Critical exponents of the order parameter of diffuse ferroelectric phase transitions in the solid solutions based on lead germanate: studies of optical rotation

Autor: D. I. Adamenko, R. O. Vlokh
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Condensed Matter Physics, Vol 25, Iss 4, p 43703 (2022)
Druh dokumentu: article
ISSN: 1607-324X
2224-9079
DOI: 10.5488/CMP.25.43703
Popis: In this work we show that the critical exponents of the order parameter (CEOPs) of diffuse ferroelectric phase transitions (DFEPTs) occurring in lead germanate-based crystals can be determined using experimental temperature dependences of their optical rotation. We also describe the approach that suggests dividing a crystal sample into many homogeneous unit cells, each of which is characterized by a non-diffuse phase transition with a specific local Curie temperature. Using this approach, the CEOPs have been determined for the pure Pb5Ge3O11 crystals, the solid solutions Pb_5(Ge_(1-x)Si_x)3O_11 (x = 0.03, 0.05, 0.10, 0.20, 0.40) and (Pb_(1-x)Ba_x)5Ge_3O_11 (x = 0.02, 0.05), and the doped crystals Pb_5Ge_3O_11:Li^3+ (0.005 wt.), Pb_5Ge_3O_11:La^3+ (0.02 wt.), Pb_5Ge_3O_11:Eu^3+ (0.021 wt.), Pb_5Ge_3O_11:Li^3+, Bi^3+ (0.152 wt.) and Pb_5Ge_3O_11:Cu^2+ (0.14 wt.). Comparison of our approach with the other techniques used for determining the Curie temperatures and the CEOPs of DFEPTs testifies to its essential advantages.
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