Lattice dynamics of ASb2O6 ( A=Cu , Co) with trirutile structure

Abstract

Raman spectroscopy experiments on single crystals of CuSb2O6 and CoSb2O6 quasi-onedimensional antiferromagnets with trirutile crystal structure were performed, with a focus on the first material. The observed Raman-active phonon modes and previously reported infrared-active modes were identified with the aid of ab-initio lattice dynamics calculations. The structural transition between monoclinic β-CuSb2O6 and tetragonal α-CuSb2O6 phases at Ts = 400 K is manifested in our spectra by a "repulsion" of two accidentally quasi-degenerate symmetric modes below Ts, caused by a phonon mixing effect that is only operative in the monoclinic β-CuSb2O6 phase due to symmetry restrictions. Also, two specific phonons, associated with CuO6 octahedra rotation and with a Jahn-Teller elongation mode, soften and broaden appreciably as T → Ts. A crossover from a displacive to an order-disorder transition at Ts is inferred.

Anisotropic phonon and magnon vibration and gate-tunable optoelectronic properties of nickel thiophosphite

“…Although phonon modes still exist at high power, the peak bandwidths are increasing at a high intensity of laser power due to a reduced phonon's lifetime, which could disappear when the power is increased further. These results further indicate that these phonon modes are softening due to thermal expansion and anharmonic phonon-phonon coupling [54] (see detailed discussion in figure 3). Figure 5(c) reveals the Raman shift of A g and B g modes under laser power excitation.…”

A Gas Sensor for Application as a Propane Leak Detector

“…These behaviors are due to the nature of the charge carrier that the semiconductor possesses. According to the literature, several semiconductor materials have been proposed for sensing applications, being some of them binary semiconductors (like NiO, CuO, WO 3 , and TiO 2 ) [11], perovskites (BaTiO 3 , NdCoO 3 , and ZnSnO 3 ) [12][13][14], spinels (AlCo 2 O 4 , NiFe 2 O 4 , and MgFe 2 O 4 ) [15][16][17], and trirutiles (MX 2 O 6 where M can be Ni, Co, or Cu and X is replaced by Sb or Ta [18,19], like NiSb 2 O 6 [20], CoTa 2 O 6 [21], and NiTa 2 O 6 [22]). Regardless of the semiconductor material used for the sensor, an electronic circuit with desirable features is required for signal adaptation: low cost, high functionality, fast response, high sensitivity, excellent repeatability, high resolution, and easy construction.…”