THERMAL TRANSFORMATIONS OF STILBITE

1966 ◽  
Vol 3 (3) ◽  
pp. 351-366 ◽  
Author(s):  
F. Aumento
Keyword(s):  
High Temperature ◽  
Amorphous Silica ◽  
Room Temperature ◽  
Cell Parameter ◽  
Maximum Temperature ◽  
Cubic Phase ◽  
Crystal Data ◽  
Thermal Transformations ◽  
Cell Parameters ◽  
Metastable Form

Stilbite samples from two localities were examined. Preliminary D.T.A. and T.G.A. investigations to 1 400 °C were followed by high temperature diffractometry. Debye–Scherrer and Guinier techniques were used to study cooled samples, Diffractometer and single crystal data were processed with a computer to calculate cell parameters and thermal expansion.Stilbite changes to a metastable form of epistilbite at 145 °C. At 240 °C and 470 °C epistilbite shows two modifications followed by gradual destruction. Semi-amorphous silica formed by this process yields β-cristobalite and anorthite at 920 °C. Anorthite is replaced, at 1 340 °C, by an unidentified cubic phase. β-Cristobalite is found to be metastable down to room temperature; its room temperature cell parameter "a" is inversely proportional to the maximum temperature of annealment.

Crystal data for NH(CH3)3GeCl3

1982 ◽  
Vol 15 (2) ◽  
pp. 247-248 ◽  
Author(s):  
A. Möller ◽  
J. Felsche
Keyword(s):  
High Temperature ◽  
Phase Change ◽  
Perovskite Structure ◽  
Room Temperature ◽  
Structure Type ◽  
Crystal Data ◽  
Space Group ◽  
Cell Parameters ◽  
Orthorhombic Modification ◽  
High Temperature Form

NH(CH3)3GeCl3, C3H10N+.Ge2+.3Cl−, crystallizes at room temperature in an orthorhombic modification with a = 9.537(2), b = 8.235(2), c = 12.138(2) Å, Z = 4, space group Cmc21. These cell parameters correspond to a derivative of the cubic perovskite structure type, with a≃b≃\sqrt{2} a cubic and c≃ 2a cubic. Unlike other chlorogermanates(II) there is not a phase change to an ionically conducting cubic high-temperature form.

High-temperature diffraction experiments and phase diagram of ZrO2 and ZrSiO4

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Akira Yoshiasa ◽  
Tsubasa Tobase ◽  
Hiroshi Arima-Osonoi ◽  
Ken-Ichi Funakoshi ◽  
Osamu Ohtaka ◽  
...  
Keyword(s):  
High Temperature ◽  
Unit Cell ◽  
Cubic Phase ◽  
Imaging Plate ◽  
X Ray Diffraction ◽  
Space Group ◽  
Cell Parameters ◽  
Time Observation ◽  
Short Time ◽  
Clear Change

Abstract High-temperature X-ray diffraction (XRD) experiments up to T = 2710 °C have been performed on ZrSiO4 and ZrO2 powders, using the container-less levitation technique. A two-dimensional imaging plate (IP) detector was used for short-time observation. The diffraction data in a wide area was projected in one dimension. The unit cell parameters, thermal expansions, and c/a ratios for ZrSiO4 (space group I41/amd and Z = 4), tetragonal ZrO2 (space group P42/nmc and Z = 2) and cubic ZrO2 (space group  F m 3   ‾ m $Fm3‾{}m$ and Z = 4) were measured to understand the high-temperature behaviors. The transition temperature between tetragonal and cubic ZrO2 was specified to be between 2430 and 2540 °C. The pre-transitional behavior was observed around 2200 °C. As no clear change in unit cell volume is evident, the phase boundary between the tetragonal and the cubic phase has been shown to be a positive slope. The ZrO2 and ZrO2–SiO2 phase diagrams are proposed based on the chemical composition and the crystal structure.

High-temperature X-ray powder diffraction study of the tetragonal-cubic phase transition in nanocrystalline, compositionally homogeneous ZrO2–CeO2 solid solutions

2008 ◽  
Vol 23 (S1) ◽  
pp. S70-S74 ◽  
Author(s):  
L. M. Acuña ◽  
R. O. Fuentes ◽  
D. G. Lamas ◽  
I. O. Fábregas ◽  
N. E. Walsöe de Reca ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
High Temperature ◽  
Powder Diffraction ◽  
Solid Solutions ◽  
Tetragonal Phase ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray ◽  
First Order

Crystal structure of compositionally homogeneous, nanocrystalline ZrO2–CeO2 solutions was investigated by X-ray powder diffraction as a function of temperature for compositions between 50 and 65 mol % CeO2. ZrO2-50 and 60 mol % CeO2 solid solutions, which exhibit the t′-form of the tetragonal phase at room temperature, transform into the cubic phase in two steps: t′-to-t″ followed by t″-to-cubic. But the ZrO2-65 mol % CeO2, which exhibits the t″-form, transforms directly to the cubic phase. The results suggest that t′-to-t″ transition is of first order, but t″-to-cubic seems to be of second order.

