The structure of crystals and melts were obtained at high temperature using X-ray absorption at the Ca K-edge on CaMgSi2O6 (diopside), CaAl2Si2O8 (anorthite), Ca3Al2O6 (C3A) and CaAl2O4 (CA) compositions. Important changes are observed above the liquidus temperature particularly for the C3A composition where all oscillations in the XANES spectra disappear. Important changes in the Ca K-edge XAN...

CaAl2O4:Eu is a persistent luminescence (PL) material in the blue light region with potentially wide commercial applications. With the doping of Nd, the decay time can be elongated to more than 19 h. These excellent properties are believed to be in close relation with the electronic structures of the dopants, the defects, and the host material. In this work, we attempt to achieve a better under...

CaAl2O4:(Eu, Nd)/TiO2-xNy composite luminescent photocatalyst was successfully synthesized by a simple planetary ball milling process. Improvement of photocatalytic deNOx ability of TiO2-xNy, together with the persistent photocatalytic activity for the decomposition of NO after turning off the light were realized, by coupling TiO2-xNy with long afterglow phosphor, CaAl2O4:(Eu, Nd). The novel pe...

Starting from high energetic attrition milled mixtures of either -Al2O3 or amorphous (Al(OH)3) with CaCO3 the binary compound calcium monoaluminate (CaAl2O4) was synthesized with high purity. The processes were carried out on samples with the nominal CaAl2O4 stoichiometry. High energetic attrition milling of the reactants does not eliminate the starting carbonate, both batches showed a high deg...

We present O MAS NMR data for crystalline calcium dialuminate (grossite), CaAl4O7 and monoaluminate, CaAl2O4. The first of these contains an oxygen tricluster site and serves as a model compound for sites of this type in aluminosilicate glasses. Tricluster site NMR parameters are distinct from those of bridging O atoms (Al-O-Al), allowing partial resolution in triple quantum MAS NMR spectra. Su...

The isoplethal sections CaAl2O4–MgO and CaAl4O7–MgO of the Al2O3–MgO–CaO ternary system have been experimentally established at 1 bar total pressure and air of normal humidity. The sections obtained provide new data and information that are in disagreement with thermodynamic evaluations and optimizations of the Al2O3–MgO–CaO ternary system published to date. These differences arise mainly from ...

the major hydraulic phase in all the calcium aluminate cements including ciment fondue is ca (caal2o4). once hydrated, it starts to form the hexagonal crystals of cah10 and c2ah8 that depending on the time and temperature of hydration convert to the cubic crystals of c3ah6 and ah3. the nature, sequence, crystallinity and microstructure of hydrated phases of commercial refractory calcium alumina...

Using a novel experimental procedure in the field of ceramics/materials science that is based on the precise microanalysis (scanning electron microscopy, coupled with wavelength-dispersive spectroscopy) of the phases that are present in equilibrated specimens, the solid-state compatibility relations in the subsystem MgAl2O4–CaAl4O7–CaO– MgO and the melting relationships in the subsystems MgAl2O...

We report methodological advances that enhance the phosphorescence efficiency of a blue-emitting calcium aluminate phosphor (CaAl2O4: Eu2+, Nd3+). The investigation of long-persistence blue-emitting phosphors is highly desirable due to their promising applications, such as white LEDs; however, the development of highly efficient blue-emitting phosphors is still challenging. Here, we have quanti...

Using the evolutionary crystal structure prediction algorithm USPEX, we showed that at pressures of Earth’s lower mantle (24-136 GPa) CaAl2O4 is only stable calcium aluminate. At above 7.0 GPa it has CaFe2O4-type with space group Pnma. This phase one prime candidate aluminous phases in Earth. We show low 5CaO • 3Al2O3 (C5A3) Cmc21, CaAl4O7 (with C2/c) and (space P21/m) are up to 2.1, 1.8 GPa, r...