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RAVEAU BERNARD, BOREL MARIE-MADELEINE, LECLAIRE ANDRE
1999 Volume 10 Pages
1-5
Published: 1999
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CHRISTIAN JÄGER, MARCUS SCHULZ, PETER HARTMANN, STEFAN BARTH, RAI ...
1999 Volume 10 Pages
6-13
Published: 1999
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The recent progress of two-dimensional NMR is described for improved structural studies of glasses, particularly of the connectivities of the various phosphate Q
n groups in terms of the nomenclature Q
njkl where the number of additional superscripts depends on the number of bridging oxygens n and where j, k and 1 denote the Q character of the bonded adjacent unit. Furthermore, applications of NMR for structural studies of plasma-sprayed hydroxyapatite are presented as well as studies of mesostructured aluminophosphates. 2D heteronuclear correlation NMR allows to locate the headgroup of the template molecule with respect to the inner surfaces of the layers.
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ZAHID AMJAD
1999 Volume 10 Pages
14-24
Published: 1999
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The performance of polymers of varying composition and molecular weight as calcium phosphate inhibitors has been investigated using the pH-stat method. Included in this study are the effects of soluble impurities and process variables on the performance of polymeric inhibitors. The results from this study help in the selection of an appropriate inhibitor for the treatment of industrial water systems.
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PIERCARLO MUSTARELLI
1999 Volume 10 Pages
25-36
Published: 1999
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Phosphate glasses are of technological interest for electrochemical devices, as bioactive materials, and also for the electronic industry. Solid-state NMR, chiefly coupled with magic angle sample spinning (MAS), is a valuable technique to obtain information on short-range order and connectivity in phosphate glasses. In this paper the most recent advances in the field will be reviewed, and more emphasis will be given to solid-state glassy electrolytes.
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JACQUES C. VEDRINE
1999 Volume 10 Pages
37-48
Published: 1999
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In this presentation emphasis has been placed on heterogeneous catalysts where phosphorous is a determining element. These correspond to phosphate based materials as vanadyl pyrophosphate used industrially for the oxidation of butane to maleic anhydride in the 630-670 K, iron phosphates and hydrogeno/hydroxy-phosphates for the oxidative dehydrogenation (ODH) of isobutyric acid to methacrylic acid in the 650-680K temperature range, zirconium hydrogeno-phosphates as layered compounds used to stabilise/entrappe catalytically active compounds as Al, Zr, or Cr, V hydroxy or hydroy-oxy macrocations species used in acid-type reactions as alkane cracking or partial oxidation reactions as ODH of light alkanes, respectively, microporous aluminophosphate molecular sieves (AIPO, MeAPO,EIAPO,..).
It is shown that the catalyst surface behave as a rather dynamic and labile surface, reconstructing under activation and/or catalytic reaction conditions and adapting itself to the stereochemistry of the reactants. In partial oxidation reactions the active sites are shown to have a molecular size and have several catalytic functions. The hydrocarbon molecule is first adsorbed, then activated, some of its hydrogen atoms are extracted while lattice oxygens are incorporated into it and electron transfer did occur through the solid material to allow oxidation reaction mechanism to proceed. The metal M cations are the active species and the role of the phosphate tetrahedra is not only to bind the MO
6, octahedra together to constitute a dense or layered compound but also to bring some specific redox and acid-base properties. In the case of microporous phosphates, the active sites are more localised and static, while their chemical (redox and/or acid-base) properties, molecular and spatial structures (porosity inducing shape selectivity) turned out to be the determining factors for their catalytic properties.
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YOSHIHIRO ABE
1999 Volume 10 Pages
49-54
Published: 1999
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MARIO GLERIA
1999 Volume 10 Pages
55-69
Published: 1999
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In this paper the history, the spectacular scientific growth and the potential practical applications of phosphazene materials are presented, together with the reasons of their limited technologic development. The strategies that have been recently designed to overcome this situation are also illustrated.
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DÖRTE STACHEL, ANNETT OLBERTZ
1999 Volume 10 Pages
70-75
Published: 1999
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Crystalline ultraphosphates are a relatively new group of phosphate-rich compounds. We tried to find out a system of systematic order in crystal-chemical sense. Some selection rules as well as necessary conditions are given. In this way, we like to bring in some light into the building principles of these very interesting inorganic polymer compounds by our proposal.
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P. REINERT, B. MARLER, J. PATARIN
1999 Volume 10 Pages
76-81
Published: 1999
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Two new porous gallophosphates were synthesized in aqueous medium using N,N,N',N'-tetramethylethylenediamine as organic template. The material obtained in the presence of fluoride anions corresponds to the fluorogallophosphate ULM-18 whereas, the other gallophosphate synthesized in the absence of F
- displays a new three-dimensional framework containing four-, five- and six-coordinated gallium atoms. The two materials were characterized by several techniques such as SEM, elemental analysis, powder X-ray diffraction and solid state NMR spectroscopy.
