Fabrication of a regenerable Ni supported NiO-MgO catalyst for methane steam reforming by exsolution

Park, Yong Sun,Kang, Misook,Byeon, Pilgyu,Chung, Sung-Yoon,Nakayama, Tadachika,Ko, Taegyung,Hwang, Haejin Elsevier 2018 Journal of Power Sources Vol.397 No.-

<P><B>Abstract</B></P> <P>Nickel nanoparticles supported on a NiO-MgO solid solution are fabricated using the exsolution process. Upon reduction, the nickel nanoparticles are exsoluted from a Ni<SUB>0·4</SUB>Mg<SUB>0·6</SUB>O solid solution powder. From the results obtained from transition electron microscopy (TEM) and temperature programmed reduction (TPR) measurements, it is concluded that the size and dispersion state of the nickel nanoparticles strongly depend on the homogeneity of the parent solid solution. Sintering the parent solid solution powder at a high temperature results in a homogeneous solid solution, which leads to a decreased reducibility of the nickel ions and, consequently, well-distributed Ni nanoparticles are successfully obtained. The metallic nickel moves reversibly to and out of the parent solid solution in response to a specific atmospheric condition. The methane steam reforming over the as-synthesized nickel nanoparticles are evaluated and appreciable degradation (1000 h) of the catalytic activity is not found for the catalyst sample that is sintered at 1000 °C followed by subsequent reduction to 800 °C.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ni nanoparticles supported on NiO-MgO solid solution were synthesized by exsolution. </LI> <LI> The growth of Ni nanoparticles depended on the homogeneity of the solid solution. </LI> <LI> The catalytic activity was not to be degraded appreciably for 1000 h of operation. </LI> <LI> The metallic nickel moved reversibly to and out of the parent solid solution. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Phase formation and luminescence properties of ternary solid-solution among tetragonal systems

Unithrattil, Sanjith,Kim, Ha Jun,Im, Won Bin ELSEVIER SCIENCE 2019 JOURNAL OF ALLOYS AND COMPOUNDS Vol.798 No.-

<P><B>Abstract</B></P> <P>A new strategy for developing solid-solution compounds from three constituent compounds was analyzed. Using this strategy, a series of yellow-light-emitting phosphors derived from ternary solid-solution host compositions were prepared using solid-state synthesis. Three vertex members, Sr<SUB>3</SUB>SiO<SUB>5</SUB> (space group <I>P</I>4/<I>ncc</I>), Sr<SUB>3</SUB>AlO<SUB>4</SUB>F (space group <I>I</I>4/<I>mcm</I>), and LaSr<SUB>2</SUB>AlO<SUB>5</SUB> (space group <I>I</I>4/<I>mcm</I>), were selected from similar crystal structures with slightly different symmetries. The crystallization space group of the composition was found to be dependent on the end members, and from the vertex of the ternary plot to the centroid, the composition assumed the space group that was more tolerant toward substitutions. All the compositions, except those lying at the periphery of the ternary plot, formed a single phase and emitted yellow light when activated with Ce<SUP>3+</SUP> ions. The luminescence properties of the 28 selected compositions on the ternary plot were analyzed. The compound that was formed from a 1:2:1 ratio of end members assumed a <I>I</I>4/<I>mcm</I> structure and showed the highest-intensity emission. Phosphor derived from the developed host lattice was analyzed for application in solid-state lighting devices by preparing a white-light emitting device.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Phase formation in ternary solid-solutions of tetragonal systems. </LI> <LI> Tetragonal structure Sr<SUB>3</SUB>SiO<SUB>5</SUB>, LaSr<SUB>2</SUB>AlO<SUB>3</SUB> and Sr<SUB>3</SUB>AlO<SUB>4</SUB>F are investigated in the preparation of ternary solid solution. </LI> <LI> Structural analysis of all the selected compositions was carried out using the Le Bail method. </LI> <LI> The detailed structural analysis of selected compositions was performed via Rietveld refinement. </LI> <LI> Ternary solid solution present great color tunability in wLED fabrication. </LI> </UL> </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>

Mg-Al 및 Mg-Zn 고용체의 진동감쇠능 비교

전중환 한국열처리공학회 2023 熱處理工學會誌 Vol.36 No.6

Damping capacities of Mg-2.5%Al and Mg-2.5%Zn (in atomic) solid solutions were comparatively investigated in order to clarify the influence of solutionized Al and Zn elements on the damping characteristics of Mg. In this study, solid solutions with similar grain size were obtained by solution treatment at 678 K for different times (24 h for Mg-2.5%Al and 36 h for Mg-2.5%Zn), followed by water quenching at RT. The Mg-2.5%Al and Mg-2.5%Zn solid solutions showed similar damping capacities in the strain-amplitude independent region of 1 × 10-6 ~ 1 × 10-5 and in the strain-amplitude dependent region below 6 × 10-4, over which the Mg-2.5%Zn solid solution possessed better damping capacity than the Mg-2.5%Al solid solution. The damping tendencies depending on strain-amplitude for the two solid solutions were analyzed and discussed in terms of similar length between weak pinning points (solutes) and different solute/dislocation interaction forces in Granato-Lücke model.

