Surface morphology and composition of nanocrystalline MoO2 produced via the thermal decomposition of the MoO2(i-C3H7NHO)2 complex

Gamma Radiation-Induced Oxidation, Doping, and Etching of Two-Dimensional MoS2 Crystals

“…Gamma Irradiation. Gamma irradiations were performed using a self-contained Foss Therapy Service Inc. 812 60 Co source located at the Dalton Cumbrian Facility, University of Manchester. The dose rates administered to the samples varied between 265 and 365 Gy/min, determined using the ionization chamber detector.…”

“…27 Only a few studies have evaluated the effect of gamma irradiation on the physical properties of 2D group VI TMDCs. Using a 60 Co source, Felix et al irradiated 1 L WS 2 crystals with an absorbed dose of 400 Gy and observed ferromagnetic hysteresis, which they attributed to a defect configuration involving one W and two S vacancies. 28 Vogl et al exposed various 1 L group VI TMDC crystals, produced by micromechanical exfoliation (MME), 29 to gamma radiation using a 22 Na source.…”

“…To the best of our knowledge, just a handful of studies have addressed the effects of the high-dose gamma irradiation of 2D MoS 2 . For example, Ozden et al utilized a 60 Co source to irradiate few-layer 2D MoS 2 films, produced by chemical vapor deposition (CVD), 37 with an absorbed dose of 1200 kGy under ambient conditions. 38 They observed the disappearance of the out-of-plane A 1g and in-plane E 2g 1 normal vibrational modes and the formation of MoO x species after irradiation, suggesting a significant increase in the chemical and structural disorder.…”

“…38 They observed the disappearance of the out-of-plane A 1g and in-plane E 2g 1 normal vibrational modes and the formation of MoO x species after irradiation, suggesting a significant increase in the chemical and structural disorder. Similarly, He et al also utilized a 60 Co source to irradiate MoS 2 , synthesized via a hydrothermal method, with absorbed doses between 1 kGy and 1000 kGy. 39 Conversely, they observed (1) no MoO x formation, (2) an improvement in crystallinity, and (3) red-shifted A 1g and E 2g 1 modes with significant intensities after irradiation.…”

“…It is evident that a comprehensive, noncontradictory understanding of the effects of the high-dose gamma irradiation on the morphology, vibrational properties, and chemical composition of 2D MoS 2 is still missing. To address these open questions, we utilized a 60 Co source to irradiate 2D and bulk MoS 2 crystals with absorbed doses between 40 and 1000 kGy. Our results show that both S atoms and Mo IV centers at the surface of the MoS 2 crystals are oxidized upon gamma irradiation under ambient conditions to yield Mo VI S y O x and sulfate species via a series of intermediates.…”