Defects, Lattice Correspondence, and Optical Properties of Spinel-like Cr3O4 Condensates by Pulsed Laser Ablation in Water

Analytical electron microscopic observations indicated that the chromium oxide nanocondensates fabricated by pulsed laser ablation in water are predominantly dodecalledral Cr3O4 With-varied extent of tetragonal (t) distortion from the spinel (sp) type following the Bain relationship [21 (1) over bar](sp)//[01 (1) over bar](1); (011)(sp)//(100)(t). The t-Cr3O4 nanocondensates have {101} twinning due to tetragonal distortion and/or a coalescence event. The additional (3/2) x (200) and 2 x (211) commensurate superstructures can be attributed to the periodic presence of Cr2+, Cr3+, and/or H+ in the 4- and/or 6-coordinated lattice sites with an internal compressive stress up to similar to 5 GPa according to X-ray photoelectron and vibrational spectroscopic evidence. The presence of internal stress and Cr2+ ion caused red shift of the UV absorbance, thus shedding light on potential optoelectronic applications of the Cr3O4 nanocondensates.