Li₁₃Mn(SeO₃)₈: Lithium-Rich Transition Metal Selenite Containing Jahn–Teller Distortive Cations

Jo, Hongil,Song, Seung Yoon,Cho, Eunjeong,So, Jongho,Lee, Suheon,Choi, Kwang Yong,Ok, Kang Min American Chemical Society 2017 Inorganic chemistry Vol.56 No.15

<P>A novel lithium-rich transition metal selenite, Li13Mn(SeO3)(8), that is composed of a Jahn-Teller distortive cation., Mn3+, in the high spin d(4) state, and a second-order Jahn-Teller (SOJT) distortive lone pair cation, Se4+, has been synthesized via hydrothermal and high temperature solid state reactions. The selenite is classified as a molecular compound consisting of MnO6 octahedra, SeO3 trigonal pyramids, and Li+ cations. Considering the Li-O interactions, the structure of Li13Mn(SeO3)(8) may be described as a pseudo-three-dimensional framework as well. The title compound is thermally stable up to 500 degrees C and starts decomposing above the temperature attributable to the volatilization of SeO2. While the MnO6 octahedra in Li13Mn(SeO3)(8) exhibit six identical Mn-O bond distances at room temperature due to the dynamic Jahn-Teller effect, a clear elongation of two Mn-O bonds along a specific direction is observed at 100 K. A series of isostructural selenites with different transition metals, i.e., Li13M(SeO3)(8) (M = Sc, Cr, and Fe), have been also successfully obtained in phase pure forms using, similar synthetic methods. Magnetic properties, spectroscopic characterizations, and local dipole moments calculations for all the synthesized selenites ate presented.</P>

Li₆M(SeO₃)₄ (M = Co, Ni, and Cd) and Li₂Zn(SeO₃)₂: Selenites with Late Transition-Metal Cations

Jo, Hongil,Lee, Suheon,Choi, Kwang Yong,Ok, Kang Min American Chemical Society 2018 Inorganic Chemistry Vol.57 No.6

<P>A series of lithium metal selenites, Li<SUB>6</SUB>M(SeO<SUB>3</SUB>)<SUB>4</SUB> (M = Co, Ni, and Cd) and Li<SUB>2</SUB>Zn(SeO<SUB>3</SUB>)<SUB>2</SUB>, were synthesized by hydrothermal and solid-state reactions. Li<SUB>6</SUB>M(SeO<SUB>3</SUB>)<SUB>4</SUB> is composed of Li<SUP>+</SUP> cations, MO<SUB>6</SUB> octahedra, and SeO<SUB>3</SUB> polyhedra, while Li<SUB>2</SUB>Zn(SeO<SUB>3</SUB>)<SUB>2</SUB> consists of Li<SUP>+</SUP>, Zn(Li)O<SUB>4</SUB> tetrahedra, and SeO<SUB>3</SUB> polyhedra. Isostructural Li<SUB>6</SUB>Co(SeO<SUB>3</SUB>)<SUB>4</SUB> and Li<SUB>6</SUB>Ni(SeO<SUB>3</SUB>)<SUB>4</SUB> crystallize in the rhombohedral space group <I>R</I>3̅, forming a three-dimensional distorted cubic lattice. Li<SUB>2</SUB>Zn(SeO<SUB>3</SUB>)<SUB>2</SUB> crystallizes in the orthorhombic space group <I>Pbam</I> and reveals a layered structure in the <I>bc</I> plane. Li<SUB>6</SUB>Cd(SeO<SUB>3</SUB>)<SUB>4</SUB> revealing a unidimensional structure crystallizes in the polar non-centrosymmetric space group <I>C</I>2, attributed to the parallel alignment of distorted CdO<SUB>6</SUB> octahedra. The direct-current magnetic susceptibility measurements unveil that Li<SUB>6</SUB>Co(SeO<SUB>3</SUB>)<SUB>4</SUB> is a canted antiferromagnet with <I>T</I><SUB>N</SUB> = 25 K, while Li<SUB>6</SUB>Ni(SeO<SUB>3</SUB>)<SUB>4</SUB> undergoes an antiferromagnetic transition at <I>T</I><SUB>N</SUB> = 54 K, having a negligible canted moment. The weak ferromagnetism observed in Li<SUB>6</SUB>Co(SeO<SUB>3</SUB>)<SUB>4</SUB> indicates the significance of spin-orbit coupling, bringing about anisotropic exchange interactions. Li<SUB>6</SUB>Cd(SeO<SUB>3</SUB>)<SUB>4</SUB> reveals a second harmonic generation (SHG) efficiency of 10 × α-SiO<SUB>2</SUB>. Dipole moment calculations on Li<SUB>6</SUB>Cd(SeO<SUB>3</SUB>)<SUB>4</SUB> indicate that the cooperative interaction of CdO<SUB>6</SUB> and SeO<SUB>3</SUB> is responsible for the observed SHG properties. Band gaps of the compounds are enlarged as atomic number increases. The effect of late transition-metal cations with different coordination numbers on the framework structures and the subsequent physical properties will be also discussed.</P><P>Different preference of local coordination environment for various late transition-metal cations influences the crystal structure and stoichiometry of mixed metal selenites.</P> [FIG OMISSION]</BR>

