Calorimetric study and Landau analysis of the phase transitions in PbZr_1–xSn_xO₃ single crystals with 0 ≤ x ≤ 0.4

Abstract

Differential scanning calorimetry experiments have been performed for PbZr 1-x Sn x O 3 single crystals where 0 ≤ x ≤ 0.4 at the temperature range of 100 -600 K. The temperatures and orders of particular phase transitions have been determined and the phase diagram was compared to dielectric measurements. The first order character of the phase transitions in PbZr 1-x Sn x O 3 was discussed. The total transitions energy and entropy at the phase transitions were calculated. The excess specific heat and excess entropy associated with the phase transitions were analysed using Landau theory. The comparison of calorimetric data with the evolution of the order parameter indicates that the phase transitions in PbZr 1-x Sn x O 3 single crystals seem to follow a mean field Landau potential. The results are compared to the earlier dielectric and birefringence experiments.

Brillouin scattering, DSC, dielectric and X-ray diffraction studies of phase transitions in antiferroelectric PbHfO3:Sn

“…Furthermore, doping may lead to the appearance of an intermediate phase. For instance, PbZr 1Àx Sn x O 3 (PZS) with x in the range 0.05-0.3 and x > 0.3 shows presence of a new intermediate AFE2 phase and MMC (multicell cubic phase) phase, respectively [15][16][17][18][19]. Under external electric field, the AFE2 phase can be reverted into the FE phase what makes PZS attractive material for engineering applications [18].…”

OrthorhombicABCSemiconductors as Antiferroelectrics

“…The P bam structure of the prototypical perovskite antiferroelectric PbZrO 3 [9] is obtained through a cell-quadrupling antipolar Pb displacement mode combined with four additional modes that further double the unit cell [15]; the P bcm structure of the antiferroelectric phases of NaNbO 3 and AgNbO 3 are similarly complex [16]. Chemical substitution into the endpoint compounds allows tuning of the critical temperature, the critical field, the electric-field induced strain and polarization, and other functional properties [14,17]. Chemical substitution is also seen to induce transitions to a distinct tetragonal antiferroelectric phase, for example in Pb 1−x Sr x (Zr 1−y Ti y )O 3 [11], and to related ferroelectric phases, for example in PbZr 1−x Ti x O 3 , also obtained as distortions of the ideal perovskite structure.…”

Thermal analysis of phase transitions in PbZr1−xSnxO3 antiferroelectric single crystals

“…While for small concentrations of Sn in PbZr 1-x Sn x O 3 , the first-order character of phase transition is maintained, together with increasing of x it gradually changes into the second-order one (in Ref. [7] it was postulated that this change will start near x = 0.25). This was directly evidenced by the thermal expansion measurements, supported by specific heat measurements and decrease in the sharpness of the transition.…”

“…Numerous experiments revealed distinct differences in physical properties of single crystals with compositions of x below and above 0.25. It is believed that all of this is due to the so-called tricritical point, the existence of which was postulated in early studies [7]. It means that around this concentration, the change from the first-to second-order phase transition at T C takes place.…”

“…Simultaneously, the large value of the dielectric permittivity at T C which is observed in both PbZrO 3 and PbZr 1-x Sn x O 3 single crystals with x \ 0.25 considerably decreases in the compositions with x [ 0.25 and another intermediate phase-IM, called also ''multiple cell cubic'' [5]-appears. In our earlier studies of specific heat [7], we found that above the value of x = 0.25, the latent heat at T C at PE-IM phase transition is absent suggesting the change of the character of the phase transition to a second order in these crystals. However, in this paper, IM phase was erroneously identified as ferroelectric one.…”