The Experts below are selected from a list of 195 Experts worldwide ranked by ideXlab platform

Nicolas Mary - One of the best experts on this subject based on the ideXlab platform.

  • soft chemical control of superconductivity in lithium iron selenide hydroxides li1 xfex oh fe1 yse
    Inorganic Chemistry, 2015
    Co-Authors: Hualei Sun, Daniel N Woodruff, Simon J Cassidy, Genevieve M Allcroft, Stefan J Sedlmaier, Amber L Thompson, Paul A Bingham, S D Forder, Simon Cartenet, Nicolas Mary
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1–xFex(OH)Fe1–ySe (x ∼ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction, and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesized samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasized by the demonst...

  • Soft Chemical Control of Superconductivity in Lithium Iron Selenide Hydroxides Li1–xFex(OH)Fe1–ySe
    2015
    Co-Authors: Hualei Sun, Simon J Cassidy, Genevieve M Allcroft, Stefan J Sedlmaier, Amber L Thompson, Paul A Bingham, S D Forder, Simon Cartenet, Daniel N. Woodruff, Nicolas Mary
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1–xFex(OH)­Fe1–ySe (x ∼ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction, and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesized samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasized by the demonstration that reductive postsynthetic lithiation of the samples turns on superconductivity with critical temperatures exceeding 40 K by displacing iron atoms from the Li1–xFex(OH) reservoir layer to fill vacancies in the selenide layer

  • soft chemical control of superconductivity in lithium iron selenide hydroxides li1 xfex oh fe1 yse
    arXiv: Superconductivity, 2014
    Co-Authors: Hualei Sun, Daniel N Woodruff, Simon J Cassidy, Genevieve M Allcroft, Stefan J Sedlmaier, Amber L Thompson, Paul A Bingham, S D Forder, Simon Cartenet, Nicolas Mary
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1-xFex(OH)Fe1-ySe (x ~ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesised samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasised by the demonstration that reductive post-synthetic lithiation of the samples turns on superconductivity with critical temperatures exceeding 40 K by displacing iron atoms from the Li1-xFex(OH) reservoir layer to fill vacancies in the selenide layer

Hualei Sun - One of the best experts on this subject based on the ideXlab platform.

  • soft chemical control of superconductivity in lithium iron selenide hydroxides li1 xfex oh fe1 yse
    Inorganic Chemistry, 2015
    Co-Authors: Hualei Sun, Daniel N Woodruff, Simon J Cassidy, Genevieve M Allcroft, Stefan J Sedlmaier, Amber L Thompson, Paul A Bingham, S D Forder, Simon Cartenet, Nicolas Mary
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1–xFex(OH)Fe1–ySe (x ∼ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction, and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesized samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasized by the demonst...

  • Soft Chemical Control of Superconductivity in Lithium Iron Selenide Hydroxides Li1–xFex(OH)Fe1–ySe
    2015
    Co-Authors: Hualei Sun, Simon J Cassidy, Genevieve M Allcroft, Stefan J Sedlmaier, Amber L Thompson, Paul A Bingham, S D Forder, Simon Cartenet, Daniel N. Woodruff, Nicolas Mary
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1–xFex(OH)­Fe1–ySe (x ∼ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction, and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesized samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasized by the demonstration that reductive postsynthetic lithiation of the samples turns on superconductivity with critical temperatures exceeding 40 K by displacing iron atoms from the Li1–xFex(OH) reservoir layer to fill vacancies in the selenide layer

  • soft chemical control of superconductivity in lithium iron selenide hydroxides li1 xfex oh fe1 yse
    arXiv: Superconductivity, 2014
    Co-Authors: Hualei Sun, Daniel N Woodruff, Simon J Cassidy, Genevieve M Allcroft, Stefan J Sedlmaier, Amber L Thompson, Paul A Bingham, S D Forder, Simon Cartenet, Nicolas Mary
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1-xFex(OH)Fe1-ySe (x ~ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesised samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasised by the demonstration that reductive post-synthetic lithiation of the samples turns on superconductivity with critical temperatures exceeding 40 K by displacing iron atoms from the Li1-xFex(OH) reservoir layer to fill vacancies in the selenide layer

Stefan J Sedlmaier - One of the best experts on this subject based on the ideXlab platform.

