Titanium phosphates were prepared with various concentrations of added glycerin as a novel white pigment for cosmetics. Their chemical composition, powder properties, photocatalytic activity, color phase, and smoothness were studied. The obtained materials had a higher Ti/P ratio than that used in preparation conditions because of the formation of titanium oxide and hydroxide. These titanium phosphates had less photocatalytic activity to protect the sebum on the skin. The obtained materials and their thermal products at 100°C showed high reflectance at the range of visible light.

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Phosphorylation of citrulline (Cit) has been achieved using inorganic cyclo-triphosphate (P_3m) in aqueous solution. The optimum condition for the phosphorylation of Cit with P_3m is Cit : P_3m = 1.75 M : 0.5 M, pH 12 and 10°C. N²-(Phosphono)citrulline was synthesized with the yield of more than 85 %. The reaction mechanism of Cit with P_3m was discussed.

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A widely-used herbicide, atrazine (ATZ), was investigated in heterogeneous photo-Fenton reaction using four Fe(III)-treated hydroxyapatites, HAP-100-Fe, HAP-200-Fe, HAP-300-Fe, and HAP-400-Fe, which were prepared from hydroxyapatites, HAP-100, HAP-200, HAP-300, and HAP-400, respectively (Taihei Chemical Industrial Co.), and compared with commercially available Fe(III) compounds, Fe₂O₃, FePO₄•2H₂O, and FeOOH. Among the Fe(III)-hydroxyapatites, HAP-400-Fe indicated the most efficient catalytic activity (ATZ consumption, 90%), which was almost equal to FePO₄•2H₂O. Although mineralization of ATZ was never detected by TOC-TN, deethylated, deisopropylated, and OH-substituted ATZs, and related oxidative degradation products were identified from LC-MS analysis of the resulting solution of ATZ photo-Fenton reaction using HAP-400-Fe.

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A new, fast proton-conducting TiO₂-P₂O₅ glass-ceramic was developed and investigated through microstructure observation and electrical conductivity measurements. TiO₂-P₂O₅ glass-ceramic samples were prepared by a sol-gel method and post-annealing heat treatment. With an increase in the post-annealing temperature, growth of TiP₂O₇ crystals in the TiO₂-P₂O₅ glassy phase was observed. In addition, a tenfold enhancement in maximum conductivity was observed after post-annealing heat treatment compared with the as-prepared sample and polycrystalline TiP₂O₇. The interfacial layer between the TiO₂-P₂O₅ glassy phase and the TiP₂O₇ crystal phase may act as a fast proton-conducting path, thereby improving the total conductivity. This hypothesis is discussed using the brick layer model.

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Phosphate materials are becoming more important as cathodes and electrolytes in electrochemical energy conversion devices. This review provides an overview of the recent advances in phosphate materials chemistry for lithium ion batteries. The synthesis and processing technologies are particularly focused to provide practical ways to develop advanced lithium ion batteries with high safety.

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The effects of hydrochloric acid (HCl) on the formation of calcium hydroxyapatite (HAp) particles produced by aging Ca(OH)₂ and sodium triphosphate (sodium tripolyphosphate, Natpp: Na₅P₃O₁₀) mixed solution at 100°C for 18 h were examined. The effect of addition of urea was also investigated. In the absence of HCl, the spherical secondary particles with ca. 60 nm in diameter composing by aggregation of spherical primary particles with ca. 20 nm in diameter were produced. Similar aggregated secondary spherical particles were formed up to HCl concentration ([HCl]) of 8 mM. On the contrary, the particles produced at [HCl]≥12 mM were elongated to c-axis and exhibit aggregated rod-like shape, though those produced at [HCl]=20 mM were spherical aggregates with ca. 20 nm in diameter. All the particles produced at [HCl]≤16 mM were HAp, though the sample produced at 20 mM was amorphous. The specific surface areas of the samples were ranged among 84-98 m²/g and were fairly agreed with the estimated value of spherical primary particle with 20 nm in diameter. The in situ IR spectra of the HAp particles exhibited very small bulk OH- band at 3570 cm^-1. This result indicated that the HAp particles are produced by aggregation mechanism and OH- ions along with c-axis in the poorly crystallized primary particles were disordered. The HAp particles with Ca/P molar ratio larger than theoretical value of 1.67 were not exhibited surface P-OH groups at 3656 and 3683 cm^-1. However, the addition of urea produces CaCO₃ (calcite) together with HAp and no single HAp crystal was produced. It was revealed that forced hydrolysis reaction of tpp was accelerated by HCl and aggregated secondary spherical particles with unique structure and high specific surface area were obtained.

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The yttrium phosphate dihydrate YPO₄·2H₂O was synthesized by thin-layer technique, and its crystal structure was obtained from X-ray powder diffraction data at room temperature. The structure of YPO₄·2H₂O was solved by direct methods and refined using the Rietveld analysis. The compound crystallizes in the monoclinic space group C2/c, with unit cell dimensions a = 6.15326(3), b = 14.99687(8), c = 5.57848(3) Å, β = 115.4319(4)°, V = 464.896(4) ų, Z = 4. It has the gypsum-type crystal structure, with metal-phosphate 2D polymeric network, parallel to the ac plane. Water molecules, coordinated by the yttrium atoms, provide hydrogen bonding between the layers, resulting into a three-dimensional network. The crystal structure of YPO₄·2H₂O is compared with that of isotypic Y_1-x(Gd,Dy,Er)_xPO₄·2H₂O (x = 0.053), investigated earlier.

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The conditions for the homogeneous coating of hydroxyapatite (Ca₁₀(PO4)₆(OH)₂; HAp) on the multi-wall carbon nanotubes (MWCNTs) were examined via the processes of (i) the acid treatment of conc. nitric and sulfuric acids at 50°C for 24 h or the citric acid at 300 and 350°C for 0.5 h in Ar atmosphere in order to form carboxyl group, and (ii) the microwave heating (100°C, 5 min) of acid-treated MWCNTs in the “apatite-dissolved solution” prepared by bubbling CO₂ gas into the commercial HAp-dispersed water. The microwave heating of surface-modified MWCNTs (the citric acid treatment at 300°C for 0.5 h) in the apatite-dissolved solution was effective in the homogeneous coating of calcium-deficient HAp (Ca/P ratio =1.57), compared to the case of surface modification by conc. nitric and sulfuric acids.

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