Determination of J-R curves by load separation criterion in highly ductile TP-based composites under high temperature conditions

2017 ◽  
Vol 182 ◽  
pp. 391-401 ◽  
Author(s):  
M. Chabchoub ◽  
B. Vieille ◽  
M. Beyaoui ◽  
M. Taktak ◽  
M. Haddar ◽  
...  
Keyword(s):  
High Temperature ◽  
Separation Criterion ◽  
Temperature Conditions ◽  
Load Separation

β-CaB4O7: A New Polymorph Synthesized under High-Pressure/High-Temperature Conditions

2003 ◽  
Vol 58 (4) ◽  
pp. 257-265 ◽  
Author(s):  
Hubert Huppertz
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Temperature ◽  
Prominent Feature ◽  
X Ray ◽  
Temperature Conditions ◽  
High Pressure High Temperature ◽  
Ir Spectroscopic ◽  
Pressure Phase

A new oxoborate β -CaB4O7 has been synthesized under high-pressure/high-temperature conditions from calcium oxide and boron oxide with a Walker-type multianvil apparatus at 7.7 GPa and 1100 °C. Single crystal X-ray structure determination of β -CaB4O7 revealed: Pmn21, a = 1058.4(1), b = 436.9(1), c = 419.4(1) pm, Z = 2, R1 = 0.0305, wR2 = 0.0587 (all data). The compound is isotypic to the known oxoborates SrB4O7, PbB4O7, and EuB4O7 exhibiting a network structure of linked BO4 tetrahedra. As a prominent feature of the tetrahedral network an oxygen atom is coordinated to three boron atoms. The relation of the crystal structure of the high-pressure phase β -CaB4O7 to the normalpressure phase α-CaB4O7 as well as the relation to the isotypic phases MB4O7 (M = Sr, Pb, Eu) are discussed. The results of IR-spectroscopic investigations on β -CaB4O7 are also presented.

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