Non-stoichiometric hydroxyapatite (HAp) microcrystals other than amorphous calcium phosphate (ACP) were directly formed at high pH region. The HAp was precipitated by adding phosphoric acid solution to calcium hydroxide aqueous suspension in room temperature with vigorous stirring. The products at pH 13 consisted of HAp microcrystals as well as calcium hydroxide. The most intense XRD peak of HAp was unified reflection of 211 and 112 although it was separated from 300 reflection. The position of strongest peak was shifted compared with that of ACP. Topotaxial relationships between the HAp and calcium hydroxide were revealed by electron diffractometry. It was suggested that the HAp microcrystals were not obtained by simple depositional reaction from aqueous solution.

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Electrical polarization was found to enhance the bone-like crystal and hetero-crystal (K₂SO₄) growth on hydroxyapatite (HAp) ceramics in a simulated body fluid and an alum solution, respectively. This enhancement was observed on the negatively polarized surface, while the crystal growth was restricted to the positively polarized surface. The dielectric properties of these HAp ceramics were investigated. Based on these results and a spectroscopic analysis, the effect was attributed to the condensation of Ca²⁺ ions on the polarized surface due to the reorientation of the lattice hydroxide ions.

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Raman spectra of hydroxyapatite have been successfully obtained at temperatures from 25°C to 1200°C in air by using a new system of ultraviolet (UV) Raman spectroscopy. The intensity of a band ascribed to the stretching vibration of the OH ion continuously decreased with increasing temperature, moreover additional bands appeared in the vicinity of the original band. The total intensity of these bands did not change significantly up to about 800°C, whereas they decreased at temperatures higher than about 800°C. This result can be interpreted as producing oxy-hydroxyapatite due to dehydration of hydroxyapatite over 800°C.

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Porous β-tricalcium phosphate (β-TCP) films were formed on 3 mol% Y₂O₃ doped ZrO₂ (3YZ) ceramics by spray-pyrolysis technique, using starting solutions with the Ca/P ratios of 0.50 and 1.67. The crystalline phase of the resulting films was mainly β-TCP; the films were porous and the thickness was~70μm.The pore-size distribution of the resulting porous films was in the ranges of 100 to 20μm, 10 to 1μm and submicrometers; this distribution may be effective to be ingrowth of new bone into the pore structure. The biocompatibility of the 3YZ ceramics coated with β-TCP was examined using osteoblastic cells (MC3T3-E1). The cells on the 3YZ ceramics coated with β-TCP were proliferated in a similar manner to the case of a dish for cell culture (control) and the 3YZ ceramics. The alkaline phosphatase activity unit DNA content of the cells cultured on the 3YZ ceramics coated with β-TCP for 21 days showed the highest value among the examined specimens.

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Fresh hydroxyapatite (HAP) was prepared in an aqueous phase by mixing CaCl₂ with K₂HPO₄ in the presence of dodecyl phosphate (DP) and arginine (Arg), where DP/Arg=1/3 in molar ratio. Arg was added in order to enhance the solubility of DP. The degree of crystallinity of the HAP decreased with a concentration of DP, because DP was adsorbed to the growth sites on the nuclei through its terminal phosphate group as a crystal poison. The effect of adsorption of DP on a ripened HAP was also studied. Though polyethylene glycol p-isooctylphenyl ether (TX-100) was scarcely adsorbed on the raw surface of HAP, it was adsorbed after pretreatment of the surface with DP. This fact was explained in terms of surface modification by the adsorption of DP. Alkyl chains of DP protruding from the surface captured those of TX-100 through hydrophobic interaction on the surface. It was concluded that the phosphate group of DP plays an important role in regulation of the crystal growth and surface modification by virtue of isomorphous substitution of phosphate group of DP for phosphate ion on the surface of HAP.

