It has been well established that LaCrO₃ exhibits an orthorhombic structure (Pnma) and undergoes a structural phase transition to rhombohedral (R-3c) when submitted to physical or chemical pressure. The doping-induced structural phase transition in the LaCr_1-xAl_xO₃ solid solution is carefully investigated by Raman Spectroscopy in this communication. Spectral band analysis of the experimental results strongly indicates that solid solution with low Al-content (x = 0.0 and 0.05) displays an orthorhombic structure characterized by the A_g, B_1g, B_2g, and B_3g vibrational modes, whereas the solid solution with high Al-content (x = 0.5 and 0.95) displays a rhombohedral structure with A_1g and E_g vibrational modes. Particularly, the decrease of intensity and the displacement of some vibrational modes with increasing of Al-content indicates that the structural phase transition from orthorhombic to rhombohedral in the LaCr_1-xAl_xO₃ solid solution is accompanied by a freezing of the (Cr/Al)O₆ octahedron vibrations. It is therefore postulated that the Al-doping in LaCrO₃ above a threshold leads to instability and structural distortions that induce a structural phase transition.

众所周知，LaCrO ₃表现出正交结构（Pnma），并且在受到物理或化学压力时会发生结构相变，变成菱面体（R-3c）。在本文中，通过拉曼光谱法仔细研究了LaCr _1-x Al _x O ₃固溶体中掺杂诱导的结构相变。实验结果的光谱带分析强烈表明，Al含量低的固溶体（x = 0.0和0.05）显示出具有A _g，B _1g，B _2g和B _3g的正交结构。振动模式，而铝含量高的固溶体（x = 0.5和0.95）显示出具有A _1g和E _g振动模式的菱面体结构。特别是，随着Al含量的增加，强度的降低和某些振动模式的位移表明，LaCr _1-x Al _x O ₃固溶体中从正交晶向菱面体的结构相变伴随着（Cr / Al）O ₆八面体振动。因此，假设LaCrO ₃中的Al掺杂超过阈值会导致不稳定性和导致结构相变的结构变形。