Abstract
We synthesized Sr- and W-doped BaTiO3 (BTO) polycrystals by using a solid-state reaction method. The X-ray diffraction results showed that Sr and W atoms occupied the Ba and Ti sites in tetragonal BTO, respectively, and there were changes in the lattice constants and the volumes in the Sr- and W-doped BTO. We found a change in the latent heat and the Curie temperature (TC) during the transition between the ferroelectric and paraelectric phases while increasing the contents of Sr and W in the Sr- and W-doped BTO. This can be explained by the fact that the doping of Sr and W atoms in BTO prevented a distinct transition between the ferroelectric tetragonal and paraelectric cubic structures by decreasing the c/a ratio to a value close to unity. This study shows a way toward a strategy for modulating a crystal structure by using proper dopants for future applications in ferroelectricity-based devices.
Highlights
In the field of condensed-matter physics, ferroelectricity has been studied for decades because spontaneous electrical polarization can be obtained without an electrostatic potential, and the direction of polarization can be tuned by using an external electric field [1,2,3]
The results of this study show that the room-temperature phases of Sr-and W-doped BTO have a cube-like structure with a reduced c/a ratio; the ferroelectricity of tetragonal BTO can be suppressed by doping the A and B sites in BTO
A-site doping with Sr atoms strongly influenced the volume of the system, resulting in a decreased c/a ratio. These universal changes in the lattice resulted in a significant decrease in TC
Summary
In the field of condensed-matter physics, ferroelectricity has been studied for decades because spontaneous electrical polarization can be obtained without an electrostatic potential, and the direction of polarization can be tuned by using an external electric field [1,2,3].Ferroelectric materials are widely applicable in piezoelectric devices, condensers, IR detectors, nonvolatile memory devices, and ferroelectric random-access memory [4,5,6].Perovskite BaTiO3 (BTO), which is the best-known ferroelectric material, undergoes a distinct transition between the ferroelectric and paraelectric phases with high latent heat (~0.3 J/g) as the transition temperature, which is called the Curie temperature (TC ) [7,8].The ferro-paraelectric transition in BTO originates from the spontaneous transition between tetragonal and cubic structures around the TC of 120 ◦ C [9,10]. Ferroelectric materials are widely applicable in piezoelectric devices, condensers, IR detectors, nonvolatile memory devices, and ferroelectric random-access memory [4,5,6]. Perovskite BaTiO3 (BTO), which is the best-known ferroelectric material, undergoes a distinct transition between the ferroelectric and paraelectric phases with high latent heat (~0.3 J/g) as the transition temperature, which is called the Curie temperature (TC ) [7,8]. The ferro-paraelectric transition in BTO originates from the spontaneous transition between tetragonal and cubic structures around the TC of 120 ◦ C [9,10]. When the room-temperature ferroelectric phase, tetragonal BTO, is heated above TC , the lattice constants of a and c become identical, resulting in a cubic structure, which exhibits no spontaneous polarization.
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