Bar plot comparing the fractional abundance of SiC₂, SiS, and SiO relative to H₂ in different environments. For G + 0.693, the abundances are obtained from this work. For L1157-B1, the SiO and SiS abundances are taken from Podio et al. (2017), while the upper limit on the SiC₂ abundance is derived in this work using the ASAI survey (Lefloch et al. 2018). The abundances of the carbon-rich AGB stars and oxygen-rich AGB stars are from Massalkhi et al. (2018, 2019) and Massalkhi et al. (2020), respectively. For the AGB stars, the height of the bar corresponds to the average fractional abundance derived in the studied samples, while the error bar refers to the wide range of values found. Downward-pointing arrows represent upper limits to the abundance.