Effect of polarizable lone pair cations on the second-harmonic generation (SHG) properties of noncentrosymmetric (NCS) Bi_2−<i>x</i>Y_<i>x</i>TeO₅ (<i>x</i> = 0–0.2)

Jo, Hongil,Kim, Yeong Hun,Lee, Dong Woo,Ok, Kang Min The Royal Society of Chemistry 2014 Dalton Transactions Vol.43 No.30

<P>Y<SUP>3+</SUP>-doped noncentrosymmetric (NCS) bismuth tellurite materials, Bi<SUB>2−<I>x</I></SUB>Y<SUB><I>x</I></SUB>TeO<SUB>5</SUB> (<I>x</I> = 0, 0.1, and 0.2), have been synthesized through standard solid-state reactions and structurally characterized by powder neutron diffraction. The reported NCS materials crystallize in the orthorhombic space group <I>Abm</I>2 (no. 39), and exhibit pseudo-three-dimensional frameworks that are composed of BiO<SUB>3</SUB>, BiO<SUB>5</SUB>, and TeO<SUB>3</SUB> polyhedra. Detailed diffraction studies show that the cell volume of Bi<SUB>2−<I>x</I></SUB>Y<SUB><I>x</I></SUB>TeO<SUB>5</SUB> decreases with an increasing amount of Y<SUP>3+</SUP>on the Bi<SUP>3+</SUP> sites. However, no ordering between Bi<SUP>3+</SUP> and Y<SUP>3+</SUP> was observed in the Bi<SUB>2−<I>x</I></SUB>Y<SUB><I>x</I></SUB>TeO<SUB>5</SUB>. Powder second-harmonic generation (SHG) measurements, using 1064 nm radiation, reveal that Bi<SUB>2</SUB>TeO<SUB>5</SUB>, Bi<SUB>1.9</SUB>Y<SUB>0.1</SUB>TeO<SUB>5</SUB>, and Bi<SUB>1.8</SUB>Y<SUB>0.2</SUB>TeO<SUB>5</SUB> exhibit SHG efficiencies of approximately 300, 200, and 60 times that of α-SiO<SUB>2</SUB>, respectively. The reduction in SHG for Y<SUP>3+</SUP>-doped materials is consistent with the lack of net moment originating from polyhedra with a polarizable Bi<SUP>3+</SUP> cation.</P> <P>Graphic Abstract</P><P>A net moment arising from polyhedra with a polarizable Bi<SUP>3+</SUP> cation is essential for the strong second-harmonic generation of Bi<SUB>2−<I>x</I></SUB>Y<SUB><I>x</I></SUB>TeO<SUB>5</SUB>. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4dt01060d'> </P>

Polar Noncentrosymmetric ZnMoSb₂O₇ and Nonpolar Centrosymmetric CdMoSb₄O₁₀: d¹⁰ Transition Metal Size Effect Influencing the Stoichiometry and the Centricity

Jo, Hongil,Ok, Kang Min American Chemical Society 2016 Inorganic Chemistry Vol.55 No.12

<P>Two new quaternary molybdenum(VI) antimony(III) oxides, ZnMoSb2O7 and CdMoSb4O10, have been synthesized in phase-pure form. The title compounds consist of highly polarizable cations, i.e., d(10) (Mo6+) and d(10) (Zn2+ or Cd2+), and lone-pair cations (Sb3+). ZnMoSb2O7 exhibits a three-dimensional framework with ZnO4, MoO4, and SbO4 polyhedra in the polar space group P2(1), whereas CdMoSb4O10 exhibits one-dimensional tubule structures with CdO6, MoO4, and SbO3 polyhedra in the space group P2(1)/m. Several synthetic efforts suggest that the the dissimilar radii of Zn2+ and Cd2+ that can accommodate polyhedra of Sb3+ cations influence the stoichiometry as well as the centricity for the reported materials. Spectroscopic, thermal, and elemental analyses are reported along with dipole moment calculations. Nonlinear optical properties and their structural origin are examined for polar ZnMoSb2O7 as well.</P>