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ROBERT GLAUM
1999 Volume 10 Pages
82-87
Published: 1999
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The method of chemical vapour transport (CVT) in a temperature gradient provides a versatile tool for synthesis, crystallization and purification of anhydrous transition metal phosphates. The whole span of now more than 60 phosphates grown on laboratory scale via the gas phase might be visualized by the thermally labile Pd
2P
2O
7 and RhPO
4, some low melting ultraphosphates (e. g.: CuP
4O
11, ZnP
4O
11) and a series of phosphates containing transition metals in otherwise not easy accessible oxidation states (e. g.: TiPO
4, V
2O(PO
4), Cr
3(PO
4)
2, Cr
2P
2O
7). The experiments are carried out in sealed silica ampoules at temperatures between 500 and 1100°C, depending on volatility and thermal stability of the phosphate. Plein chlorine or iodine in combination with a few mg of metal, metal phosphide or phosphorus as reducing agents have led to the best results with respect to crystal size, quality and growth rate. Heterogenous solid/gas as well as solid/solid equilibrium reactions determining the transport process will be discussed.
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S. DUQUESNE, M. LE BRAS, S. BOURBIGOT, R. DELOBEL
1999 Volume 10 Pages
88-93
Published: 1999
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One of the principal classes of flame retardants used in organic polymers is the phosphorus-compounds. In particular, inorganic phosphates have flame retardant properties of interest in thermoplastics. Ammonium phosphoric acids salts were first recommended two centuries ago and are still used today. However, new legislation is emphasizing the development of new flame retardant additives which are environmentally friendly. This paper reviews the different kind of inorganic phosphates used as flame retardants. It includes the use of red phosphorus, ammonium phosphates. We will also describe intumescent systems and low melting phosphate glasses.
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MAKOTO WATANABE, KYOSUKE YANO, HIROKAZU SUZUKI, MAKOTO SAKURAI
1999 Volume 10 Pages
94-99
Published: 1999
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Simple dry process of the preparation of ammonium polyphosphate form V was studied using the system of ammonium orthophosphate-urea. Ammonium polyphosphate form V was prepared by heating a mixture with molar ratios (ammonium orthophosphate/urea) of 1/2.0 to 1/0.8 it 330 to 340 °C under wet ammonia which was made by passing air through 15 and 29% of ammonia water.
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X. BOURDON, A.-R. GRIMMER, V. B. CAJIPE
1999 Volume 10 Pages
100-111
Published: 1999
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The order-disorder, ferrielectric-paraelectric transition in lamellar CuInP
2S
6 is studied using
31P solid-state MAS-NMR spectroscopy in the temperature range 255<T<355K. Two center bands are observed at the lowest measured temperature while only one is detected at the highest temperature. The former two represent the inequivalent positions for the P atoms in the ferrielectric phase. The latter corresponds to the appearance of a twofold axis through the P-P bond as the Cu
I ions undergo double-well hopping motions in the paraelectric phase. At intermediate temperatures both ferrielectric and paraelectric type resonances contribute to the spectrum at ratios which are T-dependent, indicating a transition temperature T
c= 312±1K (310±1K) for a warming (cooling) cycle. The temperature range for the coexistence is unusually wide (>70K). The presence of the ferrielectric type resonance in the paraelectric regime may be ascribed to the nucleation of polar order, while the persistence of the paraelectric signal below T
c implies residual hopping motions.
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ADLY ABDALLA HANNA, HANIEM SIBAK
1999 Volume 10 Pages
112-122
Published: 1999
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The aim of this work is reducing the iron content in crude phosphoric acid produced from dissolution of Abu-Tartur phosphate in sulphuric acid to an acceptable limit without a large reduction of P
2O
5 percentage. Several methods were used to reduce the iron content, but this work was focused on the precipitation method because the technique of this method is more suitable for Abu-Tartur project. Na
2CO
3(NaCO
2)
2, NaOH, KOH and K
4[Fe(CN)
6].3H
2O were used as a precipitating agent. The percentage of P
2O
5 and Fe in the filtrate were determined spectrophote-metrically and the precipitate was exposed to X-ray diffraction analysis. It is found that the most suitable materials are Na
2CO
3, NaOH and KOH, while sodium oxalate is a poor precipatating agent. Potassium ferrocyanide is a good one but it is not prefer because it is poisonous.
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IGOR ABARENKOV, ILIA TUPITSYN, VLADIMIR KUZNETSOV, MIKE PAYNE
1999 Volume 10 Pages
123-128
Published: 1999
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The phosphorus pentoxide crystal with Pnam symmetry containing four P
2O
5 molecules in the unit cell was calculated by
ab initio density functional theory in the local density approximation with a plane wave basis. The calculated optimized geometry is in a good agreement with experiment. The population analysis showed that the crystal has an ionic-covalent chemical bonding. An Ag atom impurity in the phosphorus pentoxide crystal was investigated within the periodic model. The distortion of the lattice around the impurity was analyzed in terms of PO
4 tetrahedra. The calculations showed that in spite of considerable deformation of the lattice the Ag impurity does not break the P-O bonding network.
