Temperature-induced phase transitions in BaTbO3 |
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| Institution: | 1. Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands;2. NWO Physics, ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK;3. ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK;1. N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 119991 Moscow, Russian Federation;2. G. K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russian Federation;1. Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG, Brazil;2. UNIFESP, Universidade Federal de São Paulo, 09972-270 Diadema, SP, Brazil;3. LIEC, Instituto de Química, Universidade Estadual Paulista, 14800-900 Araraquara, SP, Brazil;4. INCTMN-UFSCar, Universidade Federal de São Carlos, 13565-905 São Carlos, SP, Brazil;1. CNR-SPIN and Dipartimento di Fisica “E. R. Caianiello”, Università degli Studi di Salerno, I-84084 Fisciano, Sa, Italy;2. CNR-IMM UOS Napoli, Italy |
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| Abstract: | The crystal structures of BaTbO3 have been investigated over a wide temperature range between 40 and 773 K using high-resolution time-of-flight neutron powder diffraction. Two-phase transitions were observed. Below about 280 K, BaTbO3 adopts an orthorhombic perovskite structure (space group Ibmm), which is characterized by rotation of TbO6 octahedra about the pseudocubic two-fold axis. Above 280 K, BaTbO3 undergoes a first-order phase transition to a tetragonal symmetry (space group I4/mcm), in which the tilting of the octahedra is around the pseudocubic four-fold axis. As the temperature is further increased, BaTbO3 adopts the primitive cubic aristotype at about 623 K. This later phase transformation is characterized by a gradual decrease of the rotation angle, indicating a continuous phase transition, which is described by a critical exponent β=0.35. |
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