In most cases where a dilute acid w

In most cases where a dilute acid wash was not performed, the samples were washed with ethanol or deionized water. Only a few report structural investigations (e.g., X-ray diffraction) both before and after washing. (29)While almost all reports identify the room-temperature structure of BaTiO3 nanocrystals as cubic (Pm3̅m) or tetragonal (P4mm), no clear trend relating synthesis method or nanoparticle size with the observed space group has emerged from the literature. Even within the category of hydrothermal or solvothermal synthesis routes, both small (∼10 nm) and large (>40 nm) nanoparticles have been identified as cubic (18,22) or tetragonal. (10,21) Additionally, different experimental probes sometimes result in the assignment of different space groups for the same sample. In two similar cases, the authors noted a cubic structure via X-ray diffraction but local tetragonal distortions via Raman spectroscopy. (16,17) The presence or absence of BaCO3 in these studies adds to the confusion.To our knowledge, no studies have systematically investigated the effect of the washing step on the atomic-scale structure, nanoparticle morphology, or size distribution and verified or evaluated suggestions that some of the observed discrepancies in the literature may be attributed to the presence of such impurities. (10) For this work, six samples of BaTiO3 nanocubes were synthesized via a solvothermal route with sizes varying from 8 to 50 nm; half of each batch was washed with dilute acetic acid, and the other remained in the as-synthesized state. A schematic of the as-synthesized cuboidal nanocrystals is shown in Figure 1, with key components highlighted.