# Higher-order thermal motion tensor analysis and atom disorder in cubic melanophlogite

@article{Nakagawa2006HigherorderTM,
title={Higher-order thermal motion tensor analysis and atom disorder in cubic melanophlogite},
author={Takeshi Nakagawa and Kuniaki Kihara},
journal={Journal of Mineralogical and Petrological Sciences},
year={2006},
volume={101},
pages={14-22}
}
• Published 1 February 2006
• Materials Science
• Journal of Mineralogical and Petrological Sciences
The structure of the high temperature form of melanophlogite (MEP) at 84 °C was refined by using a least squares refinement that was based on the Gram-Charlier expansion of the atomic probability density functions (PDF) up to the fourth-order terms. The refinements of 95 variable parameters on the space group Pm3n converged to R = 0.0275 (Rw = 0.0313) for the 607 observed reflections in single crystal X-ray diffraction. The PDFs for three types of O atom (in total, there were four types, O1 to…
6 Citations

## Figures and Tables from this paper

X-ray studies of structural changes in melanophlogite with varying temperature
• Materials Science
• 2005
The a and c unit cell dimensions of melanophlogite (MEP) have been determined in the temperature range −50 to 700 °C, showing a different expansion behavior for the low temperature α-phase. The
High-pressure Raman study of CH4 in melanophlogite (type I clathrate)
• Chemistry
Mineralogical Magazine
• 2014
Abstract The evolution with pressure of the CH4 vibrational modes related to C-H stretching has been followed by in situ Raman spectroscopy on a single crystal of cubic melanophlogite from Varano
Single-crystal X-ray and Raman investigation on melanophlogite from Varano Marchesi (Parma, Italy)
• Chemistry
• 2008
Abstract The results of a new single-crystal structure refinement and of a Raman spectroscopy investigation on melanophlogite, a clathrate structure of SiO2, are reported. The studied sample comes
Single-crystal X-ray and Raman investigation on melanophlogite from Varano Marchesi (Parma, Italy)
• Chemistry
• 2008
The results of a new single-crystal structure refinement and of a Raman spectroscopy investigation on melanophlogite, a clathrate structure of SiO2, are reported. The studied sample comes from a new
Structural properties and phase transitions in a silica clathrate.
• Materials Science
The Journal of chemical physics
• 2011
It is predicted that a partial crystalline and amorphous sample can be obtained by recovering the sample from a pressure of ∼12-16 GPa, triggered by Si coordination number changes.

## References

SHOWING 1-10 OF 20 REFERENCES
X-ray studies of structural changes in melanophlogite with varying temperature
• Materials Science
• 2005
The a and c unit cell dimensions of melanophlogite (MEP) have been determined in the temperature range −50 to 700 °C, showing a different expansion behavior for the low temperature α-phase. The
The crystal structure of low melanophlogite
• Materials Science
• 2001
Abstract The crystal structure of the low temperature form of natural melanophlogite, 46SiO2 · 6M14 · 2M12 (M14 = N2, CO2; M12 = CH4, N2), was determined using single-crystal X-ray diffraction data
The structures of the β-cristobalite phases of SiO2 and AlPO4
• Chemistry
• 1975
Abstract The crystal structures of the ‘cristobalite’ phases of SiO4 and AlPO4 have been determined from X-ray data collected at high temperatures. A model is suggested which gives a much better fit
X-ray, DTA and Raman studies of monoclinic tridymite and its higher temperature orthorhombic modification with varying temperature
• Materials Science, Chemistry
• 2005
Unit-cell parameters, Raman scattering profiles and DTA curves were measured on monoclinic tridymite from fired silica brick. Ten peaks appear in the Raman measurements from 100 to 1250 cm at 25°C,
Studies on clathrasils. III. Crystal structure of melanophlogite, a natural clathrate compound of silica.
The high temperature form of melanophlogite, 46 Si02. 6MI4 .2M12(M12 =CH4, N2; M14= C02, N2), is cubic with space group Pm3n and a= 13.436(3) A at 200°C. The mineral is isostructural with the cubic
Molecular dynamics interpretation of structural changes in quartz
Abstract Constant temperature and constant pressure molecular dynamics (MD) simulations were applied to quartz to calculate the structural details which are indeterminable in usual X-ray structure
High-order thermal-motion tensor analyses of tridymite
• Geology
• 1986
Two least-squares methods based on the Gram-Charlier expansion and the Edgeworth expansion were applied to a test structure to examine their usefulness in analysing multimodal density distribution of
High-temperature single-crystal study of the cristobalite inversion
Single crystals of low cristobalite from Ellora Caves, India, were studied using single-crystal x-ray diffraction methods as a function of temperature through the inversion to high cristobalite. The
A contribution to the crystal chemistry of melanophlogite
Melanophlogite from the second occurrence at Chvaletice, Bohemia, forms colorless cubes on lussatite in a vein cavitSr in a metamorphosed sedimentary pyrite-rhodochrosite deposit of Algonkian age.
The α-β phase transition in cristobalite, SiO2
• Chemistry
• 1991
AbstractCristobalite, a high temperature phase of silica, SiO2, undergoes a (metastable) first-order phase transition from a cubic, $$Fd\bar 3m$$ , to a tetragonal, P43212 (or P41212), structure at