Powder Crystal Data for the High-Temperature Phases Cu4In, Cu9In4(h) and Cu2In(h)

1992 ◽  
Vol 7 (2) ◽  
pp. 107-108 ◽  
Author(s):  
G.C. Che ◽  
M. Ellner
Keyword(s):  
High Temperature ◽  
Single Phase ◽  
Crystal Data ◽  
Cell Parameters

AbstractThe high-temperature phases Cu4In, Cu9In4(h) and Cu2In(h) cannot be retained by quenching. In contrast to this, splat-cooling specimens of these alloys yielded single phase products. Cell parameters in the range of homogeneity of these phases were measured. Powder crystal data for Cu4In(W type), Cu9In4(h) (Cu9Al4type) and Cu2In(h) (Ni2In type) are given.

Reconstructive phase transition in (NH4)3TiF7accompanied by the ordering of TiF6octahedra

2014 ◽  
Vol 70 (6) ◽  
pp. 924-931 ◽  
Author(s):  
Maxim Molokeev ◽  
S. V. Misjul ◽  
I. N. Flerov ◽  
N. M. Laptash
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
High Temperature ◽  
Room Temperature ◽  
Parent Phase ◽  
High Temperature Phase ◽  
Cubic Phase ◽  
Temperature Phase ◽  
Large Rotations ◽  
Fourfold Axis

An unusual phase transitionP4/mnc→ Pa\bar 3 has been detected after cooling the (NH4)3TiF7compound. Some TiF6octahedra, which are disordered in the room-temperature tetragonal structure, become ordered in the low-temperature cubic phase due to the disappearance of the fourfold axis. Other TiF6octahedra undergo large rotations resulting in huge displacements of the F atoms by 1.5–1.8 Å that implies a reconstructive phase transition. It was supposed that phasesP4/mbmand Pm\bar 3m could be a high-temperature phase and a parent phase, respectively, in (NH4)3TiF7. Therefore, the sequence of phase transitions can be written as Pm\bar 3m →P4/mbm→P4/mnc→ Pa\bar 3. The interrelation between (NH4)3TiF7, (NH4)3GeF7and (NH4)3PbF7is found, which allows us to suppose phase transitions in relative compounds.

scholarly journals In situ high-temperature behaviour of fluor-elbaite: breakdown conditions and products

2021 ◽  
Vol 48 (6) ◽  
Author(s):  
Beatrice Celata ◽  
Paolo Ballirano ◽  
Giovanni B. Andreozzi ◽  
Ferdinando Bosi
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Structural Parameters ◽  
Unit Cell ◽  
Temperature Behaviour ◽  
Unit Cell Parameters ◽  
Thermally Induced ◽  
X Ray ◽  
Cell Parameters

AbstractThe thermal behaviour of a fluor-elbaite from Minas Gerais (Brazil) was investigated at room pressure through in situ high-temperature X-ray powder diffraction (HT-XRPD), until the breakdown conditions were reached. The variations of fluor-elbaite structural parameters (unit-cell parameters and mean bond distances) were monitored together with site occupancies, and two main internal reactions were identified: the thermally-induced Fe oxidation process counterbalanced by (OH)– deprotonation, which starts at 500 °C (773 K), followed by a partial intracrystalline Fe–Al exchange between the octahedrally-coordinated Y and Z sites. The fluor-elbaite breakdown reaction occurs between 850 °C (1123 K) and 900 °C (1173 K). The breakdown products were identified at room temperature by XRPD and the breakdown reaction can be described by the following reaction: tourmaline → B-bearing mullite + hematite + spinel + B-poor (Na, Li, H2O)-bearing glass. Boromullite itself was not observed in the final heating products, and the B-bearing mullite from the breakdown reaction exhibited unit-cell parameters a = 7.5382(2) Å, b = 7.6749(2) Å, c = 2.8385(1) Å, V = 164.22(1) Å3 (space group Pbam) consistent with an approximate Al8.5B1.5Si2O19 composition.

