New germanates RCrGeO{sub 5} (R=Nd-Er, Y): Synthesis, structure, and properties

Journal Article · Mon Sep 15 04:00:00 EDT 2008 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2008.05.043· OSTI ID:21128466

Shpanchenko, Roman V ^[1]; Tsirlin, Alexander A; Kondakova, Ekaterina S; Antipov, Evgeny V ^[1]; Bougerol, Catherine ^[2]; Hadermann, Joke; Tendeloo, Gustaaf van ^[3]; Sakurai, Hiroya; Takayama-Muromachi, Eiji ^[4]

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1. Department of Chemistry, Moscow State University, Leninskie Gory, Moscow 119992 (Russian Federation)
2. Nanophysique et Semiconducteurs Group, CNRS-Institut Neel and CEA-INAC-SP2M, 17 rue des martyrs, 38054 Grenoble Cedex 9 (France)
3. EMAT, University of Antwerp, Groenenborgerlaan 171, Antwerp B-2020 (Belgium)
4. NIMS, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

The new complex germanates RCrGeO{sub 5} (R=Nd-Er, Y) have been synthesized and investigated by means of X-ray powder diffraction, electron microscopy, magnetic susceptibility and specific heat measurements. All the compounds are isostructural and crystallize in the orthorhombic symmetry, space group Pbam, and Z=4. The crystal structure of RCrGeO{sub 5}, as refined using X-ray powder diffraction data, includes infinite chains built by edge-sharing Cr{sup +3}O{sub 6} octahedra with two alternating Cr-Cr distances. The chains are combined into a three-dimensional framework by Ge{sub 2}O{sub 8} groups consisting of two edge-linked square pyramids oriented in opposite directions. The resulting framework contains pentagonal channels where rare-earth elements are located. Thus, RCrGeO{sub 5} germanates present new examples of RMn{sub 2}O{sub 5}-type compounds and show ordering of Cr{sup +3} and Ge{sup +4} cations. Electron diffraction as well as high-resolution electron microscopy confirm the structure solution. Magnetic susceptibility data for R=Nd, Sm, and Eu are qualitatively consistent with the presence of isolated 3d (antiferromagnetically coupled Cr{sup +3} cations) and 4f (R{sup +3}) spin subsystems in the RCrGeO{sub 5} compounds. NdCrGeO{sub 5} undergoes long-range magnetic ordering at 2.6 K, while SmCrGeO{sub 5} and EuCrGeO{sub 5} do not show any phase transitions down to 2 K. - Graphical abstract: Alternating Cr-Cr separations in the chain of edge-sharing CrO{sub 6} octahedra and the constraining effect of the GeO{sub 5} square pyramids in the structures of RCrGeO{sub 5}.

• OSTI ID: 21128466
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 9 Vol. 181; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CATIONS
CHROMIUM COMPOUNDS
CHROMIUM IONS
ELECTRON DIFFRACTION
ELECTRON MICROSCOPY
GERMANATES
GERMANIUM IONS
MAGNETIC SUSCEPTIBILITY
MAGNETIZATION
ORTHORHOMBIC LATTICES
PHASE TRANSFORMATIONS
RARE EARTH COMPOUNDS
SPACE GROUPS
SPECIFIC HEAT
SYNTHESIS
X-RAY DIFFRACTION