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Although p-dimethylaminoazobenzene (methyl yellow, MY) is almost insoluble in water, it was captured on the surface of hydroxyapatite (HAP) after two different procedures in an aqueous phase: (A) by mixing MY with HAP pretreated with an aqueous solution of sodium dodecyl sulfate (SDS), and (B) by adding HAP into an aqueous solution of SDS where MY was solubilized into the micelle in advance of the mixing with HAP. The mechanism of capturing was explained in terms of the surface solubilization of MY into the adsorption layer of SDS on HAP. In other words, it was by virtue of formation of the mixed adsorption layer of SDS with MY on the surface of HAP through the hydrophobic interaction.

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BaTi(PO₄)₂ and BaTi₄(PO₄)₆ were made by heating a mixture of ammonium dihydrogen orthophosphate, titanium oxide, and barium carbonate at 1000~1400°C for 2~10h. These compounds were powdery materials with very small average particle sizes of 0.4~0.6μm and thermally stable. The thermal expansion of BaTi(PO₄)₂ and BaTi₄(PO₄)₆ were -0.63~0.02 and 0~-0.84% up to 900°C, respectively.

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H₂O₂-oxidations of methyl p-tolyl sulfide and methyl p-tolyl sulfoxide with heteropoly and isopoly tungstates were carried out in biphasic system. In these reactions catalytic activities of poly tungstates were estimated based on the reaction rates. Significant differences in catalytic behavior were found between phosphoperoxotungstate and isopoly tungstates. Phosphoperoxotungstate is a powerful catalyst for the oxidation of both sulfide and sulfoxide. Isopoly tungustate catalyzed H₂O₂-oxidation of the sulfide more effectively than that of the sulfoxide.

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Measurement of polymerization degree of condensed phosphates was examined by solid-state NMR. Broad peaks of the NMR of end- and middle-PO₄ groups of condensed phosphates were observed at about 1 and-20 ppm, respectively. The NMR. peak area ratio (Ro) of middle-PO₄ group to end-PO₄ group has the following relation with the polymerization degree (n) of polyphosphate:
Ro (middle-PO₄/end-PO₄)=(n-2)/2 Calculated polymerization degrees of polyphosphates agreed well with measured ones and it is found that the solid-state NMR technique is useful to the measurement of polymerization degree of water-insoluble solid-state condensed phosphates having a chain structure.

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The coacervation of polyphosphates usually takes place at very low pH value. We show that, in the system Na₂O-CaO - P₂O₅, the decrease of pH is due the hydrolysis of the terminal P-OH groups and that it is a consequence of the coacervation. So a very low pH is not necessary to obtain a coacervate and it is possible to form coacervates in non-acid media (even basic). The same results are obtained with other precursor systems of polyphosphate coacervates. These results may be interesting for the achievement of coacervates as industrial glasses precursors.

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The coacervation of polyphosphates permits to formulate a glass precursor in aqueous media and at ambient temperature. This reaction, which consist on a phase separation is induced by an addition of electrolyte or by a modification of the solvent properties. It depends on different parameters which are not yet entirely controlled. Some previous interpretation of this phenomenon are also inadequate. We have studied the influences of the chain length of the polyphosphates, of the solvent properties and of the electrolytes used. The results obtained indicate the possibility of coacervate achievement by univalent cation supply. They also permit an optimization of the process, for the choices of the commercial compounds, of the electrolytes and of the solvent.

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The removal and destroying of flock coating abestos are presently an important problem for the society health. Usually, these two stages like the abestos handling are studied and reated separately. In other hand the cost of abestos treatment leads to unauthorised removal and scattering. So, it will may be very interesting to find a not expensive process which will may used as aids for the removal operations and destroying of abestos. We show in this paper that the use of cheap sodium polyphosphate permits, by the formation of a coacervate phases, inside of asbestos layers, at room temperature, to agglutinate the fibers and to avoid by this way, their scattering during the abatment stage. By oven drying the asbestos-coacervate mixt leads to a formation of concrete, which permits their handling without scattering. Finally the heating of this concrete permits by a polyphosphate glass formation to destroy the fibrous structure of asbestos.

