Progress In Materials Synthesis And Processing Of Barium Titanium Oxide (BaTiO3) and Barium Strontium Titanium Oxide (BaTiSrO3) Films For Uncooled Infrared (IR) Detector Applications

2011 ◽  
Author(s):  
Wendy L. Sarney ◽  
Kimberley A. Olver ◽  
John W. Little ◽  
Frank E. Livingston ◽  
Krisztian Niesz ◽  
...  
Keyword(s):  
Titanium Oxide ◽  
Materials Synthesis ◽  
Ir Detector ◽  
Barium Titanium Oxide ◽  
Strontium Titanium Oxide ◽  
Barium Strontium ◽  
Synthesis And Processing ◽  
Barium Titanium

scholarly journals Temperature changes in the crystal structure of barium titanium oxide

1947 ◽  
Vol 189 (1017) ◽  
pp. 261-283 ◽  
Keyword(s):  
Titanium Oxide ◽  
Room Temperature ◽  
Transition Point ◽  
Linear Expansion ◽  
Temperature Structure ◽  
Barium Titanium Oxide ◽  
Temperature Changes ◽  
X Ray ◽  
Expansion Coefficients ◽  
Barium Titanium

Barium titanium oxide, which is tetragonal at room temperature, changes about 120° C to a cubic structure. This change has been followed in detail by means of X-ray powder photo­graphs taken in a 19 cm. powder camera at intervals of a few degrees over a range covering the transition point. The unit cell, which contains the formula number of atoms, retains its identity throughout the transition, and the atomic parameters are unaltered. The change is simply in the axial lengths, and these vary continuously with the temperature, though not linearly, the varia­tion becoming more rapid near the transition point. While the linear expansion coefficients along and perpendicular to the tetrad axis are large and of opposite sign, the volume expan­sion coefficient is small and positive. There is no discontinuous change either of linear spacing or of volume detectable at the transition point, but there is a sharp discontinuity in the linear expansion coefficients, and a marked increase in the volume expansion coefficient which is probably, though not certainly, discontinuous. The transition suggests a typical λ-point change. The specific heat has not been deter­mined, but the thermal expansion curve has the characteristic λ shape. Co-existence of cubic and tetragonal structures, in proportions depending on the temperature, occurs over a range of some degrees near the transition point, and is attributed to the effect of local stresses in facilitating or hindering a change between two structures whose energy difference is very small in this temperature range. Below room temperature, observations made down to -183° C suggest that the structure may have a second transition point somewhere below this and become cubic again, the change being of the same nature as that at 120° C. It is argued that the room-temperature structure can only be explained by the existence of directed bonds, and that the breaking of these bonds with increasing temperature is respon­sible for the 120°C transition. The low-temperature transition is explained by postulating a more complete set of bonds, probably an octahedral complex, which partially breaks down at this temperature to give the square formation observed in the room-temperature structure. The possible nature of the directed bonds is discussed qualitatively. The condition which makes possible the formation of such bonds is likely to be the abnormal volume available to the Ti atom, which is due to the effect of the large Ba ion in forcing apart the oxygen lattice. The directed bond system will only contribute a small part to the attractive energy of the lattice, which is mainly ionic in character. The hypothesis that directed bonds exist, whatever their origin, is used for a tentative explanation of anomalous variations of intensity of the X-ray lines observed at temperatures near the transition point.

ChemInform Abstract: BARIUM TITANIUM OXIDE (BA2TI9O20) AS A MICROWAVE DIELECTRIC RESONATOR

1976 ◽  
Vol 7 (2) ◽  
pp. no-no
Author(s):  
J. K. PLOURDE ◽  
D. F. LINN ◽  
H. M. JUN. O'BRYAN ◽  
JOHN JUN. THOMSON
Keyword(s):  
Titanium Oxide ◽  
Dielectric Resonator ◽  
Barium Titanium Oxide ◽  
Microwave Dielectric ◽  
Barium Titanium

Hydroxyapatite Nano-Barium-Strontium-Titaniumoxide Composites

2011 ◽  
Vol 484 ◽  
pp. 204-209 ◽  
Author(s):  
N. Demirkol ◽  
Eyup Sabri Kayali ◽  
Mehmet Yetmez ◽  
F.N. Oktar ◽  
Simeon Agathopoulos
Keyword(s):  
Titanium Oxide ◽  
Compression Strength ◽  
Sintering Temperature ◽  
Bovine Bone ◽  
Strontium Titanium Oxide ◽  
Barium Strontium ◽  
Load Carrying ◽  
Different Temperatures ◽  
Density Values ◽  
Mechanical And Microstructural Properties

The aim of this study is to produce and to investigate the mechanical and microstructural properties of composite materials made of hydroxyapatite, obtained from natural bovine bone and nano barium strontium titanium oxide (5 and 10 wt%). Compositions were mechanical alloyed and compacted to pellets. The samples were subjected to sintering at different temperatures between 1000oC and 1300oC. Compression strength, Vickers microhardness as well as density were measured. SEM and X-ray diffraction studies were also conducted. With increasing sintering temperature, microhardness, compression strength and density of composites increased. With increasing addition of nano barium strontium titanium oxide (BST) to bovine hydroxyapatite (BHA), microhardness values of composites decreased at all sintering temperatures, but compression strength and density values of composites showed different tendency. Compression strengths of BHA-composites at low sintering temperatures were nearly the same, but their compression strengths at high sintering temperatures decreased with increasing nano BST addition. The best mechanical properties were obtained at 1300°C sintering temperature with BHA-5wt% nano BST. Microhardness and compression strengths values of these nano–oxide composites are generally higher than that BHA-composites produced by traditional methods. Adding of nano-oxides to BHA could be a valuable method to produce rigid and high load carrying ability when compared with BHA-composites produced by conventional methods. Nano-HA and nano-oxides composites could be even better. Those nano-nano studies are still in progress.

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