Cobalt acetate co ch3coo 2 4h2o

Sodium telluride (Na₂TeO₃, Sigma Aldrich), cobalt acetate (Co(CH₃COO)₂·4H₂O, Sigma Aldrich), ascorbic acid (C₆H₈O₆), cetyltrimethylammonium bromide (CTAB, Sigma Aldrich) and deionized water from a Milli-Q-ultra pure water system (18.2 MΩ cm⁻¹) were used as the starting materials. In the hydrothermal method, 14.2 mmol of C₆H₈O₆ was dissolved in 40 ml of deionized water. Then, 0.82 mmol of CTAB was added gradually and stirred for 30 min. In the next step, 1.88 mmol of Na₂TeO₃ and 1.88 mmol of Co(CH₃COO)₂·4H₂O was dissolved in 30 ml of deionized water and slowly added to the above solution and a white TeO₂ precipitate was obtained immediately. Finally, the resultant solution was transferred into a 100 ml Teflon-lined stainless-steel autoclave that was sealed and maintained at 180 °C for 24 h in an oven, then allowed to cool to room temperature. The obtained black powder was collected and washed with deionized water and ethanol several times, and dried at room temperature. For comparison, pure Te was prepared in the absence of cobalt acetate by the same method.^{37 (link)}

NFO was prepared by the solid state method by mixing NiO (Alfa Aesar, Kandel, Germany, 99%) and Fe₂O₃ (Alfa Aesar, Kandel, Germany 99.9%) in stoichiometric proportions. The mixed powder was calcined for 2 h at 800 °C and 6 h at 1200 °C in air. CFO was prepared by the sol-gel method using cobalt acetate (Co(CH₃COO)₂.4H₂O, Sigma Aldrich, Darmstadt, Germany, reagent grade), iron nitrate (Fe(NO₃)₃.9H₂OSigma Aldrich, Darmstadt, Germany, 99.9%), and citric acid as starting reagents in a proportion of 1:2:3, respectively. These reagents were mixed in ethanol in a beaker and heated at 80 °C by continuous stirring until the solvent was completely evaporated. Then, the mixture was heated in an oven at 120 °C for 48 h. The dried material was ground in a mortar and calcined for 2 h at 700 °C. The calcined powders were ground again to destroy agglomerates. NFO and CFO ceramic targets were obtained from calcined powders at a sintering temperature of 1200 °C for 6 h and air conditions. The manufactured pellets had a diameter of 1.2 cm and an average thickness of 1.3 mm. For further analysis and laser ablation, the surface of the sintered pellets was manually ground and polished with SiC paper (Struers, Willich, Germany, 500 and 2400).