Material Specification for La:21; [La-Cu-O]
Process: Flux Growth
Notes: "... we report measurements on an untwinned single crystal of La2CuO4... Single crystals... were grown from a CuO flux, quenched, and later annealed at 650 K in N2 for a short time and cooled to 300 K over 10 h. The ultrasound sample was oriented to within 1° of its principal axes via x-rays... Sample dimensions were 1.73x1.76x0.70 MM3, all ±0.01 mm, with the b axis parallel to the small dimension and normal to the Cu-O plane."
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]
Measurement Method: Unknown density method
Cautions: Unevaluated Data
No measurement details were noted.
Specific Heat for La:21; [La-Cu-O]
| Temperature (K) |
Specific Heat (J kg-1 K-1) |
| 25.6 |
31.6 |
| 26.3 |
31.9 |
| 27.0 |
32.2 |
| 27.7 |
32.5 |
| 28.1 |
32.8 |
| 28.5 |
33.0 |
| 29.0 |
33.1 |
| 29.4 |
33.5 |
| 30.3 |
33.8 |
| 30.7 |
34.0 |
| 31.1 |
34.3 |
| 31.6 |
34.6 |
| 33.4 |
35.7 |
| 36.1 |
37.8 |
| 37.9 |
39.4 |
| 40.6 |
41.3 |
Measurement Method: Calorimetry
"Heat-capacity measurements were made with an ac technique on samples from the same batch, but not the same fragment, as the ultrasound sample and were annealed in a different run. The heat-capacity sample had a total mass of 2.2 mg (1.5x0.5x0.5 mm
3). Our calorimeter was made from thin (6x10
-4 cm) Mylar foil cut into the shape of a cross with four arms (0.4x17 mm
2), and a central square 4x4 mm
2. This central square is the calorimeter. The four arms were mechanically and thermally anchored to a Cu ring that served at the thermal bath. Au-Ag and Ge-Au alloys were evaporated onto opposite faces of the square to be used as heater and thermometer, respectively. Ag film evaporated onto the four arms provided electrical contact for the heater and thermometer and also served as the weak thermal link. The La
2CuO
4 sample was attached to the calorimeter with 0.01 mg of silicone vacuum grease. The entire assembly was maintained in high vacuum. We achieved a precision of 0.1% in heat capacity after signal averaging. The operating frequency (0.05 Hz) was chosen to be between the internal and external equilibration rates for the calorimeter and sample."
Cautions: Evaluated Data
Elasticity Tensor for La:21; [La-Cu-O]
| C11 = | 171.9 |
| C12 = | 90.4 |
| C13 = | 72.7 |
| C22 = | 171.2 |
| C23 = | 73.1 |
| C33 = | 200.0 |
| C44 = | 65.6 |
| C55 = | 65.8 |
| C66 = | 96.8 |
Measurement Method: Resonant ultrasound method
"... we are able to use a resonant method coupled with an elegant data analysis technique to deconvolute the resonant frequencies into elastic constants... The technique... involves driving a sample with a continuous acoustic signal at a point of low symmetry, such as a corner. By sweeping the drive frequency, the normal modes of vibration are determined by the response of a second transducer at the corner diametrically oppposite... our precision is 0.4% or better, and our absolute accuracy is about 1%." The recorded values are for a temperature of 297 K."
Cautions: Evaluated Data
