Unidentified Phase Transition in Polar Lanthanum Tantalate (LaTaO4)



The family of crystals with formula ABX4 represent a very interesting class of ferroelectrics that are extremely two-dimensional. Fluorides have been extensively researched but there is great potential for oxides of this class, such as LaTaO4, due to oxides being favoured for device applications. Studies have reported the evolution of morphologies of LaTaO4 with temperature, but one phase transition at ~200ºC is accompanied by an anomalously small peak in permittivity, which suggests the transition is unusual. Variable temperature XRD of this material has revealed a change in lattice parameters which coincide with the phase transition but this is suspected to be a consequence of a shift in oxygen positions. It is then suggested that by using HRPD, the change in oxygen positions can be observed across the phase transition and hence the structural distortion can be characterised.
Date made available2018
PublisherScience and Technology Facilities Council

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