Anomalous dielectric behaviour at the monoclinic to tetragonal phase transition in La(Nb0.9V0.1)O4
- Zhou, D.
- Guo, H.-H.
- Fu, M.S.
- Yao, X.
- Lin, H.
- Liu, W.
- Pang, L.-X.
- singh, C.
- Trukhanov, S.
- Trukhanov, A.
- Reaney, I.M.
DOIAbstract
La(Nb0.9V0.1)O4 has been shown by in-situ Raman spectra and X-ray diffraction to undergo a ferroelastic phase transition from monoclinic fergusonite to tetragonal scheelite (TM-T) at 350 oC, accompanied by 3.55% spontaneous strain and an abrupt change in thermal expansion coefficient (αL) from +15.5 ppm/oC to +11.4 ppm/oC. Assuming a linear relation between polarizability and temperature, an anomalous decrease in relative permittivity (εr) at TM-T is predicted from the Clausius–Mosotti relation and Shannon’s additive rule. Such an anomalous decrease in εr at a phase transition has not previously been observed in ferroic and linear dielectrics and may aid in the design of novel microwave dielectric composites
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