The Al-doped LLZO in the cubic crystal structure has shown great potential in solid-state electrolyte applications given its high room-temperature ionic conductivity and excellent thermal, chemical, and electrochemical stability. In this study, we use the highly coherent X-ray beam generated by the third-generation synchrotron sources to investigate the nanoscale structural properties of LLZO in three types of structural phases based on the level of Al doping. The single-particle diffraction reveals the coexistence of domains with two orientations of the crystal structure inside one tetragonal-phase particle and shows that insufficient Al doping results in high micro strain within the particle. By mapping the 3D displacement field with the Bragg coherent diffraction imaging, we report edges dislocation within LLZO nanoparticles in both the mixed and cubic structure, while the mixed-phase particles also present the development of smaller crystallites of different structural phase.