scispace - formally typeset
Search or ask a question
Topic

Tridymite

About: Tridymite is a research topic. Over the lifetime, 840 publications have been published within this topic receiving 14831 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: In this article, the synthesis and thermomechanical characterization of polyethylene glycol-silica cristobalite composites have been successfully performed using a coprecipitation method using silica sand from Tanah Laut, South Kalimantan.
Abstract: Synthesis and thermomechanical characterization of polyethylene glycol-silica cristobalite composites have been successfully performed. Commercial Polyethylene glycol (PEG) 4000 and natural-silica-sand-derived cristobalite (SiO2) powders were used in this research. The cristobalite ceramic powder was produced by a coprecipitation method using silica sand from Tanah Laut, South Kalimantan as the raw material. XRD data analysis for the cristobalite powder showed that it contained 98.8 wt% cristobalite and 1.2 wt% tridymite - both are polymorphs of silica. The PEG-cristobalite composition was varied in the composites at PEG weight fraction of 100, 80, 60 and 40 %. PEG and cristobalite dry powders were simply mixed and then uniaxially pressed before a heat treatment at 50 °C to form dense composite prior to characterization. Further FTIR and XRD data analyses for the densed samples showed the success of the formation of the composite. The thermomechanical properties was characterised using Dynamic mechanical analysis (DMA) instrument with shear mode. In general, at all measurement temperatures, the storage modulus (G’) of the composites was significantly improved with the addition of cristobalite, e.g. its values for 60 % cristobalite sample was 13 times that of the pure PEG sample. The pure samples showed a rubbery plateau behaviour which was not found in the composite samples. It was also found that by increasing the amount of cristobalite, the glassy transition temperature (T g) increase from 56 °C for the pure and 68 °C for the 60 % cristobalite samples respectively.

10 citations

Journal ArticleDOI
TL;DR: In this article, phase equilibria of the ternary CaO-ZnO-SiO2 system have been investigated at 1170°C to 1691°C for oxide liquid in equilibrium with air and solid oxide phases.
Abstract: Phase equilibria of the ternary CaO-ZnO-SiO2 system have been investigated at 1170 °C to 1691 °C for oxide liquid in equilibrium with air and solid oxide phases: tridymite or cristobalite SiO2 (up to two immiscible liquids), pseudowollastonite (CS) CaSiO3, rankinite (C3S2) Ca3Si2O7, dicalcium silicate (C2S) (Ca, Zn)2SiO4, tricalcium silicate (C3S) (Ca, Zn)3SiO5, lime (Ca, Zn)O, zincite (Zn, Ca)O, willemite Zn2SiO4 and hardystonite (melilite) Ca2ZnSi2O7, covering the ranges of concentrations not studied before. High-temperature equilibration on primary phase (silica) or inert metal (platinum) substrates followed by quenching and direct measurement of the Ca, Zn and Si concentrations in the phases with the electron probe X-ray microanalysis (EPMA) has been used to accurately characterize the system. Liquidus phase equilibrium data of the present authors for the CaO-ZnO-SiO2 system are essential to obtain a self-consistent set of parameters of thermodynamic models for all phases.

10 citations

Journal ArticleDOI
TL;DR: In this article, a Gamma-ray irradiation was employed to modify high density polyethyelene (HDPE) in order to impart poor interfacial interaction between hydrophobic matrix and hydrophilic Sericite-Tridymite-Cristobalite (STC) filler.
Abstract: A Gamma-ray irradiation was employed to modify high density polyethyelene (HDPE) in order to impart poor interfacial interaction between hydrophobic matrix and hydrophilic Sericite-Tridymite-Cristobalite (STC) filler. The STC filler was further treated with a silane coupling agent. The FTIR, SEM and rheological observations confirmed enhanced interactions between oxygen containing groups on the irradiated matrix (γ-HDPE) and NH2 groups of silane-treated filler (t-STC), resulting in improved mechanical properties of the composites (10 times in case of impact strength). The parameter of the theoretical model used characterizing interfacial interaction increased from 2.69 for HDPE/STC up to4 for irradiated and surface treated material.

10 citations

Journal ArticleDOI
TL;DR: In this article, high-temperature IR spectra of the orthorhombic modifications of CsZnPO 4 and CsNiPO 4 are presented and assigned.
Abstract: Caesium-bearing phosphates with the β -tridymite structure are considered as storage container for radioactive Cs. In this context, double phosphates of caesium and divalent cations, CsM 2+ PO 4 where M 2+ = Zn, Co, Mn, Mg, and Ni, have been synthesised by the precipitation method as powders and investigated by infrared spectroscopy in combination with factor-group analyses for band assignment. Comparison of the IR pattern of CsZnPO 4 and CsCoPO 4 confirms that they are isomorphic (space group P 1 2 1 / a 1 at room conditions). Both undergo T -induced phase transitions: one at 260 °C ( Pn 2 1 a) and another one at 310 °C ( Pnma ). High-temperature IR spectra of the orthorhombic modifications of CsZnPO 4 are presented and assigned. Comparison of the IR-spectrum of CsMnPO 4 with that of CsZnPO 4 ( Pn 2 1 a ) confirms that it crystallizes in the orthorhombic structure at room conditions ( Pn 2 1 a) . CsMgPO 4 crystallizes at room conditions in the orthorhombic space group Pnma , however, it tends to hydrate immediately after quenching in air forming the cubic hydrate CsMgPO 4 ·6H 2 O (space group F 43 m ). The liability to hydration is also characteristic for CsNiPO 4 . Temperature-dependent IR spectroscopy, X-ray diffraction, thermal analyses (TGA, DTA) and second-harmonic generation (SHG) revealed that pure anhydrous CsMgPO 4 (space group Pnma ) can only be stored in air at temperatures higher than 150 °C. Our study proves that CsM 2+ PO 4 , where M 2+ = Zn, Co, Mn, may be stable containers for radioactive Cs at room temperatures. However, CsMgPO 4 and CsNiPO 4 can only be used as crystalline matrices for the immobilisation of radioactive Cs when stored at temperature higher than 150 °C due to their hydrolytic instability in air. The difference in the structures of CsMg phosphate and Cs phosphates with Zn, Co, and Mn is caused by the different liability of these cations to form either ionic or covalent chemical bonds.

10 citations


Network Information
Related Topics (5)
Crystallization
81.9K papers, 1.5M citations
77% related
Crystal
90K papers, 1.2M citations
76% related
Crystal structure
100.9K papers, 1.5M citations
75% related
Graphite
56.9K papers, 1M citations
75% related
Crystallite
43.2K papers, 981K citations
75% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202315
202231
202125
202027
201920
201826