Material Specification for La:21; [La-Cu-O]
Process: Melt Processed
Notes: "Single crystals of La2CuO4 were obtained by growth on a limited number of seed crystals on a platinum crystal-holder. We used copper oxide as the solvent. The solution in a melt was cooled from 1-2 K above the temperature of spontaneous crystallization, at a rate of 1-2 K/day. Oxygen saturation was attained by annealing at 750 °C and an excess oxygen pressure of (0.2 MPa = 2 atm) for 12 h. Quenching at room temperature followed (slow cooling resulted in friable single crystals), but did cause a number of cracks to appear. ...we prepared two samples, one of which (A) had a characteristic size of 4.5 mm and the other (B) a size of about 3 mm. The working faces were derived to within about 1°. Because the samples were twinned, the working surfaces corresponding to the emergence of the [100] and [010] axes were indistinguishable by x-ray methods..."
Formula: La2CuO4
Informal Name: La:21
Chemical Family: La-Cu-O
Chemical Class: Oxide
Structure Type: Single Crystal
Manufacturer: In House
Commercial Name: In House
Production Date:
Lot Number:
Production Form:
Density (mass) for La:21; [La-Cu-O]
| Temperature (K) |
Density (g cm-3) |
| 300 |
7.07 |
Measurement Method: Unknown density method
No measurement details were noted.
Cautions: Unevaluated Data
Crystallography for La:21; [La-Cu-O]
| Crystal System: | Orthorhombic |
| Formula Units per Cell: | |
| Space Group: |
|
Cell Parameters
| Sample Number () |
Temp
K
|
a
Å
|
b
Å
|
c
Å
|
| A |
300 |
5.356 |
5.407 |
13.156 |
| B |
300 |
5.362 |
5.405 |
13.143 |
Measurement Method: X-ray diffraction
No measurement details were noted.
Cautions: Unevaluated Data
Elasticity Tensor for La:21; [La-Cu-O]
| C11 = | 223 ± 2 |
| C12 = | 132 ± 2 |
| C13 = | 96 ± 2 |
| C22 = | |
| C23 = | |
| C33 = | 272 ± 2 |
| C44 = | 68 ± 1 |
| C55 = | |
| C66 = | 105 ± 1 |
Measurement Method: Differential ultrasonic method
"When the samples were ground the working faces had a small number of cracks, but it was possible to place piezoelectric transducers mainly in regions without visible damage... we used (a frequency of about) 50 MHz. ...we developed a modification of the phase method for use with signals that traverse the sample once along the shortest path... It represents a frequency-tunable rf bridge, operating in a pulsed mode. The acoustic arm of the bridge has two delay lines with piezoelectric transducers, between which the sample can be placed. The second arm, purely electromagnetic, contains a continuous attenuator for regulating the comparison signal amplitude. The measurements are essentially differential. The mean frequency increments... corresponding to successive balancings of the bridge without... and with... the sample in the acoustic arm, are measured."
Cautions: Evaluated Data
Sound Velocity for La:21; [La-Cu-O]
| Sample Number () |
Mode () |
Temperature (K) |
Sound Velocity (km/s) |
| A |
Longitudinal |
77 |
5.66 |
| A |
Shear |
77 |
3.80 |
| B |
Longitudinal |
77 |
5.61 |
| B |
Shear |
77 |
3.74 |
Measurement Method: Differential ultrasonic method
"When the samples were ground the working faces had a small number of cracks, but it was possible to place piezoelectric transducers mainly in regions without visible damage... we used (a frequency of about) 50 MHz. ...we developed a modification of the phase method for use with signals that traverse the sample once along the shortest path... It represents a frequency-tunable rf bridge, operating in a pulsed mode. The acoustic arm of the bridge has two delay lines with piezoelectric transducers, between which the sample can be placed. The second arm, purely electromagnetic, contains a continuous attenuator for regulating the comparison signal amplitude. The measurements are essentially differential. The mean frequency increments... corresponding to successive balancings of the bridge without... and with... the sample in the acoustic arm, are measured."
Cautions: Evaluated Data
