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R Nirmala V Sankaranarayanan K Sethupathi AV Morozkin T Geethakumary Y Hariharan 《Pramana》2002,58(5-6):1101-1104
New R
2Ti3Ge4 (R=Dy, Ho and Er) intermetallic compounds have been synthesized and characterized by X-ray diffraction and low temperature ac
magnetic susceptibility, electrical resistivity and thermoelectric power measurements were carried out. The compounds crystallize
in the parent, Sm5Ge4-type orthorhombic structure (space group Pnma) and lanthanide contraction is observed as one moves along the rare-earth series.
The changeover from paramagnetic to antiferromagnetic phase happens at low temperatures and the ordering temperature scales
with the de Gennes factor. The electrical resistivity is metallic with a negative curvature above 100 K. Thermopower displays
a weak maximum at temperatures less than 50 K signifying the possible phonon and magnon drag effects. 相似文献
2.
Antipov OL Bredikhin DV Eremeykin ON Savikin AP Ivakin EV Sukhadolau AV 《Optics letters》2006,31(6):763-765
Refractive-index changes accompanying changes in population of electronic levels of Yb3+ ions in a Yb:YAG laser disk under intense diode and laser pumping have been studied by use of both a highly sensitive polarization interferometer and transient grating testing at 633 nm. The electronic change of the index that is due to excitation of the Yb3+ ions (which have different polarizability of ground state 2F7/2 and excited level 2F5/2) is strongly predominant over the thermal component. The polarizability differences are deltap (1.9 +/- 0.8) x 10(-26) and (1.95 +/- 0.25) x 10(-26) cm3 as measured at 633 nm in interferometric and transient grating experiments, respectively. 相似文献
3.
Resonant ultrasound spectroscopy was used to measure the elastic constants of bcc Ta0.33V0.67 over the temperature range 3.5–300?K; the results were compared to earlier measurements on C15 TaV2. The temperature dependence of the polycrystalline shear modulus is completely different in the two phases; that of the bcc phase decreases with temperature whereas that of the C15 phases increases in an anomalous fashion. This difference is consistent with a model involving doubly-degenerate levels at the X point of the Brillouin zone in the C15 phase with the Fermi level lying near the doubly degenerate level. This model accounted for the unusual behaviour of the C15 phase. Debye temperatures were determined from the ultrasonic measurements: 295?K for the C15 phase and 315?K for the bcc phase. 相似文献
4.
E.V. Ivakin A.V. Sukhadolau O.L. Antipov N.V. Kuleshov 《Applied physics. B, Lasers and optics》2007,86(2):315-318
Mechanisms of transient light-induced refractive-index changes in Yb-doped crystals Yb:KYW, Yb:KGW and Yb:YVO4 were studied. Relative amplitudes and lifetimes of the electronic component of phase gratings caused by the polarizability
difference of the excited and unexcited Yb3+ ions and the thermal component arising from thermalization of the pump energy were measured. Polarizability difference values
of the ground 2
F
7/2 and the excited metastable 2
F
5/2 levels at the testing wavelength of 633 nm were determined for all crystals. The thermal diffusivity of the samples was estimated
for selected directions of the thermal gradient. An athermal direction, along which the thermal component of refraction disappears,
was found in Yb:KYW crystal under specific experimental conditions.
PACS 42.70.Hj; 42.65.An; 66.30.Xj 相似文献
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