Preparation and characterizations of stable amorphous solid solution of azithromycin by hot melt extrusion

Divakar R. Jaiswar,Purnima D. Amin,Durgesh Jha 한국약제학회 2016 Journal of Pharmaceutical Investigation Vol.46 No.7

In the present study aim was to prepare stable solid solution azithromycin dihydrate (AZI) by hot melt extrusion technology (HME). Soluplus and Kollidon VA 64 were selected among polymers based on Hansen solubility parameter calculation in order to prepare amorphous of AZI. Further physicochemical properties of extrudates were characterized by DSC, FTIR, XRD, SEM and contact angle measurement. DSC revealed single broad endothermic peak in extrudates indicated miscibility of AZI into polymeric carriers, which formed monophasic solid system termed as solid solution. XRD confirmed amorphous nature of AZI in extrudates. DSC and XRD suggested molecular dispersion of AZI in polymeric carriers. Amorphous AZI exhibited statistically significant high solubility (P\0.0001) in water in comparison with pure AZI. Solid solution batch AZI 03 showed significant enhancement in solubility (P = 0.0004) in pH 6. The dissolution in dissolution medium pH 6 and water resulted in statistically significant differences (P\0.05) in the percentage amorphous AZI dissolved compared to the percentage AZI dissolved over the period of 60 min. Solid solution formulation showed better wettability than that of pure AZI. Amorphization and increased wettability attributed to solubility and dissolution rate enhancement. Assay and amorphous solid solution characteristics of AZI were found to be stable under accelerated storage condition as per ICH guideline for a period of six months. Therefore, hot melt extrusion technology was suitable method to prepare stable solid solution and dissolution rate enhancement for poorly soluble active like AZI.

Color-tunable binary solid-solution phosphor, (Sr₃SiO₅)_1-x(Sr₃AlO₄F)_x, for white LEDs: Energy transfer mechanism between Ce³⁺ and Tb³⁺

Lee, J.S.,Unithrattil, S.,Im, W.B. Elsevier Sequoia 2013 Journal of alloys and compounds Vol.555 No.-

The possibility of using a solid solution as a light convertor in white LEDs was studied. A solid solution of Sr<SUB>3</SUB>AlO<SUB>4</SUB>F and Sr<SUB>3</SUB>SiO<SUB>5</SUB> was prepared by solid-state reaction and was activated with Ce<SUP>3+</SUP>. Phosphor exhibits an asymmetric yellow-orange emission band which is broadened and red-shifted when coactivated with Tb<SUP>3+</SUP>. Decay profile analysis using the Inokuti-Hirayama model revealed that the mechanism involved was electric dipole-quadrupole interaction. The critical distance was calculated from concentration quenching data, multipolar interaction, and exchange interaction. The thermal stability of photoluminescence was investigated by assuming an Arrhenius temperature dependence, and the activation energy for thermal quenching was calculated. When analyzed in combination with an InGaN LED, the phosphor exhibited high color-rendering index and excellent correlated color temperature. These results demonstrate that this solid solution phosphor with its superior properties is highly suitable for use in white LEDs.

Rapid Synthesis of W–Cr Solid–Solution by Dielectric-Barrier Discharge-Plasma-Assisted Ball Milling

S. F. Hong,Z. C. Lu,Y. H. Liu,Q. M. He,W. Jiang,M. Q. Zeng 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.12

Supersaturated solid–solutions in a W–Cr alloy system were fabricated by conventional milling and plasma milling. The differentextension mechanisms of the solid solubility that were created by ball milling with and without discharge plasma werestudied. The solid–solubility of Cr in W for the P-milling W–Cr alloy system was higher, which indicates that plasma millingpromotes the formation of W(Cr) solid–solution more easily than conventional milling. According to Miedema’s model, inthe W–Cr alloy system, the free-energy change to form a W(Cr) solid solution by plasma milling is reduced compared withconventional milling because of the heating effect of the discharge plasma. Therefore, a higher stored energy in the grainboundaries and dislocations of the W–Cr nanograins during plasma milling makes it easier to overcome the thermodynamicbarrier in the formation of a solid–solution, when compared with conventional milling.

