Abstract
Phase relations have been established for the Ce-Ag-Ge system at 850°C by means of X-ray diffraction, light optical microscopy, and quantitative electron probe microanalysis. Phase equilibria are characterized by the existence of extended solid solutions of Ce(Ag x Ge1−x )2−y (ThSi2 type), Ce(Ag1−x Ge x )1−y , and Ce(Ag1−x Ge x )2−y (unknown structure type). New ternary compounds were found to exist: Ce∼7Ag∼8Ge∼5 (unknown structure), Ce∼6Ag∼5Ge∼9 (unknown structure), Ce3Ag4Ge4 (Gd3Cu4Si4 type), and Ce(Ag x Ge1−x )2 (AlB2 type). Ge/Si substitution was investigated for the alloy systems CeAg-Si x Ge1−x (CaIn2 type for x<0.67 and LiGaGe type for x≥0.67) and CeAg x (Si y Ge1−y )2−x (AlB2 type). Magnetic behavior was studied from susceptibility and magnetization measurements down to 1.7 K and employing magnetic fields up to 5 T. In contrast to earlier descriptions of CeAgGe to order antiferromagnetically below 4.8 K, the authors’ susceptibility and magnetization measurements revealed rather a soft ferromagnetic nature below 6.8 K. Substitution of Ge by Si, x Si=0.1, 0.33, 0.5, 0.67, and 0.75, enhances the ferromagnetic interactions. The AlB2-type alloys, CeAg0.67Ge1.33 and CeAgGe0.84Si0.16, showed soft ferromagnetism with Curie temperature (T C)=7.5 and 8.3 K, respectively. Starting from ferromagnetic binary CeGe2 (ThSi2−y type, T C=7.2 K) replacement of Ge by Ag retains the ferromagnetism below 8 K for x Ag=0.08, but changes to antiferromagnetism with ordering (Neél) temperature T N=9 K for x Ag=0.13. For CeAg2Ge2 (ThCr2Sr2 type) the antiferromagnetic type of order is confirmed, but with lower ordering temperature, (T N=4.5 K) than derived earlier. Ce3Ag4Ge4 (Gd3Cu4Ge4 type) exhibits spin-glass behavior below 7 K. Complex magnetic properties were encountered for Ce∼6Ag∼5Ge∼9 (Ce∼6Ag∼5Ge∼9 type) with two subsequent phase transitions at T N=8.5 K followed by T C=6.9 K.
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Cordruwisch, E., Rogl, P., Kaczorowski, D. et al. Constitution, structural chemistry, and magnetism of the ternary system Ce-Ag-Ge. JPE 20, 407 (1999). https://doi.org/10.1361/105497199770340941
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DOI: https://doi.org/10.1361/105497199770340941