Controlling dielectric properties of Nb + X (X = Al, Ga, In) co-doped and Nb-doped rutile-type TiO<sub>2</sub> single crystals

Kakimoto, Shota; Hashimoto, Yujiro; Kuwano, Taro; Kawasaki, Koji; Hayashi, Koichi; Hagiwara, Manabu; Deguchi, K.; Taniguchi, Hiroki

doi:10.1039/d2tc03914a

Cited by 7 publications

(2 citation statements)

References 52 publications

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“…[19][20][21] This confusion has also obscured the study, and understanding, of possible novel high permittivity intrinsic bulk phenomena 22,23 although this is still a topic of active discussion. 24,25 The time constant, τ of an RC element is dimensionless since:…”

Section: Experimental Considerations and Data Collectionmentioning

confidence: 99%

Impedance and Dielectric Spectroscopy of Functional Materials: A Critical Evaluation of the Two Techniques

Ramírez-González,

Sinclair,

West

2023

J. Electrochem. Soc.

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Impedance and dielectric spectroscopies are closely-related techniques for measuring electrical properties of materials. The techniques differ in two ways. First, impedance measurements are usually made over several decades of frequency (ie broadband) whereas most dielectric measurements are made at fixed frequency. Second, time constants that control semicircles in impedance complex plane plots and peaks in permittivity or tan δ spectroscopic plots are not the same. In impedance data, time constants represent conducting components and parallel resistance-capacitance (RC) combinations; in permittivity data they represent dielectric processes and series RC combinations. Differences between the techniques are confined to data analysis procedures and interpretation. Using broadband data, it is possible to (i) determine the best equivalent circuit to fit experimental data, (ii) unambiguously evaluate and assign resistance, capacitance and time constant parameters to regions of the material being measured and (iii) quantify departures from ideality using constant phase elements, CPEs. The advantages of using broadband measurements are highlighted with two examples: calcium copper titanate, CCTO which is often, erroneously, described as a giant or colossal dielectric; lead magnesium niobate, PMN, the classic relaxor ferroelectric whose characteristic properties are controlled entirely by the presence of non-ideality, represented by a CPE, in its equivalent circuit.

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Section: Experimental Considerations and Data Collectionmentioning

confidence: 99%

Impedance and Dielectric Spectroscopy of Functional Materials: A Critical Evaluation of the Two Techniques

Ramírez-González,

Sinclair,

West

2023

J. Electrochem. Soc.

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“…Derivative structure enumeration Oxides composed of alkaline earth and transition metal elements, with rutile, perovskite, Ruddlesden-Popper, and orthorhombic Cmcm structures, were used as prototypes for co-doping and isovalent substitutions. Co-doping in rutile TiO 2 and rutile phases 21 of SiO 2 (stishovite) and SnO 2 was explored for boosting the dielectric permittivity in these materials 7,9,13,22 . In rutile prototypes, aliovalent co-doping with III-V (Al 3+ , Ga 3+ , In 3+ , Sc 3+ , Y 3+ , La 3+ -V 5+ , Nb 5+ , Ta 5+ ) and II-VI (Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ -Cr 6+ , Mo 6+ , W 6+ ) ions was performed at the X=Ti 4+ /Si 4+ /Sn 4+ cation sites, with the general formula A (4-δ)+ B (4+δ)+ X 2 O 8 , with δ=1,2.…”

Section: Datasetmentioning

confidence: 99%

Machine learning and atomistic origin of high dielectric permittivity in oxides

Shimano,

Kutana,

Asahi

2023

Preprint

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Discovering new stable materials with large dielectric permittivity is important for future energy storage and electronics applications. Theoretical and computational approaches help design new materials by elucidating microscopic mechanisms and establishing structure-property relations. Ab initio methods can be used to reliably predict the dielectric response, but for fast materials screening, machine learning (ML) approaches, which can directly infer properties from the structural information, are needed. Here, random forest and graph convolutional neural network models are trained and tested to predict the dielectric constant from the structural information. We create a database of the dielectric properties of oxides and design, train, and test the two ML models. Both approaches show similar performance and can successfully predict response based on the structure. The analysis of the feature importance allows identification of local geometric features leading to the high dielectric permittivity of the crystal. Dimensionality reduction and clustering further confirms the relevance of descriptors and compositional features for obtaining high dielectric permittivity.

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Re-estimation of Maxwell-Wagner relaxation for novel absorbers via (Ta+Ga)-doped rutile-type TiO2 ceramics with various valence proportions and sintering temperatures

Kuwano

Hashimoto

Deguchi

et al. 2023

Journal of Alloys and Compounds

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Controlling dielectric properties of Nb + X (X = Al, Ga, In) co-doped and Nb-doped rutile-type TiO₂ single crystals

Abstract: Dielectric measurements are performed in Nb+X (X = Al, Ga, In) co-doped and Nb-doped rutile-type TiO2 single crystals before and after annealing in X2O3 powders, with which an environment of...

Cited by 7 publications

References 52 publications

Impedance and Dielectric Spectroscopy of Functional Materials: A Critical Evaluation of the Two Techniques

Impedance and Dielectric Spectroscopy of Functional Materials: A Critical Evaluation of the Two Techniques

Machine learning and atomistic origin of high dielectric permittivity in oxides

Re-estimation of Maxwell-Wagner relaxation for novel absorbers via (Ta+Ga)-doped rutile-type TiO2 ceramics with various valence proportions and sintering temperatures

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Controlling dielectric properties of Nb + X (X = Al, Ga, In) co-doped and Nb-doped rutile-type TiO2 single crystals

Abstract: Dielectric measurements are performed in Nb+X (X = Al, Ga, In) co-doped and Nb-doped rutile-type TiO2 single crystals before and after annealing in X2O3 powders, with which an environment of...

Cited by 7 publications

References 52 publications

Impedance and Dielectric Spectroscopy of Functional Materials: A Critical Evaluation of the Two Techniques

Impedance and Dielectric Spectroscopy of Functional Materials: A Critical Evaluation of the Two Techniques

Machine learning and atomistic origin of high dielectric permittivity in oxides

Re-estimation of Maxwell-Wagner relaxation for novel absorbers via (Ta+Ga)-doped rutile-type TiO2 ceramics with various valence proportions and sintering temperatures

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Controlling dielectric properties of Nb + X (X = Al, Ga, In) co-doped and Nb-doped rutile-type TiO₂ single crystals