Noncentrosymmetric (NCS) solid solutions: elucidating the structure–nonlinear optical (NLO) property relationship and beyond

Jo, Hongil,Oh, Seung-Jin,Ok, Kang Min Royal Society of Chemistry 2017 Dalton Transactions Vol. No.

<▼1><P>A series of noncentrosymmetric (NCS) solid solutions and their structure–nonlinear optical property relationship are introduced for designing novel NCS materials more systematically.</P></▼1><▼2><P>A systematic approach toward the discovering of novel functional noncentrosymmetric (NCS) materials revealing technologically useful applications is an ongoing challenge. This Frontiers article investigates a series of NCS solid solutions with respect to their crystal structure and second-harmonic generation (SHG) response. The solid solutions include NCS polar aluminoborates, Al5−xGaxBO9 (0.0 ≤ <I>x</I> ≤ 0.5), rare earth element-doped bismuth tellurites, Bi2−xRExTeO5 (RE = Y, Ce, and Eu; 0.0 ≤ <I>x</I> ≤ 0.2), layered perovskites, Bi4−xLaxTi3O12 (0.0 ≤ <I>x</I> ≤ 0.75: Aurivillius phases) and CsBi1−xEuxNb2O7 (0.0 ≤ <I>x</I> ≤ 0.2: Dion–Jacobson phases), calcium bismuth oxides, Ca4Bi6−xLnxO13 (Ln = La and Eu; <I>x</I> = 0, 0.06 and 0.12), and sodium lanthanide iodates, NaLa1−xLnx(IO3)4 (Ln = Sm and Eu; 0 ≤ <I>x</I> ≤ 1). The origin of SHG for all the NCS solid solutions is discussed and the detailed structure–nonlinear optical (NLO) property relationships are elucidated. In addition, photoluminescence (PL) properties and subsequent energy transfer mechanisms for NCS solid solutions are provided.</P></▼2>

Experimental and Theoretical Investigations for the Quaternary Mixed-Cation Zintl Phase Ca1.82(1)Eu0.18CdSb2

Kiwon Kim,Hongil Jo,옥강민,Tae-Soo You 대한화학회 2020 Bulletin of the Korean Chemical Society Vol.41 No.2

A quaternary Zintl phase Ca1.82(1)Eu0.18CdSb2 with the Ca2+/Eu2+ mixed-cations was successfully synthesized by the Pb metal-flux method and characterized by PXRD and SXRD analyses. The particular site-preference of Ca and Eu was nicely elucidated by both of the size-factor and the electronic-factor criteria.

A series of oxyfluoride chains containing asymmetric basic building units of both early- and late-transition metal cations

Ahmed, Belal,Jo, Hongil,Yoon, Sung Won,Choi, Kwang Yong,Ok, Kang Min Elsevier 2018 Journal of solid state chemistry Vol.267 No.-

