التفاصيل البيبلوغرافية
| العنوان: |
First-order character of the displacive structural transition in BaWO4. |
| المؤلفون: |
Tan Da-Yong1, Xiao Wan-Sheng1 wsxiao@gig.ac.cn, Zhou Wei1, Chen Ming1, Xiong Xiao-Lin1, Song Mao-Shuang1 |
| المصدر: |
Chinese Physics B. Aug2012, Vol. 21 Issue 8, p1-9. 9p. |
| مصطلحات موضوعية: |
*POLYHEDRA, *BARIUM compounds, *PHASE transitions, *X-ray diffraction, *RAMAN effect, *HYSTERESIS |
| مستخلص: |
Nearly all displacive transitions have been considered to be continuous or second order, and the rigid unit mode (RUM) provides a natural candidate for the soft mode. However, in-situ X-ray diffraction and Raman measurements show clearly the first-order evidences for the scheelite-to-fergusonite displacive transition in BaWO4: a 1.6% volume collapse, coexistence of phases, and hysteresis on release of pressure. Such first-order signatures are found to be the same as the soft modes in BaWO4, which indicates the scheelite-to-fergusonite displacive phase transition hides a deeper physical mechanism. By the refinement of atomic displacement parameters, we further show that the first-order character of this phase transition stems from a coupling of large compression of soft BaO8 polyhedrons to the small displacive distortion of rigid WO4 tetrahedrons. Such a coupling will lead to a deeper physical insight in the phase transition of the common scheelite-structured compounds. [ABSTRACT FROM AUTHOR] |
| قاعدة البيانات: |
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