Diagramme d'equilibre du systeme binaire Ba(PO3)2  CsPO3; donnees cristallographiques sur BaCs4(PO3)6, Ba2Cs(PO3)5 et BaCsP3O9, H2O

Equilibrium diagram of Ba(PO₃)₂  CsPO₃ system is given. Two compounds are identified: BaCs₄(PO₃)₆, Ba₂Cs(PO³₃)₅  BaCsP₃O₉.H₂O was also prepared and characterized.     

Etude du systeme AgIBiI3

The pseudo-binary system AgI-BiI₃ has been studied by differential thermal analysis (DTA) and by microcalorimetry. An eutectic point was found at 389°C for the composition BiI₃ : 85 mol.BiI₃ p.cent. Two new solid solutions have been discovered. Their existence has been confirmed by X-ray diffraction.     

Diagramme d'equilibre solide-liquide du systeme Ce(PO3)3 — AgPO3

The Ce(PO₃)₃ — AgPO₃ system was investigated by differential thermal analysis (DTA) and X-ray diffraction. Its phase equilibrium diagram was established by recording heating curves on a M5 Setaram μ-DTA aparatus. This diagram shows that the Ce (PO₃)₃—AgPO₃ system forms only one compound, AgCe(PO₃)₄, which melts in a peritectic reaction at 788°C. The chemical preparation, powder diagram and main crystallogrophic characteristics of this compound are given. AgCe(PO₃)₄, a polyphosphate isotypic with NaNd(PO₃)₄, has a monoclinic unit cell with a space group $\text{P2}{}_1\text{n}$ and parameters a = 9.717(4), b = 12.959(5), c = 7.242(2) Å, β = 91.07(2)°, Z = 4, V = 911.79 ų, d_x = 4.11. The different structure types of binary poly and metaphosphates, M₂O.Ln₂O₃.4P₂O₅, are regrouped and a correlation between each crystalline form and the corresponding M³ and Ln³⁺ cation size is dicussed.     

Preparation of (NH4)Zr2(PO4)3 and HZr2(PO4)3

(NH₄)Zr₂(PO₄)₃ has been prepared, hydrothermally, from α-zirconium phosphate in three different ways; (1) from amine intercalates at 300°C, (2) from mixtures of ZrOCl₂·8H₂O in excess (NH₄)H₂PO₄ and (3) reaction of NH₄Cl with Zr(NaPO₄)₂. Ammonium dizirconium triphosphate is rhombohedral with a = 8.676(1) and $\text{c}\text{= 24.288(5)}\text{A}\text{?}$. It decomposed on heating to HZr₂(PO₄)₃. Below 600°C a complex, as yet unindexed, X-ray pattern was obtained. A very similar X-ray pattern was obtained by washing LiTi_0.1Zr_1.9(PO₄)₃ with 0.3N HCl. Heating this phase or NH₄Zr₂(PO₄)₃, above 600°C resulted in the appearance of a rhombohedral phase of HZr₂(PO₄)₃ with cell dimensions a = 8.803(5) and $\text{c}\text{= 23.23(1)}\text{A}\text{?}$. The protons were not completely removed until about 1150°C. Decomposition of (NH₄)Zr₂(PO₄)₃ at 450°C yielded an acidic gas whereas at 700°C NH₃ was evolved. A possible explanation for this behavior is presented.     

Donnees cristallographiques sur ZnKPO4 et ZnKAsO4

Crystal data for ZnKPO₄ and ZnKAsO₄ are given. The two compounds are isotypic and crystallize in the hexagonal system.     

Etude du systeme KFYbF3

The phase diagram of the KF-YbF₃ system shows the existence of the five compounds K₃YbF₆, K₂YbF₅, KYbF₄, KYb₂F₇ and KYb₃F₁₀. We give their X-ray single crystal and powder data (except for K₂YbF₅).     

