The basic scenario of resistive switching in TiO2 (Jameson et al., 2007) assumes the formation and electromigration of oxygen vacancies between the electrodes (Baiatu et al., 1990), so that the distribution of concomitant n-type conductivity (Janotti et al., 2010) across the volume can eventually be controlled by an external electric bias, as schematically shown in Figure 1B. Direct observations with transmission electron microscopy (TEM) revealed more complex electroforming processes in TiO2 thin films. In one of the studies, a continuous Pt filament between the electrodes was observed in a planar Pt/TiO2/Pt memristor (Jang et al., 2016). As illustrated in Figure 1C, the corresponding switching mechanism was suggested as the formation of a conductive nanofilament with a high concentration of ionized oxygen vacancies and correspondingly reduced Ti3+ ions. These ions induce detachment and migration of Pt atoms from the electrode via strong metal–support interactions (Tauster, 1987). Another TEM investigation of a conductive TiO2 nanofilament revealed it to be a Magnéli phase TinO2n−1 (Kwon et al., 2010). Supposedly, its formation results from an increase in the concentrations of oxygen vacancies within a local nanoregion above their thermodynamically stable limit. This scenario is schematically shown in Figure 1D. Other hypothesized point defect mechanisms involve a contribution of cation and anion interstitials, although their behavior has been studied more in tantalum oxide (Wedig et al., 2015; Kumar et al., 2016). The plausible origins and mechanisms of memristive switching have been comprehensively reviewed in topical publications devoted to metal oxide memristors (Yang et al., 2008; Waser et al., 2009; Ielmini, 2016) as well as TiO2 (Jeong et al., 2011; Szot et al., 2011; Acharyya et al., 2014). The resistive switching mechanisms in memristive materials are regularly revisited and updated in the themed review publications (Sun et al., 2019; Wang et al., 2020).

titanium dioxide gravimetric analysis. This is done by comparing the weight of the precipitate to the weight of the original sample. By knowing the molecular weight of titanium dioxide, the percentage of the compound in the sample can be determined.


Understanding Titanium Dioxide
Separately, concerns have been raised about titanium dioxide impacting one's genetic code. This can be traced to a 2009 study which found that titanium dioxide nanoparticles caused DNA damage and genetic instability in mice. A 2022 study published in Food and Chemical Toxicology also raised concerns about the DNA-damaging effects of titanium dioxide as a food additive. The study noted that results evidenced a DNA-damaging effect, and added that there may also be impacts to chromosomal integrity, an indicator of cancer risk.
In 2023, California and New York proposed banning several food additives that are banned in Europe but legal in the United States. Titanium dioxide was among the five proposed to be banned, but in September, the additive was removed from the list of additives from the California ban list.