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A. F. ALI, E. M. A. HAMZAWY
1999 Volume 10 Pages
129-134
Published: 1999
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Nearly the middle region of the composition-triangle representing the system Li
2O-Al
2O
3-P
2O
5 was explored with respect to the dependence of the properties of the final product on both its nominal composition and preparation route. The conventional melt-quenching, precipitation, and the sol-gel methods were used. Thermal analysis and x-ray diffraction patterns were used for comparisons.
Some trend of change regarding the glass forming region and crystalline forms among each series of compositions could be noticed. These changes seem to depend on the preparation method. An increase of Al
2O
3 lead to a decrease of the crystallinity of the product sample from solutions but not from melts. Devitrified samples show Li
3PO
4 and AlPO
4 crystallization.
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NATALIA ANISIMOVA, NATALIA CHUDINOVA, ROBERT GLAUM
1999 Volume 10 Pages
135-137
Published: 1999
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The present work reports the thermal rearrangement of hydrogen phosphates of iron and alkaline metals into condensed phosphates.
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SOPHIE GLRAUD, PIERRE CONFLANT, MICHEL DRACHE, JEAN-PIERRE WIGNACOURT, ...
1999 Volume 10 Pages
138-143
Published: 1999
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Three new phases were identified in the ternary system Bi
2O
3-PbO-P
2O
5: PbBiPO
5, Pb
4BiPO
8 and Pb
5Bi
18P
4O
42. PbBiPO
5 displays a phase transformation from triclinic to monoclinic symmetry at 725°C. The crystal structures of Pb
4BiPO
8 and Pb
5Bi
18P
4O
42 were solved from single crystal diffraction data. The formula described previously as PbBi
3PO
8 was revised and is more likely Pb
3Bi
10P
3O
25.5, equivalent to PbBi
3.33PO
8.5. Its crystal structure displays a distorded 3 x 3 x 3 superstructure of a tetragonal variety of 3δ-Bi
2O
3 type
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ROBERT GLAUM
1999 Volume 10 Pages
144-149
Published: 1999
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Anhydrous phosphates of transition metals exhibit a surprising variety of colours. Even phosphates of the same cation show significantly different electronic absorption spectra. Using calculations within the framework of the angular overlap model a detailed correlation can be obtained between the observed electronic transitions and the particular coordination geometry of M
3+ in a series of anhydrous phosphates (M(PO
3)
3, MPO
4, M
4(P
2O
7)
3, and M
4P
6Si
2O
25) of trivalent vanadium and chromium. Our investigation gives evidence for the strong influence of the coordination number of oxygen on its coordination behaviour towards M
3+. While isotropic π-bonding is observed for such O
2- coordinated by P
5+ and one M
3+, oxygen with C. N.=3 (P
5+ and 2 M
3+) exhibits anisotropic π-bonding towards M
3+. Thus the π-interaction M
3+-O
2- within the plane through the two M
3+ and the bridging O
2- is significantly reduced compared to the interaction perpendicular to this plane.
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Takaya IIDA
1999 Volume 10 Pages
150-154
Published: 1999
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The trustworthy preparation method of the uncommon phase of NaH
2PO
4·H
2O is establised. It is realized in the way where hydration water is introduced into anhydrous NaH
2PO
4 by being soaked in the liquid media. Its thermal behaviour and solid-state
31P NMR spectrum are compaired with those of the common phase.
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M. KETATNI, O. MENTRE, F. ABRAHAM
1999 Volume 10 Pages
155-160
Published: 1999
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The new compound BiCoPO
5, monoclinic, P2
1/n, a = 7.2470(1)Å, b =11.2851 (2) Å, c = 5.2260(1) Å and β= 107.843(1)°, Z = 4, was synthesized and structurally characterized by powder X- ray diffraction. It is isostructural with bismuth nickel oxyphosphate BiNiOPO
4. The crystal structure is built up from a complex tridimensional assembly of (Co/Ni)
2O
10 dimers linked by PO
4 groups. This forms large tunnels running along c which host Bi
3+ cations. Smaller tunnels running along a and crossing the latter were also evidenced. It is noteworthy that the original BiNiPO
5 lattice is appreciably increased with Co
2+ cations as the transition metal. The Bi
3+ cation is surrounded by a strongly distorted oxygen octahedron. Reducing the Bi-O bonds to the three shortest, Bi environment can be considered as tetrahedral considering the BiO
3Lp polyhedron, Lp = 6s
2 lone pair. The lone pair localisation was performed from electrostatic interactions and revealed Lp - Bi distance of 0.68 Å and 0.58 Å, for Co
2+ and Ni
2+ compounds respectively.