  • soft chemical control of superconductivity in lithium iron selenide hydroxides li1 xfex oh fe1 yse
    Inorganic Chemistry, 2015
    Co-Authors: Hualei Sun, Daniel N Woodruff, Simon J Cassidy, Genevieve M Allcroft, Stefan J Sedlmaier, Amber L Thompson, Paul A Bingham, S D Forder, Simon Cartenet, Nicolas Mary
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1–xFex(OH)Fe1–ySe (x ∼ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction, and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesized samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasized by the demonst...

  • Soft chemical control of superconductivity in lithium iron selenide hydroxides li1–xfex(oh)fe1–yse
    'American Chemical Society (ACS)', 2015
    Co-Authors: Sun H, Genevieve M Allcroft, Stefan J Sedlmaier, S D Forder, Dn Woodruff, Sj Cassidy, Thompson A, Pa Bingham, Cartenet S, Mary N
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1–xFex(OH)Fe1–ySe (x ∼ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction, and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesized samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasized by the demonstration that reductive postsynthetic lithiation of the samples turns on superconductivity with critical temperatures exceeding 40 K by displacing iron atoms from the Li1–xFex(OH) reservoir layer to fill vacancies in the selenide layer.

  • Soft Chemical Control of Superconductivity in Lithium Iron Selenide Hydroxides Li1–xFex(OH)Fe1–ySe
    2015
    Co-Authors: Hualei Sun, Simon J Cassidy, Genevieve M Allcroft, Stefan J Sedlmaier, Amber L Thompson, Paul A Bingham, S D Forder, Simon Cartenet, Daniel N. Woodruff, Nicolas Mary
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1–xFex(OH)­Fe1–ySe (x ∼ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction, and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesized samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasized by the demonstration that reductive postsynthetic lithiation of the samples turns on superconductivity with critical temperatures exceeding 40 K by displacing iron atoms from the Li1–xFex(OH) reservoir layer to fill vacancies in the selenide layer

  • soft chemical control of superconductivity in lithium iron selenide hydroxides li1 xfex oh fe1 yse
    arXiv: Superconductivity, 2014
    Co-Authors: Hualei Sun, Daniel N Woodruff, Simon J Cassidy, Genevieve M Allcroft, Stefan J Sedlmaier, Amber L Thompson, Paul A Bingham, S D Forder, Simon Cartenet, Nicolas Mary
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1-xFex(OH)Fe1-ySe (x ~ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesised samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasised by the demonstration that reductive post-synthetic lithiation of the samples turns on superconductivity with critical temperatures exceeding 40 K by displacing iron atoms from the Li1-xFex(OH) reservoir layer to fill vacancies in the selenide layer

S D Forder - One of the best experts on this subject based on the ideXlab platform.

  • soft chemical control of superconductivity in lithium iron selenide hydroxides li1 xfex oh fe1 yse
    Inorganic Chemistry, 2015
    Co-Authors: Hualei Sun, Daniel N Woodruff, Simon J Cassidy, Genevieve M Allcroft, Stefan J Sedlmaier, Amber L Thompson, Paul A Bingham, S D Forder, Simon Cartenet, Nicolas Mary
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1–xFex(OH)Fe1–ySe (x ∼ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction, and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesized samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasized by the demonst...

  • Soft chemical control of superconductivity in lithium iron selenide hydroxides li1–xfex(oh)fe1–yse
    'American Chemical Society (ACS)', 2015
    Co-Authors: Sun H, Genevieve M Allcroft, Stefan J Sedlmaier, S D Forder, Dn Woodruff, Sj Cassidy, Thompson A, Pa Bingham, Cartenet S, Mary N
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1–xFex(OH)Fe1–ySe (x ∼ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction, and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesized samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasized by the demonstration that reductive postsynthetic lithiation of the samples turns on superconductivity with critical temperatures exceeding 40 K by displacing iron atoms from the Li1–xFex(OH) reservoir layer to fill vacancies in the selenide layer.

