Phosphates: Solid-State Chemistry
15 Dec 2011-pp 1-16
TL;DR: The most common anion is the orthophosphate group PO4 3 −, which is found in many solid phosphates, including hydrated and acid phosphate salts as mentioned in this paper.
Abstract: Phosphates contain oxyanions of phosphorus(V). The most common anion is the orthophosphate group PO4 3 −, which is found in many solid phosphates, including hydrated and acid phosphate salts. Oligomeric polyphosphate chains P n O3 n +1 ( n +2)− up to n = 6 and cyclophosphate rings P n O3 n n − up to n = 12 are also observed, and a unique cage ultraphosphate anion P8O23 6− is found in the Na3FeP8O23 structure. Polymeric phosphate anions include the infinite chain catenaphosphate anion (PO3 −)∞ and the ultraphosphate networks found in CaP4O11 and the lanthanide MP5O14 structures. Many compound anions and neutral frameworks such as silicophosphates, aluminophosphates, and molybdenum phosphates also exist. Phosphate species are characterized through P–O stretching and bending vibrations in infrared and Raman spectroscopies, and by 31P NMR. Phosphate structures are generally rigid, resistant to chemical attack, and (when anhydrous) insoluble and thermally stable. Some phosphate crystals have important physical properties such as ferroelectricity in KH2PO4 (potassium dihydrogenphosphate, KDP). Diffusion of extra-framework ions leads to potential uses of solid phosphates as ion exchangers and conductors, for example, NASICON based on NaZr2(PO4)3, and LiFePO4 as a cathode material for lithium-ion batteries. Vanadium phosphates are important selective oxidation catalysts. Large pore phosphates in which molecules can be adsorbed and undergo acid-catalyzed reactions have been intensively studied. These materials are crystalline microporous solids such as aluminophosphates, or lamellar structures, typically based on α-Zr(HPO4)2·H2O that can be pillared. This area of interest has led to the synthesis of many new organically templated metal phosphates, usually through hydrothermal reactions. Hydrated and acid orthophosphates can also be prepared in solution, and anhydrous phosphates are synthesized by direct high-temperature reactions and from phosphate-rich melts or fluxes. Slow cooling of melts is used to grow crystals, and quenching can result in many stable phosphate glasses. Phosphate anions do not absorb significantly in the UV–visible region and so solid phosphates also find use as optical materials such as phosphors, nonlinear crystals (e.g., KTiOPO4), and lasers. Solid phosphates constitute many minerals, notably apatites, which are also found in living organisms as rigid components such as bones and teeth. Synthetic calcium phosphate biomaterials are used for bone implants.
Keywords:
orthophosphate;
phosphate;
ionically conducting phosphates;
microporous phosphate materials;
mineral phosphates;
nonlinear optical phosphate materials;
condensed phosphate polyanions;
layered phosphate materials;
biomaterial phosphates
Citations
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TL;DR: In this article, the synthesis and single crystal X-ray structure for a new acidic pyrophosphate dihydrate CoK1.078N0.922(H2P2O7)2.
Abstract: The synthesis and single crystal X-ray structure are reported for a new acidic pyrophosphate dihydrate CoK1.078N0.922(H2P2O7)2.2H2O. The results revealed cobalt (Co) octahedrally coordinated by two...
4 citations
Cites background from "Phosphates: Solid-State Chemistry"
...Therefore, the interpretation of infrared spectrum can be made on the basis of characteristic vibrations of PO2 group, P-OH bond, and POP bridge and also of the water molecule.([16,17]) In the first region, the broad and medium bands observed in the 3264–2600 cm 1 range are due to the antisymmetric vas(OH) and symmetric vs(OH) stretching vibrations of water and (H2P2O7) 2– anions....
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TL;DR: In this article, the effects of BaO addition on the structure and thermochemistry of polyphosphate glasses were investigated with a series of vitreous compositions having the formula (100-x)NaPO3-xBaO.
3 citations
1 citations
References
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TL;DR: Corma et al. as mentioned in this paper used the Dupont Award on new materials (1995), and the Spanish National Award “Leonardo Torres Quevedo” on Technology Research (1996) on technology research (1996), to recognize the performance of zeolites as catalysts for oil refining and petrochemistry.
Abstract: It is possible to say that zeolites are the most widely used catalysts in industry They are crystalline microporous materials which have become extremely successful as catalysts for oil refining, petrochemistry, and organic synthesis in the production of fine and speciality chemicals, particularly when dealing with molecules having kinetic diameters below 10 A The reason for their success in catalysis is related to the following specific features of these materials:1 (1) They have very high surface area and adsorption capacity (2) The adsorption properties of the zeolites can be controlled, and they can be varied from hydrophobic to hydrophilic type materials (3) Active sites, such as acid sites for instance, can be generated in the framework and their strength and concentration can be tailored for a particular application (4) The sizes of their channels and cavities are in the range typical for many molecules of interest (5-12 A), and the strong electric fields2 existing in those micropores together with an electronic confinement of the guest molecules3 are responsible for a preactivation of the reactants (5) Their intricate channel structure allows the zeolites to present different types of shape selectivity, ie, product, reactant, and transition state, which can be used to direct a given catalytic reaction toward the desired product avoiding undesired side reactions (6) All of these properties of zeolites, which are of paramount importance in catalysis and make them attractive choices for the types of processes listed above, are ultimately dependent on the thermal and hydrothermal stability of these materials In the case of zeolites, they can be activated to produce very stable materials not just resistant to heat and steam but also to chemical attacks Avelino Corma Canos was born in Moncofar, Spain, in 1951 He studied chemistry at the Universidad de Valencia (1967−1973) and received his PhD at the Universidad Complutense de Madrid in 1976 He became director of the Instituto de Tecnologia Quimica (UPV-CSIC) at the Universidad Politecnica de Valencia in 1990 His current research field is zeolites as catalysts, covering aspects of synthesis, characterization and reactivity in acid−base and redox catalysis A Corma has written about 250 articles on these subjects in international journals, three books, and a number of reviews and book chapters He is a member of the Editorial Board of Zeolites, Catalysis Review Science and Engineering, Catalysis Letters, Applied Catalysis, Journal of Molecular Catalysis, Research Trends, CaTTech, and Journal of the Chemical Society, Chemical Communications A Corma is coauthor of 20 patents, five of them being for commercial applications He has been awarded with the Dupont Award on new materials (1995), and the Spanish National Award “Leonardo Torres Quevedo” on Technology Research (1996) 2373 Chem Rev 1997, 97, 2373−2419
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TL;DR: In this paper, a short review describes the evolution of the nature of microporous solids and the related concepts that were at the origin of this evolution, including the creation of very large pores, their design from topological considerations, and the introduction of computational methods.
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