X-ray diffraction and Raman spectroscopic investigations on CaZrTi2O7-Y2Ti2O7 system: Delineation of phase fields consisting of potential ceramic host materials

Phase evolution from CaZrTi2O7 (zirconolite) to Y2Ti2O7 (pyrochlore) have been delineated by systematic characterization of a series of sample with composition as Ca1-xZr1-xY2xTi2O7 (0.00 <= x <= 1.00) by powder XRD, Raman spectroscopy, SEM and EDS analyses. Comparative analyses of XRD and Raman spectra revealed sequential evolution of phases with increasing concentration of Y3+ in the compositions. From the XRD studies, three distinct phase fields, namely two layer (2M) and four layer (4M) zirconolitetypes and cubic pyrochlore-type are observed in between zirconolite (CaZrTi2O7) and Y2Ti2O7. 4M-zirconolite phase is observed in a narrow range of composition, viz. 0.35 <= x <= 0.40 while cubic pyrochlore type phase is observed in the compositions with x >= 1.20. The unit cell volume of different phases shows a non-linear increasing trend with Y3+ ion concentration which has been attributed to the distribution of cations in different structure and change in their coordination number. (C) 2016 Elsevier B.V. All rights reserved.