Solid State Synthesis, Characterization, and Nonlinear Optical Properties of a Monoclinic TricalciumSilicate, Ca3SiO5

摘要

Portland cement is widely used for the production of concrete that is a composite material in most construction industries such as buildings, roads, bridges, and runways in airports. A few main compounds found in cement clinker, a hard synthetic substance obtained by high-temperature calcination, are dicalcium silicate (Ca2SiO4, C2S), tricalcium silicate (Ca3Si95, C3S), tricalcium aluminate (Ca3Al6O_(12), C3A), tetracalcium aluminoferrite (Ca4Al8Fe8O_(28), C4AF), and some minor phases. Depending on the composition of cement constituents, important physical properties such as fineness, stability, solidification, heat of hydration, and compressibility strength may vary. Among several compounds that consist of cement, we were very interested in the tricalcium silicate (C3S). Cements containing high contents of C3S are very effective to an urgent construction work mainly attributable to the manifestation ability of fast strength. In fact, Ca3SiO5 has been known to have seven polymorphs, i.e., three triclinics, three monoclinics, and one rhombo-hedral. A monoclinic phase, "alite" is especially important, since the polymorph is the major component of Portland clinker. However, it is not easy to stabilize the high temperature monoclinic structure at room temperature. In order to stabilize the monoclinic phase at room temperature, foreign cations such as Mg~(2+) have been introduced to the structure.