Structural change of layered perovskite La2Ti2O7 at high pressures

Stability of fluorite-type La2Ce2O7 under extreme conditions

“…If the A and B cations are of the right relative sizes (r A /r B < 1.46), a disordered, fluorite-structure will form. A layered perovskite structure is stable when there is a large size difference between the cations, such as in the case for La 2 Ti 2 O 7 [24]. Most rare-earth titanate and stannate with the A 2 B 2 O 7 stoichiometry form an ordered pyrochlore structure, in which RE 3þ and Ti 4þ /Sn 4þ occupy the A-and B-site, respectively.…”

An easy sol–gel route for deposition of oriented Ln2Ti2O7 (Ln=La, Nd) films on SrTiO3 substrates

“…The Ln ¼ La, Nd, Ce, Pr compounds are monoclinic with P2 1 space group. The Ln ¼ Sm, Gd, Dy, Ho, Er, Yb are cubic with Fd-3m space group [6,8,9]. In this study, we will focus more specifically on both LTO and NTO compounds.…”

“…LTO is ferroelectric until T c ¼ 1500 1C and has a high dielectric constant e ¼ 42-62 with a low temperature coefficient and a low dielectric loss at microwave frequency [8,9]. The lattice parameters of monoclinic LTO are: a ¼ 7.812(2), b ¼ 5.5440(7), c ¼ 13.010(2)Å and b ¼ 98.66(1)1 [10].…”

Perovskite-type La2Ti2O7 mesoporous photocatalyst

“…4, all the samples were found to have the perovskite La 2 Ti 2 O 7 structure [20]. probably due to the homogeneous mixing of La and Ti atoms in all amorphous samples.…”

“…Since the XRD patterns in Fig. 6(B), (d) and (e) are attributed to La 2 Ti 2 O 7 crystal, [20] high pH condition is desirable for crystallization of La-Ti oxide to La 2 Ti 2 O 7 , similarly to the preparation condition of La-Ti oxide. In other words, the homogeneous mixing of La and Ti in the mixed oxide phase at an atomic level seems to be indispensable for the generation of conditions disallowed to form any nano-structured materials probably due to the prevention of micelle formation of CTAB.…”