Soft-mode behavior and the dipolar glass transition in KTa sub 1 minus x Nb sub x O sub 3

Journal Article · Sun Apr 01 00:00:00 EST 1990 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.41.7231· OSTI ID:6836642

Chou, H; Shapiro, S M ^[1]; Lyons, K B ^[2]; Kjems, J ^[3]; Rytz, D ^[4]

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1. Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (USA)
2. AT T Bell Laboratories, Murray Hill, New Jersey 07974 (USA)
3. Risoe National Laboratory, Postbus 49, DK-4000 Roskilde, Denmark (DK)
4. Hughes Research Laboratories, Malibu, California 90265 (USA)

An inelastic neutron scattering study of KTa{sub 1{minus}{ital x}}Nb{sub {ital x}}O{sub 3} ({ital x}=0.012) (KTN) shows that there is a marked softening of the zone-center optic mode with decreasing temperature. This mode reaches a nonzero minimum energy of {approx}0.9 meV at {ital T}=20 K and renormalizes to higher energies as the temperature is further lowered, in agreement with light-scattering results on the same sample. In addition, x-ray diffraction does not reveal any structural phase transition in this temperature range. A recent light-scattering study on a {ital x}=0.009 sample suggests that KTN has a dipolar glass phase with a transition temperature of 3 K. The present observation of incomplete softening is similar to the soft-mode behavior characteristic of other mixed systems and provides further evidence of the dipolar glass properties of KTN.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6836642
• Journal Information: Physical Review, B: Condensed Matter; (USA), Vol. 41:10; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
POTASSIUM COMPOUNDS
PHONONS
TANTALUM COMPOUNDS
COMPARATIVE EVALUATIONS
FERROELECTRIC MATERIALS
GLASS
LIGHT SCATTERING
NEUTRON DIFFRACTION
NIOBATES
PHASE TRANSFORMATIONS
VERY LOW TEMPERATURE
ALKALI METAL COMPOUNDS
COHERENT SCATTERING
DIFFRACTION
NIOBIUM COMPOUNDS
OXYGEN COMPOUNDS
QUASI PARTICLES
REFRACTORY METAL COMPOUNDS
SCATTERING
TRANSITION ELEMENT COMPOUNDS
360603* - Materials- Properties