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ANNETT OLBERTZ, DÖRTE STACHEL
1999 Volume 10 Pages
161-165
Published: 1999
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Ultraphosphates are polymeric phosphates and not yet fully investigated. The connection of their anionic network is very varied caused by different influences of the cations and their position in the network.
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ANNETT OLBERTZ, DÖRTE STACHEL
1999 Volume 10 Pages
166-170
Published: 1999
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Ultraphosphates are condensed phosphates characterized by anionic networks of two- and three connected PO
4 tetrahedra. Cations essentially influence the structure pattern od such anionic networks, which are demostrated on examples of SrHP
5O
14 and NiHP
5O
14 ultraphosphates.
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A.F. SELEVICH, A.S. LYAKHOV, A.I. LESNIKOVICH
1999 Volume 10 Pages
171-176
Published: 1999
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Phase equilibrium in the systems Ln
2O
3 - P
2O
5 - H
2O, (Ln = La-Lu and Y, molar ratio P
2O
5/Ln
2O
3 = (3÷10)/1) has been studied within the temperature range of 25-350 °C by thin layer method. The following phosphates have been synthesized: LnPO
4·nH
2O (Ln = La-Eu), LnH
3(PO
4)
2· 2H
2O (Ln = Sm-Dy, Lu, Y), LnH
3(PO
4)
2·0.5H
2O (Ln = Ho-Lu, Y), LnH
3(PO
4)
2 (Ln = Tb-Lu, Y), Ln(H
2PO
4)
3 (Ln = Nd-Dy), LnHP
2O
7 (Ln = Eu-Lu, Y), Ln
2P
4O
13-II (Ln = Ho-Lu, Y), Ln
4(P
4O
12)
3 (Ln = Tm-Lu), Ln(PO
3)
3-I (Ln = Ln-Gd), Ln(PO
3)
3-II (Ln= Tb-Lu, Y), Ln(PO
3)
3-C (Ln = Sm-Lu, Y), LnH(PO
3)
4-I (Ln = Sm, Eu), LnH(PO
3)
4-II (Ln = Eu-Er, Y), LnP
5O
14-I (Ln = La-Gd), LnP
5O
14-II (Ln = Tb- Lu, Y), Ln
2P
4O
13-I (Ln = Gd-Lu, Y); Ln
4(P
2O
7)
3 (Ln = Gd-Lu, Y). Thermal transformations of these compounds have been studied within the temperature range of 25-1000 °C. Lattice parameters of some synthesized phosphates have been calculated. Comparative diagram of crystallization fields for stable phases of rare earth phosphates has been constructed.
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LOÏC VIDAL, CLAIRE MARICHAL, LUC DELMOTTE, VÖLKER GRAMLICH, ...
1999 Volume 10 Pages
177-182
Published: 1999
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Mu-4 is a new layered aluminophosphate [(C
2H
5)
2NH
2]
4 [Al
8P
10O
40H
2][H
2O]
2.5 obtained from a quasi non-aqueous system involving diethylformamide (DEF) as the main solvent. During the synthesis, DEF is decomposed into protonated diethylamine which is occluded in the structure. The latter consists of double layers of double 4-ring units connected through 4-, 6- and 8-membered rings.
27Al and
31 P MAS,
27 Al 3Q MAS,
1H-
31 P CP-MAS and
27Al→
31P heteronuclear correlation NMR experiments were performed in order to confirm the structure of this layered aluminophosphate.
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O. COUSIN, M. RIVENET, J.C BOIVIN, F. ABRAHAM
1999 Volume 10 Pages
183-188
Published: 1999
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Partial study of the Na
2O-CaO-P
2O
5-SiO
2 system evidenced two compounds corresponding to Na
2Ca
5(PO
4)
4 and NaCa
6(PO
4)
3SiO
4, instead of Na
3Ca
6(PO
4)
5 and Na
2Ca
4(PO
4)
2SiO
4 previously reported in the literature. Na
2Ca
5(PO
4)
4 and NaCa
6(PO
4)
3SiO
4 are ordered phases both belonging to a large solid solution domain with general formula Na
2-xCa
5+x(PO
4)
4-x(SiO
4)
x. The Na
2-xCa
5+x(PO
4)
4-x(SiO
4)
x solid solution structure was shown to be a superstructure of the glaserite-type structure.
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NOBUKAZU KINOMURA, YASUHIRO FUKUTOMI, NOBUHIRO KUMADA, TAKASHI SUZUKI
1999 Volume 10 Pages
189-193
Published: 1999
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Silylation of α-zirconium phosphate was carried out using various silanes in toluene at >70 °C in a nitrogen atmosphere. The silylating reagents were dimethyldichlorosilane, dimethyloctadecylchlorosilane, dimethoxymethylchlorosilane and 1,2-bis(dimethylchlorosilyl)ethane. It was necessary to intercalate organic bases such as n-alkylamines prior to the silylation. The Si-C vibration was observed in the IR spectra of products. Unlike alkylamine derivatives of the phosphate, silylated derivatives kept their basal spacings up to about 500 °C. Furthermore, contrary to the fact that α-zirconium phosphate changes to pyrophosphate above 700 °C, pyrophosphate was not observed on heating even at 1000 °C. Silylated derivatives were thought to be changed to layered compounds containing silica as a pillar in the interlayer space by heat treatment.
