Crystalography and the behavior of optical band gap in transition metal-doped (Al+Mn) ZnO nanopowder

ZnO and Zn(0.97-x)Al0.03MnxO (x=0.00 (AlMnZ0), 0.04 (AlMnZ4), 0.05 (AlMnZ5) and 0.06 (AlMnZ6)) nanopowders that have been synthesized in powder form by using coprecipitation method at powder-based low temperature are zinc chloride (Sigma Aldrich), manganese (II) chloride tetrahydrate (Sigma Aldrich), and aluminum chloride hexahydrate (Sigma Aldrich). The powder of zinc chloride, aluminum chloride hexahydrate and manganese (II) chloride are dissolved in 0.5 M HCl, then a precipitating agent is added in the form of NaOH 5 M base into the solution by slowly dropping NaOH 5 M solution into the precursor until a pH of 10 is reached which causes the clear and transparent solution turns into milky white. In order for the reaction to run perfectly, the stirring process is carried out in a hot plate stirrer for 90 minutes at a temperature of 85 oC. After the solution is formed, it is washed with distilled water repeatedly until there is no impurities and it is filtered with filter paper to separate the precipitate from the solution. X-ray Diffraction (XRD) and Ultra Violet Visible (UV-VIS) Spectroscopy have been used to characterize ZnO nanopowder products through (Al+Mn) doping. The results show that AlMnZ0, AlMnZ4, AlMnz5 and AlMnZ6 nanopowder has the form of a hexagonal wurtzite crystal phase with a crystal size of ~38.03881–47.57561 nm. The optical band gap of ZnO nanopowder can be increased by atomic doping (Al+Mn). The increase in the optical band gap of AlMnZ0, AlMnZ4, AlMnZ5 and AlMnZ6 nanopowder is related to the Burstein-Moss effect, that is when (Al+Mn) atoms are successfully incorporated into ZnO nanopowders, there is a vacancy of the oxygen atom in the host crystal