Angle-/temperature-dependence of Raman scattering in layered NbSe3 crystal

Abstract

Distinguishing the lattice vibrational modes of different Raman peaks and further studying the temperature-dependent behaviour of the different Raman modes are fundamental subjects for Raman spectroscopy of single crystal. Herein, we conducted a comprehensive study of angle- and temperature-dependant Raman scattering behaviour in high-crystalline NbSe3 layers prepared by chemical vapour transport method. The polarization experiments performed on NbSe3’s (100) crystal surface revealed that the Raman peaks could be clearly identified as Ag and Bg vibrational modes, indicating significantly anisotropic structure. Meanwhile, the effect of charge density wave (CDW) transition on the lattice vibrational behaviour was studied by investigating temperature-dependent Raman scattering spectra above and below the CDW transition temperature. It was observed that Raman shifts versus temperature for the four prominent Raman peaks of NbSe3 which belonged to Ag vibrational mode exhibited linear softening behaviour as the temperature increased from 83k to 293k. The temperature coefficient of Raman peaks fitted by Grüneisen model further confirmed the anharmonicity of the lattice in NbSe3 crystal, suggesting that the changes of ionic positions across the CDW transition has small effect on its Raman scattering behaviour.

NbSe2 Crystals Growth by Bromine Transport

“…01-072-1621) phase with lattice cell parameters of a = 0.344(9) nm, b = 0.344(9) nm and c = 2.539(3) were obtained. In Figure 2, some faint peaks are also detected (marked with asterisks) which match the peaks in the X-ray diffraction pattern of monoclinic [17] NbSe 3 (JCPDS card no. 00-029-0950).…”

“…The spectrum in Figure 4 contains two additional features (marked with asterisks) which are identified as originating from the minor NbSe 3 inclusions in our specimen: a shoulder at the low-frequency side (~220 cm −1 ) of the A 1g line and a feature at about 145-155 cm −1 which may also be viewed as a shoulder to the broad "soft mode" band. The shoulder at 220 cm −1 coincides with the strongest A g Raman line of monoclinic NbSe 3 at ~218 cm −1 [17], and the broad feature at 145-155 cm −1 matches the frequency range of the strongest band in the NbSe 3 Raman spectrum consisting of three other A g lines at 143, 156 and 164 cm −1 [17].…”

Layer-Structured Anisotropic Metal Chalcogenides: Recent Advances in Synthesis, Modulation, and Applications

“…The 1D structure generally consists of an elongated chalcogen shell with a metal core . The well-known NWs, NRBs, and NBs of TMTC compounds are TiS 3 , − NbSe 3 , − TaSe 3 , TaTe 3 , HfTe 3 , , ZrTe 3 , , and others . Apart from the TMTCs, many M–X combinations have also been achieved in the NW form, including MX (e.g., MoTe, WTe) and M 6 X 6 (e.g., Mo 6 S 6 , − Mo 6 Se 6 , Mo 6 Te 6 , W 6 Te 6 ), mono and multi MC alloys (e.g., MoS x Se 1– x , Mo x W 1– x S, AgSeTe, and CoSeTe), chalcogenide-cluster-based semiconducting NTs, and hybrid metal organic chalcogenides .…”