Site occupancy of Ce3+ in β-Ca2SiO4: A combined experimental and ab initio study

Understanding of the Elastic Constants, Energetics, and Bonding in Dicalcium Silicate Using First-Principles Calculations

“…The experimental band gap in a series of Dy 3+ -activated Ca 2 SiO 4 phosphors was found to be in the range of 5.10–5.44 eV . From the absorption spectrum of the β-Ca 1.999 Ce 0.0005 Na 0.0005 SiO 4 host material, the band gap energy was estimated to be approximately 7.7 eV . The experimental band gap of γ-Ca 2 SiO 4 is about 5.3 eV …”

First-Principles Calculations on Polymorphs of Dicalcium Silicate—Belite, a Main Component of Portland Cement

“…Atomistic simulations using first-principles methods have already proven to be of great help in studying complex phases in cement materials. ,− Up to date theoretical studies on C2S usually focused on the β phase, either pure ,,− or doped, ,,,, or employed semiempirical interatomic potentials (IP) to study the dynamics of several C2S phases . The electronic properties of the γ, β, and α L ′ phases with their possible relation to reactivity with water were presented quite recently .…”

“…Dicalcium orthosilicate, Ca 2 SiO 4 (C2S), known also as belite, is one of the most widely manufactured materials in the world, as it constitutes about 20% of the mass of ordinary Portland cement clinker. , There is a growing interest in cements with a large belite content because materials can be produced with low energy consumption and low CO 2 footprint . Apart from its practical use for construction, C2S is a natural mineral, which is currently attracting a large number of applications, such as a bioceramic component, − a CO 2 storage material, and a matrix for optically active f and d electron dopants. − The characteristic of C2S is that in the temperature range of 500–1500 °C, it is found crystallized in five polymorphs shown in Figure , an unusually high number for a compound of the orthosilicate family A 2 BX 4 . ,, Although belite polymorphs are brought as metastable to room temperature by impurities, they are also present for the pure orthosilicate as shown using X-ray diffraction (XRD) at high temperatures. ,, Experimentally, the structures follow the sequence of phase transitions γ → α L ′ → α H ′ → α when increasing the temperature. On cooling, the order changes at low temperatures because a metastable phase known as β is inserted between the α L ′ and γ structures, especially for doped samples.…”

Phase Identification of γ- and β-Ca2SiO4 via the Rear-Earth Fluorescence Probe

“…6 γand β-Ca 2 SiO 4 usually coexist after high-temperature sintering process, 7 and recent research studies indicate that the introduction of doping ions (such as Eu 3+ , Ce 3+ , and Fe 3+ ions) in the Ca 2 SiO 4 lattice are conducive to increasing the phase content of β-Ca 2 SiO 4 in the final product on account of the existing structural distortion and possible vacancies. 6,8−10 γand β-Ca 2 SiO 4 belong to the space groups of the orthorhombic Pnma (62) and monoclinic P21/n (14), respectively. 11,12 The structural difference between the two Ca 2 SiO 4 polymorphs significantly influences their corresponding physicochemical properties.…”

“…γ- and β-Ca 2 SiO 4 usually coexist after high-temperature sintering process, and recent research studies indicate that the introduction of doping ions (such as Eu 3+ , Ce 3+ , and Fe 3+ ions) in the Ca 2 SiO 4 lattice are conducive to increasing the phase content of β-Ca 2 SiO 4 in the final product on account of the existing structural distortion and possible vacancies. ,− γ- and β-Ca 2 SiO 4 belong to the space groups of the orthorhombic Pnma (62) and monoclinic P 21/ n (14), respectively. , The structural difference between the two Ca 2 SiO 4 polymorphs significantly influences their corresponding physicochemical properties. For example, Ce 3+ ions present yellow and blue fluorescence properties in the γ- and β-Ca 2 SiO 4 hosts, respectively. − Additionally, in terms of hydration, β phase shows good hydration reactivity, while γ phase scarcely reacts with water at room temperature. − Hence, the precise identification and content determination of the γ and β phases is very important for the respective relevant application fields.…”