LiMn_0.5Co_0.5BO₃ solid solution: Towards high performance cathode material for next-generation lithium-ion battery

Ragupathi, Veena,Anbu Dinesh, J.,Panigrahi, Puspamitra,Raman, Sudarkodi,Lee, Juwon,Nagarajan, Ganapathi Subramaniam Pergamon Press 2018 International journal of hydrogen energy Vol.43 No.8

<P><B>Abstract</B></P> <P>LiMn<SUB>0.5</SUB>Co<SUB>0.5</SUB>BO<SUB>3</SUB> solid solution is synthesized by Sol-gel method. The crystal structure, morphology and the electrochemical properties of the LiMn<SUB>0.5</SUB>Co<SUB>0.5</SUB>BO<SUB>3</SUB> solid solution are analyzed. X-ray diffraction analysis result reveals the existence of monoclinic phase with <I>C</I>2/<I>c</I> space group. Raman spectroscopy result indicates the presence of Co-O and Mn-O stretching vibration. X–ray Photoelectron spectroscopy confirms the surface oxidation of Mn in the LiMn<SUB>0.5</SUB>Co<SUB>0.5</SUB>BO<SUB>3</SUB> solid solution. Transmission electron microscopy image shows the elongated spherical shaped particle with diameter of 40 nm. Galvanostatic charge – discharge studies indicate that the LiMn<SUB>0.5</SUB>Co<SUB>0.5</SUB>BO<SUB>3</SUB> solid solution delivers the first discharge capacity of 110 mAh g<SUP>−1</SUP> at C/10 rate with good stability and yield 68 mAh g<SUP>−1</SUP> at 75th cycle. The enhanced electrochemical properties demonstrated in this study will give more attention to borate based cathode material as a potential alternative to current lithium-ion battery cathodes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> LiMn<SUB>0.5</SUB>Co<SUB>0.5</SUB>BO<SUB>3</SUB> solid solution is synthesized by sol gel technique. </LI> <LI> A high first discharge capacity of 110 mAh g<SUP>−1</SUP> is achieved for LiMn<SUB>0.5</SUB>Co<SUB>0.5</SUB>BO<SUB>3</SUB>. </LI> <LI> The first discharge capacity is at least 10 folds higher than previous reports. </LI> <LI> Co doping and Li rich stoichiometry has improved the electrochemical performance. </LI> </UL> </P>

Electro-caloric eff ects in the BaTiO 3 -based solid solution ceramics

Bit Chan Kim,Chae Il Cheon 한국세라믹학회 2020 한국세라믹학회지 Vol.57 No.5

Electro-caloric eff ect (ECE) was investigated in BaTiO 3 (BT)-based solid solution ceramics, Ba(Zr,Ti)O 3 (BZT), Ba(Sn,Ti)O 3 (BST) and (Ba,Ca)(Zr,Ti)O 3 (BCZT) with the composition near an invariant critical point (ICP). The samples were fabricated by the solid-state reaction method and the ECE was obtained by an indirect measurement. The 12BZ–88BT, 9BS–91BT, and 32BCT–68BZT samples showed the best polarization–electric fi eld (P–E) hysteresis characteristics at room temperature and displayed dielectric peaks at 46, 58, and 66 °C, which are the Curie temperatures. With increasing temperature, the P–E loops changed from typical ferroelectric square shapes to paraelectric slanted shapes in the BT-based solid solution ceramics. The adiabatic temperature change due to the ECE (Δ T ECE ) showed the maximum values of 0.46 °C at 80 °C, 0.5 °C at 65 °C, and 0.47 °C at 75 °C, respectively, in the 12BZ–88BT, 9BS–91BT, and 32BCT–68BZT samples. The BT-based solid solution ceramics showed smaller maximum ΔT ECE , but broader Δ T ECE peaks at nearer room temperature than the BT ceramic. The enhancement of the ECE due to the multi-phase coexistence was not observed in BT-based solid solutions with the compositions near an invariant critical point (ICP) at which several phases coexist.

Thermally Stable and Reflective RhZn/Ag Ohmic Contacts to p-type GaN for Near-UV Flip-chip Light-emitting Diodes

박성한,성태연,전준우,오정탁 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.1

We investigated Rh-Zn solid solution (3 nm)/Ag(200 nm) schemes in order to produce thermally stable and low-resistance p-type Ohmic reflectors for high-performance flip-chip light-emitting diodes (LEDs). The Rh-Zn solid solution/Ag contacts show a specific contact resistance of 1.2 × 10^(−4) Ωcm^2 and a reflectance of about 78% at a wavelength of 395 nm when annealed at 500 ℃ for 1 min in air. Scanning electron microscopy results show that unlike Ag only contacts, the Rh-Zn solid solution/Ag contacts experience insignificant morphological degradation even after annealing at 500 ℃ for 1 min. Near-UV InGaN/GaN LEDs (1200 × 600 μm^2 in chip size) fabricated with the annealed Rh-Zn solid solution/Ag reflectors give a forward-bias voltage of 3.43 V at an injection current of 80 mA, which is lower than that (3.65 V) of LEDs with Ag only reflectors. LEDs with the annealed RhZn solid solution/Ag reflectors exhibit 43% higher light output power (at 80 mA) than the LEDs with annealed Ag contacts. X-ray photoemission spectroscopy examinations were performed to investigate possible Ohmic formation behaviors.