Photoluminescent property of mechanically milled BaWO4 powder

Photoluminescent behavior of BaWO4 powders processed in microwave-hydrothermal

“…However, this result is very different of the value related by Lima et al [8], which suggested the presence of localized energy levels into the band gap of BaWO 4 powders structurally disordered. E gap value for the crystalline BaWO 4 powders was of 5.76 eV [8]. According to the Montoncello et al [44], PL can be a fundamental tool to determine the class of energy levels that are invisible at optical absorption measurements.…”

“…E gap value for the BaWO 4 powders processed at 140 • C for 120 min in MH is very close to the reported by Afanasiev [10] and Eng et al [43]. However, this result is very different of the value related by Lima et al [8], which suggested the presence of localized energy levels into the band gap of BaWO 4 powders structurally disordered. E gap value for the crystalline BaWO 4 powders was of 5.76 eV [8].…”

“…In the last years, the literature has reported the formation of barium tungstate (BaWO 4 ) by different techniques, such as: solid-state reaction [1,2], Czochralski [3][4][5], high temperature flux crystallization [6], hydrothermal-electrochemical [7], polymeric precursor [8,9] and molten salt [10]. However, these methods generally need of high reaction temperatures, long reaction time and sophisticated equipments.…”

“…Korzhik et al [21] concluded that the green emission arises from the (WO 3 + F) center. Lima et al [8] explained that the structural disorder in the lattice is an important condition to obtain an intense and broad photoluminescence emission. We believe that all hypotheses and theories reported in the literature are correct.…”

Piezoelectric properties of 0.5(PbNi1/3Nb2/3)O3–0.5Pb(Zr0.32Ti0.68)O3 ceramics prepared by solid state reaction and mechanochemical activation-assisted method

“…This high pressure is enough to break down the particles of the powders and further refine the grains even though the overall temperature of the high-energy ball milling system does not exceed 70 • C [19][20][21], the temperature of the localized point of collision may be much higher than 70 • C, which is sufficient to initiate the phase formation. The high energy ball milling also induces structural defects and disorder [22]. All these factors favor diffusion and atomic rearrangement of the milled powder at very low temperature [19,21], which therefore reduces the sintering temperature significantly.…”