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Crystallization of heavy metal phosphates prepared from aqueous solutions is very slow. The situation could be improved when the salts were prepared from the respective metal alkoxide. The sol-gel synthesis of a group of these salts, (Zr, Ti, and Hf phosphates), from precursors of different natures was envisaged. By altering through metal precursors of different natures (inorganic or metallo-organic), and phosphate precursor of different natures (phosphoric acid or organic phosphate esters), we have shown that organic phosphates are also of advantage as the counterpart. Thermal analysis, FT-IR, and XRD results indicated more crystalline products when prepared from organic phosphates.

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The phase formations in the Na₃PO₄-InPO₄ system are investigated. Forming two compounds: Na3In(PO₄)₂ (I) and Na₃In₂(PO₄)₃(II) having β- (low-temperature) andα -modification (high-temperature) are determined. Their crystal structures are refined. The β- (I) and α-(I) crystallize in the β-K₂SO₄-like structure. β-(II) an individual structure, which is different from those of β-Na₃Sc₂(PO₄)₃. The α-(I) crystallize in the NASICON-like structure. It is stated by the thermogravimetric analyses that the transition β-(I)→α-(I) occurs irreversible at temperature 700°C and transition β-(II) ↔α-(II) occurs reversible at temperature 820°C.

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We have performed a neutron powder diffraction study of the oxyphosphates MFePO₅ (M = Cu, Ni) as a function of temperature. The structure of this allotropic variety is orthorhombic with space-group Pnma. The M^II-octahedra build strings parallel to the b-axis. The Fe^III-octahedra are alternatively connected, on both sides of these strings, by PO₄ tetrahedra. No disorder between metallic sites has been found. Our study confirms the isomorphism of these compounds with α-Fe₂PO₅. We have determined their magnetic structures which are both collinear anti-ferromagnetic with the spin of both sites directed along the b-axis. The experimental magnetic moments of Cu⁺² and Ni²⁺ correspond to the expected ionic value, on the contrary the magnetic moment of Fe³⁺ is reduced.

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Ultrasonic velocity and attenuation of two samples of Bi₂O₃-P₂O₅ glass have been measured in the temperature range 80 to 300 K. With the velocity data Lame's constants, bulk modulus and Debye temperature have been calculated. Thermally activated relaxation process is good enough to explain the temperature variation of attenuation, but to interpret the variation of sound velocity the combined effect of relaxation, anharmonicity and frozen-in fluctuation has to be taken into consideration.

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The influence of the silver on the phase formation and structures was studied in the system P₂O_5-CaO-ZnO-Ag. Homogeneous distribution of the Agparticles was realized in the materials after heat treatment at 1100-1350°C. The samples were studied by TEM, X-ray, IR spectroscopy and the microhardness was determined. It was proved that the silver stimulates the formation of polyphase materials containing mainly Zn(PO₃)₂ and in some cases Ca₃(PO₄)₂ also.

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Is investigated sulfur containing phosphate and fluorophosphate glasses on the base of barium metaphosphate and alkaline-earth fluorine in the Ba(PO₃)_2-Na₂S-MgF₂ systems. The replacement of oxygen by sulfur and fluorine in its systems bring to quantitative and qualitative changes of structural groupings. Polysulfuride [-S-S-] and fluorine [MeF₄], [MeF₆] groupings are formed, which promote essential change of barium metaphosphate glass skeleton, stabilization of glassy condition, and, accordingly, essential changes of physicochemical properties of glasses.

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The comparative investigation of the influence of strontium oxide on optical and thermooptical properties of the glasses of silicate and phosphate systems using the identical method of the processing for experimental data was carried out. It has been found that the possibility of creating the strontium containing glasses with small thermooptical constants on phosphate basis wider than on silicate one. It has been shown that strontium containing phosphate glasses can be used for creation of high quality optical and laser systems of different purpose.

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