Growth of CaxCoO2 Thin Films by A Two-Stage Phase Transformation from CaO–CoO Thin Films Deposited by Rf-Magnetron Reactive Cosputtering

Abstract

The layered cobaltates AxCoO2 (A: alkali metals and alkaline earth metals) are of interest in the area of energy harvesting and electronic applications, due to their good electronic and thermoelectric properties. However, their future widespread applicability depends on the simplicity and cost of the growth technique. Here, we have investigated the sputtering/annealing technique for the growth of CaxCoO2 (x = 0.33) thin films. In this approach, CaO–CoO film is first deposited by rf-magnetron reactive cosputtering from metallic targets of Ca and Co. Second, the as-deposited film is reactively annealed under O2 gas flow to form the final phase of CaxCoO2. The advantage of the present technique is that, unlike conventional sputtering from oxide targets, the sputtering is done from the metallic targets of Ca and Co; thus, the deposition rate is high. Furthermore, the composition of the film is controllable by controlling the power at the targets.

Lamellar Metal Oxide Based Nanoagent Realizing Intensive Interlamellar Ca2+ Release and Hypoxia Relief for Enhanced Synergistic Therapy

“…Considering Ca x CoO 2 exhibits strong absorption in the near-infrared region, which could be developed as photothermal nanoagents, accomplishing thermal-enhanced Ca 2+ release. 38 In addition, the Co metal Scheme 1. Schematic Demonstration of (a) the Synthesis of CCO@ss-SiO 2 -Ce6 and (b) Synergistic Enhanced PDT/PTT/ Heat-Facilitated Intracellular Ca 2+ Release Tumor Therapy Herein, we highlighted the therapeutic nanoagent Ca 0.35 CoO 2 @ss-SiO 2 -Ce6 (denoted as CCO@ss-SiO 2 -Ce6) with intensive interlamellar Ca 2+ release as well as hypoxia relief for enhanced synergistic therapy (Scheme 1a).…”

“…As is known, the layered cobaltates compound M x CoO 2 (M = alkali metals or alkaline earth metals), a catalogue of traditional layer transition metal oxide, contains alternate stacks of M x sheets and CoO 2 sheets. − Previous research has revealed that the unique layered structure can provide active vacancies and allow M ions to escape from interlamination, − which endows the Ca x CoO 2 to be a candidate as a Ca 2+ nanocarrier. Considering Ca x CoO 2 exhibits strong absorption in the near-infrared region, which could be developed as photothermal nanoagents, accomplishing thermal-enhanced Ca 2+ release . In addition, the Co metal with d electrons in Ca x CoO 2 would deliver catalase-mimic activity to produce oxygen to relieve the hypoxic tumor microenvironment. − Therefore, Ca x CoO 2 has demonstrated a great advance in realizing interlamellar Ca 2+ release for the enhanced synergistic therapy, providing a new way for exploring novel nanomaterials in tumor therapy.…”

Rapid growth of fully-inorganic flexible CaxCoO2 thin films from a ligand free aqueous precursor ink for thermoelectric applications

“…[6][7][8][9][10][11] The thin films of this class of materials can be promising for flexible applications if film deposition is possible on flexible substrates or otherwise transferable onto flexible platforms. Although, Ca x CoO 2 thin films have been grown by physical deposition techniques, 12,13 for scalability, chemical solution deposition (CSD) methods are often preferred over the physical methods. In particular, the CSD technique is cost-effective and facile.…”