Temperature and concentration dependences of acoustic velocity and damping in Rb[sub 1[minus][ital x]](ND[sub 4])[sub [ital x]]D[sub 2]AsO[sub 4] mixed crystals by Brillouin backscattering

Journal Article · Thu Dec 01 04:00:00 EST 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.50.16167· OSTI ID:6712628

Tu, C; Schmidt, V H ^[1]

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1. Department of Physics, Montana State University, Bozeman, Montana 59717 (United States)

The LA[100] ([ital a]-axis) Brillouin backscattering phonon spectra have been measured as a function of temperature (20--370 K) in the mixed ferroelectric (FE)--antiferroelectric (AFE) system Rb[sub 1[minus][ital x]](ND[sub 4])[sub [ital x]]D[sub 2]AsO[sub 4] (DRADA-[ital x]) for ammonium concentrations [ital x]=0, 0.10, and 0.28. The Brillouin frequency shift with decreasing temperature shows hardening (positive coupling) whose steepness decreases with higher ND[sub 4] content. For RbD[sub 2]AsO[sub 4] (DRDA), a Landau-Khalatnikov-like maximum (which persists in weaker form for [ital x]=0.10) was observed and the polarization relaxation time is estimated to be [tau][similar to]3.8[times]10[sup [minus]12]/([ital T][sub [ital c]][minus][ital T]) s, where [ital T][sub [ital c]] is the ferroelectric transition temperature. For both [ital x]=0.10 and 0.28, a broad damping peak anomaly which is stronger in [ital x]=0.28 was observed and can be connected with the dynamic order parameter fluctuations. Taking into account earlier NMR and dielectric results, we conclude that the local structure competition between FE ordering and AFE ordering is the origin of these broad damping anomalies.

• OSTI ID: 6712628
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 50:22; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360606* -- Other Materials-- Physical Properties-- (1992-)
ALKALI METAL COMPOUNDS
AMMONIUM COMPOUNDS
ANTIFERROELECTRIC MATERIALS
ARSENATES
ARSENIC COMPOUNDS
BRILLOUIN EFFECT
CHEMICAL COMPOSITION
COHERENT SCATTERING
CRYSTAL-PHASE TRANSFORMATIONS
DEUTERIUM COMPOUNDS
DIELECTRIC MATERIALS
FERROELECTRIC MATERIALS
HYDROGEN COMPOUNDS
MATERIALS
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
RUBIDIUM COMPOUNDS
SCATTERING
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K