Structural Aspects of the Dehydration and Dehydroxylation of Layered γ-Titanium Phosphate, γ-Ti(PO4)(H2PO4)⋅2H2O.

• The thermal transformations of γ-titanium phosphate, γ-Ti(PO4)(H2PO4)·2H2O, have been studied using thermogravimetric analysis, differential scanning calorimetry, X-ray powder diffraction, and temperature-resolved in-situ powder diffraction. The transformation sequence goes from γ-Ti(PO4)(H2PO4)·2H2O over a new partially dehydrated form γ‘-Ti(PO4)(H2PO4)·(2−x)H2O (x 1) to the anhydrous form β-Ti(PO4)(H2PO4) and then through a two-step condensation process where layered titanium pyrophosphate, Ti(PO4)(H2P2O7)0.5, is formed first and finally cubic titanium pyrophosphate TiP2O7. The dehydration of γ-Ti(PO4)(H2PO4)·2H2O and the dehydroxylation/condensation process from β-Ti(PO4)(H2PO4) to layered titanium pyrophosphate,Ti(PO4)(H2P2O7)0.5, was followed in-situ. A new partially dehydrated phase, γ‘-Ti(PO4)(H2PO4)·(2−x)H2O (x 1), which forms at approximately 50 °C has been detected and characterized. The unit cell is monoclinic with the lattice parameters a = 23.670(1) Å, b = 6.264(1) Å, c = 5.036(1) Å, β = 102.41(1)°, and Z = 4. Layered titanium pyrophosphate, Ti(PO4)(H2P2O7)0.5, which forms at 375 °C has been characterized. The unit cell is monoclinic with lattice parameters a = 16.271(3) Å, b = 6.319(1) Å, c = 5.122(1) Å, β = 90.59(2)°, and Z = 4.

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NATURVETENSKAP  -- Kemi -- Fysikalisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Physical Chemistry (hsv//eng)

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Physical chemistry

Fysikalisk kemi

Physical Chemistry

fysikalisk kemi

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