This is a conceptual framework for surface stoichiometrics similar to that of autocompensation. A variety of α-alumina surfaces, exhibiting a variety of surface structures, have been studied experimentally (Guo et al., 1992; Henrich, 1985). When information is available in all sources, the first two are displayed as a priority. The crucible leakages due to PbO attack pose a serious threat to crystal growth. The precursor was heated to 260 °C and the chamber was under a pressure of 16 Torr. The CLP Regulation makes sure that the hazards presented by chemicals are clearly communicated to workers and consumers in the European Union. ECHA maintains the C&L Inventory, but does not review or verify the accuracy of the information. The (0001) surface is more interesting since both the surface Al and O atoms are three-fold coordinated. A prioritisation hierarchy means that data is taken from harmonised C&L data and regulatory lists first, then REACH registrations and finally from CLP notifications. Rubber industry. It will be of interest to understand the nature of luminescence centres in sodium silicate glasses when another network modifier like PbO is also present in the glass. The excitation spectra corresponding to these samples are also shown in Figure 8.4 (right). Note that this list is not exhaustive. 1.3. Newly formed tet-PbO must be oriented to retain the disposition of the Pb2+ ions during the transition. Lustrous when freshly cut; tarnishes in moist air. For (PbO)x[(Na2O)0.25(SiO2)0.75]1−x glass having 10 mol% PbO, a broad emission peak around 400 nm is observed, on excitation at 290 nm (Fig. Lead dioxide can find applications as positive electrode in lead–acid cells as well as electrode material for electrochemical processes of practical significance (see sections entitled ‘Lead–Acid Batteries’, ‘Other Lead Batteries (Sulfuric Acid-Free)’, and ‘Other Electrochemical Applications of Lead and Lead Dioxide’). The ‘Substance identity’ section is calculated from substance identification information from all ECHA databases. Figure 1.4 clearly indicates that PbO absorbed oxygen in the temperature range from 430 to 520 °C to form Pb3O4 (or PbO1.1/3). Note that this list is not exhaustive. UV–visible absorption spectrum for (PbO)x[(Na2O)0.25(SiO2)0.75]1−x glasses with (a) x=0.1, (b) x=0.15, (c) x=0.2 and (d) x=0.25. Substances may have impurities and additives that lead to different classifications. Here you can find all of the regulations and regulatory lists in which this substance appears, according to the data available to ECHA. This is because the emission from the colour centres is expected to be significantly modified when Pb2+ along with Na+ ions are incorporated around the non-bridging oxygen atoms. [10]. Lead Oxides are mainly used as raw material in making lead glass for electronic elements, optical glass etc. 4.11. Heavy Metals in Packaging and Packaging Waste (Art. by diffusion of oxygen vacancies through the PbO layer. Workplace Signage: Annexes I and III, Directive 92/58/EEC, last amended by Directive 2014/27/EU, 5 March 2014, EU. 1.3). Of the corundum (α-Al2O3, Ti2O3, V2O3, α-Fe2O3) and ilmenite (LiNbO3, Li-TaO3) oxides that have had their surface properties examined, only the surfaces of α-alumina have been studied in any detail both experimentally and computationally. The use information is displayed per substance life cycle stage (consumer use, in articles, by professional workers (widespread uses), in formulation or re-packing, at industrial sites or in manufacturing). Richard P. Pohanish, in Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens (Seventh Edition), 2017. The bonds can be considered as approximately covalent. In the case of binary glasses, there is also a possibility for the existence of L-centres; however, the luminescences from these samples are mainly decided by the electronic transition of the Pb2+ ions. After systematic investigations, we have found that there are two main reasons leading to the crucible leakage. Use Pb3O4 instead of PbO as starting raw chemicals. The correlation between the ionic and electronic conductivity components of orthorhomb-PbO, oxygen pressure and dopant concentration (e.g. Annealing to higher temperatures results in the more complex 3×3R30° and 31×31R9° structures. In more concentrated solutions, amorphous or submicrocrystalline forms are obtained. This section is based on three sources for information (harmonised classification and labelling (CLH), REACH registrations and CLP notifications).