Question

Briefly describe why rutile and anatase (TiO2 polymorphs) should give different X-ray diffraction patterns.

Answer 1

Tio2 has two forms, rutile and anatase.

These are the stable phase of Tio2.They give xray pattern. The reasom they show XRD given below.

Phase formation The imtial Gystalline Tig phase formed dumng the Synthesis of tich films is Anatase. In structural wise, its due to the greater ease of Supt range ordered Thog octahedra in ananging into long range ordered anatase structure to the bar Constramed molecular Construction of anatase relative to rutile. Rapid recrystallisation of anatase 43 due to lower sunface energy despite the server gibbs free energy of nutile Anatase space group 14/and Rutile : Space group et, man freagonal Both Crystal structures. Consist of Tio Octanedra Sharing 2 edge rutile 54 edges in anatase The anatase to rutile transformation is reconstructive Phase differentiation and Quantification of Anatase / Rutile X ray diffraction Quantification of phase propostions usually is carried out by XRD (x ray diffraction), It utiluses the ratio of rutile peak at 27-3550 20 to the anatase peak at 25-176 20 (Values from spurt and myers experimental Analysis)

Ratio of indensities of the peak IP/JA is the gire the weight tractions of anature formula to and nutite WR INA 1.22 IR I 0.0280 Factors that may affect the accuracy of the results Preferred orientation Rutile/ Anatase Crystallites may be present in preferred onetation owing to morphogical and Sample preparation effects, which may lead to altered XRD relative peak intensities Encapsulation Rutile Crystallites grow as an overlayer of rutile on anatase particles rutile may form in the bulk of anatase growns. leaving surface layer of anatase on rutile particles there by compromising the basis for the intensities of the XRD peaks. Lattice distation. The presence of dissolved dopants or impurities espeenally of differential Solubility occup, may after the peak height and areas there by altering the relative entenities of the XRD peaks.

arc Grain Size: The transition to rutile Degree of Crystallinty: the presence of dopants may increase or decrease the degree of crystallionty, which would after the Consequent peak indensity, these dopants preferentially present in one of the phase ris accompanied by signficant grain growth, resulting in large rutile grams and small anatase grains, which would alter the ratios of XRD peak intensities orphology: Rutile may form in an acicular morphology which alter the XRO peak intensities of these grains relative to nutile Surface Nucleation of rutile: Eshanud Sunyone nucleation of rutile owing to heat and Segregation effects would increase the XRD this peak indensities of this phase; no its of estonia vormistin tortortor is it or or