Etude du systeme RbFErF3

The phase diagram of the RbF-ErF₃ system shows the existence of the four compounds Rb₃ErF₆, Rb₂ErF₅, RbEr₃F₁₀ and RbEr₂F₇. We report the X-ray powder data for the three first ones and X-ray single crystal data for RbEr₂F₇.     

Dielectric properties of Pb3 (PO4)2 | Pb3 (AsO4)2

The dielectric constants of Pb₃ (PO₄)₂ | Pb₃ (AsO₄)₂ at room temperature are intrinsic and fulfill the Lyddane - Teller - Sachs relation. At higher temperatures the specific conductivity increases with an activation energy of 0.56 eV leading to Maxwell - Wagner polarization effects thereby increasing the effective dielectric constant. Corresponding peaks in ∈' (T) are extrinsic and not attributed to structural phase transformations.     

Zur kristallstruktur von (NH4)3Ti(O2)F5

The disordered ligand positions in (NH₄)₃Ti(O₂)F₅ (cubic, space group Fm3m - O⁵_h'$\text{a}\text{= 9.23}{}_2\text{A}\text{?}$) has been studied by X-ray single crystal investigation. A 3-dimensional fourier synthesis indicates a distribution of the disordered O-Atoms on the 96j positions (Oyz) similar to (NH₄)₃ZrF₇ where a pentagonal bipyramide has been proposed for geometrie of the ZrF₇-group. Due to the short O-O distance the structure of (NH₄)₃Ti(O₂)F₅ is better described as elpasolite where one of the six octahedral ligand positions are statistically replaced by an ‘edge on’ O^2?₂-group oriented there in two possible directions.     

Preparation and properties of the Pb3(VO4)2Pb3(PO4)2 system

Single crystals of the pseudobinary system Pb₃(V_1?xP_xO₄)₂ were grown via the Czochralski technique and were studied over wide ranges of x, particularly with regard to the influence of substitution on the $\text{3}\text{?}\text{mF}\text{2}\text{m}$ transition as a function of temperature.     

Etude des systems AI3PO4-Pb3(PO4)2 avec A=Na,Ag cristallochimie et relations structurales

The phase diagrams of A^I₃PO₄-Pb₃(PO₄)₂ systems, with A=Na and Ag, are determined by high temperature X-ray diffraction and D.T.A. The only synthesized compounds in the two systems are APbPO₄ (L.T. and H.T.) and APb₄(PO₄)₃. The high-temperature forms of APbPO₄ adopt the α-K₂SO₄ type structure while the low-temperature form of NaPbPO₄ is isotypic with glaserite. The crystallographic study has revealed that the APb₄(PO₄)₃ compounds have an apatite-type structure. The existence of apatite compounds without second anion and the cationic repartition are related to the presence of lone pairs of electrons in the Pb²⁺ ions.     

Direct observation of ferroelasticity in Pb3(PO4)2  Pb3(VO4)2

Ferroelasticity has been established in the room temperature phase of Pb₃(P_xV_1-xO₄)₂, (x ≥ 0.8). The coercitive stress and the spontaneous strain have been determined and found to be 1.6 bars and ca. 3.5 · 10^?4 respectively. The effect of domain switching on double refraction and Raman spectra is clearly brought out.     

Nanoindentation study of single-crystal NaTh2(PO4)3

The single crystals of sodium dithorium orthophosphate NaTh₂(PO₄)₃ (NThP) were studied by means of micro/nanoindentation. The NThP hardness was found to be Н_N = 8.76 ± 0.18 GPa and the elastic modulus Е_N = 144 ± 1 GPa. Microhardness anisotropy of the NThP crystal unequal faces is insignificant. The non-uniformity of plastic strain observed for the NThP is caused by fracture initiation and growth in the imprint. The average fracture toughness index (K_Ic) for the NThP is estimated to be equal to 0.56 MPa m^0.5.     

