Room-temperature phase separation in weakly doped lanthanum manganites

2005 ◽  
Vol 101 (3) ◽  
pp. 535-546 ◽  
Author(s):  
N. I. Solin
Keyword(s):  
Phase Separation ◽  
Room Temperature ◽  
Temperature Phase ◽  
Lanthanum Manganites ◽  
Doped Lanthanum Manganites

scholarly journals Deformation-induced nanoscale high-temperature phase separation in Co–Fe alloys at room temperature

2007 ◽  
Vol 90 (20) ◽  
pp. 201908 ◽  
Author(s):  
Lai-Chang Zhang ◽  
Mariana Calin ◽  
Flora Paturaud ◽  
Christine Mickel ◽  
Jürgen Eckert
Keyword(s):  
Phase Separation ◽  
High Temperature ◽  
Room Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Fe Alloys

Electron Microscope study of commensurate-incommensurate phase transition in BaZnGeO4

1990 ◽  
Vol 48 (4) ◽  
pp. 172-173
Author(s):  
Naoki Yamamoto ◽  
Makoto Kikuchi ◽  
Tooru Atake ◽  
Akihiro Hamano ◽  
Yasutoshi Saito
Keyword(s):  
Phase Transition ◽  
Electron Microscope Study ◽  
Room Temperature ◽  
Hexagonal Lattice ◽  
Ferroelectric Materials ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Periodic Arrays ◽  
Modulation Wave Vector

BaZnGeO4 undergoes many phase transitions from I to V phase. The highest temperature phase I has a BaAl2O4 type structure with a hexagonal lattice. Recent X-ray diffraction study showed that the incommensurate (IC) lattice modulation appears along the c axis in the III and IV phases with a period of about 4c, and a commensurate (C) phase with a modulated period of 4c exists between the III and IV phases in the narrow temperature region (—58°C to —47°C on cooling), called the III' phase. The modulations in the IC phases are considered displacive type, but the detailed structures have not been studied. It is also not clear whether the modulation changes into periodic arrays of discommensurations (DC’s) near the III-III' and IV-V phase transition temperature as found in the ferroelectric materials such as Rb2ZnCl4.At room temperature (III phase) satellite reflections were seen around the fundamental reflections in a diffraction pattern (Fig.1) and they aligned along a certain direction deviated from the c* direction, which indicates that the modulation wave vector q tilts from the c* axis. The tilt angle is about 2 degree at room temperature and depends on temperature.

scholarly journals Structure and Properties of Ln2MoO6 Oxymolybdates (Ln = La, Pr, Nd) Doped with Magnesium

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 611
Author(s):  
Ekaterina Orlova ◽  
Elena Kharitonova ◽  
Timofei Sorokin ◽  
Alexander Antipin ◽  
Nataliya Novikova ◽  
...  
Keyword(s):  
Rare Earth ◽  
Infrared Spectroscopy ◽  
Room Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Spectroscopy Data ◽  
Structure And Properties ◽  
Hygroscopic Properties ◽  
Thermogravimetric Studies ◽  
Mg Doped

The literature data and the results obtained by the authors on the study of the structure and properties of a series of polycrystalline and single-crystal samples of pure and Mg-doped oxymolybdates Ln2MoO6 (Ln = La, Pr, Nd) are analyzed. Presumably, the high-temperature phase I41/acd of Nd2MoO6 single crystals is retained at room temperature. The reason for the loss of the center of symmetry in the structures of La2MoO6 and Pr2MoO6 and the transition to the space group I4¯c2 is the displacement of oxygen atoms along the twofold diagonal axes. In all structures, Mg cations are localized near the positions of the Mo atoms, and the splitting of the positions of the atoms of rare-earth elements is found. Thermogravimetric studies, as well as infrared spectroscopy data for hydrated samples of Ln2MoO6 (Ln = La, Pr, Nd), pure and with an impurity of Mg, confirm their hygroscopic properties.