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A.K. KIRICHENKO, L.N. KOMISSAROVA, F.M. SPIRIDONOV, M.G. ZHIZHIN, V.P. ...
1999 Volume 10 Pages
194-198
Published: 1999
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Influence of Eu
3+ introduction on structure and properties of K
3Ln(PO
4)(VO
4)
2-x (Ln = Y, La, Gd) is investigated. Samples of K
3Ln
1-yEu
y(PO
4)
x(VO
4)
2-x(Ln = Y, La, Gd; 0≤x≤2) were received by solid state method by multistep annealing from 70 to 750 °C with use of Ln
2O
3 (Ln= Y, La, Eu, Gd), KH
2PO
4, NH
4VO
3 and K
2CO
3. There are restrict or wide solid solution range is observed in systems under investigation.
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SERGEY I. LOPATIN, GERMAN A. SEMENOV, ANATOLY F. SELEVICH
1999 Volume 10 Pages
199-202
Published: 1999
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The vaporization of gallium phosphate GaPO
4 was studied by high-temperature mass spectrometry. ·Standard enthalpies of formation and atomization (kJ/mol) were derived for GaPO
3(g) (-661±35 and 1997±36), and for GaPO
2 (g) (-373±36 and 1460±37) respectively. A number of regularities are revealed from the analysis of qualitative and quantitative vapor compositions.
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KARLIS A. GROSS
1999 Volume 10 Pages
203-207
Published: 1999
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Calcium phosphates are used extensively as biomaterials for promoting bone growth and improving the fixation of bone to dental and orthopaedic devices. Calcium phosphates were introduced in the early 1980's, and are used as implants today, however more work is being conducted to produce a higher quality coating. Due to the low mechanical strength, it has been used as a filler material or a coating. Initially, hydroxyapatite was the desired material for application in coatings due to its compositional similarity to the inorganic phase of bone, but thermal decomposition during processing has produced various unexpected chemical phases. It has become necessary to expand the collection of characterization techniques to fully describe the nature of the coating and ensure a good quality coating.
A transfer of analysis techniques from thermal spray science, minerology and chemistry have been necessary to achieve a more detailed description of the coating. Characterisation is necessary for powder synthesis and preparation, coating production, and analysis of histological sections and retrieved prostheses. The latter mentioned stages require more analysis techniques for a full characterization. Techniques incorporate structural, compositional, chemical phase, microstructural, strength and dissolution assessment methods. This paper will outline the characteristics that are addressed at each characterisation stage and list the different techniques that are presently used in industry. The additional analysis requirements that still need to be developed to completely describe the coating will be described.
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S. SARDA, A. TOFIGHI, M.C. HOBATHO, D. LEE, C. REY
1999 Volume 10 Pages
208-213
Published: 1999
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Microporous ceramic-like materials can be obtained at low temperature (4 to 50 °C) from aqueous suspensions of nanocrytsalline apatite. They were associated with organic macromolecules (albumin, casein, gelatin) and their Young's modulus was determined by ultrasonic transmission technique. Young's modulus of the composites with gelatin and albumin were higher than that of mineral blocks with the same maturation time whereas casein-apatite associations gave weaker Young's modulus. This different behavior was attributed to variations in the porosity of the materials. Such associations may have potential applications as biomaterials.
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SYLVIE RAYNAUD, ERIC CHAMPION, DIDIER BERNACHE-ASSOLLANT
1999 Volume 10 Pages
214-219
Published: 1999
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Calcium deficient hydroxyapatite with Ca/P atomic ratio comprised between 1.5 and 1.667 were densified by hot pressing. Hot pressed powders were transformed into hydroxyapatite-tricalcium phosphate biphasic ceramics. After hot pressing at 1200°C, fracture strength remained below 100MPa, this was explained by the allotropic transformation β→α of TCP above 1150°C. Ceramics hot pressed at 1100°C had a fracture strength of 150 MPa when the composition contained between 8 wt% and 12 wt% of β-TCP. For lower or higher β-TCP content the strength dropped. This proved the necessity of a precise determination of Ca/P ratio. Quantitative X-ray diffraction analysis allowed a better precision than wet chemical analysis with deviations below 0.005 on Ca/P values.
