Dependencies of the lattice parameters and the coefficient of thermal expansion of TlInTe2 crystals on temperature are studied at a wide range of temperatures by using XRD, dilatometer, differential thermal analysis, and impedance spectroscopy (IS) methods. The IS measurements of the dielectric function were done along the c-axis and normal to the (110)-plane. IS for E ⊥ (110)-plane was done for two values of the amplitudes, U0 = 0.04 V and 1 V, of ac-voltage with different frequencies; moreover, the measurements for E∥c were realized at U0 = 0.04 V only. IS measurements demonstrate a sequence of the phase transitions (PTs) to the ferroelectric and the ionic conductivity states, also to a structural phase transition. Tl+ ions are shown to shift in the direction of normal to c-axis in the ferroelectric PT, but they are activated along the c-axis in the ionic conductivity PT. The dielectric function in the ionic conductivity PT is shown to increase to a huge positive value and then to drop to a big negative value, reversing its sign. An explanation of this effect is provided as a competition of Drude and polarization contribution to the dielectric function under ac-electric field. Thermal effects of the phase transitions were determined.
In the search for new materials exhibiting both ferromagnetic and semiconducting properties, approximately 10% Fe has been incorporated into the large gap semiconductor In 2 S 3 , resulting in a new spinel compound Fe 0.76 In 2.17 S 4 . Magnetic measurements show properties of a canonical spin glass state below a freezing temperature of T F = 5 K. Standard powder x-ray diffraction at room temperature revealed the cubic spinel structure. Further structural investigations by high-resolution neutron powder diffraction in the temperature range 1.6 K T 280 K confirmed the spinel structure with an almost complete cation inversion corresponding to an inversion parameter of 0.94. A mutually consistent description of the neutron diffraction data, EDX analysis and magnetic measurements show that the present compound may be written as (Fe 0.04 In 0.89 0.07 ) A (Fe 0.72 In 1.28 ) B S 4 , with denoting vacancies. No magnetic intensities could be observed, in agreement with a spin glass state.
Mit DTA, Röntgen‐Phasen‐Analysen (XPA), Mikrostruktur‐Analysen, Messung der Mikrohärte und der Widerstände werden die Bereiche der Mischkristallbildung im Titelsystem bestimmt, die bei 0‐55.0 und 70‐100mol‐% TlInSe2 liegen.
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