Structural characterization of aluminum phosphate binder

The chemical structure of aluminum phosphate binder, which is used as a sea lant for thermally sprayed coatings, was studied. Powder X-ray diffraction (XRD) analysis showed that the binder was a mixture of several phases. None of these phases could be identified from the powder XRD data only. Electro n diffraction revealed several distinct microcrystalline phases. The predom inated phase was analyzed in more detail. The three-dimensional reciprocal lattice was reconstructed from a tilt series of electron-diffraction patter ns that indicated that the main phase was the cyclohexaphosphate Al2P6O18. The similarity of the intensity distribution in the observed and simulated electron-diffraction patterns of Al2P6O18 confirmed this observation. The f ollowing unit-cell parameters were determined from the reconstructed recipr ocal lattice: a = 8.8(7) Angstrom, b = 15.5(6) Angstrom, and c 6.3(9) Angst rom, beta = 108 degrees, and Z = 2, The reflection conditions indicated tha t the space group was P2(1)/a.