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SEIJI BAN, SHIGEO MARUNO, JIRO HASEGAWA
1999 Volume 10 Pages
220-225
Published: 1999
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Needle-like apatite crystals were formed on pure titanium plate by a hydrothermal-electrochemical method at 100-200°C in an electrolyte containing calcium and phosphate ions. The width and length of the apatite needles increased with the electrolyte temperature. The aspect ratio of the apatite decreased with it. Pure titanium plates with the hydrothermal-electrochemically coated apatite at 100-200°C were soaked in a simulated body fluid from 3 to 27 weeks at 37°C. After soaking, the changes in weight of the specimens were measured, and the surfaces of the specimens were characterized. The specimens having fine apatite needles formed at 100°C showed the largest weight gain due to the deposition of the carbonate containing apatite having low crystallinity.
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GEORGE H. NANCOLLAS, WENJU WU
1999 Volume 10 Pages
226-231
Published: 1999
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Constant composition methods have been used to investigate the mechanisms of crystal growth and dissolution of calcium phosphate minerals. Interfacial tensions between water and each of these surfaces were calculated from measured contact angles using surface tension component theory. The interfacial tension values, -4.2, 4.3, 10.4 and 18.5 mJm
-2 for dicalcium phosphate dihydrate (DCPD), octacalcium phosphate (OCP), hydroxyapatite (HAP) and fluorapatite (FAP), respectively, compare well with those calculated from dissolution kinetics experiments and provide information concerning the growth and dissolution mechanisms. The much smaller interfacial tensions of OCP and DCPD in contact with water compared with those of HAP and FAP support the observation that the crystallization of the latter phases was often preceded by the formation OCP and DCPD and that both OCP and DCPD could serve as precursors to apatite growth. In addition, the ability of a surface to nucleate mineral phases is closely related to the magnitude of the interfacial energies which are also important in understanding stability of calcium phosphate colloidal dispersions.
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PANJIAN LI
1999 Volume 10 Pages
232-238
Published: 1999
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A number of materials have shown to be capable of inducing apatite formation in metasatble calcium- and phosphate-containing solutions known as simulated body fluids (SBFs). All these apatite inducers have a great number of acidic hydroxyl groups on their surfaces that include SiOH, TiOH and COOH. A hypothesis is thus proposed that a material could induce apatite formation when there are a large number of acidic OH groups present on its surface. These acidic OH groups could be introduced in the material via sol-gel processing routes and/or generated on the surface of a material as a result of its interaction with the solutions. The knowledge has been applied to develop a new process of growing an apatite film on titanium implants for enhancement of their fixation in bone.
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STEPHANIE SARDA, MONIQUE HEUGHEBAERT, ALBERT LEBUGLE
1999 Volume 10 Pages
239-244
Published: 1999
Released on J-STAGE: October 29, 2012
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Organised Molecular Systems have been used to control the synthesis of calcium phosphate, through to the role of surfactant molecules at the mineral-organic interface. The influence of various parameters on the nature of the solid obtained has been examined: nature of the oil, type of surfactant, (Ca/P)r atomic ratio in the reactants, and also ageing. This method of synthesis allows the size and the morphology to be controlled and nanometric crystals to be obtained.
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TOSHIYUKI AKAZAWA, MASAYOSHI KOBAYASHI, KEIICHIRO MATSUSHIMA, HIRONORI ...
1999 Volume 10 Pages
245-249
Published: 1999
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Spherical particles of cattle bone-originated apatites (r-HAp) were prepared by a consecutive procedure as dissolution-precipitation, spray-drying, and heat-treatment processes. The r-HAp particles obtained had effective pore structures for liquid chromatographic separation of the five proteins such as bovine serum albumin, myoglobin from horse skeletal muscle, ribonuclease A from bovine pancreas, lysozyme from chicken egg white, and cytochrome c from horse heart. The adsorption surface functions of the particles for the liquid chromatography were designed by optimizing the spray-drying conditions using a two fluid-nozzle and heat-treatment temperatures. The column packed with the r-HAp particles gave high resolution and excellent durability for the five proteins-separation because of no change in the pore size distribution curves even after more than sample injection of 300 times.
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GREGORIO VARGAS, JORGE LÓPEZ, JORGE L. ACEVEDO, JORGE ROMERO, J ...
1999 Volume 10 Pages
250-255
Published: 1999
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The effect of ultrasonic vibration on the particle size distribution of hydroxyapatite chemically precipitated from eggshells and H
3PO
4, or alternatively from calcium acetate and Na
3PO
4?12H
2O, was evaluated. For the case of hydroxyapatite aqueous suspensions with pH>10, with no particle-dispersing agent added, the average particle size decreased from 40 to 3μm in five minutes by employing an ultrasonic power of 61.75 watts and a frequency of 20 KHz.
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MIHKEL VEIDERMA, KATA TÕNSUAADU, MERIKE PELD, VILLEM BENDER
1999 Volume 10 Pages
256-261
Published: 1999
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On dynamic calcination of synthetic apatites in air-SO
2 flow up to 750-900 °C formation of CaSO
4 and Ca
2P
2O
7, and at 800-950 °C, a reaction between them with the formation ofβ-Ca
3(PO
4)
2 and partial evolvement of SO
2 takes place. The amount of SO
2 bound and evolved depends on the composition of the apatite.
