Phase transitions in K-doped MoO2

Abstract

K 0.05 MoO 2 has been studied by x-ray and neutron diffractometry, electrical resistivity, magnetization, heat capacity, and thermal expansion measurements. The compound displays two phase transitions, a first-order phase transition near room temperature and a second-order transition near 54 K. Below the transition at 54 K, a weak magnetic anomaly is observed and the electrical resistivity is well described by a power-law temperature dependence with exponent near 0.5. The phase transitions in the K-doped MoO 2 compound have been discussed for the first time using neutron diffraction, high resolution thermal expansion, and heat capacity measurements as a function of temperature. V

Evidence of phase transitions in MoO2 single crystals

“…The hysteresis between cooling and warming resistivity curves near room temperature has been related to a first-order phase transition. Similar hysteresis has been observed in the correlated K 0.05 MoO 2 compound [4].…”

“…the lattice contribution (see inset in the main panel of figure 3).When plotted in this manner, the data exhibit linear behavior in the range 2 < T 2 < 120 K 2 . The fit reveals a value of  = 1.85 (3) mJ mol −1 K −2 and β = 0.0315 (5) mJ mol −1 K −4 , which leads to a Debye temperature of Θ D = 635 K. For comparison, Debye temperature of 525 K has been reported for MoO 2 polycrystalline samples[4]. Specific heat measurement as a function of temperature for a MoO 2 single crystal.…”

“…Molybdenum oxides are well known; nevertheless, they continue to receive extensive attention because of their great stoichiometric and physical properties variety [1][2][3][4][5][6]. The ideal molybdenum dioxide is monoclinic, weakly paramagnetic, and displays a conventional metallic behavior [7,8].…”

A magnetic field tuned metal–insulator transition in unconventional metallic K‐doped MoO

“…Similar behaviors have been found for several samples with different K compositions. Previous results suggest that this transition is a first‐order phase transition .…”