Transparent conductive oxide (TCO) glass is one of most important components in dyesensitized solar cell (DSSC) device. In addition to its high electrical conductivity, transparency is another important requirement that must be achieved in fabricating TCO. One TCO film is fluorine-doped tin oxide (FTO), which can be considered as the most promising substitution for indium-doped tin oxide (ITO), since the latter is very expensive. However, the fabrication techniques for TCO film need to be carefully selected; the synthesis parameters must be properly optimized to provide the desired properties. In this work, FTO glass has been fabricated by the ultrasonic spray pyrolisis technique with different precursors, i.e. tin (II) chloride dihydrate (SnCl 2 .2H 2 O) and anhydrous tin (IV) chloride (SnCl 4 ), as well as different solvents, i.e. ethanol and methanol. For both conditions, ammonium fluoride (NH 4 F) was used as the doping compound. The resulting thin films were characterized by use of a scanning electron microscope (SEM), x-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy and a four-point probe test. The results of the investigation show that the highest transmittance of 88.3% and the lowest electrical resistivity of 8.44×10 -5 Ω.cm were obtained with the FTO glass processed with 20 minutes of spray pyrolysis deposition and 300 o C substrate heating, using SnCl 4 as the precursor and methanol as the solvent. It can be concluded that TCO fabrication with tin chloride precursors and ammonium fluoride doping using ultrasonic spray pyrolisis can be considered as a simple and low cost method, as well as a breakthrough in manufacturing conductive and transparent glass.

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Experiments have been carried out to remove magnesium ions from brine water using limestone, Rembang, Indonesia. The aim of the study was to produce brine water concentrates that were rich in lithium and did not contain magnesium elements. Brine water used has the following chemical composition: 74.67 ppm Li; 877.891 ppm Na; 1549.81 ppm K; 147.23 ppm Mg; 38.49 ppm Ca and others. The initial stages were 200 g of natural lime calcined at 900 °C for 3 hours using a furnace as a precipitation agent. It is then added to 1000 ml of brine water with a variation of 0.336 g, 1 g, 10 g, 20 g, 30 g, 40 g, 50 g by stirring for 3 hours at atmospheric pressure. The results showed that the magnesium removal from brine water began to be seen in the addition of roasted limestone of 1 g with the dominant phase as Mg0.03Ca0.97CO3 in the precipitated residue. On the addition of 10 g and 20 g of roasted limestone into brine water, the percentage of magnesium removal was almost maximum of 98.8% and 99.8% with the precipitated residues as Mg(OH)2 phases. This experiment was successful to remove magnesium from brine water so that the lithium concentration of brine water increased to 104.32 ppm Li and 105.86 ppm Li with the addition of roasted limestone of 10 g and 20 g, respectively. These results indicate that the use of roasted limestone to eliminate magnesium from brine water with low lithium grade is recommended.

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