Thermodynamical mechanisms of elastically anisotropy straining stresses in the changes of the phase transition and properties of magnetic dielectrics under T-H-P influence

• Дата: 2004
• Автори: Polyakov, P.I., Kucherenko, S.S.
• Формат: Стаття
• Мова: English
• Опубліковано: НТК «Інститут монокристалів» НАН України 2004
• Назва видання: Functional Materials
• Онлайн доступ: http://dspace.nbuv.gov.ua/handle/123456789/139445
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Цитувати: Thermodynamical mechanisms of elastically anisotropy straining stresses in the changes of the phase transition and properties of magnetic dielectrics under T-H-P influence/ P.I. Polyakov, S.S. Kucherenko // Functional Materials. — 2004. — Т. 11, № 3. — С. 461-470. — Бібліогр.: 38 назв. — англ.

Basing on experimental investigations, the role of elastically anisotropic straining stresses in the formation and change of structural phase transitions and properties of magnetic dielectric have been proposed and explained. From experimental investigations of the resonance properties of CuCI₂ • 2H₂O single crystal, being a low-temperature magnetic dielectric, a correspondence between the T, H and P influence (1 K, 4 kOe, 3 kbar) on structural phase transition has been determined. The thermomagnetic and thermobaromag-netic effects have been revealed. Their peaks have the same temperature tpp = 0 K coincident with the temperature T₂T of structural phase transition. Sign alternation in "cooling" and "heating" effects of Тр(Н) shifting are also found. The critical points PX’ Tx and P have the temperature parameter Tp = 9.2 K that differs significantly from the known TN = 4.3 K in these materials. The magnetization, field-temperature, and field-frequency dependences have been considered, and a conformity in changes of the properties before and after the structural phase transition has been established. The effect of thermo-EAS striction is found, which is a regularity in the phase state changing under thermostriction influence in magnetic dielectric. The competitive mechanisms of thermo- and magnetostriction causing changes in the high-frequency properties give rise to two resonances before and after the structural phase transition.