<P><B>Abstract</B></P> <P>Four new transition metal oxyfluorides revealing chain structures composed of asymmetric basic building units of [MO<SUB>2</SUB>F<SUB>4</SUB>]<SUP>2−</SUP> (M = Mo and W) and [M’(pz/mpz)<SUB>4</SUB>]<SUP>2+</SUP> (M′ = Cu and Ni) polyhedra, i.e., [Cu(mpz)<SUB>4</SUB>][MoO<SUB>2</SUB>F<SUB>4</SUB>] (1), [Cu(pz)<SUB>4</SUB>]<SUB>2</SUB>[WO<SUB>2</SUB>F<SUB>4</SUB>]<SUB>2</SUB> (2), [Ni(pz)<SUB>4</SUB>]<SUB>2</SUB>[MoO<SUB>2</SUB>F<SUB>4</SUB>]<SUB>2</SUB> (3), and [Ni(pz)<SUB>4</SUB>][WO<SUB>2</SUB>F<SUB>4</SUB>] (4) (pz = pyrazole; mpz = 3-methyl pyrazole) have been synthesized via hydrothermal reactions. The linear chain structures found from the title compounds are attributable to the <I>trans</I>-directing [MO<SUB>2</SUB>F<SUB>4</SUB>]<SUP>2-</SUP> octahedral moiety and hydrogen bonding interactions. Strong Jahn–Teller distortions are observed for Cu<SUP>2+</SUP> cations with d<SUP>9</SUP> configuration in compounds 1 and 2. All the compounds show both lower-energy and higher-energy absorption band gaps, which originate from the <I>d</I>–<I>d</I> transitions and the distortion of octahedral geometry of M<SUP>2+</SUP> cations, respectively. The magnetism of [Cu(mpz)<SUB>4</SUB>][MoO<SUB>2</SUB>F<SUB>4</SUB>] turns out to be described by noninteracting Cu<SUP>2+</SUP> spins rather than a spin chain due to long exchange path mediated via the nonmagnetic Mo<SUP>6+</SUP> ions. The title compounds have been also thoroughly characterized using spectroscopic and thermal analyses along with calculations of local dipole moments and the extent of out-of-center distortions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Four novel oxyfluoride chain compounds with asymmetric units were synthesized in high yields. </LI> <LI> Detailed structural analysis influencing the geometry of chains have been analyzed. </LI> <LI> Magnetic properties and electron paramagnetic resonance spectroscopy on a representative material were investigated. </LI> <LI> Dipole moments and the extent of out-of-center distortions calculations were provided. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>A series of oxyfluoride chains containing asymmetric basic building units of both early- and late-transition metal cations are reported.</P> <P>[DISPLAY OMISSION]</P>

Synthesis, second-harmonic generations (SHG), and photoluminescence (PL) properties of Ca₄Bi_6-<i>x</i>Ln_<i>x</i>O₁₃ (Ln=La and Eu) solid solutions

Jung, Hoyong,Jo, Hongil,Oh, Seung-Jin,Ok, Kang Min Academic Press 2017 Journal of solid state chemistry Vol.252 No.-

<P><B>Abstract</B></P> <P>Noncentrosymmetric (NCS) Ca<SUB>4</SUB>Bi<SUB>6-<I>x</I> </SUB>Ln<SUB> <I>x</I> </SUB>O<SUB>13</SUB> (Ln=La and Eu; <I>x</I>=0, 0.06, and 0.12) solid solutions have been synthesized through conventional solid state reactions by using CaCO<SUB>3</SUB>, Bi<SUB>2</SUB>O<SUB>3</SUB>, and Ln<SUB>2</SUB>O<SUB>3</SUB>. Crystal structures of the reported materials have been determined by powder X-ray diffraction using Rietveld method. Ca<SUB>4</SUB>Bi<SUB>6-<I>x</I> </SUB>Ln<SUB> <I>x</I> </SUB>O<SUB>13</SUB> solid solutions crystallizing in the polar NCS space group, <I>C</I>2<I>mm</I> (No. 38), are composed of uni-dimensional bands with BiO<SUB>3</SUB> and BiO<SUB>5</SUB> polyhedra. Second-harmonic generation (SHG) measurements, using 1064nm radiation, indicate that Ca<SUB>4</SUB>Bi<SUB>6-<I>x</I> </SUB>Ln<SUB> <I>x</I> </SUB>O<SUB>13</SUB> solid solutions are type-I phase-matchable and reveal moderate SHG efficiencies ranging from 30 to 80 times that of α-SiO<SUB>2</SUB>. Detailed structure-SHG property relationship analyses suggest that the net moment arising from the alignment of the asymmetric polyhedra of the lone pair cation, Bi<SUP>3+</SUP> in Ca<SUB>4</SUB>Bi<SUB>6-<I>x</I> </SUB>Ln<SUB> <I>x</I> </SUB>O<SUB>13</SUB> solid solutions is critical for the observed SHG phenomena. Photoluminescence (PL) properties measurements on Ca<SUB>4</SUB>Bi<SUB>6-<I>x</I> </SUB>Eu<SUB> <I>x</I> </SUB>O<SUB>13</SUB> solid solutions reveal the characteristic narrow emission lines attributable to <SUP>5</SUP>D<SUB>0</SUB>→<SUP>7</SUP>F<SUB> <I>j</I> </SUB> (<I>j</I>=4, …, 0) transitions and confirm the unsymmetrical coordination environment of the doped-Eu<SUP>3+</SUP> cation sites. Further PL measurements at different temperatures suggest that while Ca<SUB>4</SUB>Bi<SUB>6-<I>x</I> </SUB>Eu<SUB> <I>x</I> </SUB>O<SUB>13</SUB> exhibit the nonradiative emissions at high temperatures, the solid solutions show the radiative emissions with strong intensities at low temperatures.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Noncentrosymmetric calcium bismuth oxide solid solutions, Ca<SUB>4</SUB>Bi<SUB>6-<I>x</I> </SUB>Ln<SUB> <I>x</I> </SUB>O<SUB>13</SUB> (Ln=La and Eu) are synthesized. </LI> <LI> The net polarization originating from the lone pair cation, Bi<SUP>3+</SUP> is critical for the SHG efficiencies of the solid solutions. </LI> <LI> Ca<SUB>4</SUB>Bi<SUB>6-<I>x</I> </SUB>Eu<SUB> <I>x</I> </SUB>O<SUB>13</SUB> reveal the nonradiative and radiative emissions at high and low temperatures, respectively. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Second-harmonic generations and photoluminescence properties of noncentrosymmetric (NCS) Ca<SUB>4</SUB>Bi<SUB>6-<I>x</I> </SUB>Ln<SUB> <I>x</I> </SUB>O<SUB>13</SUB> (Ln=La and Eu; <I>x</I>=0, 0.06, and 0.12) solid solutions are reported.</P> <P>[DISPLAY OMISSION]</P>

