Phase coexistence in the mixed crystal Rb[sub 1-x](NH[sub 4])[sub x]H[sub 2]AsO[sub 4]

Miscellaneous · Wed Jan 01 00:00:00 EST 1992

OSTI ID:7165902

Pinto, N J

A study of the coexistence phenomenon in mixed crystals of rubidium ammonium dihydrogen arsenate has been done. Coexistence in this study refers to the simultaneous presence of ferroelectric and proton glass phases as temperature is lowered below the ferroelectric phase transition temperature T[sub c]. Such coexistence is found to exist in these mixed crystals only for small ammonium concentrations. The results show that coexistence exists for lower ammonium concentration than previously suggested. A study was also done on crystals with larger ammonium concentrations that show pure proton glass behavior and the results compared with the coexistence phenomenon. Dielectric, spontaneous polarization and nuclear magnetic resonance experiments on mixed crystals with small ammonium concentrations show that at low temperatures there exists intimate coexistence of ferroelectric clusters with proton glass clusters below the glass transition temperature T[sub g]. In the proton glass phase, it is observed that a spread of relaxation times due to the creation and annihilation of HAsO[sub 4] and H[sub 3]AsO[sub 4] pairs as they diffuse through the crystal. Spin lattice relaxation times for the acid deuterons in a 10% ammoniated sample show a broad T[sub 1] minimum near the glass transition temperature which is characteristic of proton glasses. Field-cooling experiments were also done on the pure proton glass. The results are consistent with dielectric measurements, but the remanent polarization was found to be extremely small. This polarization was found to depend on the rate of heating and cooling the sample while performing the experiment.

• Research Organization: Montana State Univ., Bozeman, MT (United States)
• OSTI ID: 7165902
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
AMMONIUM COMPOUNDS
PHASE STUDIES
ARSENATES
RUBIDIUM COMPOUNDS
CRYSTALS
DIELECTRIC PROPERTIES
FERROELECTRIC MATERIALS
INTERMETALLIC COMPOUNDS
SPIN-LATTICE RELAXATION
TRANSITION TEMPERATURE
ALKALI METAL COMPOUNDS
ALLOYS
ARSENIC COMPOUNDS
ELECTRICAL PROPERTIES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RELAXATION
THERMODYNAMIC PROPERTIES
360602* - Other Materials- Structure & Phase Studies
665000 - Physics of Condensed Matter- (1992-)