High-temperature X-ray powder diffraction analysis of selected ceramic mixtures

1994 ◽  
Vol 9 (1) ◽  
pp. 38-43 ◽  
Author(s):  
Sampath S. Iyengar
Keyword(s):  
High Temperature ◽  
Powder Diffraction ◽  
Inert Atmosphere ◽  
High Temperature Phase ◽  
Pure Oxygen ◽  
Temperature Phase ◽  
X Ray ◽  
Two Phases ◽  
Phase Relationships

The utility of ultra-high-temperature (2100 °C) X-ray powder diffraction technique for investigating the high-temperature phase relationships of two pseudobinary mixtures, Al2O3/Y2O3 and AlN/SiO2, is described. The in situ analysis to 1600 °C was carried out using a platinum holder and a Pt/Rh thermocouple; whereas analysis beyond 1600 °C was performed with a tungsten holder, extremely pure, oxygen-free inert gas environment, and an opticalpyrometer to monitor temperatures up to 2100 °C. The solid-state interaction between Al2O3 and Y2O3 commenced with the formation of Al2Y4O9 (YAM), a yttria rich compound, at 1300 °C followed by AlYO3 (YAP) and Al5Y3O12 (YAG) at 1400 °C. Further heating to 1500 °C and above resulted in the increased concentration of YAG at the expense of the other two phases, followed by melting of the entire sample at 2050 °C. The only phase formed during cooling (from the molten state) was YAG. AlN and SiO2 did not react with each other, in an inert atmosphere, and they remained as separate, discrete phases even at 1600 °C. In the presence of oxygen, they reacted to form mullite and cristobalite, or SIALON depending on the partial pressure of oxygen.

Correlation between High-Temperature Structural Rearrangements and Oxygen Outlet in Perovskite SrCo0.6Fe0.2Nb0.2O3−z

2010 ◽  
Vol 163 ◽  
pp. 38-41 ◽  
Author(s):  
M.G. Ivanov ◽  
A.N. Shmakov ◽  
S.V. Tsybulya ◽  
O.Yu. Podyacheva ◽  
Z.R. Ismagilov
Keyword(s):  
High Temperature ◽  
Powder Diffraction ◽  
Oxygen Deficiency ◽  
Structural Rearrangement ◽  
Structural Rearrangements ◽  
Permeable Membrane ◽  
X Ray ◽  
Two Phases ◽  
Splitting Process

Strontium cobaltite doped with Fe and Nb, SrCo0.6Fe0.2Nb0.2O3−z, with perovskite-like structure, being one of the promising materials for oxygen permeable membrane implementation, has been investigated via in situ high temperature X-ray powder diffraction on Bruker D8 Advance instrument and high-resolution powder diffraction at synchrotron radiation beamline. The oxygen outlet from the lattice has been found to stay in correlation with the structural rearrangement forming two phases with different oxygen deficiency. The activation energy of phase splitting process has been estimated to be Eactivation ≈ 0.63 ± 0.06 eV.

Crystal Structure of Bis(triethylammonium)closo-decahydrodecaborate, [(C2H5)3NH]2[B10H10]

2000 ◽  
Vol 55 (6) ◽  
pp. 499-503 ◽  
Author(s):  
Kathrin Hofmann ◽  
Barbara Albert
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Powder Diffraction ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray ◽  
Crystal System ◽  
System A ◽  
Tetragonal Crystal ◽  
Tetragonal Crystal System

The crystal structure of bis(triethylammonium)closo-decahydrodecaborate [bis(triethylammonium) decaboranate(10)], [(C2H5)3NH]2[B10H10], was determined and refined (space group Pmmn, no. 59, a = 989.7, b = 1333.7, c = 903.7 pm). The compound is a versatile starting material for many substances containing the [BioHio]2- entity and its derivatives. The closo-[B10H10]2- cluster is a bicapped square antiprism which is only slightly distorted. Its deviation from D4d symmetry is smaller than that of the B10 cages in every other compound containing this entity that have been structurally characterised. The presence of additional (N )H ---B3 interactions in form of multiple-centre bonds between the cations and the anions, which were postulated earlier and which should influence the cage symmetry, could not be confirmed. At 55 °C, the transition into a high temperature phase was investigated by X-ray powder diffraction. The high temperature phase crystallises in the tetragonal crystal system (a = 946.9, c = 1351.0 pm).

scholarly journals Synthesis and Characterization of the Amidomanganates Rb2[Mn(NH2)4] and Cs2[Mn(NH2)4]

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 676
Author(s):  
Christian Bäucker ◽  
Soeren Bauch ◽  
Rainer Niewa
Keyword(s):  
High Temperature ◽  
Single Phase ◽  
Inert Atmosphere ◽  
High Temperature Phase ◽  
Synthesis And Characterization ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ir Spectroscopic

We report the successful synthesis of Rb2[Mn(NH2)4] and Cs2[Mn(NH2)4] from ammonothermal conditions at 723 K and pressures above 850 bar. Both compounds were obtained single phase according to powder X-ray diffraction. The crystal structures were determined by single crystal X-ray diffraction. For Rb2[Mn(NH2)4] we have obtained the high-temperature phase. The structures are analyzed with respect to the earlier reported alkali metal amidomanganates. Upon heating in inert atmosphere Cs2[Mn(NH2)4] decomposes to manganese nitrides. IR spectroscopic results are reported.

