Role of the Fe-substitution in dielectric behavior of the glass–ceramic cordierite Mg2Al4Si5O18 system

2014 ◽  
Vol 454 ◽  
pp. 131-134 ◽  
Author(s):  
G. Kirat ◽  
M.A. Aksan
Keyword(s):  
Glass Ceramic ◽  
Dielectric Behavior ◽  
Fe Substitution

Grain Boundary Segregation in Titanium Dioxide: Evaluation of Relative Driving Forces for Segregation

2002 ◽  
Vol 751 ◽  
Author(s):  
Qinglei Wang ◽  
Guoda D. Lian ◽  
Elizabeth C. Dickey
Keyword(s):  
Titanium Dioxide ◽  
Driving Forces ◽  
Boundary Segregation ◽  
Solute Segregation ◽  
Dielectric Behavior ◽  
Relative Role ◽  
Transmission Electron ◽  
Fundamental Phenomenon ◽  
Versus Strain

ABSTRACTSolute segregation to grain boundaries is a fundamental phenomenon in polycrystalline metal-oxide electroceramics that has enormous implications for the macroscopic dielectric behavior of the materials. This paper presents a systematic study of solute segregation in a model dielectric, titanium dioxide. We investigate the relative role of the electrostatic versus strain energy driving forces for segregation by studying yttrium-doped specimens. Through analytical transmission electron microscopy studies, we quantitatively determine the segregation behavior of the material. The measured Gibbsian interfacial excesses are compared to thermodynamic predictions.

Key role of the expression of bone morphogenetic proteins in increasing the osteogenic activity of osteoblast-like cells exposed to shock waves and seeded on bioactive glass-ceramic scaffolds for bone tissue engineering

2014 ◽  
Vol 29 (5) ◽  
pp. 728-736 ◽  
Author(s):  
Giuliana Muzio ◽  
Germana Martinasso ◽  
Francesco Baino ◽  
Roberto Frairia ◽  
Chiara Vitale-Brovarone ◽  
...  
Keyword(s):  
Shock Wave ◽  
Alkaline Phosphatase ◽  
Shock Waves ◽  
Bioactive Glass ◽  
Bone Morphogenetic Protein ◽  
Bone Morphogenetic Proteins ◽  
Glass Ceramic ◽  
Osteogenic Activity ◽  
Morphogenetic Protein

In this work, the role of shock wave-induced increase of bone morphogenetic proteins in modulating the osteogenic properties of osteoblast-like cells seeded on a bioactive scaffold was investigated using gremlin as a bone morphogenetic protein antagonist. Bone-like glass-ceramic scaffolds, based on a silicate experimental bioactive glass developed at the Politecnico di Torino, were produced by the sponge replication method and used as porous substrates for cell culture. Human MG-63 cells, exposed to shock waves and seeded on the scaffolds, were treated with gremlin every two days and analysed after 20 days for the expression of osteoblast differentiation markers. Shock waves have been shown to induce osteogenic activity mediated by increased expression of alkaline phosphatase, osteocalcin, type I collagen, BMP-4 and BMP-7. Cells exposed to shock waves plus gremlin showed increased growth in comparison with cells treated with shock waves alone and, conversely, mRNA contents of alkaline phosphatase and osteocalcin were significantly lower. Therefore, the shock wave-mediated increased expression of bone morphogenetic protein in MG-63 cells seeded on the scaffolds is essential in improving osteogenic activity; blocking bone morphogenetic protein via gremlin completely prevents the increase of alkaline phosphatase and osteocalcin. The results confirmed that the combination of glass-ceramic scaffolds and shock waves exposure could be used to significantly improve osteogenesis opening new perspectives for bone regenerative medicine.

scholarly journals Role of Fe substitution and quenching rate on the formation of various quasicrystalline and related phases

2001 ◽  
Vol 24 (3) ◽  
pp. 257-264 ◽  
Author(s):  
Varsha Khare ◽  
R. S. Tiwari ◽  
O. N. Srivastava
Keyword(s):  
Quenching Rate ◽  
Fe Substitution

Mixed polyanion NaCo1−x (VO) x PO4 glass–ceramic cathode: role of ‘Co’ on structural behaviour and electrochemical performance

2017 ◽  
Vol 52 (9) ◽  
pp. 5038-5047 ◽  
Author(s):  
G. Suman ◽  
Ch. Srinivasa Rao ◽  
Prasanta Kumar Ojha ◽  
M. S. Surendra Babu ◽  
R. Balaji Rao
Keyword(s):  
Electrochemical Performance ◽  
Glass Ceramic ◽  
Structural Behaviour

Dielectric behavior of polyelectrolyte solutions: the role of proton fluctuation

1991 ◽  
Vol 95 (12) ◽  
pp. 4883-4889 ◽  
Author(s):  
F. Bordi ◽  
C. Cametti ◽  
G. Paradossi
Keyword(s):  
Dielectric Behavior ◽  
Polyelectrolyte Solutions

Role of acid attack in the in vitro bioactivity of a glass-ceramic of the 3CaO·P2O5-CaO·SiO2-CaO·MgO·2SiO2 system

Biomaterials ◽  
2001 ◽  
Vol 22 (14) ◽  
pp. 2013-2019 ◽  
Author(s):  
J Roman ◽  
A.J Salinas ◽  
M Vallet-Regi ◽  
J.M Oliveira ◽  
R.N Correia ◽  
...  
Keyword(s):  
Glass Ceramic ◽  
In Vitro Bioactivity ◽  
Acid Attack

scholarly journals Dielectric Properties of La2O3 Doped Composite (PbxSr1−x)TiO3 Borosilicate Glass Ceramic

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
C. R. Gautam ◽  
Devendra Kumar ◽  
Om Parkash ◽  
O. P. Thakur
Keyword(s):  
Dielectric Constant ◽  
Glass Ceramic ◽  
Perovskite Phase ◽  
Glass Ceramics ◽  
Dielectric Behavior ◽  
Effective Dielectric Constant ◽  
Glassy Matrix ◽  
Crystal Glass ◽  
Treatment Schedule ◽  
Ceramic Samples

Ferroelectric (PbxSr1−x)TiO3 (PST) perovskite phase has been crystallized in borosilicate glassy matrix with a suitable choice of composition and heat treatment schedule. La2O3 is a donor dopant for PST and can make it semiconducting. Dispersion of semiconducting perovskite phase in insulating glassy matrix in glass-ceramic samples may lead to the formation of space charge polarization around crystal-glass interface, leading to a high value of effective dielectric constant, εr. Therefore, with the aim of the developing glass ceramics with high dielectric constant, glasses in the system 64[(PbxSr1−x)O·TiO2]-25[2SiO2·B2O3]-5[K2O]-5[BaO]-1[La2O3] have been prepared (0.5≤x≤1). It is found that the addition of La2O3 strongly affected the crystallization and dielectric behavior of glass-ceramic with PST perovskite phase. All glass ceramic samples show a diffuse broad Curie peak in their εr versus T plots. Curie peak temperature, Tc, depends on compositions of the glass-ceramic samples as well as frequency of measurements.

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