  • Soft Chemical Control of Superconductivity in Lithium Iron Selenide Hydroxides Li1–xFex(OH)Fe1–ySe
    2015
    Co-Authors: Hualei Sun, Simon J Cassidy, Genevieve M Allcroft, Stefan J Sedlmaier, Amber L Thompson, Paul A Bingham, S D Forder, Simon Cartenet, Daniel N. Woodruff, Nicolas Mary
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1–xFex(OH)­Fe1–ySe (x ∼ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction, and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesized samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasized by the demonstration that reductive postsynthetic lithiation of the samples turns on superconductivity with critical temperatures exceeding 40 K by displacing iron atoms from the Li1–xFex(OH) reservoir layer to fill vacancies in the selenide layer

  • soft chemical control of superconductivity in lithium iron selenide hydroxides li1 xfex oh fe1 yse
    arXiv: Superconductivity, 2014
    Co-Authors: Hualei Sun, Daniel N Woodruff, Simon J Cassidy, Genevieve M Allcroft, Stefan J Sedlmaier, Amber L Thompson, Paul A Bingham, S D Forder, Simon Cartenet, Nicolas Mary
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1-xFex(OH)Fe1-ySe (x ~ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesised samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasised by the demonstration that reductive post-synthetic lithiation of the samples turns on superconductivity with critical temperatures exceeding 40 K by displacing iron atoms from the Li1-xFex(OH) reservoir layer to fill vacancies in the selenide layer

Genevieve M Allcroft - One of the best experts on this subject based on the ideXlab platform.

  • soft chemical control of superconductivity in lithium iron selenide hydroxides li1 xfex oh fe1 yse
    Inorganic Chemistry, 2015
    Co-Authors: Hualei Sun, Daniel N Woodruff, Simon J Cassidy, Genevieve M Allcroft, Stefan J Sedlmaier, Amber L Thompson, Paul A Bingham, S D Forder, Simon Cartenet, Nicolas Mary
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1–xFex(OH)Fe1–ySe (x ∼ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction, and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesized samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasized by the demonst...

  • Soft chemical control of superconductivity in lithium iron selenide hydroxides li1–xfex(oh)fe1–yse
    'American Chemical Society (ACS)', 2015
    Co-Authors: Sun H, Genevieve M Allcroft, Stefan J Sedlmaier, S D Forder, Dn Woodruff, Sj Cassidy, Thompson A, Pa Bingham, Cartenet S, Mary N
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1–xFex(OH)Fe1–ySe (x ∼ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction, and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesized samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasized by the demonstration that reductive postsynthetic lithiation of the samples turns on superconductivity with critical temperatures exceeding 40 K by displacing iron atoms from the Li1–xFex(OH) reservoir layer to fill vacancies in the selenide layer.

  • Soft Chemical Control of Superconductivity in Lithium Iron Selenide Hydroxides Li1–xFex(OH)Fe1–ySe
    2015
    Co-Authors: Hualei Sun, Simon J Cassidy, Genevieve M Allcroft, Stefan J Sedlmaier, Amber L Thompson, Paul A Bingham, S D Forder, Simon Cartenet, Daniel N. Woodruff, Nicolas Mary
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1–xFex(OH)­Fe1–ySe (x ∼ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction, and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesized samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasized by the demonstration that reductive postsynthetic lithiation of the samples turns on superconductivity with critical temperatures exceeding 40 K by displacing iron atoms from the Li1–xFex(OH) reservoir layer to fill vacancies in the selenide layer

  • soft chemical control of superconductivity in lithium iron selenide hydroxides li1 xfex oh fe1 yse
    arXiv: Superconductivity, 2014
    Co-Authors: Hualei Sun, Daniel N Woodruff, Simon J Cassidy, Genevieve M Allcroft, Stefan J Sedlmaier, Amber L Thompson, Paul A Bingham, S D Forder, Simon Cartenet, Nicolas Mary
    Abstract:

    Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1-xFex(OH)Fe1-ySe (x ~ 0.2; 0.02 < y < 0.15) with a wide range of iron Site Vacancy concentrations in the iron selenide layers. This iron Vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesised samples when the iron Vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher Vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low Vacancy concentration in the iron selenide layers is emphasised by the demonstration that reductive post-synthetic lithiation of the samples turns on superconductivity with critical temperatures exceeding 40 K by displacing iron atoms from the Li1-xFex(OH) reservoir layer to fill vacancies in the selenide layer