Variable Chains Found in Mixed Transition Metal Oxyfluorides with Heterocyclic Ligands

Ahmed, Belal,Jo, Hongil,Ok, Kang Min The American Chemical Society 2019 CRYSTAL GROWTH AND DESIGN Vol.19 No.6

<P>Various chain structures of six novel metal oxyfluorides containing d<SUP>0</SUP> and d<SUP>10</SUP> transition metal asymmetric polyhedra, i.e., [Zn(mpz)<SUB>4</SUB>][TiF<SUB>6</SUB>] (<B>1</B>), [Cd(mpz)<SUB>4</SUB>][TiF<SUB>6</SUB>] (<B>2</B>), [Zn(mpz)<SUB>3</SUB>][ZrF<SUB>6</SUB>] (<B>3</B>), [Cd(pz)<SUB>4</SUB>]<SUB>3</SUB>[ZrF<SUB>6</SUB>][ZrF<SUB>8</SUB>] (<B>4</B>), [Zn(pz)<SUB>4</SUB>]<SUB>2</SUB>[NbOF<SUB>5</SUB>]<SUB>2</SUB> (<B>5</B>), and [Cd(pz)<SUB>4</SUB>][NbOF<SUB>5</SUB>] (<B>6</B>; mpz = 3-methylpyrazole; pz = pyrazole), were synthesized by hydrothermal methods. Compounds <B>1</B>, <B>2</B>, <B>5</B>, and <B>6</B> consist of linear chains, whereas compounds <B>3</B> and <B>4</B> are composed of zigzag chains. Careful structural analysis suggests that the hydrogen bonding network and distinctive <I>cis</I>/<I>trans</I>-directing anionic polyhedra are responsible for the diverse chain structures. The title compounds reveal optical band gaps in the range of 5.04-5.22 eV, which might be from the octahedral distortion of M<SUP>2+</SUP> cations and the corresponding electronic transitions. Thorough spectroscopic and thermogravimetric analyses, as well as the magnitude of dipole moments and out-of-center distortions, were used to characterize the reported compounds.</P><P>The diverse chain structures in mixed transition metal oxyfluorides are attributable to the distinctive structure-directing anionic groups and hydrogen bonding interactions.</P> [FIG OMISSION]</BR>

단위 셀 Reference 저항을 사용한 ReRAM용 Multi-Level Sense Amplifier

조문성(Moonsung Jo),윤홍일(Hongil Yoon) 대한전자공학회 2010 대한전자공학회 학술대회 Vol.2010 No.6

A novel reference resistor scheme is proposed for ReRAM multi-level sense amplifier. Only one ReRAM cell is used as a reference resistor instead of four ReRAM cells. Compared to the conventional scheme, the implementations using the proposed scheme achieve 34% power savings without the increase of read time. Also, the proposed scheme enhances tolerance for the variation of voltage sources, capacitors, and cell resistance.