图13. 沿LaAlO₃衬底[001]方向外延生长的PbTiO₃薄膜组成的外延结构(010)倒易空间平面示意图

Fig.13. Schematic representation of the (010) reciprocal space map of PbTiO₃/LaAlO₃ epitaxial structure, where the substrate is LaAlO₃ with surface normal of [001] and the epitaxial film is PbTiO₃ (q_x and q_z are along [100]^* and [001]^* directions, respectively. a_{p, PTO} and a_{v, PTO} are the lattice parameters of PbTiO₃ along [100] and [001] directions, respectively. a_{p, LAO} and a_{v, LAO} are the lattice parameters of LaAlO₃ along [100] and [001], respectively. □ shows the (003) and (103) diffraction points from substrate of LaAlO₃, \text{○} shows the (003) and (103) diffraction points from epitaxial layer of PbTiO₃, "pseu" means that the epitaxial layer is pseudomorphic, "rel" means that the epitaxial layer is fully relaxed. The upper right color map inset shows the (103) diffraction points from the PbTiO₃/ LaAlO₃ epitaxial structure. The arrows "α" describes the move path of the diffraction point of the layer during relaxation. The angle of \alpha satisfies the relation of \frac{\mathrm{2}{c}_{\mathrm{12}}}{c_{\mathrm{11}}}\mathrm{t}\mathrm{a}\mathrm{n}\alpha \text{=}\mathrm{t}\mathrm{a}\mathrm{n}\text{(}\omega \text{-}\theta \text{)}, c_{\mathrm{11}} and c_{\mathrm{12}} are the elastic stiffness constants)