X-ray powder diffraction investigation of new high temperature polymorphs of CaTeO3 and CaTe2O5

2001 ◽  
Vol 16 (4) ◽  
pp. 205-211 ◽  
Author(s):  
S. N. Tripathi ◽  
R. Mishra ◽  
M. D. Mathews ◽  
P. N. Namboodiri
Keyword(s):  
High Temperature ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Solid Phase ◽  
High Temperature Phase ◽  
Unit Cell ◽  
Stable Phase ◽  
Temperature Phase ◽  
X Ray ◽  
Monoclinic Lattice

X-ray powder diffraction investigation of the new high temperature polymorphs beta- and gamma-CaTeO3 and gamma- and delta-CaTe2O5 and picnometric measurements of the room temperature phases of the two compounds have been carried out. The study led to the elucidation of their unit cell structures and assignment of entirely new lattice types and parameters to the room temperature phases of CaTeO3 and CaTe2O5 in contrast and supersession to the existing structural information. The results are as follows: CaTeO3 has only one stable phase at room temperature and temperatures up to 882 °C, i.e., α- and has a triclinic unit cell with a=4.132±0.003 Å, b=6.120±0.006 Å, c=12.836±0.013 Å, α=121.80°, β=99.72°, γ=97.26°. The first high temperature phase stable between 882 and 894 °C, i.e., β-CaTeO3, has a monoclinic lattice: a=20.577±0.007 Å, b=21.857±0.009 Å, c=4.111±0.002 Å, β=96.15°, while the next phase stable above 894 °C, i.e., γ-CaTeO3, has a hexagonal unit cell with parameters: a=14.015±0.0001 Å, c=9.783±0.001 Å, c/a=0.698. CaTe2O5 has one stable phase at temperatures up to 802 °C, i.e., α-CaTe2O5 with a monoclinic lattice and parameters: a=9.069±0.002 Å, b=25.175±0.007 Å, c=3.366±0.001 Å, β=98.29 °. The first high temperature phase stable in the range 802–845°, i.e., β-CaTe2O5, is monoclinic with unit cell parameters: a=4.146±0.001 Å, b=5.334±0.002 Å, c=6.105±0.002 Å, β=98.362 °; the next higher temperature phase stable over 845–857 °C, i.e., γ-CaTe2O5, has an orthorhombic unit cell with: a=8.638±0.001 Å, b=9.291±0.001 Å, c=7.862±0.001 Å and the highest temperature solid phase stable above 857 °C, i.e., δ-CaTe2O5 has a tetragonal unit cell with a=5.764±0.000 Å, c=32.074±0.020 Å, c/a=5.5637.

Crystal Structure of the High-Temperature Phase of a Compound Sr2ZnWO6

1992 ◽  
Vol 7 (4) ◽  
pp. 226-227 ◽  
Author(s):  
Fu Zhengmin ◽  
Li Wenxiu
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Lattice Parameter ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray ◽  
Cubic System ◽  
Measured Density

AbstractThe crystal structure of the high-temperature phase of Sr2ZnWO6 prepared by air quenching from 1200° C has been determined by means of X-ray powder diffraction. β-Sr2ZnWO6 belongs to the cubic system, with space group Fm3m and a lattice parameter a = 7.9266 Å at room temperature. Its measured density is Dm = 6.93g/cm3, and each unit cell contains four formula weights.

Crystal structure of a high-pressure/high-temperature phase of alumina by in situ X-ray diffraction

2004 ◽  
Vol 3 (6) ◽  
pp. 389-393 ◽  
Author(s):  
Jung-Fu Lin ◽  
Olga Degtyareva ◽  
Charles T. Prewitt ◽  
Przemyslaw Dera ◽  
Nagayoshi Sata ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure High Temperature

Phase Transitions in CsSnCl3 and CsPbBr3 An NMR and NQR Study

1991 ◽  
Vol 46 (4) ◽  
pp. 329-336 ◽  
Author(s):  
Surendra Sharma ◽  
Norbert Weiden ◽  
Alarich Weiss
Keyword(s):  
Phase Transitions ◽  
High Temperature ◽  
Phase I ◽  
Powder Diffraction ◽  
Perovskite Structure ◽  
Room Temperature ◽  
Monoclinic Phase ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray

Abstract The phase transitions in CsSnCl3 and CsPbBr3 have been studied by X-ray powder diffraction, by 81Br-NQR and by 'H-, 119Sn-, and 113Cs-NMR. At room temperature in air CsSnCl3 forms a hydrate which can be dehydrated to the monoclinic phase II of CsSnCl3. The high temperature phase I has the Perovskite structure, as the X-ray and NMR experiments show. The three phases of CsPbBr3, known from literature, have been corroborated. The results are discussed in the framework of the group ABX3, A = alkalimetal ion, B = IV main group ion, and X = Halogen ion

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