BM921

BM921 - lead metaniobate

Overview
BM921 is a modified lead metaniobate composition. These materials are used primarily in Probes for medical and Non-Destructive Evaluation (NDE) applications. These materials are characterized by a low dielectric constant and high frequency constant. The lower density offers a good acoustic impedance match to water. The low capacitance is an advantage in driving high frequency devices.

Features

  • Very low dielectric constant and
    high-frequency constant  

Applications

  • Thickness measurement
  • Non-destructive evaluation (NDE)
  • Linear arrays
  • Medical ultrasound 
  • High-frequency work 

PROPERTY SYMBOL BM921 UNITS
Electrical1      
Relative Dielectric Constant   KT33 165 —
Dissipation Factor   Tan d 3.5 %
Piezoelectric
Coupling Factor   kp 0.1 —
  k31 0.09 —
  k33 0.40 —
Charge Constant   d31 -7 10-12 C/N
  d33 65 10-12 C/N
Voltage Constant   g31 -5 10-3 Vm/N
  g33 42 10-3 Vm/N
Mechanical Quality Factor   QM 600 —
Frequency Constants 2   Np 3350 Hz.m
  N1 1675 Hz.m
  N4 2535 Hz.m
Elastic Modulus
Compliance   SE11 9.5 10-12 m2 /N
  SE33 14.7 10-12 m2 /N
Density   r 4.4 g/cm3
Curie Temperature   Tc 290 °C
Ageing Characteristics 3 (% change/time decade)
Coupling Factor   kp -0.5 —
Dielectric Constant   kT33 -0.1 —
Frequency Constant   Np

0.25

Hz.m

BM920 - lead metaniobate

BM920 - lead metaniobate

Notes:
1  Low field parameters;
    measured at 1 KHz

2  NP - Planar
    N1 - Longtitudinal
    N4 - Thickness

3  Reference point of time;
    24 hours after polarization