Preparation of t-ZrO2 by a sol–gel process with carbon as a phase transformation promoter

RSC Advances ◽  
2015 ◽  
Vol 5 (43) ◽  
pp. 34451-34455 ◽  
Author(s):  
Yu Liu ◽  
Weidong Chi ◽  
Hui Liu ◽  
Yueyang Su ◽  
Liang Zhao
Keyword(s):  
Phase Transition ◽  
Phase Transformation ◽  
Amorphous Carbon ◽  
Sol Gel ◽  
Cubic Phase ◽  
Sol Gel Process

Cubic phase ZrO2 can be synthesized with amorphous carbon as a phase transition promoter.

Zirconium oxide nanoparticles coated on sepiolite by sol–gel process — Their application as a solvent-free catalyst for condensation reactions

2011 ◽  
Vol 89 (3) ◽  
pp. 280-288 ◽  
Author(s):  
Sadok Letaief ◽  
Yun Liu ◽  
Christian Detellier
Keyword(s):  
Clay Mineral ◽  
Zirconium Oxide ◽  
Condensation Reaction ◽  
Sol Gel ◽  
Magic Angle Spinning ◽  
Solvent Free ◽  
Cubic Phase ◽  
Magic Angle ◽  
Solvent Free Conditions ◽  
Sol Gel Process

An inorganic nanocomposite made of zirconia nanoparticles coated on the external surfaces of the fibrous clay mineral sepiolite was prepared by using the sol–gel process under soft conditions using zirconium(IV) propoxide in 1-propanol as the precursor. The resulting materials were characterized by X-ray diffraction (XRD), thermal gravimetric analyses (TGA) and differential thermal analyses (DTA), microporosimetry, 29Si magic-angle spinning (MAS) nuclear magnetic resonance (NMR), and high-resolution transmission electron microscopy (HR-TEM). The organic material from the precursor was fully removed after calcination at 450 °C, concurrently with the crystallization of the cubic phase of zirconium oxide. The coordinated water molecules of sepiolite were fully removed and its symmetrical layered structure was folded after calcination at 650 °C, as observed by XRD and 29Si cross-polarization (CP) / MAS NMR. The arrangement of the nanoparticles of zirconium oxide on the sepiolite external surfaces maintains a fibrous morphology for the nanocomposite. This material was applied as a catalyst for the Knoevenagel condensation reaction of benzaldehyde and malononitrile under solvent-free conditions. Strongly improved yields of reaction, attributed to larger catalytically active surfaces, were obtained compared with either the sepiolite clay mineral or the zirconium oxide tested individually.

Preparation and phase transition properties of Ti-doped VO2 films by sol–gel process

2015 ◽  
Vol 78 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Yanyan Hu ◽  
Qiwu Shi ◽  
Wanxia Huang ◽  
Hongfu Zhu ◽  
Fang Yue ◽  
...  
Keyword(s):  
Phase Transition ◽  
Sol Gel ◽  
Sol Gel Process

Structures and Dielectric Properties of (Pb, La)(Zr, Ti)O3 Antiferroelectric Thick Films Prepared by Different Sintering Procedures

2012 ◽  
Vol 503 ◽  
pp. 375-380 ◽  
Author(s):  
Wen Ping Geng ◽  
Xiu Jian Chou ◽  
Yong Bo Lv ◽  
Ji Jun Xiong ◽  
Wen Dong Zhang
Keyword(s):  
Phase Transition ◽  
Electric Field ◽  
Crystal Orientation ◽  
Thick Films ◽  
Sol Gel ◽  
Temperature Dependent ◽  
Dielectric Constant And Loss ◽  
Sol Gel Process ◽  
Paraelectric State ◽  
Antiferroelectric Thick Films

(Pb,La)(Zr,Ti)O3antiferroelectric thick films were prepared on Pt (111)/ Ti/SiO2/Si (100) substrates by a sol-gel process. The effects of single annealing and multistep annealing on the structures and electric properties of the films were investigated. The crystal orientation and structure of the antiferroelectric thick films were studied. The thick films by multistep annealing have higher (100)-preferred orientation than them by single annealing. The surface of the films was more smooth, compact and uniform by single annealing. The antiferroelectric nature of the (Pb,La)(Zr,Ti)O3antiferroelectric thick films by various sintering procedures was demonstrated by P(polarization)-E(electric field) and C(capactitance)-E(electric field). The temperature dependent of the dielectric constant and loss was measured under the frequency 1, 10, and 100 kHz and comparing with traditional signal annealing, the films have phase transition from antiferroelectric state to paraelectric state by multistep annealing.

Preparation and phase transition characterization of VO2 thin film on single crystal Si (100) substrate by sol–gel process

2011 ◽  
Vol 59 (3) ◽  
pp. 591-597 ◽  
Author(s):  
Qiwu Shi ◽  
Wanxia Huang ◽  
Jiazhen Yan ◽  
Yubo Zhang ◽  
Mao Mao ◽  
...  
Keyword(s):  
Thin Film ◽  
Phase Transition ◽  
Single Crystal ◽  
Sol Gel ◽  
Sol Gel Process

Phase structure and thermal evolution in coatings and powders obtained by the sol-gel process: Part I. ZrO2−11.3 mol% Y2O3

1997 ◽  
Vol 12 (2) ◽  
pp. 493-500 ◽  
Author(s):  
P. C. Rivas ◽  
M. C. Caracoche ◽  
J. A. Martínez ◽  
A. M. Rodríguez ◽  
R. Caruso ◽  
...  
Keyword(s):  
Oxygen Vacancies ◽  
Thermal Evolution ◽  
Sol Gel ◽  
Correlation Spectroscopy ◽  
Cubic Phase ◽  
Perturbed Angular Correlation Spectroscopy ◽  
Heating And Cooling ◽  
Sol Gel Process ◽  
Fast Movement ◽  
Zirconia Powders

Yttria-stabilized cubic zirconia powders and coatings produced by the sol-gel method have been investigated by Perturbed Angular Correlation Spectroscopy (PAC). Results indicate that the metastable cubic phase is retained during heating and cooling cycles. The hyperfine interaction that describes this cubic phase, once crystallized, exhibits two components in a constant ratio of 4 : 1. The components represent different vacancy configurations. For the fast movement of oxygen vacancies starting at 750 °C, which is reflected by the damping of the hyperfine pattern, an activation energy of 0.96 eV was determined.

Effect of Y2O3 addition on the phase transition and growth of YSZ nanocrystallites prepared by a sol–gel process

2005 ◽  
Vol 351 (4) ◽  
pp. 304-311 ◽  
Author(s):  
Chih-Wei Kuo ◽  
Yueh-Hsun Lee ◽  
Kuan-Zong Fung ◽  
Moo-Chin Wang
Keyword(s):  
Phase Transition ◽  
Sol Gel ◽  
Sol Gel Process ◽  
Y2o3 Addition
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