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L. LEROUX, M. CARAYON, J. CARPENA, M. FRECHE, J.L. LACOUT
1999 Volume 10 Pages
262-267
Published: 1999
Released on J-STAGE: October 29, 2012
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The use of calcium phosphate hydraulic cements for conditioning radioactive elements, such as Sr
90, seems very interesting. The strontium was incorporated in various amounts in the liquid phase (0-10% weight). After hardening, the cement is formed by a poorly crystallized strontium calcium apatite. The incorporation of Sr in the apatitic lattice was evidenced by the correlation between the amount of Sr and the crystalline state, the (002) diffraction line shift and the thermal decomposition. This thermal decomposition (> 600°C) leads to stoichiometric and stable apatites. Mechanical properties increases with Sr % weight.
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M. RIVENET, J.C BOIVIN, F. ABRAHAM, N. RUCHAUD, P. HUBERT
1999 Volume 10 Pages
268-273
Published: 1999
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The bond nature of a (NaPO
3)
n-containing basic refractory material was investigated versus the heating temperature. At room temperature, the raw binder (NaPO
3)n was shown to contain an average of 15 units per chain leading to a binding gel formation when the refractory material is added with water. As the raw mix temperature increases, the gel converts into a mixed sodium calcium phosphate phase stable in the temperature range [500-1000°C]. Beyond 1100°C, the mixed sodium calcium phosphate reacts with intergranular silicate phases. It transforms, then, into a mixed sodium calcium silicophosphate solid solution. This high temperature silicophosphate bond exhibits a lower decomposition kinetic than that of the mixed sodium calcium phosphate which decomposes, at low temperature, into β-NaCaPO
4 and Ca
5(PO
4)
3OH.
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FATIMA ZAHRA BOUJRHAL, MOHAMMED BERRADA, RAJAA CHERKAOUI EL MOURSLI
1999 Volume 10 Pages
274-282
Published: 1999
Released on J-STAGE: October 29, 2012
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The release and the retention of radon-222, from sedimentary phosphate in which it is formed, is studied in this paper.
Radon emanation parameters were determined in the temperature range 20-900°C. The heat treatment may be regarded as having two effects: an immediate effect (radon release) and a long term effect (retention of radon).
Radon degassing rate and radon emanating power, corresponding bulk to those effects, were measured.
Structural stability of apatite was maintained during heat treatment and an expansion of apatite lattice with increasing temperature was observed.
A linear relation between radon emanation and density multiplying specific surface area.
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MAMORU AIZAWA, TEPPEI YAMAMOTO, KIYOSHI ITATANI, HIROSHI SUEMASU, AKIR ...
1999 Volume 10 Pages
283-288
Published: 1999
Released on J-STAGE: October 29, 2012
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Porous hydroxyapatite (HAp) films were formed on α-Al
2O
3 substrate by spray-pyrolysis technique, using starting solutions with the Ca/P ratios of 0.50 and 3.00. The crystalline phase of the resulting films was mainly HAp; the films were porous and the thickness was ~30 μm. Even after Scotch tape (#810) was adhered to the films and then taken off from the substrates, the films were still present on the substrate. The biocompatibility of the α-Al
2O
3 coated with HAp was examined using osteoblastic cells (MC3T3-E1). The cells on the α-Al
2O
3 coated with HAp were proliferated in a similar manner to the case of control (dish for cell culture) and the α-Al
2O
3 substrate without HAp coating; the alkaline phosphatase (ALP) activity of the cells cultured on the α-Al
2O
3 coated with HAp for 21 days showed the highest value among the examined specimens.
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ABDELMAJID BENSAOUD, MOHAMMED ELAZZOUZI, AHMED BOUHAOUSS, MOHAMMED FER ...
1999 Volume 10 Pages
289-294
Published: 1999
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The present work has been undertaken to compare the effect of maturation and chemical treatments by CO
32- and F
-- ions on the crystallinity and the electrical properties of a synthetic poorly crystallised carbonate-apatites. The tendency of these materials to crystallise during maturation or following F
- treatment was accompanied by improvement of their ionic conductivity, while a decrease of the crystallinity caused by CO
32- ions occurred with reducing of the conductivity. Frequency dependant ionic conductivity was either attenuated gradually during maturation and rapidly succeeding F
- treatment or accentuated following CO
32- treatment. These results were explained by the short-range organisation of sites with time, and by occurrence of structural order or disorder in back of chemical treatments.
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PAULA G. D. INÁCIO, PAULA A. A. P. MARQUES, M. CLARA F. MAGALH& ...
