The 'bimodal effect' of the bulk modulus of rare-earth titanate pyrochlore

First-principles calculations have been carried out to study the bulk modulus, the lattice parameters and the bond length of RE 2 Ti 2 O 7 (RE = La, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) pyrochlores. The relationship of the bulk modulus and the bond length of RE 2 Ti 2 O 7 have been analyzed qualitatively. Both the bulk modulus and the 〈RE-O 48 f 〉 bond present the “bimodal effect” and 〈RE-O 48 f 〉 bond may have a significant effect on the bulk modulus.