Dilithium heptamolybdotetragadolinate
AssigneeNCR Corporation
InventorRaghvendra K. Pandey
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Abstract
Dilithium heptamolybdotetragadolinate, Li.sub.2 Gd.sub.4 (MoO.sub.4).sub.7, is disclosed, along with three methods to prepare it. Two of the three methods are useful for growing single crystals of the material. The material exhibits electro-optic, paramagnetic and ferroelectric properties.
Claims3
A method for the preparation of dilithium heptamolybdotetragadolinate represented by the formula Li.sub.2 Gd.sub.4 (MoO.sub.4).sub.7 comprising the steps of:
- a. providing a charge of gadolinium oxide (Gd.sub.2 O.sub.3), molybdenum trioxide (MoO.sub.3) and lithium molybdate (Li.sub.2 MoO.sub.4) in a respective mole ratio of 2:6:1;
- b. firing the charge at a temperature above about 800.degree. centigrade and below about 1150.degree. centigrade;
- c. maintaining the firing temperature for a time adequate to assure molecular homogeneity in the charge;
- d. increasing the temperature to about 1130.degree. to 1250.degree. centigrade;
- e. cooling from about 1130.degree. to 1250.degree. centigrate to about 400.degree. to 600.degree. centigrade over a period of about 100 to 200 hours;
- and
- f. cooling rapidly and without control to room temperature, and at least a portion of the dilithium heptamolybdotetragadolinate is in single crystal form.
A method for the preparation of dilithium heptamolybdotetragadolinate represented by the formula Li.sub.2 Gd.sub.4 (MoO.sub.4).sub.7 comprising the steps of:
- a. providing a charge of gadolinium oxide (Gd.sub.2 O.sub.3), molybdenum trioxide (MoO.sub.3) and lithium molybdate (Li.sub.2 MoO.sub.4) in a respective mole ratio of 2:6:1;
- b. firing the charge at a temperature above about 800.degree. centigrade and below about 1150.degree. centigrade;
- c. maintaining the firing temperature for a time adequate to assure molecular homogeneity in the charge;
- d. increasing the temperature to about 1130.degree. to 1250.degree. centigrade;
- e. cooling from about 1130.degree. to 1250.degree. centigrade to about 850 to 500 degrees centigrade at a rate of about 0.5 to 5 centigrade degrees per hour;
- f. further cooling from about 850.degree. to 500.degree. centigrade to at least about 400.degree. centigrade at a rate of about 100.degree. centigrade per hour;
- and
- g. cooling rapidly and without control to room temperature, and at least a portion of the dilithium heptamolybdotetragadolinate is in single crystal form.
A method for the preparation of dilithium heptamolybdotetragadolinate represented by the formula Li.sub.2 Gd.sub.4 (MoO.sub.4).sub.7 comprising the steps of:
- a. providing a charge of gadolinium oxide (Gd.sub.2 O.sub.3), molybdenum trioxide (MoO.sub.3) and lithium molybdate (Li.sub.2 MoO.sub.4) in a respective mole ratio of 2:6:1;
- b. firing the charge at a temperature above about 800.degree. centigrade and below about 1150.degree. centigrade;
- c. maintaining the firing temperature for a time adequate to assure molecular homogeneity in the charge and;
- d. cooling the charge by means of the Czochralski vertical crystal pulling technique to yield a single crystal of dilithium heptamolybdotetragadolinate.
Dependencies are inferred from the claim text.