spark discharge in the bath with hydroxyapatite fine particles after parts of the surface of the anodized film were masked by 5mm diameter tapes. The holes on the surface of the re-anodized film were the same shape as the masking tapes and were 35μm deep.

Nanometer-sized MIIIMVO4 (MIII:La, Y; MV:V, P) particles doped with Ce3+ ions were prepared from alkaline alcohol-water mixture with MIII (NO3)3, CeCl3 and H3PO4 (or NH4VO4) under reflux (355 K). The maximum peak position of photoluminescent emissions for MIIIMVO4:Ce particles centered around 350-450 nm were strongly affected by host anions (PO4 3-, VO4 3-) in contrast to host cations (La3+, Y3+). The maximum external quantum efficiency in this work was 18.3% for LaPO4 nanocrystals doped with 0.5 mol% of Ce3+ ions, whereas those of MIIIVO4:Ce were extremely low since most of Ce3+ ions added in the ethanol-water mixture were oxidized to Ce4+ ions under reflux.

The mechanism of formation of nanocrystalline ZnO particles from the reaction of zinc acetylacetonate ([Zn(acac)2]) with 2-equivalent NaOH in boiling EtOH was investigated by characterizing the particles and following the transformation of acac moieties. The reaction was found to proceed via hydrolysis of zinc ethoxide derivatives, followed by dehydration–condensation reactions. High-resolution solid-state CP-MAS13C NMR measurements indicate that the ZnO particles are produced through Zn (acac)(OZn)n(acac) (3). Furthermore, it was suggested that acac−ligands play an important role in the generation of nanocrystalline ZnO particles by suppressing the hydrolysis–condensation of Zn(acac)(OZn)n(acac).

Ce3+-doped, inorganic-organic hybrid monoliths were prepared from Si(OCH3)4, CH3 Si(OCH3)3, CeCl3 and various functionalized silanes (FSs) such as amino- (APTM), glycidyloxy- (GPTM), trifluoro- (TFTM) and chloro-(CPTM) silanes at 60°C by the sol-gel process. The functional groups of silane coupling agents coordinated with Ce3+ ions in the inorganic-organic materials. Ce3+-doped materials were transparent under the preparation conditions of FS/Ce3+ ratio of 100 and 1.0 × 10−4 mol/cm3 of Ce3+ concentration. Optical properties such as absorption spectra, emission spectra and fluorescence quantum yield for the Ce3+-doped hybrid materials were strongly affected by the Ce3+ ion environment. Emission spectra were observed for the Ce3+-doped materials below 400 nm. The emission intensities of the materials prepared from TFTM, CPTM and without FS were approximately 100 times as much as those of materials prepared from APTM and GPTM. The fluorescence quantum yield was highest (11%) for the material prepared from TFTM hybrid materials.

Hollow copper-carbon composite particles were prepared by the decomposition of organic compounds of copper-coated nylon particles. Porous nylon powder was activated by nitrogen plasma with a microwave discharge instrument at low temperature. Fine copper particles were coated onto the activated powder by a reflux of anisole containing Cu(acac) 2 and (NH 2 ) 2 ·H 2 O in a nitrogen atmosphere. We obtained the hollow copper-carbon composite particles by heating the copper-coated nylon particles at 200 °C for 10 h.