Phase transitions, electronic properties, and superconductivity in the systemV2ZrHx

Abstract

We present experimental results for the magnetic susceptibility in the temperature range between 10 and 300 K and for the low-temperature specific heat in samples of nominal composition V&ZrH",

Acoustic investigations of the ZrV2–H system

“…At the same time the decomposition does not change the symmetry, but ordering leads to a symmetry reduction. According to the data reported in [12] the decomposition of the cubic ␣-phase into two ␣ and ␣ phases of different hydrogen concentrations (x ␣ > x ␣ ) takes place below 250 K in the range 0 < x < 1.3. Upon further decrease of the temperature down to 200 K, the formation of an ordered ␤-phase with tetragonal symmetry takes place.…”

“…The structural state of the ZrV 2 H x system at temperatures above 150 K was investigated by several authors using Xray diffraction [12], calorimetry [11,12], DTA [13], magnetic susceptibility [14], and thermal desorption [14]. In all investigations, peculiarities were observed related to structural transformations in the hydrogen sublattice.…”

Oscillatory Hydrogen Solution in ZrV2

“…Because the stratification is not accompanied by any heat effect (within the limits of calorimeter sensitivity), but only by an abrupt change of heat capacity one can suppose that the interphase boundaries lower than 160 K are primarily coherent. This is possible since the difference between the lattice parameters of the a-phase, 0.7433 nm and c of the b-phase, 0.7530 nm [5] at the considered temperatures is 1.5%.…”

“…The authors link the anomalies of the elasticity characteristics at 260 K with the ordering of hydrogen absorbed from air. Such uncontrolled penetration of hydrogen can affect, on the contrary, the superconducting properties of C-15 intermetallic compounds [5,10] which are high-field superconductors, their upper critical field exceeds 220 kOe [11].…”

Phase transitions and thermally activated hydrogen dynamics in ZrV2Hx (0≤x≤1) intermetallic compounds

“…The (x,T) phase diagram of ZrV 2 H x has been studied by several techniques [3][4][5] and its main features are established, even though for H composition below ZrV 2 H 1 the details of the possible H ordering are yet unclear. In particular, it has been proposed [4] that below room temperature, before a true hydride forms, a two-phase region exists with two distinct cubic phases, which differ in H concentration.…”