Magnetic Susceptibility of Powders of Hydrogen Intercalates of Niobium Diselenide

We have studied the structurally sensitive magnetic susceptibility of intercalates H^sub x^NbSe^sub 2^ (0 ≤ x ≤ 5.2) in the temperature range 4.2 to 300 K (the compound is obtained by intercalation by hydrogen from the gas phase in niobium diselenide powders). We have shown that intercalation leads to a reverse structural transition of the type 2H-TaS^sub 2^ [arrow right] 2H-MoS^sub 2^ at x = 0.92, which is accompanied by an abrupt decrease (by more than two orders of magnitude) in the Pauli paramagnetism all the way to the diamagnetic state. Such behavior of the magnetic susceptibility is explained by formation of negative hydrogen ions with a large ionic radius in the interval 0 < x < 0.9, and a decrease in the charge carrier concentration and the density of electron states on the Fermi surface with an increase in hydrogen amount intercalated into quasi-two-dimensional layers.[PUBLICATION ABSTRACT]