Accession Number : ADA086751
Title : The Growth of Berlinite (AlPO4) Single Crystals.
Descriptive Note : Final rept. 1 Jul 77-30 Sep 79,
Corporate Author : LITTON SYSTEMS INC MORRIS PLAINS N J AIRTRON DIV
Personal Author(s) : Drafall,Larry E ; Belt,Roger F
Report Date : Mar 1980
Pagination or Media Count : 75
Abstract : Single crystals of the berlinite mineral phase of anhydrous aluminum orthophosphate have been grown for possible surface acoustic wave applications. The desired piezoelectric form of AlPO4 is the alpha-phase which is stable from 130 to 580 C. A seeded hydrothermal growth technique was used. Nutrient was prepared by heating hydrated alumina and phosphoric acid in a sealed silver liner from 140 to 200 C at a rate of 5 deg/day and a 15 deg temperature gradient. Because AlPO4 has retrograde solubility, the nutrient was placed in a silver mesh basket in the upper, cooler portion of the liner with the seeds situated in the lower, hotter portion. A 20% free area baffle separated the two regions. Two basic techniques were used for the growth runs. The constant temperature method with a 10 C gradient produced rates of 23-25 mils/day. The rates could be varied significantly depending on such parameters as growth temperature, gradient, nutrient basket mesh size, seed orientation and baffle design. The second technique used increasing temperature at a rate of 5 C/day over the range of 140-200 C to obtain average growth rates of 22-32 mils/day. Seed orientation for most runs was (0001) plates. New growth of AlPO4 for the most part was clear and of fair quality.
Descriptors : *ALUMINUM COMPOUNDS , *SINGLE CRYSTALS , *CRYSTAL GROWTH , *PHOSPHATES , TEMPERATURE , STABILITY , EXPERIMENTAL DATA , SURFACE WAVES , PHYSICAL PROPERTIES , ACOUSTIC WAVES , RATES , PURITY , DEFECTS(MATERIALS) , ALUMINUM OXIDES , CONSTANTS , SOLUBILITY , GRAIN BOUNDARIES
Subject Categories : Crystallography
Distribution Statement : APPROVED FOR PUBLIC RELEASE