Lithuanian Journal of Physics article / Lietuvos fizikos žurnalo straipsnis

QUANTUM PARAELECTRICITY AND INDUCED FERROELECTRICITY BY GERMANIUM DOPING OF (Pb_ySn_1–_y)₂P₂S(Se)₆ SINGLE CRYSTALS
Ilona Zamaraitė^a, Andrius Džiaugys^a, Yulian Vysochanskii^b, and Jūras Banys^a
^aFaculty of Physics, Vilnius University, Saulėtekio 9, 10222 Vilnius, Lithuania
^bInstitute of Solid State Physics and Chemistry, Uzhgorod University, 46 Pidgirna St., 88000 Uzhgorod, Ukraine
Email: ilona.zamaraite@ff.vu.lt

Received 24 January 2020; revised 26 March 2020; accepted 6 April 2020

In this paper we report a dielectric study on four single crystals Pb₂P₂S₆, (Pb_0.98Ge_0.02)₂P₂S₆, (Pb_0.7Sn_0.3)₂P₂S₆ + 5% Ge and (Pb_0.7Sn_0.3)₂P₂Se₆ + 5% Ge down to 20 K. A new quantum paraelectric state was reported in the Ge-doped samples at low temperatures. In all of these materials the non-classical T² temperature dependences of inverse dielectric permittivity were observed. The dielectric constants of Pb₂P₂S₆-based single crystals were measured between 20 and 300 K. The temperature dependences of dielectric permittivity were analysed on the basis of Barrett’s model as a signature of quantum paraelectricity.

Keywords: dielectric properties, ferroelectric phase transition, quantum paraelectricity, phosphorus chalcogenide crystals, PPb₂P₂S₆
PACS: 77.22.-d, 77.80.B-

KVANTINIS PARAELEKTRIŠKUMAS IR INDUKUOTASIS FEROELEKTRIŠKUMAS ĮTERPIANT GERMANĮ Į (Pb_ySn_1–_y)₂P₂S(Se)₆ KRISTALUS
Ilona Zamaraitė^a, Andrius Džiaugys^a, Yulian Vysochanskii^b, Jūras Banys^a

^aVilniaus universiteto Fizikos fakultetas, Vilnius, Lietuva
^bUžgorodo universiteto Kietojo kūno fizikos ir chemijos institutas, Užgorodas, Ukraina

Darbe tyrinėjamos keturių kristalų – Pb₂P₂S₆, (Pb_0,98Ge_0,02)₂P₂S₆, (Pb_0,7Sn_0,3)₂P₂S₆ + 5 % Ge ir (Pb_0,7Sn_0,3)₂P₂S₆ + 5 % Ge – dielektrinės savybės intervale nuo kambario temperatūros iki 20 K. Atlikti tyrimai leido nustatyti kvantinę paraelektrinę būseną kristaluose, kuriuose buvo įterpta germanio priemaišų. Visose tirtose medžiagose stebėtas atvirkštinės dielektrinės skvarbos nukrypimas nuo Kiuri ir Veiso dėsnio, aprašytas T² temperatūrine priklausomybe. Tirtųjų kristalų dielektrinės skvarbos temperatūrinės priklausomybės analizuotos remiantis Barrett’o modeliu.

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