T. A. Zotov

Interaction of ZrFe2 doped with Ti and Al with hydrogen

The influence of doping with Ti and Al on the structure and hydrogen sorption properties of ZrFe2 was studied by XRD, XRSMA, and measurement of hydrogen absorption and desorption isotherms at pressure up to 300 MPa. The hydrogen capacity and equilibrium desorption pressures of hydrides decrease with increasing Al content at a constant ratio of Ti and Zr. The increase in the Ti content at a constant content of Al in alloys also leads to a decrease in hydrogen capacity; however, the equilibrium desorption pressures of hydrides increase considerably. Zr1−xTix(Fe1−yAly)2 (x= 0.2–0.8; y = 0.05–0.4) alloys were investigated.

Absorption of Hydrogen by V-Mo and V-Mo-Ti Alloys

We have studied the interaction of hydrogen with V-Mo and V-Mo-Ti alloys. Hydrogen absorption and desorption isotherms have been measured, the stability ranges of the forming hydride phases have been determined, and the ΔH and ΔS of the reactions involved have been calculated. X-ray diffraction results indicate the formation of three hydride phases, with FCC and BCC structures.

Hydrogen sorption and electrochemical properties of alloys: Systems Zr-Ti-Ni-V-Mn with laves phase structures

Using scanning electron microscopy and x-ray phase analysis techniques, it is shown that the C14-type Laves phase with a wide homogeneity reaching the AB2.3 stoichiometry is the main phase in the Zr0.5Ti0.5NiyV0.5Mnx alloys, where y = 0.8–1.4 and x = 0.1–1.7. With the increase in the nickel and manganese contents and in the stoichiometric ratio B/A, the hydrogen capacity decreases from 2 to 1.6 wt %, the equilibrium pressure of hydride phases increases, and the hydrides become less stable. The highest discharge capacity is reached for stoichiometric ratios AB1.7–2.3, where the maximum discharge capacity at a discharge current density of 100 mA/g is 300 (mA h)/g. Alloys that contain ferrovanadium in place of vanadium are also considered.

STUDY OF STRUCTURE, HYDROGEN ABSORPTION AND ELECTROCHEMICAL PROPERTIES OF Ti0.5Zr0.5NiyV0.5Mnx SUBSTOICHIOMETRIC LAVES PHASE ALLOYS

We continue our previous study [14, 15] of hydrogen absorption and electrochemical properties of Ti0.5Zr0.5NiyV0.5Mnx nonstoichiometric Laves phase alloys. Two series of alloys Ti0.5Zr0.5Ni1.0V0.5Mnx (x=0.1–0.4, AB1.6 – AB1.9) and Ti0.5Zr0.5Ni1.15V0.5Mnx (x=0.1–0.55, AB1.75 – AB2.2) were prepared and investigated. Their electrochemical discharge characteristics were compared with results of Ti0.45Zr0.55Ni0.7V0.45Mnx (x=0.1–1.5, AB1.25 – AB2.6) and Ti0.45Zr0.55Ni0.85V0.45Mnx (x=0.1 1.35, AB1.4 – AB2.65) alloys corresponding to our previous study. It was shown, that the rate capability increases as the nickel content in alloy series increases. However the discharge capacity of Ti0.5Zr0.5Ni1.0V0.5Mnx alloys doesn’t significantly increase as compared with Ti0.45Zr0.55Ni0.85V0.45Mnx alloys. Moreover, the discharge capacity decreases with the further increase in the nickel content in Ti0.5Zr0.5Ni1.15V0.5Mnx alloys. The values of discharge capacities at discharge current densities 100 mA/g are in a range of 310 – 390 mAh/g.

Electrochemical Behavior of Intermetallic Compounds of the Type AB5 Synthesized during the Reduction of a Mixture of Oxides and Salts by Lithium Hydride

The intermetallic compounds LaNi4.5Co0.2Sn0.3, La0.9Zr0.1Ni4.5Al0.5, Mm0.8Ni4.7Co0.2Sn0.3, Mm0.8Ni4.7Co0.2Ge0.3, MmNi4.5Co0.2Ge0.3, and MmNi4.5Co0.2Sn0.3, which are synthesized by a new method, specifically, during a high-temperature reduction of a mixture of oxides and carbonates by lithium hydride, have high homogeneity and dispersion degree. According to electrochemical charge-discharge tests, electrodes of these compounds ensure a high discharge capacity (∼300 mA h g–1) as early as after the first 2–3 cycles and their behavior is stable and reversible.

HYDROGEN ABSORPTION PROPERTIES ZrFe2 AND ZrCo2 BASED ALLOYS

In this work Zr1-xTix(Fe1-yAly)2 system and the alloys Zr0.8Ti0.2Co1.6Al0.4 and Zr0.9Gd0.1Co2 were studied with the purpose to investigate the influence of zirconium substitution by titanium or a rare earth metals on hydrogen sorption properties of IMC ZrFe2 and ZrCo2. The hydrogen absorption properties were studied by measuring PCT absorption and desorption isotherms using a high hydrogen pressure apparatus at a hydrogen pressure below 3,000 atm. Hydrogen desorption pressures and hydrogen storage capacity decrease with increasing aluminium content in Zr1-xTix(Fe1-yAly)2alloys. The catalytic effect of gadolinium addition on acceleration of reaction of ZrCo2with hydrogen was established. The thermodynamic parameters of hydrogen desorption reactions were calculated for number alloys.

Electrochemical And Hydrogen Sorption Properties of Ab5—Type Alloys Where A — La, Ce; B — Ni, Co, Mn, Fe, Cu, Cr, Al

Like other accumulator types Ni-MH batteries are unable to keep high characteristics in the temperature range -30°C to +40°C. To solve this problem the negative electrode material - intermetallic compound (IMC) hydride - must have dissociation pressure of 0.1-1.5 atm in this temperature interval. The IMC composition was calculated with mathematic model. The model describes dependence of IMC hydrides properties on IMC composition. Using calculation results series of alloys were prepared and their hydrogen absorption and electrochemical properties were studied. The best alloy is CeMn0.5Co0.25Al0.5Ni3.75. The sample has discharge capacity 275 mAh/g, keeps 95% of this value at 40°C and 40% at -30°C.

Study of Structure and Hydrogen Absorption Properties of Alloys of Ti-Mn-V System

Ti-Mn-V metallic system is practically not described in literature. In present work the investigation of the composition and structure and their influence on alloy hydrogen absorption properties was done. The alloys were prepared by arc melting with consequent annealing at 850°C. The investigation was conducted by means of X-ray, chemical and microscopic analysis and determination of “pressure-composition” isotherms.