Zirconium-doped lanthanum manganites for catalytic deep oxidation of propene

2010 ◽  
Vol 385 (1-2) ◽  
pp. 163-169 ◽  
Author(s):  
Virginie Roche ◽  
Linda Mazri ◽  
Antoinette Boréave ◽  
M.H. Ta ◽  
Laurence Retailleau-Mevel ◽  
...  
Keyword(s):  
Deep Oxidation ◽  
Lanthanum Manganites ◽  
Doped Lanthanum Manganites

Betaine arsenate, (CH3)3NCH2COO · D3AsO4: structure refinement using multiple-wavelength synchrotron radiation data

1997 ◽  
Vol 212 (9) ◽  
Author(s):  
S. Kek ◽  
M. Grotepaß-Deuter ◽  
K. Fischer ◽  
K. Eichhorn
Keyword(s):  
Crystal Structure ◽  
Synchrotron Radiation ◽  
Room Temperature ◽  
Structure Refinement ◽  
Temperature Phase ◽  
Space Group ◽  
Radiation Data ◽  
Multiple Wavelength

AbstractThe crystal structure of deuterated betaine arsenate, (CHThe both paraelectric and ferroelastic room-temperature phase of betaine arsenate crystallizes in space group

Single-Crystal X-Ray Scattering Study of Superstructures and Phase Transitions in Graphite-Hno3 and Graphite-Br2 Intercalation Compounds

1982 ◽  
Vol 20 ◽  
Author(s):  
R. Moret ◽  
R. Comes ◽  
G. Furdin ◽  
H. Fuzellier ◽  
F. Rousseaux
Keyword(s):  
Phase Transitions ◽  
Low Temperature ◽  
Room Temperature ◽  
Temperature Phase ◽  
Temperature Structure ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Temperature Liquid ◽  
Low Temperature Phase

ABSTRACTIn α-C5n-HNO3 the condensation of the room-temperature liquid-like diffuse ring associated with the disorder-order transition around 250 K is studied and the low-temperature. superstructure is examined.It is found that β-C8n-HNO3 exhibits an in-plane incommensurate order at room temperature.Two types of graphite-Br2 are found. Low-temperature phase transitions in C8Br are observed at T1 ≍ 277 K and T2 ≍ 297 K. The room-temperature structure of C14Br is reexamined. Special attention is given to diffuse scattering and incommensurability.

Metal-Alkali Catalytic Valorization of Lignocellulose Towards Aromatics and Small Molecular Alcohols and Acids in a Holistic Approach

2021 ◽  
Author(s):  
Wei Lv ◽  
Yuting Zhu ◽  
Weiqi Mai ◽  
Changhui Zhu ◽  
Qifeng Pi ◽  
...  
Keyword(s):  
Phase Separation ◽  
Room Temperature ◽  
Holistic Approach ◽  
Woody Biomass ◽  
Solvent System ◽  
Effective Strategy ◽  
One Pot ◽  
Reaction Phase ◽  
Alkali Catalysts ◽  
O Phase

Abstract In this work, we developed an approach of one-pot completely catalytic conversion of woody biomass into two value product streams: lignin-derived aromatics (68.54% monomer and 29.65% oligomer yields of lignin) and (semi-)cellulose-derived small molecular alcohols (about 59.60% of biomass mass). These could be afforded by conducting lignocellulose depolymerization over metal-alkaline catalysts in a mixture n-butanol/H2O solvent system at 250 °C and 30 bar H2. In the valorization process, the homogenous mixture of n-butanol-H2O solvents extract and depolymerize both lignin and hemicellulose, while the catalysts and H2 are essential to cleave the inter-/intramolecular linkages of lignocellulose into target products. After the reaction, phase separation of n-butanol and H2O takes place when systematic temperature at room temperature, providing a mild and effective strategy to isolate lignin-derived aromatics (n-butanol phase) from small molecular alcohols/acids (aqueous phase). Ru/C and alkali catalysts are collected by filtration from n-butanol phase and H2O phase, respectively. Meanwhile, the effect of metal-alkali coupled catalysts enables facilitating the cleavage of β-O-4 linkage of lignin and increasing the attainability of (semi-)cellulose-derived oligomers and the small molecular alcohols. This catalytic system provides a versatile valorization approach for biomass catalytic to bio-based chemicals.

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