Thermodynamic properties of single crystals based on lithium tungstate by reaction and DSC calorimetry

For the first time, single crystals of undoped lithium tungstate and lithium tungstate doped by 1.25% molybdenum were grown by the low-temperature-gradient Czochralski technique. The standard formation enthalpies, lattices enthalpies, stabilization energies, and the heat capacity were determined in the temperature range of 320-997 K. The lattice enthalpy dependence on Mo content was constructed.

Heat capacity of lithium tungstate single crystal by DSC calorimetry data in the temperature range of 319-997 K

The heat capacity of lithium tungstate single crystal (Li2WO4) was measured for the first time in the temperature range of 319-997 K. The experiments were carried out by DSC calorimetry. The Li2WO4 single crystal was first grown by low-temperature-gradient Czochralski technique with weight control. The temperature dependence of Li2WO4 heat capacity in the temperature range 319-997 K was monotonic. According to results of our studies, there were no phase transitions in Li2WO4 in the investigated temperature range.

Growth of 100 mm indium antimonide single crystals by modified Czochralski technique

Currently there is a worldwide trend to increase the diameter of crystals grown from elemental semiconductors and semiconductor compounds. According to literary data the diameter of 3–5 semiconductor single crystals grown nowadays is 4 to 6 inches. So far up to 75 mm indium antimonide single crystals have been grown in Russia. Indium antimonide is the element base for the widest field of solid state electronics, i.e., optoelectronics. Indium antimonide is used for the fabrication of 3–5 mm range linear photodetectors and photodetector arrays used as light-sensitive material in heat vision systems. Growth heat conditions have been selected and 100 mm [100] indium antimonide single crystals have been grown using the modified two-stage Czochralski technique. The graphite heating unit has been oversized to accommodate a 150 mm crucible and a 4.5–5 kg load. The results of the work have provided for a substantial increase in the yield of photodetectors. The electrophysical properties of the as-grown single crystals have been studied using the Van der Pau method and proved to be in agreement with the standard parameters of undoped indium antimonide. Using the 9-field etch method of pit counting under an optical microscope the dislocation density in the 100 mm single crystals has been measured to be ≤ 100 cm-2which is similar to that for 50 mm single crystals.

Single crystals of undoped Li2WO4 and Li2W1-0.0125Mo0.0125O4: Formation enthalpies, heat capacity in the temperature range 320-997 K

The Li2WO4 single crystal was first grown applying unique Czochralski technique with weight control and low-temperature-gradients. Single crystal of Li2WO4 is one of the perspective materials to search rare events....