Atomic layer deposition of nickel–cobalt spinel thin films

Abstract

We report the atomic layer deposition (ALD) of high-quality crystalline thin films of the spinel-oxide system (Co 1−x Ni x ) 3 O 4 . These spinel oxides are ferrimagnetic p-type semiconductors promising for several applications ranging from photovoltaics and spintronics to thermoelectrics. The spinel phase is obtained for Ni contents exceeding thex = 0.33 limit for bulk samples. It is observed that the electrical resistivity decreases continuously with x while the magnetic moment increases up to x = 0.5. This is in contrast to bulk samples where a decrease of resistivity is not observed for x > 0.33 due to the formation of a rock-salt phase. From UV-VIS-NIR absorption measurements, a change from distinct absorption edges for the parent oxide Co 3 O 4 to a continuous absorption band ranging deep into the near infrared for 0 < x ≤ 0.5 was observed. The conformal deposition of dense films on high-aspect-ratio patterns is demonstrated.

Nickel Supported on Mesoporous Zirconium Oxide by Atomic Layer Deposition: Initial Fixed-Bed Reactor Study

“…The precursor Ni-bis-2,2,6,6-tetramethyl-heptane-3,5-dionate (Ni(thd) 2 ) was synthesised from nickel(II) acetate tetrahydrate (J.T. Baker Chemical, > 98%) and 2,2,6,6,-Tetramethyl-3,5-heptanedione (Tokio Chemical Industrie Co., > 97%) according to literature methods [53,54] and purified by sublimation under vacuum before use. Mesoporous zirconium oxide (Saint-Gobain Norpro, monoclinic < 0.2 wt% SiO 2 ) was crushed and sieved to 250-450 µm particles, calcined in synthetic air (purity 5.0, Oy AGA Ab) at 600 °C for 10 h and stored in an desiccator.…”

“…This work reports an initial study to prepare nickel catalysts on a mesoporous zirconia support by ALD cycles. We used Ni(thd) 2 (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate), a traditional ALD reactant [50][51][52][53], as the nickel source; and air as the oxygen source. To our best knowledge, this work is the first to report the ALD modification of mesoporous zirconia with nickel.…”

Active IrO2 and NiO Thin Films Prepared by Atomic Layer Deposition for Oxygen Evolution Reaction

“…For the NiO samples, Tsub was varied from 110 to 120 °C, and Tdep was maintained the same at 200 °C. Hagen et al [14] reported that this deposition temperature is well above the vaporization temperatures and below the decomposition temperatures of the precursors. While for the IrO2 samples, Tsub was varied from 150 to 155 °C and Tdep was varied from 205 to 210 °C.…”

“…Generally, from the GIXRD patterns, the crystallinity Table 2 summarizes the different sublimation (T sub ) and deposition (T dep ) temperatures studied in this work. For the NiO samples, T sub was varied from 110 to 120 • C, and T dep was maintained the same at 200 • C. Hagen et al [14] reported that this deposition temperature is well above the vaporization temperatures and below the decomposition temperatures of the precursors. While for the IrO 2 samples, T sub was varied from 150 to 155 • C and T dep was varied from 205 to 210 • C. The sublimation and deposition temperatures were chosen as low as reasonably possible to study the low-temperature growth of the films required.…”

Structural and magnetic properties of frustrated GaxMn(3-x)O4(1.2 ≤ x ≤ 1.6) spinels

“…levels. They are promising in a wide range of applications such as multiferroic devices 1 , spintronics 2 , cathode materials with high energy densities 3 , microwaves 4 , sensors for ac and dc magnetic fields 5 , magnetic hyperthermia 6 , and magnetic refrigeration 7 . The diversity of their magnetic properties is associated with the complexity of their magnetic structure which leads to peculiar effects, such as magnetic frustration or multiferroicity.…”