1999 Volume 10 Pages
295-300
Published: 1999
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The purpose of this work was to study the conditions of synthesis of octacalcium phosphate. During the process of synthesis, reactant addition time of the calcium acetate solution to the ammonium dihydrogenophosphate solution as well as the reaction temperature were found to be determinant on the composition of the final solid. Synthesis performed with pH 5 and at a constant temperature of 60°C, DCPD (CaHPO
4·2H
2O) was obtained for addition times of the calcium solution between 30min and 1h30min and OCP (Ca
8H
2(PO
4)
6·5H
2O) was obtained for addition times superior to 2h without exceeding 5h. Synthesis performed with pH 5 and at a constant addition time of the calcium solution (2h45min), DCPD (CaHPO
4·2H
2O) was obtained at temperatures below 60°C, OCP (Ca
8H
2(PO
4)
6·5H
2O) was found at temperatures in the range of 60 to 80°C, and HAp (Ca
5(PO
4)
3(OH)) was obtained above 80°C.
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YOSHIYUKI YOKOGAWA, MASAMI IKEYAMA, KAORI NISHIZAWA, FUKUE NAGATA, TET ...
1999 Volume 10 Pages
301-306
Published: 1999
Released on J-STAGE: October 29, 2012
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Calcium phosphate growth on phosphorus ion implanted titanium substrate was studied. Phosphorus ions were implanted into titanium substrates with an acceleration energy of 45 KeV and in amounts of 1x10
16-3x10
17 ion/cm
2. After immersion in SBF solution, calcium phosphate was formed on the phosphorus ion implanted titanium substrate. The implanted phosphorus ions reach a depth of 200-300 nm from the surface and phosphorus ions do not exist on the surface as a result of ion implantation as revealed using AES. So implanted phosphorus ions do not participate in the calcium formation. The surface oxide of titanium grew up to 100nm and was covered by hydroxyl group in SBF solution. Calcium or phosphate ions in SBF solution can be adsorbed by the oxide surface. The deposition of calcium phosphate involves adsorption of calcium or phosphate ions leading to an elevation of the calcium or phosphate ions which in turn must accelerate the formation of calcium phosphate.
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CLAUDE PENOT, ERIC CHAMPION, PAUL GOURSAT
1999 Volume 10 Pages
307-312
Published: 1999
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Lanthanum phosphate powders were synthesised from precipitation using three different routes. Depending on synthesis conditions, these powders have the monoclinic structure of monazite (LaPO
4) or the hexagonal structure of rhabdophane (LaPO
4,0.5H
2O). Chemical analysis gave a La/P ratio of about 0.9. Rhabdophane phase remained stable up to 650°C and transformed into monazite at higher temperature.
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SEI-ICHI SUDA, SATOSHI ICHIKAWA, KIYOSHI KANAMURA, TAKAO UMEGAKI
1999 Volume 10 Pages
313-316
Published: 1999
Released on J-STAGE: October 29, 2012
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CaO-SiO
2 amorphous powder were coated with calcium phosphate in order to apply the coated powder as an adsorbent, which has large surface area and various adsorption sites. The coating of the amorphous powder, which was 0.5μm in particle size, led to be the formation of low-crystalline HAp powder that has the particle size of 20μm. The morphology of the coated powder was independent of the compositions in core powders but would depend on only the Ca
2+ and PO
43- concentrations in coating solutions.
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KAY TERAOKA, TORU NONAMI, YUTAKA DOI, HIROSHI TAODA, KATSUYOSHI NAGANU ...
1999 Volume 10 Pages
317-322
Published: 1999
Released on J-STAGE: October 29, 2012
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Fixation of orthopedic titanium implants to living bone is one of keys to achieve a successful result but still developing. Enhancement of bone formation around the implants can make a contribution to long-term stable fixation. In this study, spherical HAP ceramics (φ400-500μm) were implanted in the surface of cylinder shape pure titanium by the loading up to 1 kN at 1173 K to enhance bone formation around the implant. By this method, the spherical HAP ceramics were mechanically held on the surface of the pure titanium.
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MASATO WAKAMURA, KAZUHITO HASHIMOTO, TOSHIYA WATANABE
1999 Volume 10 Pages
323-328
Published: 1999
Released on J-STAGE: October 29, 2012
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Colloidal Ca
10(PO
4)
6(OH)
2 (CaHAP) particles doped with Ti(IV) ions in different atomic ratios, Ti/(Ca+Ti) = X
Ti, by a coprecipitation method were characterized by TEM, UV, FTIR, XPS and ICP. The photocatalytic activity of the modified CaHAP particles was confirmed by acetaldehyde decomposition. Ca(II) ions of CaHAP were substituted by Ti(IV) ions in one to one at X
Ti ≤ 0.1. When doped at X
Ti > 0.1 irregular particles of amorphous titanium phosphate were formed besides long rectangular particles of CaHAP. X
Ti of the surface phase of the particles was much less than that of the whole particle; Ti(IV) is less contained in the surface phase than the bulk one. UV absorption took place on Ti(IV)-doped CaHAP particles but not on unmodified particles. The decomposition of acetaldehyde by Ti(IV)-doped particles under UV irradiation was detected, while the unmodified CaHAP particles was inactive for the reaction.
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