The bandgap of a semiconductor material can be determined

All the chemical reagents used in the experiments were obtained from commercial sources as analytical grade reagents and used without further purification. In a typical experiment, 1 mmol of Tungsten hexachloride (WCl6) (0.3966 g) was dissolved in GSK503 glycol (50 ml) with ultrasonicated and vigorous stirring. Subsequently, 2 mmol of Bi(NO3)3⋅5H2O (0.9701 g) was added into the solution under ultrasonicated and vigorous stirring to form a transparent mixture solution. Then, 20 mmol of urea (1.2 g) was added and magnetically stirred until it was dissolved completely. The resulting precursor solution was finally transferred into a 100 ml Teflon-lined stainless steel autoclave. The autoclave was solvothermally treated at a ethylene certain temperature for certain time, then allowed to cool naturally to room temperature. The products were obtained by centrifugation and washed several times with distilled water and absolute alcohol, dried at 80 °C for 12 h subsequently. The solvothermal temperature and time were selected as the experimental variables for the preparation of the samples. Situation1: the solvothermal temperature was 90 °C, 120 °C, 150 °C, 180 °C for 30 h respectively. Situation 2: the solvothermal temperature was 150 °C for 5.5 h, 5.67 h, 5.83 h, and 6 h respectively.