Atmospheric pressure plasma enhanced chemical vapor deposition (AP-PECVD) using Surfx Atomflow(TM) 250D APPJ was utilized to synthesize amorphous silicon carbonitride coatings using tetramethyldisilizane (TMDZ) and hexamethyldisilizane (HMDZ) as the single source precursors. The effect of precursor chemistry and substrate temperature (T(s)) on the properties of a-SiCN:H films were evaluated, while nitrogen was used as the reactive gas. Surface morphology of the films was evaluated using atomic force microscopy (AFM); chemical properties were determined using Fourier transform infrared spectroscopy (FTIR); thickness and optical properties were determined using spectroscopic ellipsometry and mechanical properties were determined using nanoindentation. In general, films deposited at substrate temperature (T(s)) < 200 °C contained organic moieties, while the films deposited at T(s) > 200 °C depicted strong Si-N and Si-CN absorption. Refractive indices (n) of the thin films showed values between 1.5 and 2.0, depending on the deposition parameters. Mechanical properties of the films determined using nanoindentation revealed that these films have hardness between 0.5 GPa and 15 GPa, depending on the T(s) value. AFM evaluation of the films showed high roughness (R(a)) values of 2-3 nm for the films grown at low T(s) (<250 °C) while the films grown at T(s) ≥ 300 °C exhibited atomically smooth surface with R(a) of ~0.5 nm. Based on the gas-phase (plasma) chemistry, precursor chemistry and the other experimental observations, a possible growth model that prevails in the AP-PECVD of a-SiCN:H thin films is proposed.

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An unanticipated superparamagnetic response has been observed in cobalt ferrite materials after thermal treatment under inert atmosphere. Cobalt ferrite particles were prepared via normal micelle precipitation that typically yields Co x Fe 3−x O 4 nanoparticles ͑x = 0.6− 1.0͒. While samples thermally treated under oxygen show majority spinel phase formation, annealing in nitrogen gas yields materials consisting of Co-Fe alloy, FeS, and CoFe 2 O 4 spinel. After thermal treatment, thermomagnetic studies reveal composition-insensitive, but highly treatment-sensitive, saturation magnetization, coercivity, blocking temperature, and Verwey transition temperature dependence. Extremely high saturation magnetization ͑159 emu/g͒ with low coercivity ͑31 Oe͒ was observed for one of the treated compositions, which drastically deviates from prototypical cobalt ferrite with large magnetocrystalline anisotropy. We attribute such unique magnetic response to Co-Fe alloy coexisting with FeS and CoFe 2 O 4 spinel where the diameter of the metallic phase is below the superparamagnetic limit. While thermal treatment in nitrogen was not anticipated to yield Co-Fe alloy, chemisorbed surfactant molecules ͑i.e., sodium dodecylsulfate͒ are postulated to act as reducing agents in the present scenario.

Amorphous hydrogenated silicon carbonitride (a‐SiCN:H) thin films are synthesized by atmospheric pressure plasma enhanced chemical vapor (AP‐PECVD) deposition using the Surfx Atomflow™ 250D APPJ source with triethylsilane (HSiEt3, TES) and nitrogen as the precursor and the reactive gases, respectively. The effect of the substrate temperature (Ts) on the growth characteristics and the properties of a‐SiCN:H films was evaluated. The properties of the films were investigated via scanning electron microscopy (SEM), atomic force microscopy (AFM) for surface morphological analyses, Fourier transform infrared spectroscopy (FTIR), and X‐ray photoelectron spectroscopy (XPS) for chemical and compositional analyses; spectroscopic ellipsometry for optical properties and thickness determination and nanoindentation to determine the mechanical properties of the a‐SiCN:H films. Films deposited at low Ts depict organic like features, while the films deposited at high Ts depict ceramic like features. FTIR and XPS studies reveal that an increases in Ts helps in the elimination of organic moieties and incorporation of nitrogen in the film. Films deposited at Ts of 425 °C have an index of refraction (n) of 1.84 and hardness (H) of 14. 8 GPa. A decrease in the deposition rate between Ts of 25 and 250 °C and increase in deposition rate between Ts of 250 and 425 °C indicate that the growth of a‐SiCN:H films at lower Ts are surface reaction controlled, while at high temperatures film growth is mass‐transport controlled. Based on the experimental results, a potential route for film growth is proposed.

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