scholarly journals PENGARUH PANJANG STACK SELUBUNG KABEL TERHADAP PERUBAHAN SUHU PADA SISTEM PENDINGIN TERMOAKUSTIK

2017 ◽  
Vol 2 (2) ◽  
pp. 119
Author(s):  
Indah Kharismawati ◽  
Hanif Rafika Putri
Keyword(s):  
High Temperature ◽  
Heat Exchanger ◽  
Room Temperature ◽  
Initial Temperature ◽  
Temperature Drop ◽  
Maximum Temperature ◽  
Thermoelectric Cooler ◽  
Thermoelectric Coolers ◽  
Temperature Changes ◽  
Sheath Material

Research on environmentally friendly thermo-acoustic coolants uses a heat exchanger from the cable sheath material. The resonator tube used in the thermoelectric cooler is a 5.25 cm diameter PVC (polyvinyl chloride) tube with a length of 87 cm. Variations in stack lengths of 4cm, 5cm, 6cm, 7cm, and 8cm were performed to obtain results on thermoelectric coolers. Results are available on the use of stack length 4 cm high temperature 21.6 oC from the initial temperature), the stack length 5 cm high temperature 21.1 oC from the initial temperature (room temperature), the stack length of 6 cm resulted in a maximum temperature drop of 22.6 oC from the initial temperature (room temperature), the stack length of 7 cm resulted in a maximum temperature drop of 22.0 oC from the initial temperature (room temperature), while the stack length of 8 cm resulted in a decrease in temperature maximum of 23.3 oC from the initial temperature (room temperature). Keywords: Thermoacoustic, stack, temperature changes.

Multifunctional role of dysprosium in HfO2: stabilization of the high temperature cubic phase, and magnetic and photoluminescence properties

2017 ◽  
Vol 19 (29) ◽  
pp. 18957-18967 ◽  
Author(s):  
Sandeep Kumar ◽  
S. B. Rai ◽  
Chandana Rath
Keyword(s):  
High Temperature ◽  
Hafnium Oxide ◽  
Room Temperature ◽  
Cubic Phase ◽  
Photoluminescence Properties ◽  
Crystalline Structures

Hafnium oxide (HfO2) can exist in different crystalline structures such as monoclinic at room temperature, tetragonal at 1700 °C and cubic at 2600 °C.

Phase relations in the Ba–Sr–Co–Fe–O system at 1273 K in air

2009 ◽  
Vol 42 (2) ◽  
pp. 153-160 ◽  
Author(s):  
Zhèn Yáng ◽  
Ashley S. Harvey ◽  
Anna Infortuna ◽  
Ludwig J. Gauckler
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Solid State Reaction ◽  
Room Temperature ◽  
Solid State Reaction Method ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
X Ray

Selected compositions of the Ba–Sr–Co–Fe–O system were synthesized from powders by the solid-state reaction method. Samples were equilibrated at 1273 K for 36 000 s in air. The resulting powders were characterized by X-ray diffraction (XRD) at room temperature and by high-temperaturein situXRD. The phases present in the BaxSr1−xCoyFe1−yO3−δsystem are outlined for 1273 K in air. For most of the quaternary compositions, the cubic perovskite is formed, except for the compositions withx= 1 (excludingy= 0.4),y= 1 andx,y= 0.8, where the phases mainly show hexagonal distortions, andx, y= 0, for which a predominant cubic phase is mixed with other phases.

scholarly journals High-Temperature X-Ray Diffraction and Fluorescence Spectra of SnSe Single Crystal

2019 ◽  
Vol 73 (6) ◽  
pp. 519-524
Author(s):  
Jahangir Huseynov ◽  
Rena Mamedova ◽  
Ibrahim Abbasov ◽  
Dunyameddin Askerov ◽  
Khaver Sadig
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Fluorescence Spectra ◽  
Room Temperature ◽  
Coefficient Of Thermal Expansion ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Stockbarger Method

Abstract The temperature dependence of unit cell parameters was studied using high-temperature X-ray diffraction and the coefficient of thermal expansion of SnSe single crystal was determined. Fluorescence spectra of SnSe single crystal grown by the Bridgman-Stockbarger method were examined using a Cary Eclipse spectrophotometer at room temperature in the wavelength range 200–900 nm. When the samples were irradiated by a pulse at a wavelength of 230 nm, the fluorescence spectra exhibited maxima at wavelengths 313.07, 423.03, 458.93, 495.07, and 530.00 nm.

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