Structural Change in Phosphorus-Bearing Dicalcium Silicates

Abstract

Structures of (Ca22)(Si1P)4 crystals were examined as a function of x ranging from 0.03 to 0.40. All of the samples were heated at the stable temperature region of the -phase and then quenched in water. The phase constitution at ambient temperature was classified into three categories according to the fraction of the -to-H transition. When the transition was completed as in the crystals with x0.100, the and L phases were obtained, the relative amounts of which were determined by the start and finish temperatures of the L-to-martensitic transformation. With 0.125x0.150, the -totransition was incomplete. Dur ing further cooling, the product -phase was inverted to the L-phase, and the residual -phase was invert ed to the incommensurate phase successively. Because the start temperature of the L-to-transformation was lower than ambient temperature, the L-phase was stabilized. With x0.175, all of the crystals were free from the -totransition. The crystals with 0.175x0.225 were made up exclusively of the incom mensurate phase. A good correlation existed between the modulation wavelength (=N) and the P/(Si+P) ratio (=x) as N=4.134-1.56x(0.175x0.250). With 0.275x0.300, the crystals were isostructural with -Ca2Si4. The hexagonal phase with 0.350x0.400, probably a transition product from the -phase, showed two-dimensional modulations along the -axis with N=2 and along the c-axis with N=3.

The Effect of Heat Treatment on the Emission Color of P-Doped Ca2SiO4 Phosphor

“…Here, the box in the chemical formula represents vacancies according to a previous paper [6]. The P-doped C 2 S:Eu 2+ phosphor with x = 0.06 exhibited the highest PL intensity among those with 0 ≤ x ≤ 0.20 [12].…”

“…A series of structural studies of P-doped C 2 S crystals has demonstrated that the incorporation of P most effectively stabilized the high-temperature phases of C 2 S [6]. Hence, the authors present the idea of utilizing the P-doped C 2 S as the host material of Eu 2+ -activated phosphors.…”

Structural and Crystal Chemical Investigation of Intermediate Phases in the System Ca2SiO4–Ca3(PO4)2–CaNaPO4

“…Electron microprobe analyses suggest additional substitution of Ca by Na, Ca 15− x Na x (PO 4 ) 2+ x (SiO 4 ) 6− x , with x = 0.1, while retaining one vacancy. The M‐site vacancies and the P/Si distribution have been discussed to be the reason for an incommensurate superstructure . In none of the published phase diagrams of the system Ca 2 SiO 4 –Ca 3 (PO 4 ) 2 has this phase been considered.…”

“…The M-site vacancies and the P/Si distribution have been discussed to be the reason for an incommensurate superstructure. 17 In none of the published phase diagrams of the system Ca 2 SiO 4 -Ca 3 (PO 4 ) 2 has this phase been considered. The structure of the twin domains of Ca 15 (PO 4 ) 2 (SiO 4 ) 6 can be interpreted as a superlattice (4 9 a, b, c) of the a 0 Hform of the Ca 2 SiO 4 polymorphic series.…”

Phenomenological analysis of α′L-to-β martensitic transformation in phosphorus-bearing dicalcium silicate

“…7,8 The shape change associated with the martensitic transformations creates stresses in both the parent and the product phases. 2,12 In order to increase our understanding of the martensitic behavior and thermoelasticity of the a 0 L -to-b transformation in C 2 S(ss), the phenomenological crystallographic theory has been applied to this transformation in the present study. 9 Such a group formation, called self-accommodation, leads to an effective reduction in the elastic stresses.…”