Tin Titanate - the hunt for a new ferroelectric perovskite.

Author(s) Gardner, J.; Thakre, A.; Kumar, A.; Scott, J.F.
Journal Rep Prog Phys
Date Published 2019 Aug 01

We review all the published literature and show that there is no experimental evidence for homogeneous tin titanate SnTiO<sub>3</sub> in bulk or thin-film form. Instead a combination of unrelated artefacts are easily misinterpreted. The X-ray Bragg data are contaminated by double scattering from the Si substrate, giving a strong line at the 2-theta angle exactly where perovskite SnTiO<sub>3</sub> should appear. The strong dielectric divergence near 560K is irreversible and arises from oxygen site detrapping, accompanied by Warburg/Randles interfacial anomalies. The small (4 μC/cm<sup>2</sup>) apparent ferroelectric hysteresis remains in samples shown to be pure (Sn,Ti)O<sub>2</sub> rutile/cassiterite, in which ferroelectricity is forbidden. Only very recent work reveals real bulk SnTiO</sub>3<sub>, but it possesses an ilmenite-like structure with an elaborate array of stacking faults, not suitable for ferroelectric devices. Unpublished TEM data reveal an inhomogeneous SnO layered structured thin films, related to shell-core structures. The harsh conclusion is that there is a combination of unrelated artefacts masquerading as ferroelectricity in powders and ALD films; and only a trace of a second phase in PLD film data suggests any perovskite content at all. The fact that X-ray, dielectric, and hysteresis data all lead to the wrong conclusion is instructive and reminds us of earlier work on copper calcium titanate (a well-known boundary-layer capacitor).

DOI 10.1088/1361-6633/ab37d4
ISSN 1361-6633
Citation Gardner J, Thakre A, Kumar A, Scott JF. Tin Titanate - the hunt for a new ferroelectric perovskite. Rep Prog Phys. 2019.

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