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TL/OSL Properties of Calcium Oxide Nanophosphor
Published in Odireleng Martin Ntwaeaborwa, Luminescent Nanomaterials, 2022
K.R. Nagabhushana, Sonia Hatsue Tatumi, D. Prakash
Inorganic oxides are binary compounds of oxygen with an element and classified into acidic or basic oxide based on their characteristics. Inorganic oxides can be prepared by direct heating of element with oxygen, the reaction of oxygen with compounds at high temperatures, oxidation of metals and non-metals with nitric acid [7]. Inorganic materials are ionic compounds, consisting of cation and anion linked by ionic bonding and they are electrically neutral. The ions are defined by their oxidation state, and their ease of creation can be inferred from the ionization potential (cations) and/or from the electron affinity (anions) of the parent elements. The inorganic oxides are characterized by high melting point. Inorganic salts are typically poor electric and thermal conductors in the solid state.
Investigation on Ash Fusion and Slagging Properties of Coal under Reducing Atmosphere
Published in Combustion Science and Technology, 2023
Yanqing Niu, Yu Lei, Yuan Lv, Guangyao Wang, Siqi Liu, Shi’En Hui
Consequently, multi-component phase diagrams constructed through experiments have been widely used as a simple and high-precision method to forecast the AFTs, especially for a specified fuel (Bostrom et al. 2012; Folgueras et al. 2005; Ninomiya and Sato 1997; Niu, Tan, Hui 2016b; Niu et al. 2016a, 2015; Van Dyk 2006). Yet, most multi-component phase diagrams were constructed on the basis of only 3–5 simulated ash compositions, such as SiO2-Al2O3-CaO (Folgueras et al. 2005; Ninomiya and Sato 1997), SiO2-Fe2O3-CaO (Folgueras et al. 2005), SiO2-Al2O3-K2O (Niu et al. 2016a, 2015), SiO2-Al2O3-FeO-CaO (Kondratiev and Jak 2001; Kong et al. 2014), and K2O(+Na2O)-CaO(+MgO)-SiO2 (Bostrom et al. 2012). These, inevitably, cause deviations from the true coal ash, which is mainly composed of SiO2, Al2O3, CaO, MgO, Na2O, K2O, Fe2O3, and few TiO2. Based on the network theory, Si4+ and Ti4+ (acting as network former) build the ash network and increase the slag viscosity, AAEMs (alkali and alkali earth metals, including Na+, K+, Ca2+ and Mg2+) and Fe2+ (acting as network modifier) disrupt the network and thus decrease the slag viscosity, whereas Al3+ and Fe3+ show amphoteric and act as either network formers or modifiers (Chen et al. 2017; Duchesne et al. 2012; Hsieh, Kwong, Bennett 2016; Neuville 2006; Vargas, Frandsen, Dam-Johansen 2001). The base/acid ratio (B/A = (CaO+MgO+Na2O+K2O+Fe2O3)/(SiO2+ Al2O3+ TiO2)) has been used to evaluate or predict the ash fusion and slagging tendency (Wang et al. 2008). The network formers of silica oxide (SiO2), alumina oxide (Al2O3) and titanium oxide (TiO2) are acid oxides and promote the elevation of AFTs. While the network modifiers of calcium oxide (CaO), magnesium oxide (MgO), sodium oxide (Na2O) and potassium oxide (K2O) as well as iron oxide (Fe2O3) are basic oxides (Niu et al. 2011; Wang et al. 2008), which facilitate the decrease of AFTs and the formation of molten ash. Besides, the SiO2/Al2O3 mass ratio and AFTs, especially FT, present high linear correlations with the critical viscosity temperature (Hsieh, Kwong, Bennett 2016; Song et al. 2010).