Topic
Tridymite
About: Tridymite is a research topic. Over the lifetime, 840 publications have been published within this topic receiving 14831 citations.
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TL;DR: KAlSiO4-O1 is closely related to the stuffed derivatives of tridymite, although the topology of the Si/Al-ordered framework is different and the crystals are affected by inversion, pseudo-orthorhombic and pseudo-hexagonal twinning.
Abstract: Crystals of KAlSiO4-O1 (potassium aluminium silicate) were synthesized using a flux method and analysed utilizing single-crystal X-ray diffraction and electron microprobe analysis. Both methods confirm that the crystals are nonstoichiometric according to K1−xAl1−xSi1+xO4 with x = 0.04 (1). KAlSiO4-O1 is closely related to the stuffed derivatives of tridymite, although the topology of the Si/Al-ordered framework is different. Six-membered rings of UUDDUD and UUUDDD (U = up and D = down; ratio 2:1) configurations are present in layers parallel to the ab plane. In contrast, the framework of tridymite exhibits UDUDUD rings. The crystals are affected by inversion, pseudo-orthorhombic and pseudo-hexagonal twinning.
11 citations
TL;DR: The crystal structure of Zn 2 (BO 3 )(OH) 0.75 F 0.25 is determined ab initio from X-ray and neutron powder data in this article.
11 citations
TL;DR: In this article, the effects of ZrSiO4 to 30 Li 2 O 70 SiO 2 powdered glass were investigated by means of differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM).
11 citations
TL;DR: Upon cooling from its hexagonal high-temperature modification, AlPO4 (aluminium phosphate) tridymite successively transforms to several displacively distorted forms, including a normal structure-incommensurate-lock-in phase transition sequence.
Abstract: Upon cooling from its hexagonal high-temperature modification, AlPO4 (aluminium phosphate) tridymite successively transforms to several displacively distorted forms, including a normal structure–incommensurate–lock-in phase transition sequence. The space-group symmetries in this series are P1121, P1121(αβ0) and P212121, respectively. The distortion pattern of the intermediate P1121 phase can be described as alternate shifts of adjacent layers of tetrahedra coupled with tilting of the tetrahedra. The symmetry and direction of the shifts are different from the analogous SiO2 tridymite modification. The atomic displacement parameters of the O atoms are strongly anisotropic due to thermal motions of the rigid tetrahedra. Condensation of a lattice vibration mode results in the formation of an incommensurate structural modulation below 473 K. The 3+1 superspace-group symmetry of the modulated phase is P1121(αβ0).
11 citations
11 citations