含钛磷酸盐玻璃NaTi2(PO4)3-0.9Ca3(PO4)2的析晶行为

利用差热分析、X射线衍射仪、液氮吸附BET孔经测试仪对组成为NaTi2(PO4)3-0.9 Ca3(PO4)2的含钛磷酸盐玻璃的析晶行为进行了研究.通过对该玻璃相继进行成核、析晶和酸浸泡处理制备了NaTi2(PO4)3骨架多孔微晶玻璃.证明该玻璃在646℃8h成核处理过程中产生了旋节分解特征的成分偏聚,形成了富TiO2玻璃相和富CaO玻璃相交错生长的连通结构,成核处理后的玻璃在738℃析晶过程中依次在富钛相和富钙相中析出NaTi2(PO4)3和β-Ca3(PO4)2.成核过程对析晶的促进作用是通过促进NaTi2(PO4)3的析出而实现的.     

Etude cristallographique du systeme FeSSc2S3 preparations et structures de FeSc2S4 et Fe0.85Sc2.10S4

The crystal structures of FeSc₂S₄ and Fe_0.85Sc_2.10S₄ have been determined by three dimensional X-ray diffraction. The cubic cells, space group Fd3m, have lattice constants $\text{a}\text{= 10,501}\text{A}\text{?}$ for FeSc₂S₄ and $\text{a}\text{= 10,444}\text{A}\text{?}$ for Fe_0.85Sc_2.10S₄. Iron is divalent and scandium trivalent. FeSc₂S₄ is a direct spinel structure, Fe_0.85Sc_2.10S₄ is near a spinel structure. Only 0,5 iron atom is on every 8a position; 0,175 Fe and 1,05 Sc lie on octahedral 16d and 16c site.     

α-Pb3(PO4)2 — A pure ferroelastic

Single crystals of Pb₃(PO₄)₂ were grown by the Czochralski technique. Transparent oriented crystal sections exhibit a pattern of ferroelastic domains which are readily movable with applied external stress. The high-temperature parent phase, β-Pb₃(PO₄)₂, transforms to the α modification at 180°C. _This transformation corresponds to the Aizu (1) species, 3mF2/m, which supports full ferroelasticity. The predicted number of domain walls have been observed.     

Synthese et conductivite des verres du systeme B2O3Na2ONa2SO4

New glasses with sodium ion carriers have been obtained in the B₂O₃Na₂ONa₂SO₄ system. Their conductivities have been measured vs temperature and composition. Raman spectroscopy brings information about the behavior of sodium sulfate in the vitreous matrix.     

Etude magnetique des phases du systeme Fe2O3TeO2 structure magnetique de Fe2TeO5 à 4,2°K

The magnetic study of the three compounds isolated in the Fe₂O₃ - TeO₂ system are described. Among them, Fe₂TeO₅ is antiferromagnetic with T_N ? 360°K. The magnetic structure is discussed and corresponds with the P2'₁/c Shubnikov group.     

Sol–gel synthesis and luminescence of unexpected microrod crystalline Ca5La5(SiO4)3(PO4)3O2:Dy phosphors employing different silicate sources

Ca₅La₅(SiO₄)₃(PO₄)₃O₂ doped with Dy³⁺ were synthesized by sol–gel technology with hybrid precursor employed four different silicate sources, 3-aminopropyl-trimethoxysilane (APMS), 3-aminopropyl-triethoxysilane (APES), 3-aminopropyl-methyl-diethoxysilane (APMES) and tetraethoxysilane (TEOS), respectively. The SEM diagraphs show that there exist some novel unexpected morphological structures of microrod owing to the crosslinking reagents than TEOS as silicate source for their amphipathy template effect. X-ray pictures confirm that Ca₅La₅(SiO₄)₃(PO₄)₃O₂:Dy³⁺ compound is formed by a pure apatitic phase. The Dy³⁺ ions could emit white light in Ca₅La₅(SiO₄)₃(PO₄)₃O₂ compound, and the ratio of Y/B is 1.1, when the Dy³⁺ doped concentration is 1.0 mol%.