Phase transition in the mixed crystals Tb_pY_1−pAsO₄

Abstract

The energy of the four lowest crystal field levels of Tb3+ in the mixed crystals Tb,Y1 -pA804 i s investigated in the range of the crystallographic and magnetic phase transition as a function of temperature and Tb-concentration (0.2 < p 1). The results show that, in contrast to the magnetic ordering, the interaction causing the crystallographic transition is of long range and hence a simple molecular field theory fits the experimental data. For small Tb-concentrations, the feature of this system are superimposed by effects of internal strains caused by the substitution of Tb8+ by Ys+ ions.Die Energie der vier tiefsten Kristallfeldzustiinde der Tbs+-Ionen im Mischkriitallsystem Tb,Y1 -pAsO, wird im Bereich des kristallographischen und des magnetischen Phaseniibergengs als Funktion der Temperatur und der Tb-Konzentration (0,2 < p 1) untersucht. Da der kristallographische Phaseniibergang, im Gegensatz zum magnetischen, von langreichweitigen Wechselwirkungen verursacht wird, liefert eine einfache Molekularfeld-Theorie gute Ubereinstimmung mit den experimentellen Ergebnissen. Bei kleiner Tb-Konzentration miissen jedoch innere Verspannungen im Kristall beriicksichtigt werden, die durch Substitution von Tb8+ durch Ys+ verursacht werden. 13.

Predicting the Stability of the Solid-Solution Sc1−xLnxAsO4 and TbxLn1−xAsO4 Orthoarsenates

“…This does not allow comparing the calculation results with the experimental data for the systems under study. At the same time, polymorphic transitions in solid solutions of the Tb x Y 1x AsO 4 and Tb x Tm 1x AsO 4 systems at temperatures below 30 K were previously studied [24,25]. It was found that, in the Tb x Y 1x AsO 4 system, the temperature of the phase transition from tetragonal symmetry to rhombic one increases regularly from 5.8 to 27.3 K when x varies from 0.32 to 1, and in the Tb x Tm 1x AsO 4 system, when x changes from 0 to 1, it increases from 6.1 to 25.5 K [24,25].…”

“…At the same time, polymorphic transitions in solid solutions of the Tb x Y 1x AsO 4 and Tb x Tm 1x AsO 4 systems at temperatures below 30 K were previously studied [24,25]. It was found that, in the Tb x Y 1x AsO 4 system, the temperature of the phase transition from tetragonal symmetry to rhombic one increases regularly from 5.8 to 27.3 K when x varies from 0.32 to 1, and in the Tb x Tm 1x AsO 4 system, when x changes from 0 to 1, it increases from 6.1 to 25.5 K [24,25]. This indicates in the first case a wide range of formation of solid solutions, and in the second case, the presence of unlimited miscibility of components at temperatures of about 30 K.…”

“…The results of critical decomposition temperatures for these systems (56 and 139 K, respectively; Table 2), considering the accuracy of the calculation method (close to 100 K), are consistent with the results of Refs. [24,25].…”

Jahn-Teller effects in the mixed vanadate/phosphate crystalsTbV1−xPxHirano1, Wakabayashi2, Loong3 et al. 2003Phys. Rev. B

“…[5][6][7][8][9][10][11][12][13][14][15][16][17] In general, a reduction of the transition temperature T D was observed in these mixed compounds. A modified molecular-field model was developed to explain the experimental data.…”

Investigations on the mixed Jahn-Teller system (Tbx, Dy1-x)VO4. I. Phase diagram, specific heat and spectroscopic measurements

“…The temperature dependence of the order parameter and the specific heat were published only for mixtures distorting like TbV0, [14,17,19,201. For mixtures containing Dy3+, only the transition temperatures (and some dielectric data) are known [15,18,211.…”