Temperature-dependent XRD, IR, magnetic, SEM and TEM studies of Jahn–Teller distorted NiCr{sub 2}O{sub 4} powders

Journal Article · Wed May 15 00:00:00 EDT 2013 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2013.03.023· OSTI ID:22306296

Maczka, M.; Gągor, A.; Pikul, A.; Macalik, L.; Hanuza, J.

In the present work we report detailed structural, magnetic and phonon properties of NiCr{sub 2}O{sub 4} powders synthesized via a simple coprecipitation method. Temperature-dependent XRD as well as temperature-dependent IR studies reveal that cubic to tetragonal phase transition is lowered due to size effects. Observed changes in the IR spectra indicate that the paramagnetic–ferrimagnetic phase transition taking place at 74 K is related to further lowering of symmetry to orthorhombic system. Assignment of modes was proposed and factor group analyses in three possible symmetries were carried out. Our results show strong anomalies due to the Jahn–Teller tetragonal distortion and weak due to the orthorhombic distortion and onset of collinear ferrimagnetic order. Shifts of wavenumbers observed below 31 K, where the onset of antiferromagnetic ordering occurs, were attributed to spin–phonon interactions. - Graphical abstract: XRD pattern of NiCr{sub 2}O{sub 4} sample synthesized via a coprecipitation method followed by calcination at 1000 {sup o}C. - Highlights: • NiCr{sub 2}O{sub 4} starts to crystallize near 750 °C. • Coexistence of cubic and tetragonal phases of NiCr{sub 2}O{sub 4} was revealed. • Temperature of the Jahn–Teller distortion is lowered due to the size effects. • Evidences of tetragonal and orthorhombic distortions were found. • Weak spin–phonon interactions were evidenced.

• OSTI ID: 22306296
• Journal Information: Journal of Solid State Chemistry, Vol. 201; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALLOCATIONS
ANTIFERROMAGNETISM
CALCINATION
COPRECIPITATION
INFRARED SPECTRA
INTERACTIONS
JAHN-TELLER EFFECT
MAGNETIZATION
ORTHORHOMBIC LATTICES
PARAMAGNETISM
PHASE TRANSFORMATIONS
PHONONS
POWDERS
SCANNING ELECTRON MICROSCOPY
SPIN
TEMPERATURE DEPENDENCE
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION