Temperature and Pressure Dependent Properties of A3Ti2O7*

Theoretical models of the A3Ti2O7 system suggest that electric polarization is due to the combination of the coherent TiO6 octahedral rotation and tilting, both being nonpolar. For the doped A3Ti2O3 systems, different size atoms enable the possibility of site-selective substitution in A’ or A site to tune the TiO6 octahedral rotation and tilting. In this work, a structural study over a broad range of temperatures and pressures has been conducted by x-ray diffraction, Raman spectroscopy, x-ray absorption spectroscopy, x-ray pair distribution function measurements and DFT modeling. The long-range and local symmetries and local atomic and electronic structural changes will be discussed and compared with previous work.