scholarly journals ESR-Untersuchungen zum Jahn-Teller-Effekt des Cu2+-Ions in oxidischen Perowskiten

1969 ◽  
Vol 24 (10) ◽  
pp. 1518-1525
Author(s):  
C. Friebel ◽  
D. Reinen
Keyword(s):  
Phase Transition ◽  
Tetragonal Phase ◽  
Esr Spectra ◽  
Ligand Field ◽  
X Ray ◽  
Field Spectroscopy ◽  
Jahn Teller ◽  
Low X ◽  
Ligand Field Parameters ◽  
Tetragonal Phase Transition

Abstract The ESR-powder-spectra of the perovskite-mixed-crystals M2II (CuxZn1-xW)O6 [MII=Sr, Ba] and Sr2(CuxZn1-xTe)O6 , which have been investigated by means of conventional X-ray-techniques and ligand-field-spectroscopy 1,2, are described and the results extensively discussed. The conclusions can be summarized as follows: (a) At very low x-values isolated, dynamically Jahn-Teller-distorted CuO6-octahedra are present in the cubic matrices, which can be frozen into tetragonally elongated polyhedra at 4.2 °K; (b) At high x-values the CuO6-entities are statically JT-distorted with the long axes lined up along the c-axis of the macroscopically tetragonal phases; (c) The ESR-spectra around the cubic-tetragonal phase-transition are complex, containing signals of obviously magnetically coupled Cu2+-ions; (d) The g-values "follow" the ligand-field-parameters quantitatively. Comparative data of some other compounds are given.

High-Temperature Synchrotron X-Ray Powder Diffraction Study of the Orthorhombic–Tetragonal Phase Transition in La0.63(Ti0.92,Nb0.08)O3

2002 ◽  
Vol 164 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Roushown Ali ◽  
Masatomo Yashima ◽  
Masahiko Tanaka ◽  
Hideki Yoshioka ◽  
Takeharu Mori ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Diffraction Study ◽  
Powder Diffraction ◽  
Tetragonal Phase ◽  
X Ray ◽  
Tetragonal Phase Transition

Variable temperature and high-pressure crystal chemistry of perovskite formamidinium lead iodide: a single crystal X-ray diffraction and computational study

2017 ◽  
Vol 53 (54) ◽  
pp. 7537-7540 ◽  
Author(s):  
Shijing Sun ◽  
Zeyu Deng ◽  
Yue Wu ◽  
Fengxia Wei ◽  
Furkan Halis Isikgor ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Low Temperature ◽  
Tetragonal Phase ◽  
Computational Study ◽  
Variable Temperature ◽  
X Ray Diffraction ◽  
Lead Iodide ◽  
X Ray ◽  
Tetragonal Phase Transition

Single crystals of [(NH2)2CH]PbI3 undergo a cubic-to-tetragonal phase transition at low temperature and high pressure.

Orthorhombic to tetragonal phase transition in the RBa2Cu3O7−δ system studied by in - situ X-ray powder diffraction measurements

1988 ◽  
Vol 23 (10) ◽  
pp. 1409-1415 ◽  
Author(s):  
Y. Ueda ◽  
A. Mitushima ◽  
H. Toda ◽  
N. Kojima ◽  
M. Yoshikawa ◽  
...  
Keyword(s):  
Phase Transition ◽  
Powder Diffraction ◽  
Tetragonal Phase ◽  
X Ray ◽  
Tetragonal Phase Transition

Spektroskopische Untersuchungen zum Jahn-Teller-Effekt des Cu2+-Ions in Verbindungen vom Typ A2CuL6, II / Spectroscopic Investigations with Respect to the Jahn-Teller Effect of Cu(II) in Compounds of the Type A2CuL6, II

1974 ◽  
Vol 29 (9-10) ◽  
pp. 634-641 ◽  
Author(s):  
Claus Friebel
Keyword(s):  
Structure Determination ◽  
Qualitative Agreement ◽  
Spectroscopic Data ◽  
Ligand Field ◽  
Orthorhombic Distortion ◽  
X Ray ◽  
Bond Lengths ◽  
Field Spectroscopy ◽  
Jahn Teller ◽  
Jahn Teller Effect

By means of EPR and ligand field spectroscopy a refinement of the Ba2CuF6 structure within the [CuF4/2F2]2--layers consisting of axially elongated CuF6-octahedra, 2-dimensionally connected by corners in an antiferrodistortive order, is given. In qualitative agreement with a recent structure determination by X-ray analysis the spectroscopic data prove, that the equatorial planes of the coupled CuF6-polyhedra form an angle of 2 γ > 90° (corresponding to a disturbed type of antiferrodistortive order). In contrast to 2 γ= 101° found by the X-ray investigation, the spectroscopic results suggest 2 γ = 119 (± 1)°, the consequence of which is an elongation of the Cu—F bond lengths and a remarkable orthorhombic distortion of the CuF6-octahedra.

Spektroskopische Untersuchungen zum Jahn-Teller-Effekt des Cu2+-Ions in Verbindungen vom Typ A2 CuL6, I / Spectroscopic Ivestigations with Respect to the Jahn-Teller-Effect of Cu(II) in Compounds of the Type A2CuL6, I

1974 ◽  
Vol 29 (5-6) ◽  
pp. 295-303 ◽  
Author(s):  
Claus Friebel
Keyword(s):  
Esr Spectra ◽  
Ligand Field ◽  
X Ray ◽  
Octahedral Sites ◽  
Structural Differences ◽  
Structure Determinations ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Ligand Field Spectra ◽  
Atomic Parameters

Structural relations between perovskite-related lattices of the type A2CuL6 and the perovskite compounds A2(12) [BCu](6)L6 (1: 1 order in the octahedral sites, elpasolite type) are demonstrated by two examples, the compounds A,Cu(OH)6 [A = Ba, Sr] and Ba2CuF6. From the ESR spectra a coupling of Jahn-Teller-distorted Cu-ligand-octahedra in these compounds corresponding to a “disturbed” type of antiferrodistortive order can be deduced. This result is in agreement with recent X-ray structure determinations. The ligand field spectra of the hydroxocuprates(II) indicate tetragonally elongated CuO6-octahedra with very long axial distances. From the ESR investigations further conclusions can be drawn concerning structural differences between the Ba- and the Sr-compound [Sr2Cu(OH6)], the atomic parameters of which are still unknown.

Study of the tetragonal-to-tetragonal phase transition of theA15pseudobinary alloyNb3Sn1−xSbxby neutron and x-ray scattering

1982 ◽  
Vol 25 (1) ◽  
pp. 364-371 ◽  
Author(s):  
Y. Fujii ◽  
J. B. Hastings ◽  
M. Kaplan ◽  
G. Shirane ◽  
Y. Inada ◽  
...  
Keyword(s):  
Phase Transition ◽  
Tetragonal Phase ◽  
X Ray ◽  
X Ray Scattering ◽  
Tetragonal Phase Transition ◽  
Ray Scattering
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