Heavily donor-doped, optically translucent ferroelectric barium titanate ceramics through defect chemical engineering

CrystEngComm ◽  
2019 ◽  
Vol 21 (18) ◽  
pp. 2854-2862 ◽  
Author(s):  
Christian Pithan ◽  
Hayato Katsu ◽  
Rainer Waser
Keyword(s):  
Solid State ◽  
Barium Titanate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Chemical Engineering ◽  
Ceramic Processing ◽  
Solid State Route ◽  
Titanate Ceramics ◽  
Conventional Ceramic Processing

The possibility of preparing translucent ferroelectric heavily donor-doped BaTiO3 ceramics rich in TiO2 has been demonstrated by conventional ceramic processing based on the synthesis via the solid state route and on subsequent sintering and annealing at high levels of oxygen partial pressure.

Decrease in Resistance of Ceria Oxygen Sensor Induced by 10 mol% Hf and Zr Doping

2005 ◽  
Vol 888 ◽  
Author(s):  
Noriya Izu ◽  
Woosuck Shin ◽  
Ichiro Matsubara ◽  
Norimitsu Murayama
Keyword(s):  
Solid State ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Solid State Reaction ◽  
Pressure Range ◽  
Oxygen Sensor ◽  
Cubic Phase ◽  
Doped Ceria ◽  
Oxygen Gas ◽  
Resistive Type

ABSTRACTResistive type sensors using 10 mol% Hf-doped ceria and 10 mol% Zr-doped ceria, which had a single cubic phase obtained by solid state reaction, were fabricated and their sensing properties were investigated. The resistance and resistivity of the 10 mol% Hf-doped ceria or 10 mol% Zr-doped ceria were smaller than those of non-doped ceria. In the case of the same temperature of solid state reaction, the resistance and resistivity of the 10 mol% Hf-doped ceria were much smaller than those of the 10 mol% Zr-doped ceria. Furthermore, in the case of the same dopant, the resistance and resistivity of the sensor prepared from the solid state reaction at 1773 K were much smaller than those at 1673 K. The sensor using the 10 mol% Hf-doped ceria could be used as an oxygen gas sensor in wide oxygen partial pressure range and could be applicable to a λ sensor and a universal A/F sensor.

Examples of the Practical Use of Non-Stoichiometric Compounds

1994 ◽  
Author(s):  
Koji Kosuge
Keyword(s):  
Solid State ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Pressure ◽  
Closed System ◽  
Electromotive Force ◽  
Solid Electrolytes ◽  
Coulometric Titration ◽  
Preparation Methods ◽  
Basic Characteristics

In this chapter, we describe four kinds of non-stoichiometric compound, which are or will be in practical use, from the viewpoint of preparation methods or utility. As a first example, the solid electrolyte (ZrO2)0.85(CaO)0.15 is described, which are discussed in Sections 1.4.6–1.4.8 from the viewpoint of basic characteristics. The second example is the magnetic material Mn–Zn ferrite, for which the control of non-stoichiometry and the manufacturing process will be described. Then the metal hydrides or hydrogen absorbing alloys, which are one of the most promising materials for storing and transporting hydrogen in the solid state, are described, mainly focusing on the phase relation. Finally, we describe the relation between the control of composition and the growth of a single crystal of the semiconductive compound GaAs, which is expected to give electronic materials for 1C and LSI etc. Solid electrolytes, which show ionic conductivity in the solid state, are considered to be potential materials for practical use, some are already used as mentioned below. Solid electrolytes have characteristic functions, such as electromotive force, ion selective transmission, and ion omnipresence. Here we describe the practical use of calcia stabilized zirconia (CSZ), (ZrO2)0.85(CaO)0.15, the structure and basic properties of which are discussed in detail in Sections 1.4.5–1.4.8. The most simple practical application of CSZ is for the gauge of oxygen partial pressure, as mentioned in Sections 1.4.7 and 1.4.8. The oxygen partial pressure P2o2 in the closed system as shown in Fig. 3.1 can be measured, taking the air as the standard oxygen pressure P1o2. The electromotive force (EMF) of this concentration cell is expressed as . . . E = (RT/4F)ln(P1o2/ P2o2) . . . This principle is applied in the measurement of oxygen partial pressure in laboratory experiments and of the oxygen activity of slag in refineries. Based on the principle of coulometric titration (see Section 1.4.8), the oxygen partial pressure of a closed system can be kept constant by feedback of the EMF, in the oxygen pressure range 1 to 10−7 atm. By use of this closed system, investigations on redox reactions of metals and also enzyme reactions have been carried out.

High temperature X-ray diffraction studies of the decomposition mechanism of YBa2Cu3O7−δ at an oxygen partial pressure less than 10 Pa

1995 ◽  
Vol 10 (3) ◽  
pp. 165-169 ◽  
Author(s):  
W. Pitschke ◽  
W. Bieger ◽  
G. Krabbes ◽  
U. Wiesner
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Solid State Reaction ◽  
Peritectic Reaction ◽  
Decomposition Reaction ◽  
Primary Decomposition ◽  
X Ray Diffraction ◽  
X Ray

The crystallographic data of YBa2Cu3O7−δ, Y2BaCuO5, BaCu2O2, and YBa4Cu3O9 at high temperatures and p(O2)<10 Pa have been derived on the basis of HT-XRD measurements. Whereas Y2BaCuO5 expands nearly isotropically, YBa2Cu3O7−δ and BaCu2O2 show anisotropic expansions. Furthermore, the first decomposition step of the considered compounds at p(O2)<10 Pa was observed. BaCu2O2 melts congruently at T ≍ 1273 K and Y2BaCuO5 decomposes via a peritectic reaction into Y2O3, Y2BaO4 and melts at T ≍ 1323 K. A solid-state reaction into Y2BaCuO5 and BaCu2O2 was indicated for YBa2Cu3O7−δ at T ≍ 1123 K. Because YBa4Cu3O9 becomes unstable at T ≍ 1123 K, this compound cannot be formed by the primary decomposition reaction of YBa2Cu3O7−δ

Rapid Prototyping Methodologies for Ceramic Micro Components

2009 ◽  
Vol 154 ◽  
pp. 1-7 ◽  
Author(s):  
P.R. Chalker ◽  
K.M. Berggreen ◽  
A.T. Clare ◽  
J. Singh ◽  
C.J. Sutcliffe
Keyword(s):  
Raman Spectroscopy ◽  
Barium Titanate ◽  
Rapid Prototyping ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Laser Power ◽  
Sintered Material ◽  
Selective Laser Sintering ◽  
Sintering Atmosphere ◽  
Powder Bed

This paper investigates the rapid prototyping of components from ceramics. Selective laser sintering of barium titanate powder has been investigated as a potential route to manufacturing freeform electro-ceramic based components. Raman spectroscopy has been used to investigate the effect of laser power and oxygen partial pressure on the phase and composition of the sintered material. It is shown that the sintering laser power strongly influences the composition. As the laser power is increased during sintering, the Eg mode of anatase becomes evident at 640 cm-1. When the oxygen partial pressure in the sintering atmosphere is reduced from 19% to 0.2% the whole depth of the powder bed sampled by Raman spectroscopy resembles bulk anatase.

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